Analysis of Operating Voltage Characteristics of UHV Transformer Medium-Voltage Side Reactive Power Compensation

The UHV transformers reactive power compensation(RPC) is equipped with two types of medium-voltage side compensation(MSC) and low-voltage side compensation(LSC). The LSC scheme commonly used in China does not conform to the MSC scheme adopted by relevant international standards. The compensation effect and equipment investment are different between these two schemes. Focusing on the 1000kV UHV autotransformer developed by Chinese, this paper theoretically analyzes reactive power loss(RPL) during operation and the influence of MSC/LSC on the operating voltage(OV). Then simulation is carried out with PSCAD/EMTDC software, analyzing and comparing the fluctuation level and compensation effect of each bus voltage when RPC is performed on different sides of the UHV transformer. The results show that the voltage fluctuation(OF) generated by the RPC on the medium-voltage side of the main transformer is lower than that on the low-voltage side, and the higher the compensable capacity, the smaller the equipment footprint and cycle investment.