THREE PHASE GRID CONNECTED PV SYSTEM WITH LVRT CONTROL STRATEGY

In power system the transient short circuit faults result in low voltages in the lines. Due to this, performance of the loads connected to the grid will be affected. In order to maintain constant grid voltage during transient faults, reactive power must be controlled accordingly. In order to supply the required reactive power during dynamic fault condition, conventionally Distribution Static Synchronous Compensator (D-STATCOM), Unified power flow controller (UPFC), Unified Power Quality Conditioner (UPQC) etc. were proposed. In order to reduce the installation and operating cost, Low Voltage Ride through (LVRT) is one of the upcoming technique to supply the necessary reactive power during low voltage condition. In this technique a Photo Voltaic (PV) system should stay connected to the grid and injects reactive power in order to maintain constant grid voltage during fault conditions. After the grid voltage recovers to its nominal value, the PV system needs to provide real power as fast as possible, so as to maintain real power balance which therefore helps the whole system recovery.