Electric Power Systems Research (03787796)206
Overcurrent and overvoltage can damage converter valves, DC capacitors and transformers in the VSC-HVDC systems. Therefore, a proper starting-up mechanism is needed to avoid overcurrent and overvoltage. Overcurrent occurs in the second stage of the starting-up procedure due to rapid response of controllers, high dVDC/dt and malfunction of PLL. Traditional methods reduce overcurrent, but they cause an increase in starting-up time duration. In this paper, a new control method is proposed to apply in the second stage of the starting-up procedure. Not only does the proposed method restrain overcurrent and overvoltage, but it also reduces time duration of starting-up. In addition, the proposed method reduces dVDC/dt and can limit the starting-up current to any desired value. Furthermore, the proposed method has a simple control system and does not need any extra elements, leading to a simple manufacturing. The operation and design principles of the proposed method are investigated in detail. Finally, the proposed control method is verified by simulation and experimental results of a bipolar two-level VSC-HVDC. © 2022 Elsevier B.V.
IEEE Transactions on Industrial Electronics (02780046)69(3)pp. 2157-2165
Two-level converter and modular multilevel converter (MMC) are the most commonly used converters in voltage-source converter-based high-voltage direct current (VSC-HVdc) system. Pole-to-ground fault is the most probable temporary dc fault in a bipolar VSC-HVdc system, which causes a voltage drop across the faulty pole and an overvoltage on the healthy pole. In order to restart the system after fault clearance, it must first eliminate the unbalanced voltage on the poles. The speed of voltage rebalancing is so important issue for fast restarting. In this article, a new voltage rebalancing method comprised of a simple auxiliary circuit is proposed in the bipolar two-level VSC-HVdc. The proposed scheme not only has fast restarting speed but also minimize power losses during restoration. Moreover, its control system is simple. The principles of the proposed scheme, design considerations, and control method of that are investigated. Finally, the proposed scheme is verified by the simulation and experimental results in a bipolar two-level VSC-HVdc. © 1982-2012 IEEE.
International Transactions on Electrical Energy Systems (20507038)30(12)
This paper demonstrates the functionality and control of the gate-controlled series capacitor (GCSC), a new FACTS device composing a pair of antiparallel GTOs in parallel with a fixed capacitor, to mitigate subsynchronous resonance (SSR) in a thermal generation plant connected to a series compensated transmission line. Firstly, by the use of both small-signal stability analysis and time-domain simulation, it is revealed that the studied system compensated by the series fixed capacitor is potentially unstable due to the first torsional mode. Then, in order to take benefits of series compensation without the risk of SSR, the fixed capacitor is replaced by GCSC. The capability and effectiveness of the GCSC to damp SSR are validated using modal analysis and time-domain simulation. Furthermore, GCSC is used in conjunction with a fixed series capacitor to minimize the overall cost of compensation. For this purpose, unlike previous studies, a linear controller is used to stabilize the system. In this study, the IEEE First Benchmark Model is considered as a case study, and MATLAB/Simulink is used as a tool for modeling and design of the control system. Also, time-domain simulations are done using PSCAD/EMTDC. © 2020 John Wiley & Sons Ltd
Nowadays, to overcome power quality and power factor problems at AC input mains of power systems, various active (Power Factor Correction) PFC techniques are widely employed which utilize switch-mode converters and controller circuits to achieve the aims. Amongst them, in this paper, PFC-based zeta converter and single-phase PWM-rectifier are designated as efficient PFC circuitry to mitigate the Total Harmonic Distortion (THD) and also increase Power Factor (PF). This paper focuses on control and design, analysis, and performance evaluation of each PFC topology separately in the presence of brushless DC motor. The design complexity and number of element required in the PFC circuits are contributing factors to be regarded. Since, the larger these quantities are, the more destructive impact they have on the system reliability and expense. In this regard, this letter, compares the designed PFC-based zeta converter and single-phase PWM-rectifier in terms of their performance, application, design complexity and the number of required elements. The proposed PFC converter topologies are modeled and simulated in Matlab-Simulink environment and then are evaluated through some case studies. © 2019 IEEE.
Electric Power Components and Systems (15325016)47(19-20)pp. 1841-1853
The current source inverter (CSI) is more suitable for use in photovoltaic applications than the voltage source inverter (VSI), but this structure has two main constrains: inability to feed unbalanced load and high common mode voltage (CMV). Despite the merits, use of CSI is limited due to these constrains. A three-phase CSI with a neutral-leg is presented in this paper, compared to the conventional three-phase CSI to overcome mentioned limitations, in which load unbalance under a PV system is dealt in a microgrid. An innovative three-dimensional space vector modulation (3D-SVM) is suggested for the four-leg CSI inverter. This novel 3D-SVM technique is very simple compared to the existing methods and computational complexity is too low. Operating principles, equivalent circuit and SVM is discussed for the four-leg inverter. Then, a balancing technique is applied to the four-leg inverter using the developed 3D-SVM, where simulations validate the capability of the inverter in supplying balanced load voltages; 4-leg inverter generates balanced sinusoidal voltages even under severe unbalanced load current. © 2020, © 2020 Taylor & Francis Group, LLC.
The starting-up strategy is an important issue for voltage source convert-high voltage direct current (VSC-HVDC) system. If a VSC-HVDC system starts up without any auxiliary system, overvoltage and inrush current will occur. This large overvoltage can cause serious damage on the DC capacitors and this large inrush current at turn-on may destroy the switches in converter. In this paper, starting-up steps in a three-phase two-level VSC-HVDC system is studied with details. The effect of capacitor and inductor values and also circuit breaker closing time on overvoltage and inrush current are investigated attentively. Possible methods for control overvoltage and inrush currents during starting-up are presented, and a comparison has been made between them in terms of power dissipation and cost. Eventually, the best auxiliary starting-up system is selected in terms of costs. Substantial simulations conducted on PSCAD/EMTDC platform. © 2019 IEEE.
This study deals with a power factor correction (PFC) based Vienna converter for Switched Reluctance Motor (SRM) drive for medium power applications. Compared with the traditional two-level or three-level unidirectional rectifier, Vienna rectifier is the appropriate choice for its advantage such as only half numbers of the switches, simple structure, high-power efficiency and ability to realize unity power factor with proper control strategy. The PFC-based Vienna converter is designed to operate in continuous inductor current mode and feed two SRM drives from one power supply simultaneously. The proposed drive is designed to operate over a wide range of speed control with improved power quality at ac mains. The performance of the proposed drive is compared with Diode Bridge Rectifier (DBR) and it is validated with simulation results. Simulation of the proposed system for feeding SRM has been done in MATLAB software. The proposed topology provides almost lower input current THD, which is found to be about 0.25% and improved power factor up to 1. © 2018 IEEE.
In this paper, design and simulation of two different hybrid electric vehicle topologies (Parallel HEV and Series HEV) is proposed. Also, a comparison between parallel and series design for hybrid electric vehicles is studied. Each of the topologies has many parameters that calculated at optimal operation point. Design main parts are comprises select of electric motor, design of controller and calculation of battery capacity. After the calculation parameter above, these values are applied to ADVISOR (ADvanced VehIcle SimulatOR). In different cycles, the outputs of the two topologies are compared each other and the results are presented in each section. Finally, according to these results the proper structure for sedan vehicle is chosen. © 2018 IEEE.
In this paper, a new variable switching frequency algorithm is proposed in which the switching frequency is varied in response to the variation in the operating conditions. The proposed algorithm is based on online junction temperature estimation. The proposed estimation model is based on Foster-type and power loss calculations for PWM IGBT inverter system. The proposed variable switching frequency algorithm can decrease power losses and so increase the efficiency of the inverter without deteriorating the harmonic performance Moreover, the lifetime of the inverter can be increased due to the narrower junction temperature profile that can be achieved by this algorithm when compared to the fixed switching frequency counterpart. © 2018 IEEE.
This paper presents a modeling and simulation of two different vehicles topologies (parallel hybrid electric vehicle and series hybrid electric vehicle) using the ADVISOR (ADvanced Vehicle SimulatOR). An accurate analysis of the performance of a hybrid electric vehicle, as well as of its consumption and pollution level, requires a dynamic analysis of its behavior. Two kinds of simulation tools for electric and hybrid electric vehicles exist: steady state and dynamic tools. An accurate analysis of the vehicle performance requires a dynamic model that includes many components such as its electric motor, its batteries and its motor controller. The central controller of this sedan consists of I/O Board, Adapter and Microcontroller of motor drive. In a first step, the vehicle components are sized, using a power flow analysis, to meet the requirements of energy and power of a typical 'Sedan vehicle'. In a second step, simulation results are presented and discussed to analysis complexity and performance. © 2017 IEEE.
Emerging Science Journal (26109182)1(3)pp. 135-144
Inverter systems that feed electrical power from photovoltaic (PV) system into the grid must convert the direct current of the PV array into the alternating current of the grid. In many applications, it is important for a converter to be lightweight, highly reliable, input/output isolated, flexible and operable in a boost mode. These features can be achieved by using a High-Frequency inverter which involves an isolated DC-DC stage and DC-AC section, which provides AC output. This paper proposes a new three phase topology, based on multi stage converter and PV system in order to use in medium and high power applications. The Perturb and Observe (P&O) method is used for maximum power point tracking (MPPT) control of PV array. The switching control signals for three-phase inverter are provided by hysteresis control method. Also, the comparison between the proposed topology and traditional structures has been conducted and finally the simulation researches are performed in a closed-loop control system by MATLAB/Simulink software to verify the operation of the proposed structure. The results represent better performance of the introduced system over traditional topologies. © This is an open access article under the CC-BY license.
