Abstract:

The usage of distributed generation resources, particularly distributed generation with renewable sources, has increased to generate electrical power close to consumers. One of the factors that can reduce penetration of distributed generation resources is the limitation of power quality, such as harmonic distortions. Distributed generation sources, in addition to producing power, due to using of power electronic converters and changing the power flow, increase harmonic currents. On the other hand, local compensation of reactive power by parallel capacitor banks is one of the effective methods to reduce power system losses and harmonic distortions. Since the capacitor impedance varies at different frequencies and resonance can be produced at harmonic frequencies, providing an efficient method to optimize capacitor banks' placement in the presence of nonlinear loads and distributed generation is important. In this paper, first the adverse effects of distributed generation on power system harmonic distortions and therefore on power quality are illustrated by experiments. The problem of the optimal capacitor placement in the presence of nonlinear loads and distributed generation (wind power) is then expressed as a fuzzy multiobjective model. In the proposed model, annual profit maximization resulting from loss reduction, bus voltage deviation minimization, and reduction of power system harmonics are considered as optimization objectives. The presented model is solved with a PSO algorithm and a special version of the backward-forward sweep considering the system harmonics. Efficiency of the proposed model is demonstrated by running experiments on an 18-bus IEEE distributed network.

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