Parameter Identification of Electromagnetic Unit in Capacitive Voltage Transformer

Capacitive voltage transformer (CVT) is composed by a capacitive divider unit and an electromagnetic unit. In order to simulate CVT's performance, it is necessary to establish the equivalent model of CVT and obtain all the equivalent parameters. The equivalent parameters of the capacitive voltage divider unit can be measured; however, the electromagnetic unit is a sealed chamber, and its parameters are hard to obtain directly. The paper proposes a 220kV CVT circuit model incorporates divider insulation parameters, and the CVT measurement errors under different loads are obtained by the load error characteristic test. For the electromagnetic model is fixed and parameters are uncertain, the load error data is fitted by the genetic algorithm and LM algorithm. The equivalent electrical parameters of CVT electromagnetic unit are obtained, and the equivalent CVT circuit model is constructed by combining the parameters of the capacitive voltage divider.