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IET Electric Power Applications (17518660) 19(1)
PM-assisted synchronous reluctance machines are becoming so attractive for electrical machine designers because of their lower cost due to minor usage of PMs in comparison to IPM and SMPM machines. Besides, they can effectively utilise both the magnetic and reluctance torques, thus, they can play an important role in many industrial applications including electric transportation systems. Up to now, more or less, the conventional distributed-windings are employed in design of the synchronous reluctance machines. However, recent advancements have seen the adoption of fractional-slot concentrated windings (FSCWs) due to their shorter end-winding length, simpler structure, and higher slot fill factor. Although FSCWs offer these advantages, they also suffer from higher magnetomotive force (MMF) space harmonics, which can lead to undesirable effects such as localised iron saturation and increased core losses. The main target of the present research was introducing the winding layouts, which have the benefits of both FSCWs and distributed windings to use in PM-assisted synchronous reluctance machine. To solve the problems related to FSCWs, in this research, the stator slot-shifting has been developed and new types of fractional-slot winding topologies, comprising significantly low MMF harmonics and short-end windings length have been proposed. Based on these proposed winding configurations, a prototype machine was built as case study; and analytical results, finite element analysis, and experimental tests were conducted to validate the machine’s characteristics. Although in the proposed machine the winding is converted to overlapped type and is not concentrated anymore, but the obtained results show significant advantages over the conventional design in terms of air-gap flux density, back electromotive force, torque profile, power factor, power losses, efficiency and flux weakening capability. © 2025 The Author(s). IET Electric Power Applications published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.
Journal of Modern Power Systems and Clean Energy (21965420) 13(1)pp. 228-240
The increase in the number of sensitive loads in power systems has made power quality, particularly voltage sag, a prominent problem due to its effects on consumers from both the utility and customer perspectives. Thus, to evaluate the effects of voltage sag caused by short circuits, it is necessary to determine the areas of vulnerability (AOVs). In this paper, a new method is proposed for the AOV determination that is applicable to large-scale networks. The false position method (FPM) is proposed for the precise calculation of the critical points of the system lines. Furthermore, a new method is proposed for the voltage sag monitor (VSM) placement to detect the fault locations. A systematic placement scheme is used to provide the highest fault location detection (FLD) index at buses and lines for various short-circuit fault types. To assess the efficiency of the proposed methods for AOV determination and VSM placement, simulations are conducted in IEEE standard systems. The results demonstrate the accuracy of the proposed method for AOV determination. In addition, through VSM placement, the fault locations at buses and lines are detected. © 2013 State Grid Electric Power Research Institute.
IET Electric Power Applications (17518660) 18(10)pp. 1200-1213
The vibration and acoustic noise of a permanent-magnet synchronous motor are analysed and evaluated. Acoustic noise sound levels, their prominent frequencies, and the noisiest motor speed range are predicted. According to many resources, the radial vibration of the stator system due to the magnetic attraction between rotor permanent magnets and stator iron teeth is the main reason for the acoustic noise propagation of the PMSMs. The dominant orders of the spatial circumferential harmonics of the radial magnetic forces (RMFs) have been investigated and compared. The complete and complicated mechanical components, materials, and harmonics of the magnetic forces of the motor and their interaction are simplified and equalised to a vibration model, which consists of the interaction between the stator system and the dominant harmonic orders of the RMFs. Based on this approach, the simplest and most adequate semi-analytical-FEM model for noise prediction in PMSMs is proposed. This model, in addition to simplification, clarifies the role of the main mechanical and electromagnetic origins of noise generation. The acoustic noise prediction, using the proposed method has been compared with the experimental results. There is a proper agreement between the analytical, the FEM, and measurement results. © 2024 The Author(s). IET Electric Power Applications published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.
Today, power quality is a crucial issue that greatly impacts distribution networks. Short-term and long-term power quality phenomena play a significant role in the overall performance of the network. Voltage sag, a type of short-term power quality issue, has higher occurrence rate compared to other power quality phenomena. The primary sources of voltage sag include transient symmetrical/asymmetrical faults, starting large motors, and transformer energizing. Although Numerous methods have been suggested for identifying the root cause of voltage sag incidents, the impact of noise and measurement error is often overlooked. In this paper, an assessment of the impact of noise and measurement error on voltage sag source localization methods is provided. Firstly, four of the most important methods proposed in this regard are described, and then the performance of each of them is examined with and without considering noise and potential measurement errors. Simulation conducted on the standard IEEE 33-bus network illustrate that methods utilizing a set of measurement data are robust to noise and measurement error. In contrast, methods using individual measurement data samples are vulnerable to noise and measurement error, leading to mistake conclusions. © 2024 IEEE.
IEEE Transactions on Transportation Electrification (23327782) 10(2)pp. 3482-3491
An innovative control method for reducing the torque ripple of non-sinusoidal brushless dc motors in field weakening regions based on direct power control is proposed here. Torque ripple, due to the disproportionate stator current and its non-sinusoidal back EMF voltage, is one of the known drawbacks of brushless dc motor drives. Upon motor speed acceleration, the waveform of the stator current becomes distorted, which in turn intensifies the torque ripple. This proposed method is able to control the motor speed from zero to values higher than the base speed range. The realization of the proposed method in the stationary reference-frame makes the method implementation simple and robust. In addition to controlling motor speed, by applying a three-phase conducting method instead of the conventional two-phase conducting method and control of instantaneous input power into the rotor in the proposed method, the torque ripple is also reduced, simultaneously. The torque ripple reduction and robustness of the proposed method are compared with the phase advance angle (PAA) method through simulation and experimental. The results indicate the superiority of the proposed method in both the steady- and transient-states. Moreover, the implementation of the proposed method on a prototype brushless direct current (BLDC) drive is successfully evaluated. © 2015 IEEE.
CES Transactions on Electrical Machines and Systems (20963564) 8(4)pp. 404-413
In this manuscript, a new axial-flux permanent-magnet machine (AFPMM) is designed, analyzed, improved, and successfully tested. A double-sided AFPM generator with four layers of stator winding is initially designed using a well-known quasi-3D analytical method. Then, the designed machine is simulated using commercial software. It is shown that modification techniques are required to improve the performance of both the torque ripple and the ratio of the third to the fundamental harmonics of the induced voltage. Therefore, a new improvement technique is proposed, in which the layers of the stator winding are shifted relative to each other. While this new technique significantly improves the third harmonic problem, the design still has a high torque ripple and, thus, it is suggested to combine the proposed method with the conventional magnet shifting technique. It is revealed numerically that the resulting combination properly resolves both third harmonic and torque ripple problems. Therefore, this design is considered the main design of the present manuscript. In the end, a prototype of the main design is manufactured and tested. It is shown that the measurement results are in good agreement with those of numerical software.①. © 2024 CES.
CES Transactions on Electrical Machines and Systems (20963564) 8(3)pp. 264-273
Multi-phase machines are so attractive for electrical machine designers because of their valuable advantages such as high reliability and fault tolerant ability. Meanwhile, fractional slot concentrated windings (FSCW) are well known because of short end winding length, simple structure, field weakening sufficiency, fault tolerant capability and higher slot fill factor. The five-phase machines equipped with FSCW, are very good candidates for the purpose of designing motors for high reliable applications, like electric cars, major transporting buses, high speed trains and massive trucks. But, in comparison to the general distributed windings, the FSCWs contain high magnetomotive force (MMF) space harmonic contents, which cause unwanted effects on the machine ability, such as localized iron saturation and core losses. This manuscript introduces several new five-phase fractional slot winding layouts, by the means of slot shifting concept in order to design the new types of synchronous reluctance motors (SynRels). In order to examine the proposed winding’s performances, three sample machines are designed as case studies, and analytical study and finite element analysis (FEA) is used for validation.①. © 2024 CES.
Takarli, Reza ,
Amini, Ali ,
Khajueezadeh, Mohammadsadegh ,
Zarbil, Mohammad Shadnam ,
Vahedi, Abolfazl ,
Kiyoumarsi, Arash ,
Hatampour, Zahra ,
Takarli, R. ,
Amini A.H. ,
Khajueezadeh, M. ,
Zarbil, M.S. ,
Vahedi, A. ,
Kiyoumarsi, A. ,
Tarzamni, H. ,
Kyyra, J. IEEE Access (21693536) 11pp. 81224-81255
Finding efficient and satisfactory energy storage systems (ESSs) is one of the main concerns in the industry. Flywheel energy storage system (FESS) is one of the most satisfactory energy storage which has lots of advantages such as high efficiency, long lifetime, scalability, high power density, fast dynamic, deep charging, and discharging capability. The above features are necessary for electric vehicles (EVs), railways, renewable energy systems, and microgrids. Also, electrical machines, power electronics converters, and control systems are the cores of energy transfer in FESS. Therefore, they have a critical role in determining efficiency, power rating, power factor, cost, angular velocity, and volume of FESS. So, in this study, the FESS configuration, including the flywheel (rotor), electrical machine, power electronics converter, control system, and bearing are reviewed, individually and comprehensively. Additionally, the mentioned components have been categorized to be a guide for future research. The investigated electrical machines are compared by Finite Element Analysis (FEA). Subsequently, our laboratory's measurement results are reviewed experimentally showing the progress in the field of FESS, such as designing robust control algorithms and an Interior Permanent Magnet-Synchronous Reluctance Machine (IPM-SynRM) to use in FESS.
One of the most effective winding type for use in electric machines is fractional slot concentrated winding (FSCW). These winding type prepares the shortest end-winding length for electric machines. In addition, they can tolerate the fault condition more in compare to other windings type. Besides, higher copper fill factor, lower cogging torque, simple construction and field weakening capability are another merits of FSCWs. Unfortunately, in compare to conventional distributed-windings, FSCWs have high space Magnetomotive Force harmonics (MMF harmonics). These unwanted harmonics will cause core saturation (localized saturation), mechanical vibration, acoustic noise and iron losses. In order to develop winding benefits, many methods have been introduced. This manuscript introduces some new three-phase windings, by using the stator slot shifting concept. The novelty of this paper is introducing some new winding topologies for the first time. An analytical study and the 2-D FEM are applied to three sample-designed synchronous reluctance machines to evaluate the new winding's characteristics as case studies. © 2023 IEEE.
IEEE Transactions on Power Delivery (19374208) 38(6)pp. 4157-4165
With the growing use of sensitive loads and distributed generations (DGs), power quality is of great importance in distribution networks (DNs). Voltage sag is a significant power quality disturbance. Hence, monitoring of the voltages and currents of the network is necessary to identify the voltage sag occurrence and its location. However, installing measuring units at every busbar in very expensive. In this article, an optimal method for locating the voltage sag monitors (VSMs) in DNs is proposed, considering the DGs. The proposed method is based on the DN zoning algorithm that utilizes the matrix of voltage sag transfer coefficients. The optimal number of zones is determined based on the proposed threshold value or the financial limits. Then, in each zone, the electrical center busbar is determined by solving an optimization problem. The electrical center busbar in each zone is chosen as the optimal location of the VSMs. The location, size, type, and control strategy of DGs, and the network structure affect the optimal location of the VSMs. The proposed method is implemented in different simulation scenarios at the IEEE 33 bus test system and the simulation results show the efficiency of the proposed algorithm. © 1986-2012 IEEE.
IET Electric Power Applications (17518660) 17(1)pp. 92-108
Fractional-slot concentrated-windings are appreciated for their simple construction, short end-winding length, high copper fill factor, low cogging torque, good field-weakening capability and fault-tolerant ability. However, in comparison to the conventional distributed windings, the fractional-slot concentrated-windings are characterised with high space magnetomotive force (MMF) harmonics, which results in undesirable effects on the machine performance, such as localised core saturation, eddy current loss in the rotor and noise and vibration. In order to improve winding characteristics, several techniques have been developed recently. This manuscript introduces the 5 new winding topologies by using the general concept of stator slot shifting. It means that, in order to cancel undesirable MMF harmonics, by doubling (or tripling or even multiplying) the slot number and dividing the winding and then relatively shifting the winding by one (or more) slots, the undesirable harmonics have been eliminated effectively. The best choice is chosen according to the lowest amount of the MMF harmonic, highest value of winding factor and torque desirable characteristics. At the end, comprehensive comparisons for the designed synchronous reluctance motor (SynRel) equipped with proposed windings and also distributed winding are presented. The analytical study and 2D FEM analysis results show that it is possible to get an ideal low space-harmonic winding topology, and consequently, a low torque ripple for these motors. © 2022 The Authors. IET Electric Power Applications published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.
IEEE Transactions on Transportation Electrification (23327782) 9(3)pp. 3769-3779
In this article, a second-order sliding mode control (SMC), based on super-twisting algorithm, is proposed for direct power control (DPC) of the brushless dc (BLDC) motor. The proposed controller uses a super-twisting scheme that requires only sliding surface information and can handle system uncertainties and external disturbances, well. This scheme can improve the BLDC motor torque ripple by solving the disadvantages of the conventional SMC method, such as the chattering effect and high-frequency switching control. This method is simple and robust for the BLDC motor's biggest challenge, torque ripple, which does not require any voltage and current control loops or complex reference frame transformations. The simulation results of the proposed method are compared with the DPC and model predictive control (MPC) methods, which indicate the superiority of the proposed method in both the steady and transient states. Moreover, the motor parameters variation in the tracking of active and reactive power are discussed. In addition, the practical results of the proposed method in both cases of speed and load variation show the effectiveness of this method in reducing power (torque) ripple and current total harmonic distortion (THD) and increasing the system's efficiency compared to other methods. © 2015 IEEE.
IEEE Transactions on Instrumentation and Measurement (00189456) 71
Power quality disturbances can cause damages to the electrical network's customers. Therefore, nowadays, power quality is considered an essential issue in distribution networks. In this regard, voltage sag is of a lot of significance among power quality disturbances. The first step in the reduction of damages caused by voltage sag is to determine the location of the disturbance source. Furthermore, recent attention to distributed generation (DG) particularly in distribution networks led to the inefficiency of the previous voltage sag source location (VSSL) approaches. In this article, a new method based on voltage and current measurement data is proposed, in which cosine similarity (CS) is used to locate a voltage sag source. In the proposed method, the CS sign between two data sets is used to identify the relative location of the voltage sag source. Simulation results are presented for different scenarios in the IEEE 33 bus test network. In doing so, various issues including VSSL, voltage sag original type (symmetric/asymmetric short-circuits or motor starting), the fault resistance, the x/r ratio of the grid lines, DG size, DG location, measurements error, and current transformer saturation are studied in simulations. The simulation results confirm the performance of the proposed method for the voltage sag source locating. Moreover, the comparison with some previous methods shows that the proposed method gives a better response in determination of location of the voltage sags. © 1963-2012 IEEE.
International Transactions on Electrical Energy Systems (20507038) 31(7)
This paper proposes a hybrid adaptive strategy to control virtual inertia of virtual synchronous generators (VSGs). The proposed technique can provide low frequency oscillation (LFO) damping and simultaneously improve primary frequency control (PFC) performance metrics. To this end, a control variable is defined to control extremum values of the VSG inertia during PFC process. The control variable uses an estimation of the grid frequency gradient to identify the PFC process stages following a power deficit event. The extremum of the VSG inertia to provide LFO damping is governed based on the control variable. In particular, the minimum value of the VSG inertia is restricted to its base value during the frequency arresting process in order to moderate the frequency rate of change. In contrast, the maximum value of the VSG inertia is limited to its base value in frequency recovery period to achieve a faster frequency recovery. The efficiency of the suggested method is validated through a power system with VSG penetration level as 50% of the system generation rating. The achieved results verify the superiority of the proposed scheme in the PFC improving and the LFO damping in comparison to the conventional strategy. Moreover, the suggested approach can efficiently decrease the required size of the VSG energy storage by about 50%. © 2021 John Wiley & Sons Ltd.
IET Generation, Transmission and Distribution (17518687) 15(18)pp. 2618-2631
The present paper devises a second-order system frequency response (SFR) model for power systems integrating virtual synchronous variable speed wind turbines (VSWTs). The inertial response model of full converter VSWTs, in which grid-side converters are controlled using a virtual synchronous generator concept, is developed. The derived model is incorporated into the traditional SFR model deployed to estimate the frequency behaviour of the synchronous generators following infeed loss contingencies. The proposed SFR model formulates interaction between the VSWTs rotor speed reduction and the system frequency drop. The system loads inertia is also included in the SFR model. Additionally, an analytical approach to derive the suggested SFR model for the large power system including VSWTs with different capacities and operating points is presented. Solving the proposed model gives the analytical functions for estimating deviations in the system frequency as well as VSWTs rotor speed variations. Finally, the accuracy of the devised SFR model is verified through the time-domain simulations of a modified IEEE 39-bus system. Particularly, impact of the VSWTs virtual inertia on the efficiency of the proposed SFR model is studied. © 2021 The Authors. IET Generation, Transmission & Distribution published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology
IET Generation, Transmission and Distribution (17518687) 15(17)pp. 2446-2459
Improving network power quality through harmonic reduction requires recognition of Harmonic Sources (HSs) to drive them to compensate their harmonics. This paper proposes a new method for equitable distribution of the Harmonic Compensation Cost of the network among the HSs based on the Harmonic Contribution Matrix. Each element of the Harmonic Contribution Matrix is the harmonic contribution of a specific source to the harmonic voltage of a specific bus. The output of the proposed method is a penalty curve for each HS over time. The amount of the fine estimated for each individual HS per hour is a function of not only the contribution of that HS to the harmonic voltage of different buses, but also the contribution of the Harmonic Compensation Cost from the perspective of each bus, nominal voltage of each bus, and the sensitivity of each bus to the harmonic voltage. The proposed algorithm is evaluated on the IEEE 14-bus network and Esfahan regional electrical power network in Iran. The simulation results demonstrate the capability of the proposed method to allocate the hourly penalty curve to the HSs. © 2021 The Authors. IET Generation, Transmission & Distribution published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology
International Transactions on Electrical Energy Systems (20507038) 30(4)
Synchronous Machines (SMs) are the corner stone of the power systems that have so far been dominantly studied. Considering high penetration of renewable energy sources, for example, wind energy conversion system; the Virtual SM concept is recently presented in the literature in order to inspire from SM to change the dynamic behavior of converter-based RESs. Accordingly, it is instructive to have insight into the different SM modeling approaches. In this paper, three most common SM parameter determination techniques within the framework of the well-known two-reaction theory are firstly discussed. Afterward, relationships between these techniques are addressed through their backgrounds and SM's time-constants comparisons. Furthermore, a new systematic approach is proposed to determine SM's time constants using rewriting SM's state-space equations on the basis of the path of the flux linkage penetration into the rotor core following a short-circuit fault occurrence. According to the proposed approach, an analytical method to approximate the time-domain variations of the machine variables during a three-phase short circuit fault is also derived. Last, numerical and simulation results are provided to investigate the effectiveness of the proposed method. For this purpose, two different SMs are taken into consideration. © 2020 John Wiley & Sons Ltd
IET Generation, Transmission and Distribution (17518687) 14(15)pp. 2901-2914
Nowadays, the determination of the contribution of individual customers to the harmonic pollution of an electric power network is very essential for power quality improvement. In this study, four new indices are introduced to investigate the effect of harmonic contribution (HC) of the pollutant customers for an arbitrary time period without any access to a network model. These indices are defined according to data measured at the connection point of the suspicious loads and targeted buses under study. In this regard, a continuous HC matrix is developed where its entries are determined by using a new multi-point and continuous HC calculation method without having to measure the phase angle, which makes this method practical and cost-effective. The method and indices are applied to a standard power network-based calculation example. In addition, experimental measurements, which are gathered based on the Isfahan city and Iran electric power transmission systems, are carefully analysed. The results demonstrated the capability of the proposed algorithm to evaluate the effects of harmonic sources in power networks. © 2019 The Institution of Engineering and Technology.
IEEE Transactions on Transportation Electrification (23327782) 6(1)pp. 52-61
Synchronous reluctance (SynRel) and permanent magnet (PM)-assisted SynRel (PMASynRel) machines with hyperbolic-shaped flux barriers are gaining more interest in commercialized products of known companies, because of their high saliency ratio. This article presents a faster approach for calculation of the air-gap flux density distribution and the electromagnetic torque of these machines than the finite-element method (FEM). The method is based on the conformal mapping (CM) techniques and magnetic equivalent circuit (MEC) solutions. A suitable CM is introduced to compute the magnetic reluctance of hyperbolic-shaped rotor flux barriers. The analytical method is then implemented on both SynRel and PMASynRel machines with the same stator structure as the Prius interior PM motor and five hyperbolic flux barriers per pole in their rotors. The accuracy of analytical results is assessed by the finite-element analysis (FEA). © 2020 IEEE.
IET Electric Power Applications (17518660) 14(4)pp. 552-560
In this study, the effect of adding of new stator and rotor slots on cogging torque of a transverse-flux permanentmagnet (TFPM) machine with flux concentrators is studied. To reduce the cogging torque, the widths and the positions of the slots of concern are improved through three-dimensional finite element method (3D-FEM). After that, to validate the 3D-FEM results, cogging torque is determined by applying a Schwarz-Christoffel (SC) conformal mapping. To apply this transformation, the 3D TFPM structure with axially magnetised PM is converted into a 2D structure with radially magnetised PMs and cogging torque of the machine is predicted using both the analytical method and 3D-FEM. The agreement in the obtained results through this SC mapping and the 3D-FEM method is the indicative of the accuracy of the efforts. © 2019 The Institution of Engineering and Technology.
IET Electric Power Applications (17518660) 14(12)pp. 2378-2388
The objective of this article is to study how the stator step skewing method can lead to the reduction of the cogging torque of a transverse-flux permanent-magnet (TFPM) machine with flux concentrators. Three structures are analysed and compared in terms of their influence of the skewed displacement on the cogging torque using the three-dimensional finite element method (3D-FEM). Thereafter, to validate the FEM results, cogging torque is calculated by applying a Schwarz-Christoffel (SC) conformal mapping. To apply this transformation, the 3D TFPM generator structure with axially magnetised permanent magnets (PMs) is converted into a 2D structure with radially magnetised PMs and the cogging torque of the machine is predicted using both the analytical method and 3D-FEM. The accuracy of the approach is demonstrated by the adequate agreement between the results obtained through this SC mapping and those of the 3D-FEM. In addition, two 100 W prototyped TFPM machines are designed, simulated, manufactured and tested to validate the effects of the step-skewed stator yoke on the predicted cogging torque and back-EMF. © The Institution of Engineering and Technology 2020
International Transactions on Electrical Energy Systems (20507038) 29(3)
This paper presents a new analytical technique for modelling the impact of static eccentricity (SE), dynamic eccentricity (DE), and mixed eccentricity (ME) faults on electromotive force (EMF) or Back-EMF, output voltages and currents of surface-mounted permanent-magnet (SMPM) machines. This model is based on the combination of the complex relative permeance and the eccentricity relative air-gap permeance. It presents explicit formulas for no-load and on-load, field distribution, magnetic flux, EMF/Back-EMF, and output voltages and currents of SMPM for different types of eccentricity fault. Furthermore, a new eccentricity model is presented and applied, which can cover more eccentricity fault types; some of them have not been so far considered in the literatures. Analytical results are validated by time-stepping finite element method results. The analytical and numerical results refer to the fact that the SE does not cause any new frequency component in the EMF/Back-EMF and currents spectra. However, the same is true in the case of DE and ME faults where some frequency components appear in the EMF/Back-EMF and currents spectra, not only around the fundamental harmonic but also around some other harmonics. © 2018 John Wiley & Sons, Ltd.
Malekpour, M. ,
Azizipanah-abarghooee, R. ,
Zare, M. ,
Kiyoumarsi, A. ,
Terzija, V. International Journal of Electrical Power and Energy Systems (01420615) 108pp. 9-18
There are numerous formulations and methods for representing synchronous machine (SM) in stability studies. However, most of them need to convert manufacturer's data given in the form of transient/sub-transient time constants and reactances, to the equivalent circuit parameters as resistances and leakage reactances of rotor windings. This study derives a new explicit synchronous machine model formulation by direct utilization of the transient/sub-transient time constants and reactances in the SM model formulation. Firstly, state-space equations are derived with flux linkages as state variables. Then, some entries of coefficient matrix are determined in terms of the manufacturer's data using short- and open-circuit time constants concepts. Other entries are calculated using this phenomenon that the flux linkage penetrates gradually into rotor core, following a sudden fault. Finally, voltage-behind-reactance (VBR) form of the proposed formulation is provided to a direct machine-network interfacing. Also, the developed formulation is compared with the Park's model in a single-machine-infinite-bus (SMIB) and 36-zone 75-machine Great Britain (GB) system using DIgSILENT PowerFactory software. The analytical and simulation results illustrate that the proposed explicit formulation is as efficient and precise as the well-known Park's model. © 2018
COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering (03321649) 38(2)pp. 893-914
Purpose: This paper aims to present an analytical method, which combines the complex permeance (CP) and the superposition concept, to predict the air-gap magnetic field distribution in surface-mounted permanent-magnet (SMPM) machines with eccentric air-gap. Design/methodology/approach: The superposition concept is used twice; first, to predict the magnetic field distribution in slot-less machine with eccentric air-gap, the machine is divided into a number of sections. Then, for each section, an equivalent air-gap length is determined, and the magnetic field distribution is predicted as a concentric machine model. The air-gap field in the slot-less machine with eccentricity can be combined from these concentric models. Second, the superposition concept is used to find the CP under eccentricity fault. At this end, the original machine is divided into a number of sections which may be different from the one for slot-less magnetic field prediction, and for each section, the CP is obtained by equivalent air-gap length of that section. Finally, the air-gap magnetic field distribution is predicted by multiplying the slot-less magnetic field distribution and the obtained CP. Findings: The radial and tangential components of the air-gap magnetic flux density are obtained using the proposed method analytically. The finite element analysis is used to validate the proposed method results, showing good agreements with the analytical results. Originality/value: This paper addresses the eccentricity fault impact upon the air-gap magnetic field distribution of SMPM machines. This is done by a combined analysis of the complex permeance (CP) method and the superposition concept. This contrasts to previous studies which have instead focused on the subdomain method. © 2019, Emerald Publishing Limited.
IET Generation, Transmission and Distribution (17518687) 13(1)pp. 73-80
Today, with the restructuring of the power systems, it is possible to implement a program, such as the demand response for the harmonic issues, and use customers to reduce the harmonic level of the network. In this study, a new method is presented based on harmonic pricing to control the harmonic level of the network. Given the fact that the power system is usually infected by the background harmonics, the basis for pricing is the harmonic contribution determination in order to impose a fine fair on the customers. Usually, the determination of the harmonic contribution at each harmonic order is done separately; therefore, a new index is presented, to sum up, the dominant orders in determining the harmonic contribution. This can provide an appropriate impression of the harmonic emission level at the point of common coupling. Simulation results on the standard IEEE 14-bus network show that customers are encouraged to control their harmonic level with a fair harmonic pricing, otherwise, the independent system operator can install harmonic filters at appropriate buses, using the fines received from the customers. © The Institution of Engineering and Technology 2018.
Electric Power Components and Systems (15325016) 46(8)pp. 957-973
This paper presents a method for modeling the effects of static eccentricity, dynamic eccentricity, and mixed eccentricity faults on the electromotive force (emf) of the surface-mounted permanent magnet generators (SMPMGs). The model is based on the combination of conformal mapping method (complex relative permeance) and eccentricity relative air gap permeance and it presents explicit formulas for no-load magnetic field distribution, magnetic flux, and emf in SMPMGs under different eccentricity fault types, some have not been so far considered elsewhere. The analytical and also numerical results show that there are some side-band components in the emf signature which can be used as eccentricity fault index. Analytical results validate by time-stepping finite element method (TSFEM) results. © 2018, © 2018 Taylor & Francis Group, LLC.
IEEE Transactions on Power Electronics (08858993) 32(12)pp. 9117-9130
In this paper, an overall power control strategy is proposed for control of a fixed-pitch small-scale wind energy conversion system operating at both underrated and overrated wind speeds. At underrated wind speeds, the dynamical behavior of the rotor is considered, and the optimal reference torque is generated without the need of wind speed sensors through a robust variable structure observer with the aim of maximum power point tracking. At overrated wind speed, the flux-weakening strategy is invoked to let the machine exploit maximum electrical torque under given current and voltage constraints. As a new approach, the optimal reference flux magnitude together with a reference torque angle is provided by online numerically solving an optimization problem in the whole wind speed range. Moreover, a space-vector-modulation -based direct torque control (SVM-DTC) is used to track the provided references for flux magnitude and torque angle. In particular, the SVM-DTC is composed of a reference voltage vector calculator providing a desired voltage vector. The effectiveness of the proposed overall power control strategy is verified not only by applying the strategy to a commercial 10-kW wind turbine simulated in MATLAB/Simulink, but also by experimental results derived from a developed laboratory setup. © 1986-2012 IEEE.
Turkish Journal Of Electrical Engineering And Computer Sciences (13000632) 25(1)pp. 172-183
The distribution static compensator (DSTATCOM) is used for various purposes such as load balancing, harmonic rejection, and power factor correction (PFC) in power distribution networks. In unbalanced and polluted power systems, the classic definition of power factor cannot be used for PFC due to the existence of harmonics and negative sequence components in voltage and current waveforms. In this paper, PFC is performed using the IEEE power factor definition for harmonic and unbalanced environments. Moreover, the application of a proportional-resonant (PR) controller is proposed as an effective controller in the stationary frame for DSTATCOM performance improvement. The PR controller is used in the abc-frame for load balancing and is then compared theoretically and by simulation with the conventional PI controller, which has the main drawback of steady-state error when used in the stationary frame. To improve the DSTATCOM structure, an LCL harmonic filter is used as it is advantageous over the L/LC filter in terms of the size of the filter. The proposed DSTATCOM compensates for the disturbances in the source current imposed by nonlinear, unbalanced, and low power factor loads. Simulation results show the capability of the DSTATCOM including the proposed PR controller in improving the power quality of distribution systems. © 2017 TÜBITAK.
IEEE Transactions on Power Electronics (08858993) 32(4)pp. 2964-2975
In this paper, a new advanced deadbeat direct torque and flux control (A-DB-DTFC) system is proposed that improves the steady-state and transient-state performances of the permanent-magnet synchronous motor by adopting two improved deadbeat methods. Whenever the error between the torque and its reference value is low, an improved deadbeat method is adopted by the A-DB-DTFC system, in which the phase and time duration of the voltage vector applied to the motor are adjusted in a manner that the stator flux and torque reach their reference values after just one control cycle. Whenever the torque error is high, another deadbeat method is adopted by the A-DB-DTFC system, where the voltage vector phase is adjusted such that the fastest torque response is achieved. In order to assess the effectiveness of the proposed A-DB-DTFC system, the steady-state and transient-state performances of the motor are tested in MATLAB software and in practice, where the simulation and experimental results confirm that the proposed control system reduces the torque and stator flux ripples and achieves the fastest dynamic response. The comparative assessment with the recent DB-DTFC method indicates that the proposed A-DB-DTFC system yields lower torque and flux ripples and a faster dynamic response with the advantage of a lower computation complexity. © 1986-2012 IEEE.
IEEE Transactions on Magnetics (00189464) 53(12)
An extended analytical method for predicting the open-circuit air-gap field distribution in interior permanent magnet (IPM) machines equipped with multilayer Permanent Magnets (PMs) is proposed in this paper. This presented method is based on the conformal mapping technique. The mapping is used to calculate the relative permeances, which consider the effect of stator slots and rotor saliency on the magnetic field distribution. The open-circuit air-gap field distribution in a multi-flux-barrier IPM can be predicted through the superposition principle. The analytical solution is implemented on: an eight-pole, 50 kW IPM motor used in 2004 Toyota Prius hybrid electric vehicle and four IPMs with two, three, four, and five flux barriers per pole. To verify this extended method, the results are compared with those obtained from the finite-element analysis. © 1965-2012 IEEE.
Journal of Electrical Engineering and Technology (19750102) 12(4)pp. 1357-1368
The lack of controllability over the wind causes fluctuations in the output power of the wind generators (WGs) located at the wind farms. Distribution Static Compensator (DSTATCOM) equipped with Battery Energy Storage System (BESS) can significantly smooth these fluctuations by injecting or absorbing appropriate amount of active power, thus, controlling the power flow of WGs. But because of the component aging and thermal drift, its harmonic filter parameters vary, resulting in performance degradation. In this paper, Quantitative Feedback Theory (QFT) is used as a robust control scheme in order to deactivate the effects of filter parameters variations on the wind power generation power smoothing performance. The proposed robust control strategy of the DSTATCOM is successfully applied to a microgrid, including WGs. The simulation results obviously show that the proposed control technique can effectively smooth the fluctuations in the wind turbines' (WT) output power caused by wind speed variations; taking into account the filter parameters variations (structural parameter uncertainties). © The Korean Institute of Electrical Engineers.
IEEE Access (21693536) 5pp. 14490-14501
The quantitative feedback theory is adopted as a robust control scheme for the distribution-static-compensator (DSTATCOM) in order to deactivate the effects of variations in its harmonic filter parameters on the fault ride through the capability of wind turbines (WTs). These variations may be due to factors like component aging and thermal drift. The DSTATCOM is applied in parallel with the wind generation (WG) together with a bridge-type-fault-current-limiter in series, to improve FRT capability of the WT. This proposed robust control strategy of the DSTATCOM is applied to a microgrid, including WG. The performance of this proposed scheme is simulated in PSCAD/EMTDC environment and the results indicate its efficiency. © 2013 IEEE.
IEEE Transactions on Power Electronics (08858993) 31(5)pp. 3738-3753
In this paper, a new predictive direct torque control (DTC) method is proposed, improving the dynamic response of the classical DTC and reducing the torque- and flux-ripples through a voltage vector with an optimal phase. In the transient state, the voltage vector phase is selected in a manner where the fastest dynamic response is achieved, while in the steady state, this phase is selected in a manner where the stator flux amplitude reaches its commanding value at the end of the control cycle. In the steady state, the selected vector is applied to the motor with an optimal time duration calculated to achieve the minimum torque ripple. The five-segment space-vector modulation is used to synthesize the voltage vector, where a fixed switching frequency is obtained. To investigate the effectiveness of the proposed method, steady-state and transient-state performances are tested in the MATLAB software and in practice. Both the simulation and experimental results confirm that the proposed method reduces the torque and flux ripples effectively while improving the dynamic response of the classical DTC method. The comparative investigation of the proposed method with the recent DTC methods indicates that the proposed method has lower ripples in the steady state and a faster dynamic response in the transient state. © 2015 IEEE.
IEEE Transactions on Industrial Electronics (02780046) 63(6)pp. 3876-3888
In this paper, a new predictive direct torque control (DTC) method is proposed, which improves the dynamic response of the conventional DTC in the transient state and yields the minimum torque and flux ripples in the steady state through an optimal voltage vector. At the steady state, the magnitude, phase, and time duration of the voltage vector are adjusted in a manner where the minimum torque and flux ripples are obtained; whereas in the transient state, the voltage vector parameters are adjusted in a manner where the fastest dynamic response is achieved. The space-vector modulation is used in synthesizing the selected voltage vector where a fixed switching frequency is achieved. In order to improve the control system efficiency, the principle of maximum torque per ampere is adopted in obtaining the commanding stator flux magnitude. To investigate the effectiveness of the proposed method, the steady-state and transient-state performances are tested in MATLAB software and in practice. The simulation and experimental results confirm that the proposed method yields the minimum torque and flux ripples while improving the dynamic response of the conventional DTC. The comparative investigation with an existing predictive DTC method indicates that the proposed method has a better performance in both the steady state and transient state. © 2015 IEEE.
IET Renewable Power Generation (17521416) 10(9)pp. 1264-1277
This study presents an overall power control strategy for control of fixed-pitch small-scale wind energy conversion system (WECS). The overall power control strategy is designed in such a way that the WECS efficiently operates for both underrated and overrated wind speeds. At underrated wind speeds, maximum power point tracking is achieved through a proportional-integral (PI) mechanical torque controller while no wind speed sensor is required. The PI mechanical torque controller together with a high-gain observer, estimating mechanical torque, generates the reference electrical torque. At overrated wind speed, the control strategy limits the generated power to rated power of generator via an anti-windup algorithm. In this case, the flux weakening strategy then is invoked. The optimal (reference) flux magnitude is provided by off-line numerically solving an optimisation problem. An space-vector modulation (SVM)-based direct-torque control (DTC) is used to track the electrical torque and flux references. In particular, the SVM-DTC is composed of a reference voltage vector calculator providing a desired voltage vector. The effectiveness of the proposed overall power control strategy is verified by applying the strategy to a commercial 10 kW wind turbine simulated in MATLAB/Simulink. © 2016 The Institution of Engineering and Technology.
Electric Power Components and Systems (15325016) 44(19)pp. 2212-2223
The main aim of this work is to present the results of the shape design optimization process of an interior permanent-magnet synchronous motor. The shape design optimization process is accomplished based on the variations of the rotor structure using the Taguchi method. The time-stepping finite-element method is used for analysis of the motor. It is found that the optimal two-layer Machaon design has the lowest torque pulsation compared with the other structures. Finally, the optimized Machaon and preliminary one-layer interior permanent-magnet synchronous motors, which are amended from industrial three-phase induction motors, are manufactured. The results of numerical, analytical, and practical tests are in good agreement. © 2016, Copyright © Taylor & Francis Group, LLC.
Research Journal of Applied Sciences, Engineering and Technology (discontinued) (20407459) 10(9)pp. 997-1006
An adaptive robust variable structure speed controller is designed for wide range of desired velocity control of a Permanent Magnet Linear Synchronous Motor (PMLSM). This is performed for comprehensive nonlinear model of PMLSM including non-idealities such as detent force, parameter uncertainty, unpredicted disturbance and nonlinear friction. The proposed method is based on the robust Sliding Mode Control (SMC) in combination with an adaptive strategy for a wide range of velocity. The simulation results are provided for the above mentioned comprehensive model of PMLSM with a variable velocity profile. Moreover, as an evaluation criterion, a Proportional-Integral (PI) controller is designed whose parameters are optimally tuned by the Particle Swarm Optimization (PSO) algorithm for better comparison. © Maxwell Scientific Organization, 2015.
Darijani, A. ,
Kiyoumarsi, A. ,
Dehkordi, B.M. ,
Lari, H.A. ,
Bekhrad, S. ,
Rahimi monjezi, S. Iranian Journal Of Electrical And Electronic Engineering (17352827) 11(1)pp. 52-60
Permanent-Magnet Synchronous Generators (PMSGs) exhibit high efficiency and power density, and have already been employed in gearless wind turbines. In the gearless wind turbines, due to the removal of the gearbox, the cogging torque is an important issue. Therefore, in this paper, at first, design of a Permanent-Magnet Synchronous Generator for a 2MW gearless horizontal-axis wind turbine, according to torque-speed and capability curves, is presented. For estimation of cogging torque in PMSGs, an analytical method is used. Performance and accuracy of this method is compared with the results of Finite Element Method (FEM). Considering the effect of dominant design parameters, cogging torque is efficiently reduced. © 2015 Iran University of Science and Technology. All rights reserved.
International Journal of Power and Energy Systems (10783466) 34(3)pp. 91-98
Power quality monitoring of many sites of an electric power system produces an enormous amount of unstructured data covering the various types of power quality indices. The collected data are not in a suitable form to give insights to the general power quality conditions of a particular site or a particular area within the network. This paper proposes a global power quality index (PQI) which is based on data mining and pattern classification approaches. Firstly, the continuous and discrete PQIs are annually analyzed, normalized and merged. Then, the analyzed indices are classified according to their cost coefficient, and the power quality levels for all distribution sites are determined using the Fast-independent component analysis (ICA) data mining algorithm. Finally, an application example for future explanations is presented.
Iranian Journal Of Electrical And Electronic Engineering (17352827) 10(4)pp. 324-332
In Permanent-Magnet Synchronous Generators (PMSGs) the reduction of cogging torque is one of the most important problems in their performance and evaluation. In this paper, at first, a direct-drive vertical-axis wind turbine is chosen. According to its nominal value operational point, necessary parameters for the generator is extracted. Due to an analytical method, four generators with different pole-slot combinations are designed. Average torque, torque ripple and cogging torque are evaluated based on finite element method. The combination with best performance is chosen and with the analysis of variation of effective parameters on cogging torque, and introducing a useful method, an improved design of the PMSG with lowest cogging torque and maximum average torque is obtained. The results show a proper performance and a correctness of the proposed method. © 2014, Iran University of Science and Technology. All rights reserved.
Transactions of the Institute of Measurement and Control (14770369) 35(3)pp. 342-352
The IEC 61000-4-15 flickermeter has been widely accepted as an international standard for flicker severity measurement. In this paper, the implementation of an improved IEC flickermeter by an ARM microcontroller-based digital system with low cost and simple proposed prototype hardware is presented. The improvements include replacing a band-pass filter with a more appropriate filter and considering the model of various lamps. The operation of the improved flickermeter is evaluated in a simulated power system in Simulink of MATLAB software with its flicker source an arc furnace. Finally, a manipulated hardware for implementation of the improved flickermeter is proposed based on ARM microcontroller, and its performance is evaluated with some real-time experimental measurements. © The Author(s) 2012.
Modelling of the three phase electric arc furnace and its voltage flicker mitigation is the purpose of this paper. The arc furnace model is implemented referring to an actual electric plant installed in Mobarakeh, Isfahan, Iran. For modelling of the electric arc furnace, at first, the arc is modeled using current-voltage characteristics of a real arc, i.e., the arc current samples as inputs and their corresponding voltages as outputs in the equivalent circuit of the furnace and its supply system. Then, the arc random characteristic has been taken into account by modulating the ac voltage by a band limited white noise. Electric arc furnace compensation with static VAr compensator, Thyristor controlled reactor combined with a fixed capacitor bank (TCR/FC), is discussed for closed loop control of the compensator. Instantaneous flicker sensation curves, before and after accomplishing compensation, are measured based on IEC standard. In closed loop control, two different approaches are considered; the former is based on voltage regulation at the point of common coupling (PCC) and the later is based on enhancement of power factor at PCC. A new method for controlling TCR/FC compensator is proposed. This method is based on applying a predictive method with closed loop control of the TCR/FC. In this method, by using the previous samples of the load reactive power, the future values of the load reactive power are predicted in order to consider the time delay in compensator control.
Journal of the Chinese Institute of Engineers, Transactions of the Chinese Institute of Engineers,Series A/Chung-kuo Kung Ch'eng Hsuch K'an (02533839) 35(4)pp. 421-429
The flicker phenomenon, as a power quality aspect, can be measured by the standard IEC flickermeter that has been widely accepted as an international standard for flicker severity measurement. The standard IEC flickermeter is unable to measure the flicker effect of various lamps. It is possible that interharmonics appear in a system that causes flicker in some kinds of lamps but the IEC flickermeter shows that flicker does not exist in those systems. In this paper, this deficiency is evaluated and an appropriate way for considering the effect of various lamps is presented by decomposing the lamp-eye-brain model into two parts. From laboratory work, the gain factors of two kinds of lamps are obtained and evaluated using the measuring system of the IEC flickermeter. In order to estimate the gain factor of a lamp through an appropriate transfer function, the particle swarm optimization (PSO) algorithm is also applied. In a simulated system whose flicker source is a welding system, flicker effect on various lamps is evaluated. © 2012 The Chinese Institute of Engineers.
Expert Systems with Applications (09574174) 38(10)pp. 12643-12653
Precise speed control of an Interior Permanent Magnet Synchronous Motor (IPMSM) drive becomes a complex issue due to the nonlinear nature of its developed torque. The system nonlinearity becomes severe when the IPMSM drive operates in the field weakening region. In order to achieve perfect control characteristics, the main purpose of this paper is to present a detailed comparison of various intelligent based controllers for flux weakening speed control of an IPMSM drive. In this paper, the Brain Emotional Learning Based Intelligent Controller (BELBIC), Genetic-Fuzzy Logic Based Controller (GFLBC), as well as genetic-PI based controller, are considered. BELBIC is a computational model of emotional processing mechanism in the brain. The effectiveness of the proposed BELBIC controller-based IPMSM drive is verified by simulation results at different operating conditions. Moreover, control regimes such as Maximum Torque Per Ampere (MTPA) control and flux weakening (FW) control as well as voltage and current constraints have been successfully applied. The results prove BELBIC's perfect control characteristics, such as fast and smooth speed response, low maximum starting current, adaptability to speed and load changes and robustness to parameter variations, disturbance and sudden one-phase interruption. © 2010 Elsevier Ltd. All rights reserved.
Journal of Power Electronics (15982092) 11(2)pp. 228-236
The δV10 or 10-Hz flicker index, as a common method of measurement of voltage flicker severity in power systems, requires a high computational cost and a large amount of memory. In this paper, for measuring the δV10 index, a new method based on the Adaline (adaptive linear neuron) system, the FFT (fast Fourier transform), and the PSO (particle swarm optimization) algorithm is proposed. In this method, for reducing the sampling frequency, calculations are carried out on the envelope of a power system voltage that contains a flicker component. Extracting the envelope of the voltage is implemented by the Adaline system. In addition, in order to increase the accuracy in computing the flicker components, the PSO algorithm is used for reducing the spectral leakage error in the FFT calculations. Therefore, the proposed method has a lower computational cost in FFT computation due to the use of a smaller sampling window. It also requires less memory since it uses the envelope of the power system voltage. Moreover, it shows more accuracy because the PSO algorithm is used in the determination of the flicker frequency and the corresponding amplitude. The sensitivity of the proposed method with respect to the main frequency drift is very low. The proposed algorithm is evaluated by simulations. The validity of the simulations is proven by the implementation of the algorithm with an ARM microcontroller-based digital system. Finally, its function is evaluated with real-time measurements.
European Transactions on Electrical Power (15463109) 21(1)pp. 824-838
Electric arc furnaces (EAFs) produce voltage fluctuations and flicker because of the reactive power severe variations. Furthermore, these loads absorb a large amount of reactive power. The static VAr compensators (SVCs) have been widely used by the industrial customers with arc furnaces to compensate the reactive power due to the quick response of the power electronic devices. In this paper, reactive power compensation in the steel industrial plant with several EAFs by utilizing open-loop controlled thyristor controlled reactor/fixed capacitor (TCR/FC) compensator is performed. The TCR/FC compensator is usually applied in conventional steel making plants; one is in Mobarakeh/ Isfahan, Iran which is considered as the case study in this paper. Simulation results show that, although open-loop controlled TCR/FC is effective for compensating reactive power, it cannot efficiently compensate the fluctuations of the reactive power and reduce the flicker intensity. © 2010 John Wiley & Sons, Ltd.
Precise speed control of an Interior Permanent Magnet Synchronous Motor (IPMSM) drive becomes a complex issue due to complex coupling among its winding currents and the rotor speed as well as the nonlinear nature of the developed torque. The system nonlinearity becomes severe when the IPMSM drive operates in the field weakening region. The main purpose of this paper is to present the implementation of an emotional controller for flux weakening speed control of an IPMSM drive. The proposed controller is called Brain Emotional Learning Based Intelligent Controller (BELBIC) and is a computational model of emotional processing mechanism in the brain. The effectiveness of the proposed BELBIC controller-based IPMSM drive is verified by simulation results at different operating conditions. Moreover, control regimes such as Maximum Torque per Ampere (MTPA) control and Flux Weakening (FW) control as well as voltage and current constraints have been successfully applied. The results prove BELBIC's perfect control characteristics, fast response, simple implementation and adaptability to speed, load and parameter changes. © 2011 IEEE.
In this paper a hybrid sensorless speed method for Interior Permanent-Magnet Synchronous Motors (IPMSM) is proposed. This method works efficiently at very low up to rated speed. An adaptive full-order observer has been implemented in medium and high speeds using fictitious permanent-magnet model. At standstill and low speeds a signal injection method is augmented to an adaptive observer for better estimation. Adopted signal injection method superimposes a pulsating voltage on the voltage reference in the stator reference frame. In order to achieve good performance, a Maximum Torque Per Ampere (MTPA) vector controller is incorporated with a synchronous frame decoupling scheme. Since in applied control method the motor parameters are widely utilized, a Recursive Least Square algorithm (RLS) has been applied to online parameter identification. Finally, in order to evaluate the performance of the proposed method, a comprehensive set of simulations were performed. ©2010 IEEE.
Physics Letters, Section A: General, Atomic and Solid State Physics (03759601) 374(41)pp. 4226-4230
Permanent Magnet Synchronous Motor (PMSM) experiences chaotic behavior for a certain range of its parameters. In this case, since the performance of the PMSM degrades, the chaos should be eliminated. In this Letter, the control of the undesirable chaos in PMSM using Lyapunov exponents (LEs) placement is proposed that is also improved by choosing optimal locations of the LEs in the sense of predefined cost function. Moreover, in order to provide the physical realization of the method, nonlinear parameter estimator for the system is suggested. Finally, to show the effectiveness of the proposed methodology, the simulation results for applying this control strategy are provided. © 2010 Elsevier B.V. All rights reserved.
Journal of Electrical Engineering and Technology (19750102) 5(1)pp. 116-128
Modeling of the three phase electric arc furnace and its voltage flicker mitigation are the purposes of this paper. For modeling of the electric arc furnace, at first, the arc is modeled by using current-voltage characteristic of a real arc. Then, the arc random characteristic has been taken into account by modulating the ac voltage via a band limited white noise. The electric arc furnace compensation with static VAr compensator, Thyristor Controlled Reactor combined with a Fixed Capacitor bank (TCR/FC), is discussed for closed loop control of the compensator. Instantaneous flicker sensation curves, before and after accomplishing compensation, are measured based on IEC standard. A new method for controlling TCR/FC compensator is proposed. This method is based on applying a predictive approach with closed loop control of the TCR/FC. In this method, by using the previous samples of the load reactive power, the future values of the load reactive power are predicted in order to consider the time delay in the compensator control. Also, in closed loop control, two different approaches are considered. The former is based on voltage regulation at the point of common coupling (PCC) and the later is based on enhancement of power factor at PCC. Finally, in order to show the effectiveness of the proposed methodology, the simulation results are provided.
COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering (03321649) 29(3)pp. 667-685
Purpose - The purpose of this paper is to present a 3D finite element model of the electromagnetic fields in an AC three-phase electric arc furnace (EAF). The model includes the electrodes, arcs, and molten bath. Design/methodology/ approach - The electromagnetic field in terms of time in AC arc is also modeled, utilizing a 3D finite element method (3D FEM). The arc is supposed to be an electro-thermal unit with electrical power as input and thermal power as output. The average Joule power, calculated during the transient electromagnetic analysis of the AC arc furnace, can be used as a thermal source for the thermal analysis of the inner part of furnace. Then, by attention to different mechanisms of heat transfer in the furnace (convection and radiation from arc to bath, radiation from arc to the inner part of furnace and radiation from the bath to the sidewall and roof panel of the furnace), the temperature distribution in different parts of the furnace is calculated. The thermal model consists of the roof and sidewall panels, electrodes, bath, refractory, and arc. The thermal problem is solved in the steady state for the furnace without slag and with different depths of slag. Findings - Current density, voltage and magnetic field intensity in the arcs, molten bath and electrodes are predicted as a result of applying the three-phaseACvoltages to theEAF. The temperature distribution in different parts of the furnace is also evaluated as a result of the electromagnetic field analysis. Research limitations/implications - This paper considers an ideal condition for the AC arc. Non-linearity of the arc during the melting, which leads to power quality disturbances, is not considered. In most prior researches on the electrical arc furnace, a non-linear circuit model is usually used for calculation of power quality phenomena distributions. In this paper, the FEM is used instead of non-linear circuits, and calculated voltage and current densities in the linear arc model. The FEM results directly depend on the physical properties considered for the arc. Originality/value - Steady-state arc shapes, based on the Bowman model, are used to calculate and evaluate the geometry of the arc in a real and practical three-phase AC arc furnace. A new approach to modeling AC arcs is developed, assuming that the instantaneous geometry of the AC arc at any time is constant and is similar to the geometry of a DC arc with the root mean square value of the current waveform of the AC arc. A time-stepping 3D FEM is utilized to calculate the electromagnetic field in the AC arc as a function of time. © Emerald Group Publishing Limited.
Journal of Electrical Engineering (1339309X) 61(1)pp. 37-43
Torque pulsations have prominent effects on the performance of brushless permanent- magnet (PM) machines. There are different sources of torque ripples in PM motors. These torque pulsations depend on the shape of the flux density distribution in the airgap region. For predicting the open-circuit airgap field distribution in brushless PM motors, a two dimensional (2-D) analytical method, in which the direction of magnetization, either radial or parallel and the effect of the stator slot-openings are taken into account, is used. The method uses an improved 2-D permeance model. In order to evaluate the accuracy of this method, a 2-D time-stepping FEM coupled with the two motion equations is used. A 3-phase, 36-slot, 4-pole, 5 HP, brushless PM motor is modeled by two methods. In this analysis both, the radial and parallel magnetization of the brushless motor are considered. The results obtained by the analytical method are compared with those obtained by FE analysis that shows the valuable accuracy of the analytical method for performance calculations in design and optimization processes. © 2010, Versita. All rights reserved.
International Review on Modelling and Simulations (19749821) 3(6)pp. 1241-1248
State space analysis can be successfully used to analyze the amplifier, load and the feed back circuits when they are all connected to each other. The main advantages of state space analysis of feedback amplifiers are the possibility of discussion of internal and structural nonlinearities and eigenvalue analysis of the whole amplifier. In this paper, state space analysis of a microwave amplifier is completely discussed. In this model, the effects of internal noise both in gate to source and drain to source junctions, are briefly taken into account. The transfer functions as well as input and output driving impedances of the amplifier are determined using proper state variables. This analysis will be valid when the network is in a linear region. © 2010 Praise Worthy Prize S.r.l. - All rights reserved.
Flicker phenomenon, as a power quality component, can be measured by the standard IEC flickermeter that has been widely accepted as an international standard for flicker severity measurement. In industry applications, the standard IEC flickermeter suffers from some deficiencies. Among them, it is unable to measure flickers caused by interharmonics whose frequencies are higher than 85Hz. It also is unable to measure the effect of the various lamp flickers. In addition, it is unable to determine direction of flicker source with respect to a monitoring point. In this paper, these deficiencies are improved respectively by designing an improved filter, using the border graph of gain factor of various lamps and by using flicker power to determine direction of a flicker source. At the end, the proposed flickermeter is evaluated in a simulated system, that its flicker source is a welding system. ©2010 IEEE.
Kiyoumarsi, A. ,
Hassanzadeh, M. ,
Kouhi-fayegh-dehkordi, A. ,
Hatam-poor, Z. ,
Moalem, M. Electrical Engineering (14320487) 92(4-5)pp. 141-149
This paper presents two-dimensional (2D) transient finite element solutions of an 100 MVA three-phase electric arc furnace (EAF). In practice, it was observed that there were a few high-voltage arcs between upper side of high-carrying current electrodes and EAF roof. To specify the operation and performance of this EAF, a 2D time-stepping finite element method (FEM) program was developed and induced voltages between the roof and the electrodes at different load conditions were predicted. In addition, the effective value of induced voltages between the roof, electrodes, and water pipes by which the roof was being cooled was measured. The results obtained using the FEM simulations proved that in unbalanced and asymmetrical operations of this EAF, high-voltage arcing may occur. © 2010 Springer-Verlag.
Chaos, Solitons and Fractals (09600779) 42(3)pp. 1755-1765
In this paper, a chattering-free sliding mode controller design for uncertain chaotic systems is presented. Since the implementation of the sliding mode control may cause a significant problem of chattering, many modified methodologies have been developed to overcome this drawback. However, each of them has own problems such as lack of robustness against disturbance variations, steady-state error, large convergence time and effect on transient performance. This paper proposes an improved sliding mode control strategy in which a modified sliding condition in a continuous function in control signal is taken into account instead of discontinuous part and also it adds an auxiliary continuous control to the control input. Then, the stability of controlled system is proved by using Lyapunov's direct method. The usefulness of this proposed method for eliminating the chattering phenomenon in transient and steady states, in the face of uncertain chaotic systems with disturbances, is well appeared. For this purpose, the Lorenz system is studied and its simulation results are presented to demonstrate the effectiveness of the proposed control scheme. © 2009 Elsevier Ltd. All rights reserved.
International Journal of Applied Electromagnetics and Mechanics (13835416) 30(1-2)pp. 83-93
In this paper three different rotor eccentricities, i.e., static, dynamic and a combination of them, in the rotor of rotating electrical machines are studied by considering a relative permeance function in which variations of the airgap length have been included. The airgap flux density distribution that involves the effects of rotor eccentricity is calculated using the new relative permeance function. In this study, the cylindrical rotor shape is considered. The comparison of the results of this analytical method with which obtained by transient finite element method will also be considered in future studies. 2009 IOS Press and the authors. All rights reserved.
Journal of Electrical Engineering and Technology (19750102) 4(3)pp. 370-376
The influence of magnetic saturation on electromagnetic field distribution in both a permanent-magnet direct-current (PMDC) motor and a field-winding (wound-field) direct-current (FWDC) motor, with the same output mechanical power, has been studied. In this paper, an approximate analytical method and time-stepping Finite Element Method (FEM) are used for prediction of Back-EMF and electromagnetic torque. No-load and rotor-lucked conditions, according to experimental measurements, and the FEM and analytical method studies of the motors have been considered. A sensitivity analysis has also been successfully accomplished on the major design parameters that affect motor performance. At last, these two DC motors are compared, in spite of their differences, on the basis of measured output characteristics.
Journal of Electrical Engineering and Technology (19750102) 4(2)pp. 175-184
In this paper, a method for optimal measurement placement in the problem of static harmonic state estimation in power systems is proposed. At first, for achieving to a suitable method by considering the precision factor of the estimation, a procedure based on Genetic Algorithm (GA) for optimal placement is suggested. Optimal placement by regarding the precision factor has an evident solution, and the proposed method is successful in achieving the mentioned solution. But, the previous applied method, which is called the Sequential Elimination (SE) algorithm, can not achieve to the evident solution of the mentioned problem. Finally, considering both precision and economic factors together in solving the optimal placement problem, a practical method based on GA is proposed. The simulation results are shown an improvement in the precision of the estimation by using the proposed method.
AC electric arc furnaces (EAFs) highly reduce power quality of the network by generating disturbances such as flicker and harmonics. These disturbances are due to the nonlinear electromagnetic and thermal field behaviors of the AC arcs. Analysis of these nonlinear behaviors is required for improving power quality in the network. This paper presents a three-dimensional finite element modeling of the electromagnetic fields in an AC three-phase electric arc furnace. The model includes the electrodes, arcs and molten bath. Current density, voltage and magnetic field intensity in the arcs, molten bath and electrodes are predicted as a result of applying the three-phase AC voltages to the EAF. This model does not consider the instantaneous geometry of the arc, instead a constant geometry, which is adjacent to the geometry of a DC arc with a DC current equal to the RMS value of the current waveform, is considered. Electromagnetic field of the AC arc in the time-domain is also modeled using the three-dimensional finite element method. ©2009 IEEE.
In this paper, a new method for shape design optimization, using sensitivity analysis on the finite element (FE) model of an interior permanent magnet synchronous motor, is proposed. Average torque is our objective for optimization. It shows the optimized motor has more average torque in compare with the conventional motor. © 2008 IEEE.
In this paper, at first, an optimized resonant capacitor is designed for a practical induction furnace with parallel resonant inverter, by using Lagrange's method. Then, rectifier and inverter snubber circuits are designed. To access a control system, a passive linear controller is also designed. Meanwhile the whole system is started and load is changing, the controller, by changing firing angle of the rectifier, provides proper DC current for inverter such that output power of inverter will be fixed at a favorite amount. Also, to protect resonant capacitor from over voltages that may happen in the system, sufficient margins for firing angle of rectifier are properly designed. © 2008 IEEE.
The static compensators are capable of improving the power quality indices in the power systems. Since the Electric Arc Furnace (EAF) acts as a non-linear time-variant load, it deteriorates the power quality. Thus, with a suitable design of the static compensators the consumed power by the electric furnace can be controlled. In this regard, firstly, a power system with an electric furnace is simulated. In the next step, in order to improve the power quality indices, a Thyristor Switched Capacitor (TSC) VAr compensator is designed optimally and then simulated. The TSC static compensator is designed so that the great variations of the furnace reactive power can be measured accurately. In addition, the designed static compensator creates a reduction in the voltage and current transients at the Thyristor terminals as well as generating the suitable pulses for them. Also, a suitable harmonic filter is proposed to improve the performance of the power system. © 2008 IEEE.
WSEAS Transactions on Environment and Development (17905079) 4(6)pp. 503-512
Subsidence is settling of the earth's surface because of different factors. Ground movements, mining activities, gas, oil and water, withdrawal are some examples that can causes ground subsidence. In recent years it has been proven that in dry areas because of extensive ground water withdrawal, the rate of subsidence increases rapidly (more than 10 centimeters in a year). A decrease in ground water level will causes an increase in effective stresses at clay layers which results consolidation of lower layers. The behavior can be modeled using finite element technique to predict the future settlement. In this paper the relationship between classical soil parameters and parameters used in numerical is driven for a single well water table lowering. It is possible to approximate the model by assuming elastic time dependent behavior due to decrease in water table level that calculates with a computer software that's name is 'WTAQ" (Water Table Aquifer). For this purpose specialized finite element model was established and related to classical soil mechanics consolidation parameters. In this research subsidence of different lands in Sirjan and also Shahrekord are compared.
In this paper a new quasi-resonant DC link inverter is considered and this circuit is mathematically analyzed. Commutation time resonant circuit components are designed according to minimization of commutation times and power losses. Two new modulation methods are also proposed. After completion of circuit design, the whole motor drive is simulated. The major advantage of the proposed inverter is to control each inverter leg switch independently; as a result, the PWM switching control is much simpler than the conventional one. Finally, the designed inverter is used for feeding an induction motor drive to verify the effectiveness of the proposed design. © 2008 IEEE.
WSEAS Transactions on Mathematics (11092769) 7(6)pp. 396-405
The equations of ultrasonic wave propagation in Cartesian coordinates are functions of 27 partial displacement derivatives, which first derived and then transformed into cylindrical coordinates. The new obtained functions are functions of 27 partial displacements of first and second order derivatives in cylindrical coordinates too and they will be linearized using a perturbation method based on the Taylor series expansion. A displacement wave, which propagates in a body, composed of two general part; static displacement part and also small dynamic displacement part. Happening of the small dynamic displacement of a particle around its static situation, Taylor series expansion can be written around this point. Using this determined static situation and considering only the two first components of Taylor series expansion, the equations of motion will be linearized. Tremendously lengthy algebraic operations involved in the derivation and linearization process, all of the mathematical manipulations are performed using Mathematica.
Electric arc furnace is of the non-linear loads for which different models have been suggested in order to its functioning analysis so far and it can have great effects on its neighboring generators. The goal in this paper is to study the effects of precision modeling on the power system local generator shaft. For this purpose, three models nearer to reality are employed for furnace simulation so as to study its effect on the generator shaft and on the point of connection among the turbines. The new method employed in this research is to consider different stages of melting and the use of the most suitable furnace model for simulation in that stage. So, an attempt is made to consider - the important stages of melt - which can affect the generator and to use a model which can describe the furnace operation in the best possible way in each stage. By using the graph of torque waves exercised on the generator shaft, the existing problems are studied and analyzed. © 2008 IEEE.
In this paper, a new method for shape design optimization, using sensitivity analysis on the finite element (FE) model of an interior permanent magnet (IPM) synchronous motor, based on torque waveform, is proposed. Torque pulsations are our objective function for minimization. The optimized motor has lower torque ripple and more average torque in comparison with the previous motor. © 2008 IEEE.
In this paper, an adaptive controller is designed to control an Electric Arc Furnace (EAF) electrode. For this purpose, a nonlinear model for EAF is considered. Piecewise-linearization method is used and based on the Lyapunov's method an adaptive control rule is achieved. EAF different operating conditions are considered and in each condition the system response by using proposed adaptive controller is compared with its response with PI controller which is usual controller for EAF. At first minutes of melting process, scrap surface changes suddenly. When the scraps are melted, the distance between electrode tip and melted material surface is considered to change sinusoidal containing the white noise. Also the effect of noise in current measurements is investigated. In all conditions the controller should change the electrode position so that the effective value of arc current remains constant. Additionally several conditions that don't occur in actual EAF are simulated to compare the response of those nonlinear systems that have transfer functions similar to EAF, with adaptive and PI controller. © ICROS.
This paper examines transient finite element solutions of an 100 MVA three phase electric arc furnace (EAF). In practice, it was observed that there were a few high voltage arcs between upper side of high-carrying-current electrodes and the EAF roof. In order to specify the operation and performance of this EAF, a two dimensional time stepping finite element method (FEM) was developed and induced voltages between the roof and the electrodes at the worst conditions were predicted. In addition, there were some measurements of effective value of induced voltages between the roof, electrodes and water pipes by which the roof was cooled. At the end, accordingly, the FEM simulations proved that in unbalanced and asymmetrical operations of this EAF, the probability of high voltage arcing remained. © ICROS.
Kiyoumarsi, A. ,
Eshtehardiha, S. ,
Poodeh, M.B. ,
Eshtehardiha, S. ,
Poodeh, M.B. ,
Kiyoumarsi, A. 2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 1639-1644
Static Synchronous Compensator (STATCOM) is a device capable of solving the power quality problems at the power system. These problems happen in milliseconds and because of the time limitation, it requires the STATCOM that has continuous reactive power control with fast response. In this way, optimal exploitation of STATCOM by classical controllers has been a controversial issue in reputable journals. One of the most common controlling devices in the market is the Proportional-Integral-Derivative (PID) controller. In this article, the STATCOM is controlled by PI and PID controllers. The best constant values for PID controller's parameters are laboriously obtained through trial and error, although time consuming. Genetic algorithm is employed to find the best values for PID controller's parameters in a very short time. The simulation results show an improvement in current control response. These methods are tested in MATLAB, and their results are obtained. © ICROS.
Power supplies normally provide a constant output voltage. In most of the applications a DC-DC converter is controlled by a voltage mode or a current mode controller. The DC converters are employed to feed electric vehicles, telephone sets and civil invertors, or for induction motors and frequency control. In this regard, optimal exploitation of DC transforms by classical controllers has been a controversial issue in reputable journals. Due to their switching property included in their structure, DC-DC converters have a non-linear behavior and their controlling design is accompanied with complexities. But by employing the average method it is possible to approximate the system by linear system and exploiting linear control methods. In this paper, control methods to control Buck converters by Linear Quadratic Regulator (LQR) controllers as well as optimal locating of the poles by genetic algorithm have been employed. All the analysis and simulations to duplicate on the above converter by MATLAB software were performed. The simulation results show the improvement in voltage control response. ©ICROS.
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 2162-2165
In this paper, we propose a MLP learning algorithm based on the parallel tangent gradient with modified variable learning rates, PTGVLR. Parallel tangent gradient uses parallel tangent deflecting direction instead of the momentum. Moreover, we use two separate and variable learning rates one for the gradient descent and the other for accelerating direction through parallel tangent. We test PTGVLR optimization method for optimizing a two dimensional Rosenbrock function and for learning of some well-known MLP problems, such as the parity generators and the encoders. Our investigations show that the proposed MLP learning algorithm, PTGVLR, is faster than similar adaptive learning methods. © ICROS.
In this paper, the control of a double mass and spring system as a physical model of a flexible arm robot is considered. The main goal of design is to use an appropriate control method that produces suitable external torques such that the whole system can be completely stabilized and controlled. For this purpose, mathematical model of the system is required which is achieved by Lagrange's equations in the first part of the paper. Since the controller design in this paper is based on state space description, these dynamical equations are re-written in the form of state-space equations and are linearized about an operating state. After examining the controllability of the system, a state feedback controller and also a Linear Quadratic Regulator (LQR) are designed. Moreover, since in these controllers the states of the system are required, a suitable full-order state estimator is developed as well. Finally, simulation results are provided to show the effectiveness of the proposed controllers. © ICROS.
In this paper, a double- mass and spring system Is considered as a benchmark for future studies on flexible arm robots. By using an appropriate control method and applying suitable external torques, the system can be completely stabilized and controlled. This requires the exact mathematical model of system. To achieve mathematical description, the system behavior is described by Lagrange's equations. Then these dynamical equations are written In the form of state-space equations. Finally, simulation results are presented to show the effectiveness of derived mathematical model for further analysis and synthesis. © 2007 IEEE.
Scientia Iranica (23453605) 13(4)pp. 364-372
Although there are analytical methods for field calculation in surface-mounted synchronous motors, accurate analytical methods for predicting airgap flux density distribution in Interior-type Permanent-Magnet (IPM) synchronous motors are not available. In this paper, a novel method for analytical prediction of flux distribution, based on Schwarz-Christofell transformation techniques, is proposed to evaluate the airgap flux density distribution in an IPM motor. To validate the accuracy of the new analytical method, the results are compared with transient Finite Element Method (FEM) results. © Sharif University of Technology.
Kiyoumarsi, A. ,
Moallem, M. ,
Fahimi, B. ,
Kiyoumarsi, A. ,
Moallem, M. ,
Fahimi, B. 2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 71-71
In this paper, analytical solution to magnetic field distribution and accurate performance prediction of an Interior Permanent Magnet Synchronous motor (IPMSM) has been obtained using a novel transformation technique. The effect of stator slots, rotor saliency, and magnet shapes are considered in this model. To validate the accuracy of the new analytical method, results are compared with those obtained using transient Finite Element Method (FEM). © 2006 IEEE.
IEEE Transactions on Magnetics (00189464) 42(11)pp. 3706-3711
Optimal shape design of an interior permanent-magnet (IPM) synchronous motor can substantially reduce its torque pulsation. However, the shape design variations should be feasible and practical. We report on an optimal shape design obtained by drilling small circular holes in the rotor. We found that an optimal location and radius of the holes effectively suppresses the torque pulsation of the IPM drive for various loads under steady-state conditions. The optimal design at rated load is considered as the final design. We use a transient finite-element analysis that is coupled with motion and adequate electric excitation for optimization purposes. An evaluation of the optimal design at various operating conditions showed torque ripple reduction and average torque improvement under all load conditions. The optimal design also shows improvement in the field-weakening region for high-speed operation. © 2006 IEEE.
The influence of magnetic saturation on electromagnetic field distribution in both permanent-magnet direct current (PMDC) and field winding (wound field) direct-current (FWDC) motors with the same output mechanical power, have been studied. In this paper, an approximate analytical method and Finite Element Method (FEM) are used for prediction of air gap flux density distribution. No-load and rotor-lucked conditions, according to experimental measurements, and the FEM and analytical method studies of the motor, have been studied. A sensitivity analysis has also been done on the major design parameters that affect motor performance. At last, these two DC motors are compared, in spite of their differences, on the basis of measured output characteristics.
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 642-648
Optimal shape design of interior permanent-magnet(IPM) synchronous motor has large effect in reducing the torque pulsation of the motor. However, the shape design variations should be feasible and manufacturable. In this research, optimal shape is obtained by drilling small circular holes in rotor. Optimal position and radius of these holes are found to effectively suppress the torque pulsation of IPM motor-drive on different steady-state and load conditions. A coupled magnetic field, electrical circuit, and mechanical system program is developed for the optimization purpose. Time stepping finite element method is used for the magnetic field analysis. The optimal design has been evaluated at different operating conditions, which shows good improvement in all load conditions. The optimal design also shows improvement in the field weakening region for high speed operation. © 2005 IEEE.
This paper presents a model for the Interior permanent magnet induction machines in the direct and quadrature axis of the rotor reference frame. This model is a model for dynamic simulation and can be used to simulate the transient behaviors of the motor during startup and load suddenly changes. In this model such as other dynamic models of the induction or synchronous machines the inductances are linear and there is no saturation effect. The advantage of this model is its simplicity and low solution time.
International Journal of Engineering, Transactions B: Applications (1728144X) 17(1)pp. 51-58
Both the cogging and electromagnetic torques depends on the shape of the flux density distribution in the airgap region. A two-dimensional (2-D) analytical method for predicting the open-circuit airgap field distribution in brushless permanent magnet motors, considering the direction of magnetization, i.e., radial or parallel, and the effect of real shape of stator slot-openings is presented in this paper. It involves the solution of the governing field equations in polar coordinates in airgap and magnet regions. This method uses a new 2-D relative permeance function. For the comparison purposes, a 2-D finite element (FE) analysis is used for the analysis of a fully-pitched, double-layer windings brushless permanent-magnet (PM) drive. The results obtained by this method are very close to those obtained by FE analysis especially at the corner tips of the tooth.
