基于Hanning卷积窗的DFT介质损耗角测量算法

在高压电气设备介质损耗角在线监测中,DFT算法用于介质损耗角(介损角)测量时,系统频率的波动所造成的非同步采样将会产生泄露效应,从而会影响介损角测量精度。文章详细地分析了DFT算法非同步采样造成的泄露效应,提出了一种基于Hanning卷积窗的DFT介质损耗角测量算法。该算法采用Hanning卷积窗对电流和电压信号进行加权,利用频谱相位差校正法进行频谱校正以获得基波相位,根据电流与电压的基波相位差计算出介损角。通过仿真给出了该算法在电压频率波动和白噪声变化时计算所得介损角的变化情况,通过分析验证了该算法的有效性。

A DFT Algorithm of Dielectric Loss Angle Measurement Based on Hanning Convolution Window

In on-line monitoring dielectric loss angle of high voltage electric equipment, When dielectric loss angle is measured by DFT algorithm, the measurement accuracy is influenced by leakage effect of asynchronous sampling due to fluctuation of power systems frequency. In this paper, leakage effect of DFT algorithm caused by asynchronous sampling is analyzed in detail, a DFT algorithm of dielectric loss angle measurement based on Hanning convolution window is presented, and this algorithm can improve the measurement accuracy of dielectric loss angle. The power systems current and voltage signals are weighted by the Hanning convolution window, the fundamental phase angles are calculated with spectral phase difference correction method, the dielectric loss angle is calculated by the phase difference of the fundamental current and voltage. The dielectric loss angle of calculation with changes of the parameters such as voltage frequency and white noise are simulated, the validity of the algorithm is verified by analysis.