Reactive current injection based modified LVRT control for grid interfaced converter-less solar PV system

Abstract

As the integration of renewables like solar PV, wind etc. with utility is increasing day by day, the main issue arises is to maintain the stability of grid. In order to maintain this criteria grid operators are frequently upgrading the grid codes. According to these grid codes, it is required that during momentary disruption in the utility side, solar PV inverters will remain connected and this aspect is often termed as low-voltage-ride-through (LVRT) of solar PV inverters. For such purpose, PV inverters are assembled with certain control logics to ensure smooth operation and ride through the disturbance period according to the grid code. This article proposed an enhanced LVRT controller for grid-connected photovoltaic inverters. The controller features an adaptive reactive current injection mechanism based on maintaining constant dc link voltage in a converter-less solar PV system. These innovations improve inverter compliance with grid codes and enhance voltage dip recovery. Simulation of grid interfaced PV system is done in MATLAB and tested on OPAL-RT during real time scenarios.