梯形小波变换及其在电力系统频率跟踪中的应用

提出了梯形复值小函数及其相应的复值小波变换。梯形复值小波函数具有良好的局部化特化和对称性，借助它能准确地分辨出信号中所包含的幅值信息和相位信息。梯形小波函数具有平坦的频率特性，因而梯形小波变换较容易捕捉到信号的频率偏移。文中利用梯形复值小波变换，对电力系统的频率突变信号进行了频率跟踪，同时分析了发电机失磁故障信号频率变化情况，证明了基于梯形复值小波变换的电力系统频率跟踪是一种有效的方法。

TRAPEZOID WAVELET TRANSFORM AND ITS APPLICATION IN POWER SYSTEM FREQUENCY TRACKING

In this paper, the trapezoid complex wavelet function and associated trapezoid wavelet transform is presented. This complex wavelet function possesses better localizability and symmetry, therefore, by means of trapezoid wavelet transform, the amplitude and phase information in the signal can be accurately distinguished. By comparison with other wavelet functions, trapezoid complex wavelet function has even frequency characteristic, and so trapezoid complex wavelet transform easily catch frequency deviation of signals. By use of trapezoid complex wavelet transform, the discontinuity of frequency characteristics of signals in power system is tracked, at the same time the frequency variation in signal of loss of field fault of generator is analyzed. In this paper it is proved that the power system frequency tracking based on trapezoid complex wavelet transform is a very effective method and obvious benefit could be brought about through applying this method.