变电站容性设备介质损耗角的高精度测量方法

针对绝缘设备泄漏电流非常微弱且容易被噪声淹没的问题,以磁通门传感器组成差动方式来提取泄漏电流,克服了互感器角差和比差带来的误差影响。利用小波变换及自适应网络构成的数字低通滤波器,实现对泄漏电流的正交分量信号电阻性漏电流、电容性漏电流的数字滤波,有效地提取了基波相位。通过信号发生器及四象限乘法器构成的硬件正交分解器对漏电流信号分解,再配合数字滤波,较好地解决了电网频率波动带来的频谱泄漏,并抑制了栅栏效应。母线电压、泄漏电流经同一滤波网络,产生的附加相移相等,保证基波相位的稳定,提高了介损值测量的精确度。仿真及实验结果表明,该方法提高了绝缘设备在线监测的精度,为绝缘设备故障诊断提供可靠的依据。

Research of high precision measurement method of substation capacitive equipment dielectric loss angle

Directed at the solution to the leakage current which is weak and more likely to be submerged by noise,as occurs in the insulation equipment,this paper introduces some steps to extract the leakage current using the differential fluxgate sensor and eliminate the influence due to the angle error and the ratio error of the transformers.These steps consist of using the digital low-pass filter wavelet composed of transform and the adaptive network to filter the resistive leakage current and the capacitive leakage current of the orthogonal signal and thus effectively extract the fundamental harmonic,using the vector multiplier consisting of the signal generator and the four quadrant multiplier to achieve the orthogonal decomposition of the leakage current signal and the digital filter,and finding a better solution to the spectrum leakage caused by the grid frequency fluctuation and therefore inhibiting the barrier effect.The passage of bus voltage and the leakage current through the same filter network generates the additional equal phase shift,thus ensuring the stability of the fundamental wave phase,hence a greater resolution of the leakage current.Simulation and experiment indicate that this method serves to enhance the precision of the insulation equipment on-line monitoring,and provides a more reliable basis for the diagnosis of the insulation equipment fault.