IMPROVEMENT OF POWER SHARING IN GRID INTERFACED SOLAR PV SYSTEM

Abstract

The world moves to the direction of highly proliferation of photovoltaic (PV) panels. This orientation is caused by energy demand, decarbonization strategy and expansion and resilience of power distribution network. The PV systems would need to provide ancillary services for sustainable grid operation. The ancillary services can be grid voltage or frequency support. This thesis focuses on modelling the PV system for grid voltage instability mitigation. The model predictive control (MPC) technique is chosen among different technique for its non-linearity, flexibility and intuitive understanding. The recent papers are reviewed for ideas in MPC approach, voltage deviation mitigation strategy, MPPT and other converters and control systems. The procedure for designing low power PV system topology is described. One of the MPC approaches is chosen and elaborated for low power rating with voltage instability mitigation strategy. The boost controller technique, which is based on the modification of perturb and observe (P&O) algorithm, is added to complete the PV system. The dynamic performance of the PV system is tested over different grid voltage level cases in Matlab simulation. The designed PV system control has high capability in handling grid voltage sags and surges. The regulation of switching frequency variation is discussed to further improve current THD and reduce filter’s inductor size. The approaches to regulate switching frequency are attempted with a penalty in the objective function, adaptation to simple LCL filter and LCL filter with parallel damping resistor. It is observed that the LCL filter form of the controller further reduces switching frequency spectrum, which decreases filtering quality. The hardware-in-the-loop test is covered.