Coordinated control strategy for UPQC and its verification

This paper researches profoundly on the coordinated control of UPQC (unified power quality conditioner). By analyzing the radical reasons of coupling effect between UPQC series unit and shunt unit, a simple and practical coordinated control strategy for UPQC series unit and shunt unit is proposed, i.e. by introducing corresponding voltage corrective link directly to UPQC series unit and shunt unit respectively, and by suitable mode of PWM in addition, the coupling effect between its series unit and shunt unit is eliminated fully. Therefore, the complex degree of the whole UPQC control system is simplified greatly. Combined with a power quality waveform tracking method based on H_infin control, the coordinated control between UPQC series unit and shunt unit is implemented by the proposed strategy. The experimental results indicate that the method can eliminate the steady-state phase shift and amplitude attenuation of the voltage tracking compensation of series unit and the current tracking compensation of shunt unit for UPQC. Finally, the unified power quality multi-function control of UPQC is achieved