面向油浸式变压器类绕组暂态电压测量的耦合电容传感器优化设计

Optimization of Coupling Capacitive Sensor for Measurement of Transient Voltage in Oil-Immersed Transformer Type Windings

变压器类绕组暂态电位分布研究对绕组类设备的绝缘设计具有重要意义。根据浸油状态下变压器类绕组暂态电压非接触式测量的实际工程要求,对耦合电容传感器的结构及尺寸进行了优化设计。获取了电容传感器与不同信号处理电路组合时的高、低频响应特性,验证了优化后耦合电容传感器在合理选择信号处理电路的情况下具有良好的高、低频响应特性,可用于双指数波(中低频暂态电压)及高频暂态电压(very fast transient overvoltage,VFTO)的测量。实验研究了测量电缆长度对传感器输出信号的影响。结果表明,增加测量电缆长度会在增大传感器分压比的同时降低上、下限截止频率,故在实验中应尽可能采用较短的电缆来提高测量准确性。

Researches on transient voltage distribution characteristics of transformer type windings are of great significance for insulation design.Based on engineering requirements of non-contact measurement of transient voltage in transformer type windings under oil-immersed conditions,this paper optimized structure and size of coupling capacitive sensor.Response characteristics of the optimized sensor were acquired with different signal processing circuits and both good high and low frequency response characteristics were proved for the optimized coupling capacitive sensor when matching appropriate signal processing circuits,and it is suitable for application of measurement of double-exponential impulse（middle/low frequency transient voltage） or high frequency transient voltage（VFTO）.Influence of cable length on output signal was also studied.Experiential results indicated that increase of cable length would lead to increase of divider ratio and degradation of both upper and lower cut-off frequency.Short cables are preferred in experiments to improve measurement accuracy.