Low Voltage Ride Through Control Method of Photovoltaic Grid-connected Inverter Based on Model Current Predictive Control

Abstract

With the growth of the capacity of the grid-connected photovoltaic power station accessed to the grid, the grid-connected operation photovoltaic power generation system demonstrates increasing competitiveness. When the power system voltage sags due to a short circuit fault, a low voltage ride-through control strategy was proposed to improve the stability of the power system in response to the serious consequences of a large-scale photovoltaic power plant suddenly taking off the network. Based on the established model current prediction control strategy of the inverter, the low voltage ride through control strategy of the voltage symmetrical sag on the grid side was designed. According to the grid voltage drop depth, the reference values of the active and reactive components of the output current were obtained, and the active and reactive power were redistributed during the voltage drop. Meanwhile, the output current from inverter was controlled with limiting amplitude to make inverter support grid with wattles power under the premise of undercurrent for current. A simulation model of grid-connected PV system was built in Matlab/Simulink, and the simulation results show the proposed LVRT operation can be realized under unbalanced grid voltage conditions.