An efficient frequency and amplitude tracking method for real-time power quality monitoring

Current and voltage harmonics distortion is an important issue in power quality (PQ) of power systems. In order to monitoring the PQ of distributed generators in real-time, an efficient method for tracking power harmonic parameters is presented in this paper. Firstly, a state-space model used for non-stationary harmonic analysis is constructed based on the definition of instantaneous frequency, in which, amplitudes and phases are taken as states and frequencies as time-varying parameters of a dynamic system. Thereafter, the harmonic tracking problem can be considered as estimating the states and parameters simultaneously. To solve this problem, a prediction error minimization (PEM) based algorithm was proposed and evaluated using computer simulations. The experimental results proved that the algorithm is not sensitive to frequency or amplitude variation and converges very fast.