Realization of UPQC H∞ coordinated control in Microgrid

Aiming at the complicated power quality problems with the coexistence of voltage quality and current quality in Microgrid, a comprehensive regulation technology of power quality is urgently needed, which makes unified power quality conditioner (UPQC) have widespread application fields. As a multiple power quality conditioner, UPQC gathers the functions of voltage quality compensator, current quality compensator and energy storage device in the integrated manner, meeting the needs of comprehensive power quality control for the Microgrid. In this paper, the advanced H∞ control theory is adopted for further development on the UPQC generalized controlled system, and the Riccati solution method of the H∞ controller is presented. Through analyzing the coupling effect between UPQC series unit and shunt unit, a design method of UPQC coordinated controller based on H∞ control theory is proposed. The simulation and experimental results show that the proposed method can realize UPQC series unit voltage tracking compensation and shunt unit current tracking compensation simultaneously without steady-state phase shift and amplitude degradation. Moreover, the proposed method radically eliminates the coupling effect between UPQC series unit and shunt unit, and realizes the multiple power quality coordinated control functions of UPQC.