Publication Date: 2023
International Journal of Energy Research (1099114X)2023
Nowadays, consumption of different energy carriers is increasing due to the division of community activities in various sectors such as residential, commercial, and industrial. The energy hub concept is used to meet the demands of different energy carriers in these sections. In this paper, a new method for energy management of a microgrid is presented in an intelligent network based on three types of commercial, residential, and industrial energy hubs. In the energy hubs, a wide range of components, including renewable and nonrenewable generation units, converters, storage devices, intelligent parking lots consisting of electric vehicles, P2G units, and cogeneration units, are used to supply electrical, heating, cooling, and natural gas energies. Some parameters like renewable generations, energy demands, and arriving and departure time of electric vehicles are considered to be uncertain, and a relevant method is applied to provide a near-realistic profile for them. In addition, a demand response paradigm has also been proposed for three types of electrical, heating, and cooling demands at the hub output side. Therefore, in this method, a mixed integer linear programming model is proposed based on benefit and reduction of emission caused by the activity of gas-burning units for short-term planning and obtaining an optimal solution for generation and sending loads in a distribution network containing energy hubs. To evaluate the performance of the proposed modeling and structure, the presented approach is applied on a modified 33-bus IEEE test network. According to the results of the energy management model, it is possible to significantly increase benefits and also obtain a smoother consumption pattern in consumption with financial incentives. © 2023 Majid Abbasi Gharai et al.
Publication Date: 2022
International Journal of Electrical Power and Energy Systems (01420615)139
Penetration of inverter-based distributed energy (DG) resources into power grid has notably risen in recent years. Hence, new grid code standards require DGs to remain connected to the main grid even during faults and inject a certain amount of reactive power. However, in weak grids and during severe voltage faults, converters may fail to maintain their synchronization with the main grid. A main cause for this synchronization instability is the improper operation of synchronization unit which is phase locked loop (PLL). In literature, imitating the transient stability analysis of synchronous generators, swing equation and Equal Area Criterion (EAC) are applied to study the synchronization of grid-connected converters. In this paper, a new method based on EAC and swing equation is proposed to keep the damping coefficient in the swing equation positive, and consequently increase the maximum buffer area in EAC. Hence, the synchronization stability of voltage source converters (VSCs) connected to weak grids is enhanced. When the fault is detected, the proposed technique simply adds a certain gain of frequency deviation to the PLL and does not need any additional information of grid changes. The simulation results in MATLAB verify the viability of the proposed controller. © 2022 Elsevier Ltd
Publication Date: 2022
International Journal of Electrical Power and Energy Systems (01420615)138
False data injection (FDI) attacks can significantly impact on economic performance of electricity markets in modern power systems. These attacks can be stealthily accomplished by cyber-attackers for the purpose of profitability through financial arbitrage in electricity markets. In this paper, a new strategy of FDI attack based on Monte Carlo is proposed for an attacker participating in an electricity market, who has overmuch imperfect level of the network information. This piece of information, including both the connection /disconnection situation and admittance values of the transmission lines is denominated as topology and parametric uncertainties, respectively. Herein, a probable model is offered for analyzing the uncertainties by the Monte Carlo simulation (MCS). Afterwards, considering the probable errors of uncertainties, the attack strategy is designed in such a manner that the attacker obtains the most profit based on the contribution of each transmission line. The numerical results on two PJM 5-bus and IEEE 30-bus test networks could obviously demonstrate the success of such limited attackers in current electricity markets. © 2022 Elsevier Ltd
Publication Date: 2022
Electric Power Systems Research (03787796)205
The economic operations of real time (RT) electricity markets are vulnerable to false data injection (FDI) attacks, designed by cyber-attackers. Strategically, the RT locational marginal prices (LMPs) are stealthily altered by manipulating some of measurement data and it provides conditions for profitable financial misconduct in the electricity market. This paper proposes a new Monte Carlo-based FDI attack strategy for a cyber-attacker, who has very limited knowledge about the topology and parametric information of targeted network, which called an attacker with model topology-parametric uncertainties (TPUs). The main feature of the proposed attack is that despite the model errors, the attacker can guarantee the stealthy and profitable attack in advance, since the attack is designed based on an optimization problem of worst-case robust against uncertainties. Two 5-bus PJM and 30 IEEE bus systems are used to demonstrate the success of such cyber-attacks in real-time electricity markets. © 2021 Elsevier B.V.
Panah, P.G.,
Cui, X.,
Bornapour, S.M.,
Hoshmand, R.,
Guerrero, J.M. Publication Date: 2022
International Journal of Hydrogen Energy (03603199)47(25)pp. 12443-12455
Green hydrogen is produced through different methods in the lab but only a few technologies are commercialized. Cost reduction is widely expected to compete with the existing carbon-emitting alternatives. This paper compares alkaline, proton exchange membrane, and solid oxide electrolysis cells as the dominant technologies. Economic analyses with scale-up effects show meaningful differences between PEM and alkaline electrolyzers as relatively settled methods and solid oxide as an immature technology. Monte Carlo simulations on grid-connected electrolysis using the Danish electricity market confirm that both PEM and alkaline electrolyzers can already produce hydrogen with less than 3 €/Kg if taxes and levies are removed. The price may even drop below 2 €/Kg after the mass adoption of all three technologies. Furthermore, if electricity is delivered at half prices, the levelized cost of hydrogen falls around 1 €/Kg. The capabilities for cost reduction after scaling-up are 33%, 34%, and 50% in alkaline, PEM, and solid oxide electrolyzers respectively while they could get intensified with subsidization to 56%, 59%, and 70%. The results indicate that solid oxide electrolyzers can be as economical as alkaline and PEM ones. However, grey hydrogen seems to remain unbeatable without subsidized electricity and/or carbon tax adjustments. © 2022 Hydrogen Energy Publications LLC
Publication Date: 2022
Sustainable Cities and Society (2210-6707)78
Extreme dust storms (EDSs) are rare natural disasters, occurring with a higher rate of incidence and severity in recent years in coastal areas with humid climate. EDSs can hamper the operation of power distribution systems (PDSs) and other related urban infrastructures, and damage PDS insulation equipment. In this paper, a bi-level stochastic mixed-integer linear programming model is proposed for PDS resilience enhancement against EDSs. In the proposed model, the investment cost and total expected operating costs under the EDS conditions are minimized while considering uncertainties and PDS financial and operational constraints. The proposed actions for PDS resilience enhancement include pre-and post-EDS actions. Pre-EDS actions include simultaneous hardening of lines and substations, optimal placement of sectionalizing switches, and installation of emergency generators (EGs) in critical points. Post-EDS actions include damaged lines and substations repair, optimal network reconfiguration, power dispatch of EGs and optimal load shedding. The planning results at different budget levels show that coordinating pre-and post-event actions can reduce investment costs besides reducing operational costs. Implementation of the proposed model on the IEEE 33-bus test system and a large-scale PDS in Khuzestan province, a coastal province in southwestern Iran, confirms the efficiency of the proposed method for PDS resilience enhancement planning. © 2021
Publication Date: 2022
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.
Panah, P.G.,
Hoshmand, R.,
Gholipour, M.,
Macana, C.A.,
Guerrero, J.M.,
Vasquez, J.C. Publication Date: 2021
Sustainable Energy Technologies and Assessments (2213-1388)48
Islanded microgrids with high shares of RES are more exposed to frequency disturbances. The largest generator is typically in charge of frequency regulation. This study tries to upgrade this monopoly to a competitive market. A novel framework is proposed to invite prosumers of any kind/size to participate in a local ancillary service market. A multi-criteria decision-maker is developed to select the proper service from the pool of bids. Flexibility Flags and Prosumer Deviation Index are introduced to quantify the behaviors of individuals and the stability of autonomous microgrids. Furthermore, an innovative reward/punishment framework is suggested for the billing of subscribers. In this method, the extra cost of the activated reserved power is solely compensated by disturbance makers rather than the conventional way of blindly charging all subscribers for frequency regulation. An urban microgrid including electric vehicles, micro combined heat/power generator, thermostatic loads, and kinetic energy storage is considered for the performance assessment. The results indicate that electric vehicles and flexible loads are privileged. Also, the bill of the planned loads for the regulation service falls from 46–48% down to 3–6% under the proposed framework while the cost of frequency regulation drops by 59% when the unnecessary reserved power is modified. © 2021 Elsevier Ltd
Publication Date: 2021
Journal of Energy Storage (2352152X)41
Today, implementation of an efficient and economical energy management system (EMS) in industrial smart grids- given the rising trend in electrical load consumption and restrictions in ramping up the power plants' capacities- cannot be underestimated. Optimal planning avails itself of the exploitation manner of existing energy resources alongside appropriate employment of demand response (DR) programs and available electric vehicles (EV) in parking lots of immense industrial centers as storage sites in energy management systems in industrial smart grids have been seriously considered. This article introduces a new perspective in the simultaneous use of demand response loads and available electric vehicles in parking lots toward energy management of industrial virtual power plants (IVPPs) aiming at augmenting the system's profits as well as increasing the grid reliability under peak load conditions and cutting down on industrial centers load shedding. The objective function of the problem is formulated within the framework of short-term production planning for distributed energy resources (DER) and conventional ones in conjunction with DR programs and EV in such a way that the IVPPs' profits are maximized. In order to validate the performance of the proposed method, we have applied and tried on the second zone of IEEE-RTS standard grid. The outcomes accrued from various simulations point to the fact that the presence of EV within the boundaries of EV's parking lots prompts considerable increase in IVPPs' storage amount and consequent decline in exploiting full power grid capacity. Utilizing DR programs for responding load and selecting best scheduling schemes for each IVPP during various times of a day-night cycles will bring about a reduction in operation costs, de-peaking as well as an enhanced performance of EV's parking installations. © 2021 Elsevier Ltd
Publication Date: 2021
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
Publication Date: 2021
Sustainable Energy Technologies and Assessments (2213-1388)45
Due to a growing trend in electricity consumption and limitations in expanding the capacity of power plants, the issue of privatizing and restructuring the electricity industry has come to the fore. In this regard, with the emergence of competitive markets, drawing upon responsive programs and electric vehicles in planning smart networks has become an intense topic of research. This paper presents a new method for programming industrial virtual power plants (IVPP) considering synchronous presence of demand response programs and electric vehicles. The proposed algorithm aims at maximizing the proceeds from industrial networks through demand response planning and managing the energy consumption of electrical vehicles. The algorithm is implemented in Zone 2 of the modified version of the IEEE Reliability Test System. The simulation results show that the presence of electric vehicles in the parked position will increase the storage capacity of the IVPPs, whereupon the consumption load on IVPPs is reduced. Using demand response programs in this regard and selecting the best program for each IVPP at different times of the day cuts back on both network operating costs and high consumption peaks, whereby an improvement in the efficiency of electric vehicles parking schemes is obtained. © 2021 Elsevier Ltd
Publication Date: 2021
IET Generation, Transmission and Distribution (17518687)15(7)pp. 1136-1143
With the increasing penetration of inverter based distributed generation, recent grid codes do not permit the disconnection of converters as soon as fault happens. Considering the fact that electrical grids are not purely inductive, the grid connected converters face instability issues by fault occurrence. Converters applying Phase Lock Loop (PLL) are not able to synchronize with the weak grid during deep low voltage faults. This paper proposes a novel control strategy based on virtual impedance to maintain the synchronization of grid connected converters during heavy decrease of the grid voltage. Utilizing a virtual impedance and the measured current at the point of common coupling, the inverter can be virtually synchronized to a point which has a stronger connection. The virtual impedance can be a rough estimation of the line impedance or resistance from point of common coupling to the fault point. Furthermore, to avoid the need for impedance estimation, a simple technique is also proposed. Simulation results with MATLAB confirms the competence of the proposed method in improving the synchronization stability of the grid connected converters. © 2020 The Authors. IET Generation, Transmission & Distribution published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology
Publication Date: 2021
IEEE Transactions on Instrumentation and Measurement (00189456)70
Increasing power quality disturbances is one of the significant concerns of power systems that have attracted attention in recent years. One of the most important power quality disturbances is flicker. Flicker not only leads to flickering lighting systems but also damages network equipments, especially those with a high degree of sensitivity. As power systems are restructured, it is possible to take some measures against polluting subscribers. In this article, a new short-circuit-based method is proposed for determining the flicker transfer coefficient. Moreover, four new indices are introduced to assess the effect of flicker sources on target buses' voltage. In the proposed indices, the flicker sensitivity coefficient and the amount of load supplied by each target bus are considered. Using these indices, one can take an accurate impression of the effect of one or more flicker sources on the target buses' voltage. Finally, using the proposed indices, a new flicker propagation pricing method is presented, which can be used to penalize the flicker sources based on their flicker contribution in the target buses. To demonstrate the effectiveness of the proposed method in determining the contribution of flicker sources, the simulations are conducted on IEEE 14-bus test system. The simulation results show that by doing so, while taking into account the introduced indices, it is possible to identify and evaluate the contribution of different flicker sources. Moreover, experimental measurements are conducted on Isfahan region power system as a part of Iran transmission network. Finally, as a result, by applying proper penalty fees to subscribers, it is possible to reduce the flicker level of the network. © 1963-2012 IEEE.
Publication Date: 2021
IET Renewable Power Generation (17521416)15(1)pp. 58-72
Today, with growing expansion of renewable energy resources, electricity production is accompanied by uncertainties. The usage and optimal management of energy storage is one of the effective ways to compensate for these uncertainties. Compressed air energy storage (CAES) is one of the two bulk electricity storage methods for power systems, burning natural gas (NG) to extract the stored energy. Therefore, the NG price uncertainty and gas availability along with carbon emission resulting from burning NG can affect optimal bidding result of this unit. Hence, this study addresses the optimal bidding problem of CAES and wind units, considering the aforementioned issues, while taking into account uncertainties of day-ahead (DA) and balancing market prices, wind speeds, and NG prices and availability. Furthermore, the dynamics of natural gas flow in the pipeline is modelled. The stochastic programming (SP) method is proposed for solving this problem while taking risk into consideration. The scheduling has been presented for participation of generating company in DA and carbon emission markets. Simulation results indicate the capability of the proposed method in optimal bidding of CAES units while taking gas-burning related constraints into consideration. © 2020 The Authors. IET Renewable Power Generation published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology
Publication Date: 2020
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.
Publication Date: 2020
Sustainable Cities and Society (2210-6707)59
Power markets are undergoing structural alterations in accordance with emerging technologies. Traditional market rules and participants' behaviour are currently dominated by conventional power plants and synchronous generators. Renewable energy sources have gradually found their market share in the generation party specifically in developed countries. Apart from new energy resources, Demand Response Programs (DRP) have garnered attention due to substantial capabilities and potentials. This paper particularly sheds light on two flexible loads of Plugin Electric Vehicles (PEV) and cooling/heating responsive loads. PEV parking lots can be modelled as stochastic battery storages partially available for power exchange over short intervals. Besides, cooling/heating systems are naturally shiftable loads in short time horizons without deteriorating the resident's convenience. This study provides a comparative view of short-term power regulating markets in terms of bidding constraints and payment mechanisms. Consequently, a typical park & ride is considered as a reconfigurable urban microgrid to participate in short term regulating markets under different constraints. The results confirm that the internal coordination between the sub-units of microgrid brings more flexibility to enhance the total profitability. In addition, it is shown that the bidding constraints, as well as time slots, can be influential particularly in intermittent situations. © 2020 Elsevier Ltd
Publication Date: 2020
IET Electrical Systems in Transportation (20429738)10(2)pp. 213-223
Using different types of generation systems in ships, which are known as all-electric ships, can play a key role in increasing economic benefits in the long term. On the other hand, electrical energy storage systems (EESSs) provide flexibility for supporting the electrical load of ships in the presence of renewable energy sources and the other generation units. Since power demands of a ship are not limited to an electrical load, combined heat and power (CHP) units can be considered as backup units for heat-only units in addition to their economic and environmental advantages. In this study, new optimal power management is presented to handle a generation scheduling problem of a cruise ship for 12 h time intervals. In this regard, this method is based on the Lagrangian relaxation approach, a subset of ε-constraint approaches, and the use of marginal cost to determine the performance of EESS in each time interval by taking all the constraints into account. The capability of the proposed algorithm is analysed by simulation results of a cruise ship, including conventional, CHP, EESS and heat-only units, in order to achieve minimum operation cost with a short runtime. © The Institution of Engineering and Technology 2019
Publication Date: 2020
Journal Of Operation And Automation In Power Engineering (24234567)8(2)pp. 152-163
After extreme events such as floods, thunderstorms, blizzards and hurricanes there will be devastating effects in the distribution networks which may cause a partial or complete blackout. Then, the major concern for the system operators is to restore the maximum critical loads as soon as possible by available generation units. In order to solve this problem, this paper provides a restoration strategy by using Distributed Generations (DGs). In this strategy, first, the shortest paths between DGs and critical loads are identified. Then, the best paths are determined by using a decision-making method, named PROMOTHEE-II to achieve the goals. The uncertainties for the output power of DGs are also considered in different scenarios. The IEEE 123-node distribution network is used to show the performance of the suggested method. The simulation results clearly show the efficiency of the proposed strategy for critical loads restoration in distribution networks. © 2020 University of Mohagheg hArdabili. All rights reserved.
Publication Date: 2020
Journal of Energy Storage (2352152X)29
Today in developed megacities, municipal waste incinerators are a practical solution although they require a relatively high initial investment. On the other hand, E-Transport is growing in metropolitans along with the Renewable Energy Sources (RES). This study proposes an Urban Micro Grid (UMG) consisting of a Waste-to-Energy Combined Heat and Power generation unit (WtE-CHP) and series of Plugin Electric Vehicles (PEV). The main purpose is to provide ancillary services through the incorporation of PEVs as fast-responsive storages. The parking lots may aggregate to form PEV clusters and make bilateral contracts with WtE-CHP to be able to participate in the regulating power markets. A Crow Search Algorithm (CSA) is developed for the UMG operation. In addition, a data analysis section is provided focusing on the behavior of urban drives to extract the realistic probabilities for PEVs available during the daytime. Moreover, the power market of Denmark east (DK2) is considered for the case study of Copenhagen. The results confirm that in case the UMG succeeds in selling the products in the regulating up market, the economic value per MW is remarkably enhanced and the total profit is escalated. © 2020 Elsevier Ltd
Publication Date: 2020
International Journal of Emerging Electric Power Systems (1553779X)21(2)
Nowadays, the sustainable energy management of industrial environments is of great importance because of their heavy loads and behaviors. In this paper, the Virtual Power Plant (VPP) idea is commented as a collected generation to be an appropriate approach for these networks handling. Here, Technical Industrial VPP (TIVPP) is characterized as a dispatching unit contains demands and generations situated in an industrial network. A complete structure is proposed here for possible conditions for different VPPs cooperation in the power market. This structure carries out a day-ahead and intra-day generation planning by choosing the best Demand Response (DR) programs considering wind power and market prices as the uncertain parameters. A risk management study is likewise taken into account in the proposed stages for contingency conditions. So, some component changes, like, regular demand changes and single-line outage are prepared in the framework to authorize the suggested concept in the contingency situation. To determine the adequacy and productivity of the proposed strategy, the IEEE-RTS modified framework is examined to test the technique and to evaluate some reassuring perspectives too. By the proposed methodology, the delectability of DR projects is uncovered in industrial networks and the improvement level of load shedding and the lower cost will be achieved. © 2020 Walter de Gruyter GmbH, Berlin/Boston.
Publication Date: 2020
International Transactions on Electrical Energy Systems (20507038)30(4)
The observability of power systems during the parallel restoration of subsystems is one of the most important issues for system operators to accomplish the restoration task as quick as possible. Thus, this article proposes a coordinated optimal plan to solve the observability and sectionalizing problems by determining the locations of phasor measurement units (PMUs) and subsystems. Also, the impact of renewable energy resources on power system sectionalizing and the reliability value of power generation are taken into account in the proposed model. The objective functions that are considered in the optimization problem are the cost of wide-area measurement system (WAMS), the worst observability index among all subsystems and the lowest value of quality among all subsystems based on the reliability of subsystems. Since there are three contradictory objective functions, a multi-objective problem (MOP) is proposed as a mixed-integer nonlinear problem (MINLP). The Pareto curve of the proposed MOP is extracted by using a particle swarm optimization (PSO) algorithm. Two standard power grids are considered to validate the suggested technique. The outcomes of simulations confirm that the observability value of all sections is enhanced during the parallel restoration of the system. Also, the results show that the quality of subsystems in the presence of renewable energy resources is enhanced. © 2019 John Wiley & Sons Ltd
Publication Date: 2020
International Journal of Electrical Power and Energy Systems (01420615)116
This paper proposes a two-layer hierarchical control structure to realize compensation of voltage unbalances optimally in different buses of islanded microgrids. The primary layer controls the microgrid voltage and frequency. The secondary layer is used to realize the unbalance compensation of the sensitive load bus (SLB). Improvement of the voltage unbalance factor (VUF) at the SLB may lead to an increase in VUF at local buses and/or DG terminals. A complementary part is designed and added to the secondary control in order to tune the compensation portion of each DG source while limitations of VUF at DG terminals and local buses are considered too. This method realizes multi-power-quality-level control through a simple yet effective solution. Simulation results are given to demonstrate the advantages of the proposed control scheme. © 2019 Elsevier Ltd
Publication Date: 2020
Journal of Energy Engineering (19437897)146(1)
This paper proposes the idea of independent models of a microgrid (MG) based on operation modes. In grid-connected operation, optimal power flow is proposed to minimize the power generation cost. A new decision variable was introduced to represent a MG as an equivalent unit from the viewpoint of the upstream network. In island operation, contingency condition was considered and reliability improvement of the MG through load restoration is proposed. A new performance index is proposed to model MGs as small self-adequate islands in contingency. The main distinction between this research and the literature is the consideration of the uncertainty of the components of the MG. Monte Carlo simulation (MCS) was used as a framework to consider the uncertainty of components, including load consumption, renewable power generation, and fault duration. The proposed probabilistic models can be used to assess the generation adequacy and to indicate vulnerable loads in grid-connected and island operation modes, respectively. The proposed method was applied to the IEEE 69-bus test system and the results were discussed. © 2019 American Society of Civil Engineers.
Publication Date: 2019
Energy (0360-5442)188
The use of storage systems has recently been increased to cope with the uncertainties related to renewable energy sources and also to increase the flexibility required for applying energy management system. Energy management system is considered as a key factor to enhance the effective performance of Microgrids regarding energy demand boosting. Since any parking lot with electric vehicles can participate in distribution systems as a storage unit, this paper employs a new technique for parking management system to develop competition between electric vehicles owners inside the parking lot. Parking lot is responsible to support energy management system to decrease the operation cost and to increase the reliability in grid-connected and islanding modes of Microgrid. The new method considers the stochastic behaviors of electric vehicles, including their arrivals and departures with their bids. The strategy of energy management system is based on determining the output power of generation units and the operation mode of the parking lot. This system also provides the demand response programs to consumers for load shifting. A multi-objective optimization problem is used to optimize both the operation cost and the reliability of the Microgrid. The capability of the proposed algorithm is verified by simulation results. © 2019 Elsevier Ltd
Publication Date: 2019
IET Generation, Transmission and Distribution (17518687)13(20)pp. 4630-4641
After occurring extreme events distribution systems might be disconnected from the main grid, and there will be a complete blackout in the distribution network. In such situations, the only way to re-energise loads is to use available microgrids (MGs). Since power outputs of MGs are limited, the major concern for system operators is to energise the maximum critical loads (CLs) during the time needed for fault isolation and maintenance. To solve this problem, this study provides a systematic restoration process by using MGs. First, after the fault clearance the shortest paths between MGs and CLs are identified by Dijkstra's algorithm. Then, the best paths are determined by using a new modified analytic hierarchical process (AHP) algorithm and fuzzy logic to achieve four goals: Increasing restored energy, reducing path preparing time, decreasing number of switching operations and reducing unavailability of path. In the modified AHP, the parameters are so tuned that the engineers' personal preferences are eliminated for selecting the best restoration paths. Also, the uncertainty of available energy of MGs is considered. The IEEE 123-node distribution network with MGs and CLs is used for simulations. Results clearly show the benefits of using this method for CL restoration. © The Institution of Engineering and Technology 2019.
Publication Date: 2019
Iranian Journal of Science and Technology - Transactions of Electrical Engineering (23641827)43pp. 15-37
Optimal scheduling of power plants is an important problem in power system operations. This problem is a complex programming approach based on the dimension of power systems, number, and types of power generation units. In recent years, the penetration of renewable energy sources (RES) as clean, cheap, and green resources of energy has been increased in power systems. Therefore, the classic power generation scheduling problem is converted to a large-scale mixed-integer non-linear and stochastic optimization problem. In this regard, a review of various optimal scheduling problems in restructured power systems, their solution methods, advantages, and disadvantages is introduced in the presence of RES in this paper. © 2018, Shiraz University.
Publication Date: 2019
Renewable and Sustainable Energy Reviews (1364-0321)108pp. 355-368
Using different types of renewable energy sources considering their uncertainties causes numerous challenges for minimizing the operation cost and maximizing the reliability of system. Hence, stochastic programming is an essential tool to consider the system uncertainties. This paper presents a day-ahead energy management system to decrease the operation cost and increase the reliability of a Microgrid considering a number of challenges for supporting electrical and thermal loads. In the proposed method, micro-CHP units, renewable energy sources, auxiliary boiler and energy storage system are all responsible for supplying the electrical and thermal loads. The problem is formulated as a multi-objective optimization problem. Moreover, the influence of considering the electrical energy storage system as a non-ideal battery with charge/discharge efficiency less than 1 is investigated. Also, demand response programs are provided based on load shifting contracts to consumers. A scenario-based approach is used to cover the uncertainties of renewable energy sources, market price and electrical load. Besides, this paper considers both islanding and grid-connected modes of Microgrid and investigates the influence of demand side management on operation cost and reliability in both modes. The capability of the proposed algorithm is analyzed by simulation results of a 3-feeder Microgrid. © 2019 Elsevier Ltd
