Frequency adaptive instantaneous power quality analysis using frequency locked loop based Kalman filter technique

This paper proposes the application of frequency locked loop (FLL) based on the second order generalized integrator (SOGI) and a Kalman filter (KF) for frequency adaptive instantaneous power quality (PQ) analysis. The FLL tracks the time-varying grid voltage fundamental frequency adaptively. The orthogonal waveforms of fundamental and harmonic components of grid voltage waveform are extracted using the quadrature signal generator (QSG)-SOGI and a linear Kalman filter (LKF), respectively. The fundamental voltage amplitude is obtained from the orthogonal voltage waveforms as provided by the QSG-SOGI and is fed to an extended Kalman filter (EKF) to extract the instantaneous flicker level (IFL). The proposed SOGI-FLL-KF technique provides accurate instantaneous results for PQ analysis based on the measurement of phasor quantities. Synthetically generated grid voltage waveforms are used in MATLAB/Simulink for instantaneous PQ analysis by the proposed SOGI-FLL-KF technique. The simulation results show that the proposed technique can be used as an effective technique for frequency adaptive instantaneous PQ assessment.