信号幅值变化时的电力系统动态频率测量

Measurement of power system dynamic frequency when signal amplitude changes

讨论了信号幅值变化对电力系统频率测量结果的影响，通过对各种测频算法所基于的信号幅值在一定时间间隔内不变的基本假设的分析引出了信号视在频率的概念，证明了在信号幅值变化时视在频率是信号真实频率与部分高频分量（约１００Ｈｚ）的迭加，各种测频算法不可能直接得到信号的真实频率，其测量结果具有与视在频率相同的主要特征，即含有一定的高频分量。提出了对测量结果进行再处理的必要性。

? This paper discussses the effect that signal amplitude changes have on the results of frequency measurement in power systems, advances the concept of signal's apparent frequency based on the analysis of the basic assumption of different frequency measurement approaches, proves that the apparent frequency is the superposition of actual signal frequency and some high frequency components(close to twice the normal frequency, about 100 Hz in 50 Hz systems), and frequency measurement approaches can not get the actual frequency directly, instead of that, the results of approaches are more similar to the apparent frequency and also contains some high frequency components. The paper then provides an approach to derive the actual signal frequency from the measured frequency and gives a simple example. 