Grid Fault Ride Through Capability of Voltage Controlled Inverters for Photovoltaic Applications

Abstract

Fault ride through (FRT) capability is one of the challenges faced in today's large-scale grid photovoltaic (PV) power system. Solar PV systems are designed to disconnect, and remain offline for 5 mints when tripped by loss of grid voltage. However, The PV system, by itself, cannot differentiate between transient and sustained grid voltage loss. It behaves in the same manner in the two cases, i.e., disconnect, stay offline for five minutes and then makes re-connection trial. Staying offline for fiveminutes unnecessarily wastes considerable amount of clean energy from the PV, may affect the power balance of the grid and many other adverse effects of service discontinuity. This paper presents a new control strategy for grid FRT capability of a large grid connected PV System to increase the stability and reliability of the PV system, in which a photovoltaic inverter can be controlled to pass transient faults. Our strategy is to control the inverter so that it disconnects from the grid when the current exceeds a specific value for a specific time otherwise, it still connected and ride-through the faults to ensure continuous output power under transient fault conditions. A case study of a 100 KW PV power system simulated to ensure the proposed control. The results show the ability of the proposed control method to manage various types of grid faults. A case study of a 100 KW PV power system simulated to ensure the proposed control. The results show the ability of the proposed control method to manage various types of grid faults.