Frequency and harmonic evaluation using non-linear least-squares technique

With increasing harmonic pollution in the power system, monitoring and analysis of harmonic variations has become important. Because of limitations associated with conventional algorithms, particularly under supply-frequency drift and transient situations, a new approach based on non-linear least-squares parameter estimation is proposed as an alternative solution for high-accuracy evaluation. The proposed algorithm determines simultaneously the supply-frequency variation, the fundamental-amplitude variation, as well as the harmonic-amplitude variation. Examples are used to demonstrate the effectiveness of the algorithm.