A Stages Compensation and Control Strategy for Series Power-Quality Regulator

A novel stages compensation and control strategy suitable for a series power-quality regulator (SPQR) based on a voltage-source converter (VSC) inverter is proposed in which steady operation stage, overrun operation stage, and recovery operation stage are included. The presag voltage compensation, minimum energy compensation, and maximum energy compensation strategies are adopted to the three stages, respectively, based on the characteristics of the three stages. The double closed-loop control with feedbacks from load voltage and filter capacitor current is used in each stage. Moreover, the dc capacitor voltage regulation control for SPQR is applied in the steady operation stage. To avoid switching disorder during the stage change, a criterion based on voltage magnitude of the dc capacitor and source side is proposed. Simulation results in EMTDC/PSCAD show that voltage disturbances of the steady and transient state can be compensated by using the proposed compensation and control strategy and, at the same time, the dc capacitor voltage can be stabilized. The proposed strategy makes it possible to use the dc capacitor as the energy source of SPQR with the merit of a simple main circuit topology.