Enhancement of Fault ride through strategy for single-phase grid-connected photovoltaic systems

Increasing efficiency and decreasing cost of Photovoltaic (PV) panels has led to the rise of many PV Plants. Considering their evolution, Grid standards require PV systems to remain connected and support the grid by providing reactive power during a fault. In order to achieve this, a control system that provides Fault-Ride-Through (FRT) capability for grid-connected PV systems is proposed. The FRT requirements, i.e., injecting a minimum 2% reactive current for every 1% change in the voltage, and limiting the current overshoot of the voltage source converter switches are met by the designed controller. During a fault, when the active power of the PV plant is decreased, the controller allows reactive power to be injected into the grid. In case the fault prolongs over a certain stipulated time as described by grid codes then the PV system is disconnected from the grid until the fault is cleared. Simulations verify that the proposed control system achieves the FRT requirements when providing FRT for symmetrical and asymmetrical faults.