Frequency measurement in power networks in the presence of harmonics using fourier and zero crossing technique

A new approach to the design of a digital algorithm for network frequency estimation is proposed. The algorithm is derived using Fourier and zero crossing technique. The Fourier method is used as digital filter and zero crosing technique is applied to the cosine and sine components of the original signal which can be corrupted by higher harmonics. The algorithm showed a very high level of robustness as well as high measurement accuracy over a wide range of frequency changes and it can be used for frequncy tracking in power networks when the higher harmonics are presented in voltage or current signals. The theoretical basis and practical implementation of the technique are discribed. To demonstrate the performance of the developed algorithm, computer simulated, as well as real life data records, are processed.