Review Of Reference Current Identification

Active power filters are required to compensate for the harmonic distortion of the supply arising from downstream nonlinear loads by identifying the distortion of the load current and injecting a compensating current into the ac system. Crucial to the compensation performance of the filter is the identification of the reference current. In the design process, explicit consideration of the elements of the reference current is necessary to achieve harmonic current cancellation, reactive power compensation, load balancing and neutral current compensation. Upstream poor quality supply voltage compromises the identification process and thus the compensation effectiveness. In this paper, a review is made of the significance of the elements that make up the reference current and their consideration or limitation in various reference identification methods.