一种用于频率偏移时有效值计算的修正方法

在中低电压等级的线路测控保护一体化装置中，可以较容易地实现手动同期功能，但两侧频率相差较大时，采用相同时间间隔采样会对模拟量有效值的计算带来很大误差。文中分析了频率偏离额定值较大时，利用傅里叶算法计算有效值的误差，提出了一种修正幅值的实用方法。通过理论分析和数字仿真表明该修正方法使有效值的计算精度大大提高，而且计算量增加不大，有很好的实用价值。

Modified Method for Virtual Value Measurement with Frequency Deviation

Hand-synchronization can be easily realized in the integrated protection relay and RTU for MV and LV line. If the frequencies between bus bar and transmission line are raueh different, the sampling with the same time interval will bring about errors in the Fourier algorithm. An effective method is presented to modify the errors in the Fourier algorithm when power frequency deviates from 50 Hz. The theoretical analysis and digital simulation indicate that the modified method can enhance precision by little calculations. Therefore it has great practical value in the proiect application.