Multi-Objective Solar Power Conversion System With MGI Control for Grid Integration at Adverse Operating Conditions

Abstract

This article presents a new control for the multi-functional operation of a grid-connected solar power conversion system (SPCS). It is a combination of several generalized integrals for grid synchronization as well as fundamental load current component extraction. This multiple generalized integral (MGI) control is designed to overcome the demerits of conventional integral controllers with inadequate operation at adverse grid conditions such as grid frequency variation, phase jumps, DC offsets, noise, harmonics and other waveform distortions. The control is designed to separate the load power accurately into two-parts, i.e. active fundamental part (AFP) and non-active fundamental part (NAFP). This control extracts the AFP of the load current even during the disturbed grid and unbalanced load conditions. According to the comparison with the load current AFP and the photovoltaic (PV) available power ( $P_{pv}$ ), three operating modes are used such as bright mode, dim mode and dark mode. During the bright mode, the total load power is being supported by the system and the remaining power is injected to the grid, the load power is shared by the system and the grid during the dim mode, and the load current AFP is supported by the grid during the dark mode. In every mode of operation, the SPCS mitigates the total load demanding NFAP and thereby keeping the grid currents as sinusoidal and in-phase with the fundamental grid phase voltages and maintaining the IEEE-519 grid power quality standard. This system is modelled and the performance is simulated in MATLAB/Simulink platform, and simulated results are presented. A prototype of the system, is developed in the laboratory and test results at various operating conditions are reported for validation of the system.