一种电压闪变实时高精度检测研究

Study of Real-time High-accuracy Detection for Voltage Flicker

传统闪变检测方法以准确提取调幅波包络线为前提,过程复杂,运算量大。将时域卷积法直接用于闪变检测,提出先将电压闪变信号通过三角函数分解转化成间谐波信号,设计了一种时频滤波器,用Hilbert变换抑制负半轴频率,通过时域卷积法高精度地检测到信号各次谐波与间谐波的频率、幅度与相位,并由信号转化等式求得电压闪变信号的频率、幅度与相位。对被间谐波污染的闪变信号,检测结果不受影响。仿真结果表明:时域卷积法直接检测闪变信号,估计信号参数,实现过程简单,运算量小,且有一定抗噪能力强,有效提高了低信噪比条件下闪变信号的检测精度,适合电压闪变的实时检测。

Traditional voltage flicker method is based on the exact extraction of the envelope, whose process is complex and the computational burden is heavy. Application of time-domain convolution in estimation of voltage flicker is proposed in this paper. It decomposes the flicker signal into the interharmonic signal by trigonometric function. A time-frequency filter is designed and negative half-axis frequency of the flicker signal is restrained with Hilbert transform. The frequencies, amplitudes and phases of any order harmonics and interharmonics are obtained directly by means of time domain convolution. The frequencies, amplitudes and phases of the flicker signal are obtained by the signal transform equations. According to the flicker signal polluted by the interharmonic, the testing results are the same. The simulation indicates that it is easy and fast to estimate the parameters by detecting the flicker signal directly. Time-domain convolution method is insensitive to noise and has improved the estimation precision, therefore it fits real-time detection.