Performance of a new high speed digital technique for measuring power system frequency

An algorithm for the digital evaluation of power system frequency has been presented. The algorithm calculates the instantaneous frequency of a narrow band representation of the measured signal which may be either voltage or current. Digital filters are used to band-limit the measured signal and also to perform an orthogonalisation process which is required for the frequency evaluation. Finally a moving average filter is used to further filter the frequency estimates. Under simulated tests, the algorithm gives highly accurate and fast evaluation of the power system frequency. The results show that the algorithm is stable under dynamic power system conditions yet is unaffected by fast transients. Applications for this algorithm include load shedding schemes where a fast response time is required and as a basis for rate of change of frequency measurement