Grid Synchronization of a PV System With Power Quality Disturbances Using Unscented Kalman Filtering

This paper proposes a new grid integration control scheme for a single-stage PV system connected to a three phase grid, that implements an Unscented Kalman Filter algorithm (UKF) to abstract the fundamental components of the PCC voltage and load current. The dc link capacitor voltage and the PCC voltage are regulated using a Proportional Integral (PI) controller. UKF effectively extracts the fundamental components of the PCC voltage and the load current. The simulation and real-time studies show that the proposed UKF-PI control scheme effectively extracts the maximum PV power and mitigates the load current harmonics by decreasing the Total Harmonic Distortion (THD) of the utility grid current. The THD is within the limits prescribed by the IEEE 519. The performance of the proposed scheme is verified under grid voltage sag and swell conditions. The results obtained envisage that effective grid synchronization is achieved with Power Quality Disturbances, i.e., the grid current is sinusoidal while the PCC voltage is regulated by providing appropriate reactive power.