Grid voltage offset and harmonics rejection using second order generalized integrator and kalman filter technique

This paper proposes the application of second order generalized integrator (SOGI) and Kalman filter (KF) technique for the rejection of DC offset and harmonics from the distorted grid voltage waveform. The SOGI is used to estimate the orthogonal waveforms of grid voltage fundamental frequency component. On the other hand, the linear Kalman filter (LKF) is used to reject the DC offset and harmonics present in the distorted grid voltage waveform. The resonance and harmonic frequencies of the SOGI and LKF, respectively, are provided by the frequency locked loop (FLL). The proposed technique provides better results to reject the DC offset and harmonics as compared to the multiple SOGI (MSOGI) technique. The improved performance of the proposed technique is due to the use of LKF which not only rejects the DC offset and harmonics but also non-sensitive to the change of SOGI´s gain. Synthetically generated grid voltage waveforms are used in MATLAB/Simulink to depict the superior performance of the proposed SOGI-LKF technique as compared to the MSOGI with/without offset rejection technique.