Genetically Optimized Fuzzy Placement and Sizing of Capacitor Banks in Distorted Distribution Networks

Abstract

Abstract-A genetic algorithm (GA), in conjunction with fuzzy logic (FL) (approximate reasoning), is proposed for simultaneous improvement of power quality (PQ) and optimal placement and sizing of fixed capacitor banks in distribution networks with nonlinear loads imposing voltage and current harmonics. Economic cost is defined as the objective function and includes the cost of power losses, energy losses, and that of the capacitor banks while the voltage limits, number/size of installed capacitors at each bus, and the PQ limits of harmonic standard IEEE-519 are considered constraints. Fuzzy approximate reasoning is used to calculate the fitness function in order to consider the uncertainty of decision making based on the suitability of constraints (S THD , S V ) and the objective function (cost index) for each chromosome. Simulation results for the 18-bus and 123-bus IEEE distorted networks using the proposed GA-FL approach are presented and compared with those of previous methods. The main contribution is an improved fitness function for GA, capable of improving the objective function while directing the PQ constraints toward the permissible region using fuzzy approximate reasoning. This method leads to computing the (near) global solution with a lower probability of getting stuck at a local optimum and weak dependency on initial conditions while avoiding numerical problems in large systems.Index Terms-Capacitor, fuzzy logic (FL), genetic algorithm (GA), harmonics, placement, power flow and optimization, power quality (PQ), sizing.

Optimal Capacitor Placement Techniques in Transmission and Distribution Networks to Reduce Line Losses and Voltage Stability Enhancement: A Review

“…A four-stage methodology based on SA, GA, TS and the hybrid GA-Fuzzy logic algorithm to solve a combinatorial optimization problem with a non-differential objective function is presented in [55]. The solution methodologies are preceded by a sensitivity analysis to select the candidate capacitor installation locations.…”

Three-Phase Harmonic Analysis Method for Unbalanced Distribution Systems

“…Many methods have been proposed to analyze and eliminate the harmonic impact produced by nonlinear loads [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Among them, harmonic analysis is one of the most powerful tools for harmonic impact analysis.…”

“…Owing to the unbalanced line sections and loads in distribution systems, a three-phase harmonic analysis method is essential to accurately analyze the harmonic impact on distribution systems [7][8][9][10][11][12]. The harmonic analysis is also the basic tool for harmonic filter design and harmonic resonance mitigation and has to be done repeatedly for each harmonic order [13][14][15][16]; therefore, the accuracy and efficiency are both important issues for a well-designed harmonic analysis method. Conventional harmonic analysis methods [7][8][9][10][11] don't consider the special topological characteristics of distribution systems such as the unbalanced loads and radial network structure; therefore, the solution accuracy cannot be further improved and computational time cannot be effectively reduced.…”

Capacitor Placement and Sizing in Distorted Distribution Systems Using Simplified Direct Search Algorithm

“…However, in radial distribution systems, the presence of harmonic distortion have to be considered for compensating reactive power by adding shunt capacitors. Because the installation of shunt capacitors in the distorted distribution systems can cause resonances, increase active power loss, extensive reactive power demand, and overvoltage, if determining the location and size of capacitors without considering the presence of harmonics in the systems [2].…”

“…Many research have taken into account the presence of harmonic current and voltage to optimize the placement and size of shunt capacitors using different methods, such as Genetic Algorithm(GA) [1], Genetic Algorithm with Fuzzy Logic (GA-FL) [2] and Fuzzy Set Theory (FST) [3] in a balanced three-phase systems. Moreover, in unbalanced three-phase system, Particle Swarm Optimization (PSO) [4] and Harmony Search Approach (HSA) [5] have been applied to find the optimal location and size of shunt capacitors in the distorted distribution systems.…”