Unified power quality conditioner (UPQC): the principle, control and application

This paper deals with unified power quality conditioner (UPQC), which aims at the integration of series-active and shunt-active power filters. The main purpose of a UPQC is to compensate for voltage imbalance, reactive power, negative-sequence current and harmonics. This paper discusses the compensation principle and control strategy of the UPQC in detail. Experimental results obtained from a laboratory prototype of 20 kVA are shown to verify the viability and effectiveness of the UPQC.