Instantaneous power quality analysis using frequency adaptive kalman filter technique

This paper proposes the application of frequency locked loop (FLL) based Kalman filter (KF) technique for frequency adaptive instantaneous power quality (PQ) analysis. In the proposed technique, the FLL is integrated with the linear Kalman filter (LKF) to estimate the time-varying grid fundamental frequency. The LKF is used to estimate the orthogonal waveforms of fundamental and harmonics components present in the distorted grid voltage waveform based on the fundamental angular frequency extracted by the FLL. The amplitude of grid fundamental frequency component obtained by the LKF is fed to the extended Kalman filter (EKF) to extract the instantaneous voltage flicker. The proposed FLL based KF technique tracks the time-varying grid voltage parameters instantaneously, adaptively and accurately. Moreover, the proposed technique has reduced the complexity and convergence time of the KF as the grid fundamental angular frequency is extracted separately by the FLL. Synthetically generated grid voltage waveforms are used in MATLAB/Simulink to demonstrate the effective application of the proposed technique. The simulation results show that the proposed technique can be used as an efficient technique for frequency adaptive instantaneous PQ assessment.