12 kV一二次融合开关设备接地故障信号的高可靠性解析

High Reliability Analysis of Grounding Fault Signal of 12 kV Primary and Secondary Fusion Switchgear

为满足一二次融合成套开关设备接地故障测试的特定测量要求,提出了改进三点插值DFT算法,实现极短时波动周期下信号的高精度频率估计。算法基于最大旁瓣衰减窗,将DFT频谱实部和虚部拆分并分别进行三点插值计算估计;进而采用几何平均计算以消除负频率泄漏干扰影响;同时根据所得插值公式对算法在噪声下的统计特性进行了严格的数学证明。采用仿真验证算法有效性和准确性,仿真结果显示算法能够在任意波动周期及噪声干扰下,保持相对稳定且精度极高的校正估计准确性;最后将算法应用于实际12 kV一二次融合检测装置标准接地故障波形发生器输出信号的频率估计,实验结果显示算法能够满足文中所需的测量精度要求。

According to the special requirements of the ground fault test signal of the primary and secondary fusion switch,an improved three-point interpolated DFT algorithm to achieve high precision frequency estimation is proposed under the very small cycles in this paper.Based on the maximum sidelobe decay window(MSDW),the algorithm splits the real and imaginary parts of the DFT spectrum and calculates the three-point interpolation separately.Then the geometric mean calculation is used to eliminate the negative frequency leakage interference.Finally,according to the obtained interpolation formula,the statistical characteristics of the algorithm under noise are strictly mathematical proof.Furthermore,multiple simulations are used to verify the validity and accuracy of the algorithm.The results show that the algorithm can not only maintain relatively stable and high accuracy of correction and estimation under any fluctuation period,but also has strong resistance.Finally,it is applied to the frequency estimation of the measured ground fault waveform signals,which lays the foundation for the accurate reproduction of the input and output ground fault waveform of the 12 kV primary and secondary fusion detection device.