Trends of real time controlled active power filters

Primarily nonlinear loads, which are mainly power electronics loads, cause power system harmonics. Injected current harmonics into the power system lead to distorted voltages at the point of common coupling (PCC). These distorted voltages result in poor power factor operation and unacceptable current/voltage distortion levels. Harmonic filtering is one of the potential solutions. There are two types of power filters: passive filters where the filter components are passive; and active filters where the filter has a controlled current or voltage source single or three-phase inverter. Only active filters are considered in this paper.