VSC Control of Grid Connected PV for Maintaining Power Supply During Open-Phase Condition in Distribution Network

The grid-connected photovoltaic (PV) system with battery energy storage (BESS) has been in use for many demand-related issues. This article discusses the use of grid-connected PV with BESS in case of open-phase condition in the distribution system. An open-phase condition at medium voltage (11 kV) will result in continuous voltage sag at low voltage (LV) voltage level (400 V), which may be detrimental to various kind of loads, especially for constant power loads. This article presents an approach to mitigate such a scenario by using a control strategy for voltage source converter of grid-connected PV connected to the distribution transformer terminal. The utility of the proposed configuration is demonstrated as the voltage is restored in all phases at the LV level during an open-phase fault at the MV level, and results obtained for selected possible loading conditions have been presented. For further validating the proposed control strategy in real-time conditions, experimental verification is also done on an NI-based PXI hardware setup along with an Opal-RT based hardware in the loop system, and results for the same have been presented.