Droop based Low voltage ride through implementation for grid integrated photovoltaic system

This paper signifies the development of an efficient and cost-effective control scheme for operation of grid integrated photovoltaic (PV) system under low voltage ride through (LVRT) condition. During LVRT If the PV system was to disconnect from the grid, the disconnection further aggravates the situation by causing larger disturbance than what was caused by the fault. To stabilize the system and prevent the flow of over current during LVRT it is necessary to control the reactive power injection in the system. The proposed scheme balances the active power though proportional gain regulation of plug in controller. Compared to the conventional LVRT method, this method is more cost effective. A normal maximum power point tracking (MPPT) scheme is implemented during normal operation. But in case of fault condition, an extra proportional controller is added to assist the droop characteristics of photovoltaic power voltage curve and attain system stability. Simulation has been performed on a grid integrated PV system of 4kW and LVRT conditions are tested. It is observed that the response of controller is fast and seamless during transition mode.