Unified Power Quality Conditioner based on current source converters for harmonic mitigation using a decoupled control strategy

The Unified Power Quality Conditioner (UPQC) is used to improve the power quality and is based on the union of a series active filter and a shunt active filter. The resulting topology has the characteristics of both filters and can compensate voltage and currents disturbances and improve the customer´s power quality. The topology based on current source converters (CSC-UPQC) has a good dynamic behavior to mitigate voltage disturbances as it uses a first order filter in the series stage. This allows a rapid response while using low switching frequencies without the problems associated with the resonance of the second order filter as required in the voltage source topology. This work develops a control scheme based on a non-linear control scheme for load current harmonic compensation by the shunt stage. The proposed control scheme regulates the load voltage under fast PCC voltage disturbances meanwhile the load currents harmonics are mitigated.