School of Information Engineering, Xiangtan University, Xiangtan 411105, China

In order to achieve coordinated power distribution between series and parallel units, the conventional compensation strategy of unified power quality conditioner(UPQC)with energy storage will cause phase jump of load voltage before and after compensation, which has an effect on the phase jump sensitive load. Therefore, this paper proposes a capacity allocation strategy for full compensation of load voltage amplitude and phase in UPQC with energy storage. The proposed strategy enables the load voltage to be fully compensated. By using the characteristic that the energy storage unit is able to provide active power, the appropriate parallel compensation current is selected and its amplitude is kept constant, which reduces the amplitude of the compensated power supply current. Thus, the series unit keeps a low compensation capacity, and the capacity configuration of series unit of UPQC is reduced. The results of simulation and low-voltage small-power prototype experiments show that the proposed strategy can achieve full compensation of load voltage and reduce the compensation capacity of series unit of UPQC.