New tracking algorithm for power system frequency

In many power system protection and control schemes' it is necessary to accurately measure and track the system frequency. It is important to carry out on-line calculation of the supply frequency and its variation. Extra care is also needed to deal with significant frequency fluctuations to ensure satisfactory interpretation of the measurements. Conventional techniques assume that the waveform to be analysed is a pure sine wave. However, this paper presented the development of an innovative and reliable frequency-tracking technique based on digital filtering which does not rely on the sinusoidal assumption. The proposed power system frequency estimation algorithm does not require DFT, least squares estimation and orthogonal filters. The algorithm is based on a digital all-pass filter. The estimated frequency derived from the fundamental and filtered fundamental components is not affected by any shift in the system frequency. The algorithm does not require expensive high speed microprocessor such as digital signal processor. It is easy and straight forward to implement the frequency estimation algorithm in real time with low cost microcontroller. Site measurement and computer simulation demonstrate that the method to measure fluctuating frequencies is technically superior to the previous approaches.