Fault Ride-through Strategy For Two-stage Gpv System Enabling Load Compensation Capabilities Using Ekf Algorithm

This paper proposes an extended Kalman filter (EKF) based control strategy for fault ride-through operation in two-stage grid-connected photovoltaic (GPV) system. The controller accounts for nonlinear loads in the system, grid harmonic-currents elimination and grid-currents balancing even during the harmonic/distorted grid voltages. The IEEE standard-1547.4 compels the distributed resource to ride-through during voltage disturbances caused by faults. For the ride-through operation, a limit is imposed on PV active power injection to prevent inverter over-currents and DC-link energy aggregation, which reduces the lifetime of DC-link capacitor. The reactive power is fed to the grid, as per the depth in voltage-sag. The de-rated PV array power is supplied in cases where the inverter cannot handle the utmost PV-power. The power quality improvement is ensured using EKF state estimator, which precisely estimates the fundamental load currents. In distribution network with modern nonlinear loads, especially at far radial ends, the grid voltages are prone to huge diversions and the proposed controller provides a possible solution to maintain active/reactive power support and maintain power quality in the network.