Investigate on the Reliability of Electronic Voltage Transformer Based on Capacitive Voltage Dividing with Low Capacity Under the Transient Impulse Voltage
Transfer overvoltage can be easily generated in the low voltage side of EVT(Electronic Voltage Transformer)based on capacitive voltage dividing under the transient impulse voltage of power grid.The overvoltage may damage the secondary equipment which connects with the voltage divider of EVT, resulting in the reliability of the whole EVT being reduced dramatically.Two typical impulse voltages are chosen, which are standard lighting voltage and VFTO (Very Fast Transient Overvoltage caused by disconnect or operation), to study the capacitance value of voltage divider influencing on the transient characteristic of the overvoltage at the low voltage side due to the transient impulse voltage working.The amplitude value and the dominant frequency distribution of overvoltage in the low-voltage side are calculated with different main capacitance value (C1=500pF and C1=75pF).Factors, such as the front time, the voltage rise rate and the voltage polarity of the transient voltage and the parameters of grounding network effecting on the low-voltage side overvoltage are analyzed as well.The research results show that① As the value of the main capacitance C1 is smaller, the overvoltage generated at the low voltage side is lower.② The shorter front time and the faster voltage rise rate of transient impulse voltage lead to higher low-voltage side overvoltage;③The grounding network parameter inductance L has significant effect on the characteristics of low voltage side overvoltage.If the value of L is larger, the overvoltage of low-voltage side is higher.④The value of the overvoltage caused by VFFO is always higher than that caused by the standard lighting voltage no matter how to change the parameters of grounding network under the condition of C1=75pF;If C1=500pF and L<10μH, low-voltage side overvoltage caused by VFTO is higher than that caused by standard lighting voltage, but when L>20μH, the result is inversed.
impulse voltage electronic voltage transformer capacitive voltage dividing reliability grounding network
XiXiu Wu Ge Yan Yu Feng Benjin Wang Shipu Wu
School of Automation, Wuhan University of Technology Wuhan, China China Electric Power Research Institute Wuhan, China
国际会议
温州
英文
139-144
2014-11-16（万方平台首次上网日期，不代表论文的发表时间）