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1.
The impact of reactive power control on the electricity market equilibrium is investigated. The effects of limitations on the reactive power generation and absorption, and load power factor adjustments, are examined using a novel electricity market equilibrium model that solves large-scale nonlinear power systems with asymmetric strategic firms. The algorithm implemented employs the linear supply function theory for bid-based pool markets. AC power flow analysis is used to represent the electricity network, incorporating variable price-responsive active and reactive load demands. The significance of the reactive power modeling in the electricity market equilibrium is demonstrated using the IEEE 14-bus and IEEE 118-bus systems. It is shown that variations on the reactive power in the system result in different market outcomes, as incentives are given to the strategic generating firms to alter their bidding strategies. The convergence characteristics of the IEEE 118-bus system are graphically presented and discussed to demonstrate the superior computational performance of the proposed algorithm in producing results under strict binding constraints and heavy transmission congestion conditions. 相似文献
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Differential evolution algorithm (DEA) is an efficient and powerful population-based stochastic search technique for solving optimization problems over continuous space, which has been proved to be a promising evolutionary algorithm for solving the ORPD problem and many engineering problems. However, the success of DEA in solving a specific problem crucially depends on appropriately choosing trial vector generation strategies (mutation strategies) and their associated control parameter values. This paper presents a differential evolution technique with various trial vector generation strategies based on optimal reactive power dispatch for real power loss minimization in power system. The proposed methodology determines control variable settings such as generator terminal voltages, tap positions and the number of shunts compensator to be switched, for real power loss minimization in the transmission systems. The DE method has been examined and tested on the IEEE 14-bus, 30-bus and the equivalent Algerian electric 114-bus power system. The obtained results are compared with two other methods, namely, interior point method (IPM), Particle Swarm Optimization (PSO) and other methods in the literature. The comparison study demonstrates the potential of the proposed approach and shows its effectiveness and robustness to solve the ORPD problem. 相似文献
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This paper presents quasi-oppositional differential evolution to solve reactive power dispatch problem of a power system. Differential evolution (DE) is a population-based stochastic parallel search evolutionary algorithm. Quasi-oppositional differential evolution has been used here to improve the effectiveness and quality of the solution. The proposed quasi-oppositional differential evolution (QODE) employs quasi-oppositional based learning (QOBL) for population initialization and also for generation jumping. Reactive power dispatch is an optimization problem that reduces grid congestion with more than one objective. The proposed method is used to find the settings of control variables such as generator terminal voltages, transformer tap settings and reactive power output of shunt VAR compensators in order to achieve minimum active power loss, improved voltage profile and enhanced voltage stability. In this study, QODE has been tested on IEEE 30-bus, 57-bus and 118-bus test systems. Test results of the proposed QODE approach have been compared with those obtained by other evolutionary methods reported in the literature. It is found that the proposed QODE based approach is able to provide better solution. 相似文献
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This paper presents multi-objective differential evolution (MODE) to solve multi-objective optimal reactive power dispatch (MORPD) problem by minimizing active power transmission loss and voltage deviation and maximizing voltage stability while varying control variables such as generator terminal voltages, transformer taps and reactive power output of shunt VAR compensators. MODE has been tested on IEEE 30-bus, 57-bus and 118-bus systems. Numerical results for these three test systems have been compared with those acquired from strength pareto evolutionary algorithm 2 (SPEA 2). 相似文献
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This paper addresses the problem of reactive power control of distributed generation (DG) units in the medium voltage (MV) distribution systems to maintain the system voltages within the predefined limits. An efficient approach for the load flow calculation is used here which is based on the topological structure of the network. It has been formulated for the radial distribution systems. A direct voltage sensitivity analysis method is developed in this paper which is also based on the topological structure of the network and independent of the network operating points. Thus, the sensitivity matrix is calculated once with the load flow program and it is used in all the system working conditions. The problem of DGs reactive power control is formulated as an optimization problem which uses the sensitivity analysis for linearizing the system around its operating points. The objective of the optimization problem is to return the system voltages inside the permitted range by using the reactive power of DGs in an optimal way. The optimal solutions are obtained by implementing particle swarm optimization (PSO) algorithm. Then, the results are verified by running a load flow considering new values of DGs reactive power. The procedure is repeated as long as a voltage violation is observed. Simulation results reveal that the proposed algorithm is capable of keeping the system voltages within the permitted limits. 相似文献
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为了提高电力系统的运行效率和经济性能,用群搜索优化算法(Group Search Optimizer)对电力系统各控制变量进行合理配置,以此减少电力系统无功损耗。群搜索优化算法是一种新兴的群智能优化算法,该算法把群成员分为发现者、追随者和游荡者三种,其中游荡者的位置随机选定,这有效地避免了其他算法容易陷入局部最小值问题。选定电力系统中无功投入量、电压变比、发电机端电压等作为控制变量,通过群搜索优化算法对控制变量进行迭代计算和潮流计算,最终计算出最小的网络损耗及其对应的控制变量值。最后用Matlab7.6对IEEE-14、30节点系统进行仿真,并与其他群智能优化算法进行对比,结果显示,群搜索算法的收敛较快且稳定,最终证明了群搜索算法对无功优化的优越性。 相似文献
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R.P. Bhatele J.D. Sharma O.D. Thapar 《International Journal of Electrical Power & Energy Systems》1985,7(4):247-252
This paper presents a mathematical formulation of optimal reactive power control problem via loss minimization and voltage control. The model minimizes real power losses, deviation from the optimal active power despatch policy, and the difference between percentage sharing of reactive power by controlling the generator terminal voltage magnitudes, transfer tap setting, and reactive power sources. The constraints set include power flow equations and limits on the variables. A method is developed to solve this problem using reduced gradient and Fletcher's update. Several test problems were solved using the developed technique. Correction to the groups of decision variables are applied simultaneously as well as hierarchically, and the results are compared for 6-bus, 30-bus, and 103-bus sample systems. 相似文献
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A.H. Khazali M. Kalantar 《International Journal of Electrical Power & Energy Systems》2011,33(3):684-692
This paper presents a harmony search algorithm for optimal reactive power dispatch (ORPD) problem. Optimal reactive power dispatch is a mixed integer, nonlinear optimization problem which includes both continuous and discrete control variables. The proposed algorithm is used to find the settings of control variables such as generator voltages, tap positions of tap changing transformers and the amount of reactive compensation devices to optimize a certain object. The objects are power transmission loss, voltage stability and voltage profile which are optimized separately. In the presented method, the inequality constraints are handled by penalty coefficients. The study is implemented on IEEE 30 and 57-bus systems and the results are compared with other evolutionary programs such as simple genetic algorithm (SGA) and particle swarm optimization (PSO) which have been used in the last decade and also other algorithms that have been developed in the recent years. 相似文献
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The paper presents the bacterial foraging optimization algorithm (BFOA) and particle swarm optimization (PSO) algorithm based robust controllers for voltage deviations due to the variation of reactive power in an isolated wind-diesel hybrid power system. The isolated wind-diesel system consists of wind energy conversion system (WECS) utilizing a permanent magnet induction generator (PMIG). Further, a synchronous generator (SG) is used with the diesel engine set for power generation. The mismatch between generated and consumed reactive power in the system causes voltage fluctuations, which will occur at generator terminals. These oscillations further causes reduction in the stability and quality of the power supply. The static synchronous compensator (STATCOM) and an automatic voltage regulator (AVR) are used to suppress voltage fluctuations in an isolated wind-diesel hybrid power system. The STATCOM is used as a reactive power compensator and the AVR is used to keep the terminal voltage constant for the synchronous generator. Both STATCOM and AVR are having proportional and integral (PI) controllers with single input. In modeling for the system, a normalized co-prime factorization is applied to show the possible unstructured uncertainties in the power system such as variation of system parameters and generating and loading conditions. The performance and robust stability conditions of the control system are formulated as the optimization problem, which is based on the Hα loop shaping. BFOA and PSO algorithms are implemented to solve this optimization problem and to achieve PI control parameters of STATCOM and AVR simultaneously. In order to show the efficiency of the proposed controllers, the performance of the proposed controllers is compared with the performance of the conventional controller and genetic algorithm (GA) based PI controllers for the same wind-diesel system. The dynamic responses of the system for four different small-disturbance case studies has been carried out in MATLAB environment. 相似文献
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A. A. Abou El-Ela A. M. Kinawy R. A. El-Sehiemy M. T. Mouwafi 《Electrical Engineering (Archiv fur Elektrotechnik)》2011,93(2):103-116
This paper proposed a procedure to solve the optimal reactive power dispatch (ORPD) problem using ant colony optimization
(ACO) algorithm. The objective of the ORPD problem is to minimize the transmission power losses under control and dependent
variable constraints. Proposed sensitivity parameters of reactive power at generation and switchable sources are derived based
on a modified model of fast decoupled power flow. The proposed ACO-based algorithm is applied to the IEEE standard 14-bus,
30-bus systems, and a real power system at West Delta Network as a part of the Unified Egyptian Network. The obtained simulation
results are compared with those of conventional linear programming, genetic algorithm, and particle swarm optimization technique.
Simulation results show the capability of the proposed ACO-based algorithm for solving the ORPD problem, especially with increasing
the system size. 相似文献
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针对传统的配电网无功优化调节手段离散化、难以实现电压的连续调节等问题,研究了含风电场的配电网无功优化模型和算法,分析了双馈感应电机的无功发生能力,将风电场作为连续的无功调节手段参与配电网无功优化。并针对风电出力随机性的特点,用场景功率描述风电的随机出力,使之更具代表性。考虑了配电网的网损、电压偏差以及电压稳定性指标,建立了多目标无功优化模型。提出了基于量子粒子群算法(QPSO)的无功优化方法,该算法通过波函数描述粒子的状态,增加了种群的多样性,有效地避免了种群早熟等问题。用该算法对改进的IEEE33节点进 相似文献
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在光伏发电蓬勃发展的背景下,光伏电站参与电网无功/电压控制的需求也日趋强烈,有效评估光伏电站的无功控制能力具有重要的理论和现实意义。然而,光伏电站无功控制能力评估研究仍在起步阶段且难度较大,需从评估指标体系构建、指标权重赋值、综合关联评估多个方面进行深入探索。鉴于此,提出了一种基于动态时间弯曲关联分析的光伏电站无功控制能力评估方法,解决综合评估指标体系建立及层次分析赋值问题的同时,将无功控制能力指标评估问题转化为空间上的模式距离关联匹配问题,采用动态时间弯曲法实现不同序列间的关联分析,计算标准、参考及待评估指标序列的关联匹配系数,进而确定无功控制能力等级,实现综合分级评估。并开展典型系统评估应用,验证所提评估方法的适应性及有效性。 相似文献
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Almoataz Y. Abdelaziz Yasser G. Hegazy Walid El-Khattam Mahmoud M. Othman 《电力部件与系统》2015,43(3):320-333
Abstract—This article presents a novel algorithm for optimal planning of a dispatchable distributed generator connected to the distribution networks. The proposed algorithm modifies the traditional firefly method to be able to deal with the practically constrained optimization problems by proposing formulas for tuning the algorithm parameters and updating equations. The proposed algorithm rigidly determines the optimal location and size of the distributed generation units in order to minimize the system power loss without violating the system practical constraints. Moreover, the optimal distributed generator location and minimum size for achieving a certain specified power loss are determined using the proposed method and compared to the results of a proposed heuristic technique. The distributed generation units in the proposed algorithms are modeled as voltage controlled nodes with the flexibility to be converted to constant power nodes in the case of reactive power limit violation. The proposed algorithms are implemented in MATLAB and tested on the IEEE 33-bus and the IEEE 37-nodes feeder. The results that are via comparison with published results obtained from other competing methods show the effectiveness, accuracy, and speed of the proposed method. 相似文献
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《International Journal of Electrical Power & Energy Systems》2013,44(1):304-312
The paper presents a reliable and fast load flow solution by using a real-coded genetic algorithm (RCGA), bus reduction technique and sparsity technique. The proposed load flow solution firstly used reduction technique to eliminate the load buses. Then, the power flow problem is solved for the generator buses only using real-coded GA to calculate the phase angles. Thus, the load flow problem becomes a single objective function, where the voltage magnitudes are specified resulted in reduced computation time for the solution. Once the phase angle has been calculated, the system is restored by calculating the voltages of the load buses in terms of the calculated voltages of the generator buses. A sparsity technique is used to reduce the computation time further as well as the storage requirements. The proposed load flow solution also can efficiently solve the load flow problems for ill-conditioned power systems whereas the conventional RCGA alone fails to solve these systems. The proposed method was demonstrated on 14-bus IEEE, 30-bus IEEE and 300-bus IEEE, and a practical system 362-busbar Iraqi National Grid. The proposed solution has reliable convergence, a highly accurate solution and much less computing time for on-line applications. The method can conveniently be applied for on-line analysis and planning studies of large power systems. 相似文献
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This paper presents a newly developed teaching learning based optimization (TLBO) algorithm to solve multi-objective optimal reactive power dispatch (ORPD) problem by minimizing real power loss, voltage deviation and voltage stability index. To accelerate the convergence speed and to improve solution quality quasi-opposition based learning (QOBL) concept is incorporated in original TLBO algorithm. The proposed TLBO and quasi-oppositional TLBO (QOTLBO) approaches are implemented on standard IEEE 30-bus and IEEE 118-bus test systems. Results demonstrate superiority in terms of solution quality of the proposed QOTLBO approach over original TLBO and other optimization techniques and confirm its potential to solve the ORPD problem. 相似文献
19.
In order to study long-term frequency and voltage dynamics of interconnected power systems under cascading events, the paper has developed a proper mathematical model and simulation algorithm for it with network structure preserved. Similar to the traditional dynamic power flow, the proposed model assumes that the system has survived in the transient stability and has enough damping torque. Therefore, the relative swings among generator rotors in one area will be neglected in long-term dynamics; and each control area is assumed to have a uniform frequency, represented by its area center of inertia (COI). Fast decoupled method has been extended to solve the structure-preserved multi-area network equations. Computer test results from a modified IEEE30-bus power system demonstrate the validity and effectiveness of the proposed model and algorithm. The work establishes a simulation platform for future study on long-term frequency and voltage stability control strategy and coordination of interconnected power systems. 相似文献