Numerical Investigation on Influence of Ambient Electric Field on Error Characteristic of Capacitive Voltage Transformer

Capacitive voltage transformer (CVT) is widely used for voltage measurement in power systems. According to practical operations, ambient electric field severely influences measurement error of CVT. To study error characteristics of CVT related to ambient electric field, 3D finite element models of 500 kV CVT along with surrounding electrified equipment (arrester, high-voltage lead, as interfering factors of ambient electric field) are established. Besides, a three-phase CVT equivalent model is built to study influence of interphase interference on error characteristics of CVT. Simulation shows that measurement error is related to the distance between CVT and arrester, height of the arrester pillar and high voltage terminal potential of arrester. Furthermore, variations in angle and length of high-voltage lead would also impact on error of CVT. Effect of interphase interference on CVT error weakens with the increase of interphase distance. Validity of simulation results is verified with off-line experiments.