Five step-low frequency switching active power filter for network harmonic compensation in substations

This papcr prescnts the performance evaluation of an active vower filter that uscs a five-stev current source inverter. Theuse of a multi-stcp inverter implies lower frequency switching,thereby allowing the introduction of highcr power switching devices. Thc control filter uses a frequency domain approach in which line current harmonics arc cxtractcd using an FFT routine. A compensating current rclated to the harmonic components of the load current is gencrated. This compensating current is injectcd at thc point of common coupling to canccl the load current distortion. The algorithm used to gencrate the compensating function is presented and the systemʹs ability to reduce current harmonics with lower frequency switching is demonstrated through simulations and a low power prototype.