The electronic capacitive voltage transformers error characteristics research and parameter optimization design

The mathematical model of electronic capacitive voltage transformers (ECVT) in the power system is built by analyzing the sensing principles and applied environment of the ECVT, and point out that the existence of the distribution stray capacity is the key factor effecting to the transformer accuracy. From the viewpoint of the equivalent circuit, the interaction mechanism of the ECVT measuring error caused by stray capacity and the interphase interference is quantitatively analyzed. The structure finite element calculation model of the condenser divider of ECVT in 220 kV power system is built using the finite element software. The distribution stray capacitance matrix for the voltage divider is measured by simulating its static electric field. The parameters of the condenser divider are optimized by using the ECVT mathematical models established. The experiment results show that the measuring accuracy of ECVT is within 0.2 levels with the nominal capacitance of the condenser divider more than 3500 pF. This paper provide reference basis for error analyzing and parameters optimization design of ECVT.