Optimal Design and Control Implementation of UPQC Based on Variable Phase Angle Control Method

As one of the most promising solutions to mitigate the power quality (PQ) problem of the modern power systems, the unified PQ conditioner (UPQC) draws considerable attentions. Since the UPQC consists of two sets of power converters, it will greatly increase the manufacturing investment of the setup. In this paper, the optimal volt-ampere (VA) ratings of the converters in the UPQC are investigated due to system compensating requirements. The phase angle control (PAC) method is discussed and illustrated to have the feature of changing the online VA loading by adjusting the corresponding displacement angle. On the basis of the variable PAC method, a two-stage algorithm is utilized to optimize the ratings of the shunt and series converters in order to obtain the maximum utilization rates of the power converters in the UPQC. Moreover, the corresponding control algorithm is utilized to reduce the proposed UPQC online VA loadings for the different compensating operations. The proposed UPQC is compared with other approaches to highlight the advantage of the proposed optimization algorithm. The proposed algorithms are also validated with the simulation and the real-time control hardware-in-loop results of the designed system.