| Summary: | Active power filters (APFs) are widely accepted power electronic devices for compensating harmonic currents produced by nonlinear loads. The conventional technology used for APFs is a proportional-plus-integral (PI) controller. However, both the conventional approaches for determining the PI coefficients and also its structure may not provide satisfactory results under transient operating conditions such as a sudden change of load. Therefore, this paper proposes a proportional-integral-derivative fuzzy logic controller (PID-FLC) to improve the steady-state and transient performances of the conventional APF controllers. First, particle swarm optimization (PSO) is utilized to determine the optimal coefficients of the proposed PID-FLC. Then, the direct current control approach is used to generate the reference harmonic signals from the non-sinusoidal load current while an adaptive hysteresis-based current control is selected to control the compensating currents. Simulation results for a power system connected to a nonlinear load are generated to investigate the dynamic performance of APF equipped with the conventional-PI (C-PI), optimized-PI (OPT-PI), optimized-PID (OPT-PID) and optimized-PID-FLC (OPT-PID-FLC) controllers using MATLAB/SIMULINK software.
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