Photovoltaic units convert solar energy into electricity. The power of these plants is dependent on the amount of solar radiation, and because the solar radiation is variable, the production power also changes over time, and its effect on various issues, including the o More
Photovoltaic units convert solar energy into electricity. The power of these plants is dependent on the amount of solar radiation, and because the solar radiation is variable, the production power also changes over time, and its effect on various issues, including the operation of the power system, should be investigated. In the operation of the power system, to maintain the balance of production and consumption, some reserve is considered. In the past, the amount of reserve was considered as a percentage of load or power, and in probabilistic methods it is calculated based on risk. In the well-being model of power system, both the probabilistic model and the empirical rules are used to determine the indices. This model is based on risk and the amount of reserve is higher than the capacity of the largest unit. In this paper, the well-being model of the power system with the presence of photovoltaic plants is obtained. For this purpose, the reliability model of the photovoltaic plant is obtained by considering the failure of the components and changes in solar radiation. The simulation results are also presented to investigate the impact of photovoltaic plants on well-being model indices
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Background and Purpose: With influx of sustainable and renewable energy with high penetration into the production system, Compressed Air Energy Storage (CAES) could be used for creation of an acceptable adequate and smooth Electricity production system. CAES plants oper More
Background and Purpose: With influx of sustainable and renewable energy with high penetration into the production system, Compressed Air Energy Storage (CAES) could be used for creation of an acceptable adequate and smooth Electricity production system. CAES plants operate on electricity markets by storing energy when electricity prices are low and producing electricity when prices are high. An essential condition for the profitability of the CAES in hybrid systems is appropriate strategy for CAES operation about the sale and purchase of energy. This study aimed to determine optimal operating strategy for CAES systems fluctuating-hourly electricity market with high penetration of renewable wind power. Method: In this study, with simulation of production system of Khorasan Regional Electricity Company power plants which among all, the theoretical optimal strategy provides the highest net income for the storage unit. But since the market price of the upcoming hourly-fluctuating market is not pre-determined, two prognostic and historical practical-operational strategies have used for Setting up compressed air energy storage system. Findings: The results show that prognostic and historical practical-operational strategies, on average have 93% and 89% of theoretical optimal strategy s’ net income, respectively, in all six simulated capacities for compressed air energy storage system. Discussion and Counclusion: Based on the results, it is necessary to use power storage in order to increase grid stability and reliability of production in hybrid systems with high renewable power penetration; because a Black-Start must be ready in grid for Possible Black-Out situations which could provide load of grid in the least possible time. Use a CAES could be a great way that not only guarantees reliability and stability of grid in emergencies, but also is economically feasible and have operational suitable profit.
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In this paper, the improvement of low frequency oscillation (LFO) damping in a power system including SVC is investigated. To achieve this goal, a new control strategy has been presented in which the multi-model controller is optimized using the linear optimal controlle More
In this paper, the improvement of low frequency oscillation (LFO) damping in a power system including SVC is investigated. To achieve this goal, a new control strategy has been presented in which the multi-model controller is optimized using the linear optimal controller (LOC) and the particle swarm algorithm (PSO). The control bank in the multi-model controller includes three LOC controllers that generate optimal signals through the linearization of the nonlinear equations of the system and the minimization of an energy function to be combined by the Bayes recursive algorithm simultaneously to the generator excitation system and SVC. In order to generate an optimal linear signal, Riccati's equation must be solved; Riccati's equation includes two weight matrices Rric and Qric. These matrices elements are optimized by PSO algorithm. The PSO algorithm has calculated the optimal Rric and Qric with two different objective functions of maximizing the eigenvalues and minimizing the area under the speed curve. To evaluate the MMC-LOC-PSO control strategy, the symmetrical three-phase error is applied to the worst bus and the results of these two objective functions are compared. The simulation of the single machine power system has been done by MATLAB. The proposed control strategy, while maintaining stability, also effectively damps the LFOs, in addition, the permanent rotor speed and rotor angle error have also been favorably pushed to zero.
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One of the most important concerns for power system operators is how to execute the restoration process after having a blackout. In doing so, the parallel restoration is the most common method in which the desired islands are first formed and then the load of each secti More
One of the most important concerns for power system operators is how to execute the restoration process after having a blackout. In doing so, the parallel restoration is the most common method in which the desired islands are first formed and then the load of each section is restored separately at the same time. In the next step, the islands must be synchronized with having a minimum standing phase angle (SPA) between them. To do this, an optimal multi-objective scheme is defined in this paper in order to coordinate both load restoration and SPA reduction problems. The objective functions of the proposed model are the minimization of the static phase angle and the energy not supplied in which the desired constraints are also considered. For optimization process the teaching and learning optimization algorithm (TLBO) is used as a proposed technique and compared with some other intelligent algorithms. The simulations are performed by creating a connection between MATLAB software and DIGSILENT. The results obtained on the IEEE 39-bus power system show the efficiency of the proposed model.
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Maintaining the voltage profile of the power system within the appropriate bound has been a key factor for the proper operation of system equipment, especially during disturbances. However, due to the uncertainty of the load powers and the limitation in equipment rating More
Maintaining the voltage profile of the power system within the appropriate bound has been a key factor for the proper operation of system equipment, especially during disturbances. However, due to the uncertainty of the load powers and the limitation in equipment ratings, achieving this goal has become a challenge. High voltage substations play an important role in voltage control, because these substations can be a primary connection point between the high voltage transmission network and the distribution system. The nature of local voltage control, the variety of control tools and the interaction between them, have made this type of control difficult. In this paper, a centralized voltage/reactive power control method is presented based on phasors measured by PMUs installed in grid substations. In this method, the tap changing of transformers and step switching of capacitor banks have been determined by the central controller based on system voltages and network equations. In addition, the appropriate values of the operating point of the generators have been carried out based on economic dispatch in each period of optimization. The consistent and efficiency of the proposed method have been investigated through simulation in MATLAB software environment.
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Power system stabilizers (PSSs) are usually utilized for damping synchronous generator torque in order to reduce these oscillations by producing complementary control signals for the generator excitation system.In this study, we used a non-linear power system stabilizer More
Power system stabilizers (PSSs) are usually utilized for damping synchronous generator torque in order to reduce these oscillations by producing complementary control signals for the generator excitation system.In this study, we used a non-linear power system stabilizer based on synergetic control theory and a thyristor-controller series capacitor (TCSC) simultaneously in order to damp electromechanical oscillations and overcome the problems of linear approximation in a non-linear system which limits system stability in a neighborhood of equilibrium. The proposed synergetic combination of power system stabilizers is completely based on a simplified non-linear model of the system. In order to examine the simultaneous effect of these controllers, we investigated the simulation in single- and multi-machine power systems under various turbulences. Simulation results indicated that the simultaneous performance of TCSC and the synergetic power system stabilizer (SPSS) show a high capacity for damping oscillations and improving stability as compared with SPSS and PSS tuned with genetic algorithm (GAPSS) in any non-linear dynamic power system.
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The sympathetic Inrush current that occurs in series and parallel transformers can cause the creation of two major problems in the protection of power transformers. The main problem is that the peak of the inrush current for this case is more severe rather than common i More
The sympathetic Inrush current that occurs in series and parallel transformers can cause the creation of two major problems in the protection of power transformers. The main problem is that the peak of the inrush current for this case is more severe rather than common inrush current that the protection system may mal-operate. Besides, when a common protection system is designed for parallel transformers, the line input current, the vector summation of the input currents, will be detected as a single-phase fault that can cause the incorrect operation of the protection system. For this purpose, this paper presents a novel approach based on Lissajous of current signal for detection of inrush current phenomenon. The proposed method detects the faults very quickly; as well as, this method has appropriate operation under noisy conditions, like white Gaussian noise. This method is evaluated using a network consist of 230 to 63 kV parallel transformers with vector group ynd11. The results show that the proposed method performs better than conventional industrial schemes, such as second harmonic, zero-crossing, and waveform analysis method.
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The purpose of this paper is to improve the dynamic stability of power systems equipped with offshore wind farms and HVDC transmission lines. Since wind farms are affected by environmental factors and cannot have a constant production capacity, the effect of wind turbin More
The purpose of this paper is to improve the dynamic stability of power systems equipped with offshore wind farms and HVDC transmission lines. Since wind farms are affected by environmental factors and cannot have a constant production capacity, the effect of wind turbine and HVDC system on power oscillation mode is investigated and a suitable solution for selecting input-output signals and stabili­zing complementary controller design is proposed. In the proposed method, using the concepts of controllability, observability and decomposition of single values, the best path for the design of the complementary controller is selected among the input-output signals, then the stabilizer controller is designed based on neural networks and to improve frequency Stability-Voltage is used. The simulation results show that the proposed controller performs better than the classical controllers in terms of response speed, settling time, and voltage fluctuations in the presence of disturbances and confirms the performance of the selected control system.
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In general, the basis of operation of most fault current limiters is to reduce the short-circuit current by adding a large impedance to the system at the time of the fault. However, fault current limiters differ in the type of impedance and how the impedance adds and re More
In general, the basis of operation of most fault current limiters is to reduce the short-circuit current by adding a large impedance to the system at the time of the fault. However, fault current limiters differ in the type of impedance and how the impedance adds and removes the system. In this paper, taking into account three different locations for installing fault current limiter in a sample power network, as well as changing the type (inductance or resistance) and its impedance value in an extensive range, the effects of these parameters on the stability of the power system have been investigated and analyzed. The criterion used for the first time in this article by the authors to examine and evaluate the transient stability of the power system is the method of the difference between the accelerating and decelerating area. The basis of this method is based on the equal area criterion. Other issues addressed in this paper are presenting a method for locating and determining the optimal value of fault current limiter impedance to improve the stability of the power system. Also, the effect of fault clearing time on transient stability has been studied when the fault current limiter is present in the power grid.
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Torsional torques on turbine-generator shaft which are yields of disturbances in power systems, can reduce the useful lifetime of shaft. In this paper, these oscillations will be damped and controlled by novel Power System Stabilizers (PSSs). Complex PSS which is used i More
Torsional torques on turbine-generator shaft which are yields of disturbances in power systems, can reduce the useful lifetime of shaft. In this paper, these oscillations will be damped and controlled by novel Power System Stabilizers (PSSs). Complex PSS which is used in this paper will act on the excitation system in generator set and also on the controller of in High Voltage Direct Current (HVDC) system. This PSS uses three terms (generator angle deviation, frequency oscillation and capacitor voltage deviation in HVDC system) of the study system which includes two ties AC and DC. This is the reason that this PSS is named novel one against the conventional PSSs. In order to adjust the PSS parameters to damp the oscillations, genetic algorithm is used. To improve the application of this PSS, fuzzy logic control methods are also used which has notable effect on controlling the oscillations in study system. The simulation results show the effectiveness of designed PSS in controlling the torsional torques in turbine-generator shaft.
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This paper presents a new method for designing of power system stabilizer (PSS) based on sliding mode control (SMC) technique. The control objective is to enhance stability and improve the dynamic response of the multi-machine power system. The mathematical model of the More
This paper presents a new method for designing of power system stabilizer (PSS) based on sliding mode control (SMC) technique. The control objective is to enhance stability and improve the dynamic response of the multi-machine power system. The mathematical model of the synchronous generator is first transformed into a form that facilitates the design of nonlinear control schemes. Then, a sliding mode controller is proposed. In order to test effectiveness of the proposed scheme, simulation will be carried out to analyze the small signal stability characteristics of the system about the steady state operating condition following the change in the parameters of the system and to the disturbances. For comparison, simulation of a conventional control PSS (lead-lag compensation type) will be carried out. The main approach is to focus on the control performance which later is proven to have the degree of shorter reaching time and lower spike.
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The stability of frequency and voltage is one of the basic principles in the power systems. One of the latest control measures for power system frequency control and stability is load shedding. A fast and optimal adaptive load shedding method using Artificial Neural Net More
The stability of frequency and voltage is one of the basic principles in the power systems. One of the latest control measures for power system frequency control and stability is load shedding. A fast and optimal adaptive load shedding method using Artificial Neural Networks (ANN) is presented in this paper. In this paper, the total power generation and the total existing load in power system were selected as the ANN inputs. This method has been tested on theNew England test system. The simulation results show the ability of this frequency control algorithm for optimal solving problem related to conventional method.
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The congestion management system is a systematic approach, collaboratively developed and implemented throughout a metropolitan region that provides for the safe and effective management and operation of new and existing transportation facilities through the use of deman More
The congestion management system is a systematic approach, collaboratively developed and implemented throughout a metropolitan region that provides for the safe and effective management and operation of new and existing transportation facilities through the use of demand reduction and operational management strat­e­gies. In this paper we try to present some points which should be investigated in congestion management problems. We calculate different kinds of congestion problems which may be occurred in our network. Here, the hybrid model is used to solve problems in the electricity market to solve the congestion problem in the network and Benders techniques is used together with an optimal power flow (OPF). In fact, by using of Benders algorithm the problem is divided into two major and minor problems. Therefore, the major problem related to the economy sector and no network is included and the minor problem is to solve the network and examine the accuracy of the network. Benders algorithm has been tested on a standard network IEEE 24 bus and Matlab software is used to implement the algorithm.
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In the power system, any change in the input or any disturbance causes oscillations in frequency, voltage, and real and reactive power. The Power System Stabilizer (PSS) stands out as a re-nowned and effective equipment for damping power system oscillations, extensively More
In the power system, any change in the input or any disturbance causes oscillations in frequency, voltage, and real and reactive power. The Power System Stabilizer (PSS) stands out as a re-nowned and effective equipment for damping power system oscillations, extensively explored in studies aimed at enhancing the dynamic stability of power systems. Challenges such as low-frequency fluctuations and the intricate nature of power systems have spurred the application of intelligent methods and optimization algorithms for addressing PSS-related issues. In this paper, a brief review of the studies conducted in the field of meta-heuristic optimization algorithms for PSS design is presented. Meta-heuristic methods are divided into three groups, and based on them, more than 200 articles have been studied in the field of PSS parameter optimization. The balance between exploration and exploitation is a common theme among all meta-heuristic meth-ods. Researchers and practitioners of meta-heuristic optimization methods belong to a wide range of audiences in the fields of power systems optimization, who will benefit from this research
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Electromechanical oscillations in power systems usually exist due to incompatible conditions and disturbances in the network. Meta-heuristics using search strategy are used to find near-optimal solutions. Typically, the implementation of this approach involves the utili More
Electromechanical oscillations in power systems usually exist due to incompatible conditions and disturbances in the network. Meta-heuristics using search strategy are used to find near-optimal solutions. Typically, the implementation of this approach involves the utilization of a fitness function to assess the candidate solutions. In nature-inspired metaheuristics optimization algorithms, an analogy from nature is used to generate approximate solutions for practical optimization problems. This work presents a comprehensive investigation into various nature-inspired optimization algorithms, including ant colony optimization, genetic algorithm, and bat algorithm. The primary focus of this paper is to explore their efficacy in the coordinated design of Power System Stabilizers (PSS) and Flexible Alternating Current Transmission Systems (FACTS). The objective of this coordinated design is to improve energy system stability and mitigate power system oscillations. Finally, new directions are provided to researchers who work in the field of applications of nature-inspired optimization algorithms and coordination configuration of PSS and FACTS regulators.
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