Hybrid Power Transformer Voltage Control Strategy for Grid-connected Photovoltaics

The access of new energy field stations to the distribution network is prone to voltage overruns, power fluctuations and other problems, affecting the safe and stable operation of the power system. Hybrid power transformers can achieve dynamic regulation of the target bus voltage through the regulation of power electronic devices to alleviate the power quality problems of the power system. In this paper, the equivalent circuit of hybrid power transformer is constructed, the mathematical model of hybrid power transformer voltage regulation is deduced, and after revealing the mechanism of PV grid-connected voltage overrun and voltage fluctuation, the hybrid power transformer voltage regulation control strategy for PV grid-connected scenarios is proposed. Simulation results show that the proposed control strategy can effectively alleviate the voltage overrun problem brought about by the instantaneous grid-connection of PV system, and the hybrid power transformer can control the target node voltage to be stable at the commanded value under the working conditions of PV output change and load surge.