Indian Grid Code Based Low Voltage Ride Through Control Development for Large Scale Solar PCS

Abstract

To meet with increasing demand of user's load, the integration of solar generation is promoted by various governments. As a mandatory requirement, the solar generation source should follow the grid code to maintain the grid stability as well as to enhance the system robustness by complying standards such as Low Voltage Ride Through (LVRT). In this paper, a control strategy for solar inverter is addressed with emphasising the LVRT operation based on reactive power injection. The proposed control strategy enables solar inverter to ride through grid voltage changes as per the Indian grid code without blocking of inverter's switching pulses. The fast response of current controllers along with feedforward control is adopted for cooperative operation of solar inverter during grid faults. The fast response of current controller is desired to shorten the reactive power recovery time, while the feedforward control is used to avoid current spike at the instance of grid fault. The proposed LVRT control strategy for solar inverter is validated by hardware test results of 1.25 MW solar inverter. The hardware test results confirm that the LVRT operation of solar inverter is in compliance with Indian grid code standard.