Simulation Study of the Measurement Characteristics of Equipotential Shielding Capacitor Voltage Divider

The online measurement of transient voltages is crucial for maintaining the reliability and safety of ac power systems. With the construction of UHV/EHV ac power systems, the voltage levels of ac equipment continue to increase, and traditional capacitor voltage dividers (CVDs) become unreliable due to the instability of their ground capacitance. This article proposes an equipotential shielding CVD (ES-CVD) and conducts simulation research on its measurement characteristics. The results show that a stable measurement can be guaranteed when the distance to the ground is greater than ten times the diameter of the measuring spherical conductor. The ES-CVD can effectively prevent the electric field strength on the surface of the measuring spherical conductor from exceeding the critical discharge field strength. The high-voltage wire to be measured and adjacent high-voltage wires have a significant impact on the ground capacitance of the measuring spherical conductor. However, the shielding electrode can significantly reduce their impact. Compared to a CVD without a shielding electrode, a divider with a shielding electrode can reduce the measurement error by one order of magnitude, which meets the measurement requirements of transient voltage. The research results in this article can provide a reference for measuring high-voltage ac transient voltage.