Review of Control Strategies for Active Power Filters

Abstract: In present days electricity has become non-separable from human life. Every sphere of human life is dependent on some or other equipment/machine in households, hospitals, industry etc. The consumers have different load patterns such as non-linear loads, switching etc. Such utility pattern results in harmonic generation and reactive power disturbances in the distribution system. The harmonics and reactive power cause a number of undesirable effects such as malfunction in sensitive equipment, over voltage by resonance, increased heat in conductor, harmonic voltage drop across the network impedance and thereby affects other customer loads connected at Point of Common Coupling (PCC). These undesirable effects are overcome to a great extent by deploying Active Power Filters (APF) at PCC. The power quality of a Distribution System can be improved by eliminating harmonics and disturbances due to reactive power. This is achieved by injecting required amount of compensating current to cancel out the harmonics and power disturbances and restore sinusoidal nature of voltage and current waveforms. This improves the power quality and helps protect the sensitive loads from malfunction thereby preventing damage. This paper presents a comprehensive review of Active Power filter configurations, their control strategies and the performance evaluation metrics such as Total Harmonic Distortion (THD) for different control strategies. Keywords: Point of Common Coupling (PCC), Active Power Filters (APF), Total Harmonic Distortion (THD).