SINGLE-PHASE GRID-CONNECTED PHOTOVOLTAIC SYSTEMS WITH DYNAMIC VOLTAGE SUPPORT FOR LOW-VOLTAGE RIDE THROUGH OPERATION

Abstract

The article introduces a dynamic voltage support (DVS) scheme designed to achieve low-voltage ride-through 
(LVRT) with a grid-connected photovoltaic (PV) inverter during voltage sag faults. The DVS scheme involves 
the development of an additional reactive active current control mode, derived from a conventional reactive 
current control approach, to ensure stable system operation and improved effectiveness, particularly in low
voltage networks with lower X/R ratios at the point of common coupling. The performance of the proposed 
controller is evaluated through simulations of a 4 kW system for voltage sag faults and further validated through 
real-time simulations and experimental setups. The results demonstrate that the active and reactive power are 
regulated in compliance with grid code requirements, enabling the controller to achieve LVRT within the time 
limits of grid standards during symmetrical faults, making it suitable for fast transient events. This allows the PV 
system to operate under its nominal capacity, thereby avoiding undesirable grid disconnection events.