Development of Intelligent Fuzzy PQ-FRT Control Strategy for Grid-Connected Solar PV System

Due to ever-increasing demand for electric power, there is large scale penetration of renewable resources into the grid, especially solar PV systems. Therefore, it is essential that the solar PV systems remain connected to the grid, during normal and fault conditions. Under occurrence of grid fault, it is seen that there is an occurrence of voltage sag and overcurrent condition at Point of Common Coupling (PCC) and an overshoot in dc link voltage of the inverter. This leads to an imbalance in the power flow from solar PV into the grid. To overcome this condition, this paper proposes a Fuzzy based real and reactive power control strategy (Fuzzy PQ-FRT) for Low Volt-age Ride Through (LVRT) for a single stage grid connected solar PV system. The proposed method is simulated in MATLAB under symmetrical fault conditions. It is seen that, upon implementation of the proposed strategy, over current condition is reduced by 46% from that of uncontrolled condition. Also, dc link voltage and voltage sag conditions are improved greatly, enhancing LVRT capability of the system hence ensuring the solar PV systems remain connected to the grid even during fault conditions according to grid code. The proposed method is also validated in a real-time hardware setup, showing an improvement in PCC voltage during fault occurrence.