Control of Grid Tied Solar Inverter with Low Voltage Ride Through

Abstract

The objective of the paper is to develop a control strategy to meet the Low/High Voltage Ride Through (L/HVRT) grid code for a grid connected PV inverter to work under sag/swell condition. Proposed system is designed to stay connected to the grid during the sag/swell period for specified time duration as demanded by the Grid code, without damaging the power electronic converters. During normal operation inverter is designed to inject active power to the grid. A space vector-based sag detection algorithm along with a Current Limit Control (CLC) of inverter is developed. The proposed CLC extracts the active and reactive power from PV system as stipulated by the sag conditions of the grid. The PV operating point is made to shift away from MPP under sag conditions and returns to MPPT control when system voltage resumes. The developed control strategy is capable to restrict the current during sag/swell within the tolerable limits for the inverter to exhibit L/HVRT competency.