Sector Wise Modified Droop Control to Improve Voltage Regulation and Current Sharing in Parallel Boost Converter Interfaced DC Microgrid

Abstract

Photovoltaic (PV) panel interfaced multiple parallel boost converter with storage interface is essential for forming dc microgrid. Impedance shaping or droop coefficient adjustment of individual converters is essential to achieve better voltage regulation (VR) and proportional current sharing. However, the voltage droop with increased loading is not linear even with dual-loop control, where the outer loop is voltage mode with droop coefficient adjustment and the inner one is a current loop. The loading range is narrow to maintain VR within the limit. This nonlinearity in droop coefficient after certainly, enhanced loading is due to load-dependent converter output impedance and converter nonidealities. In this work, a sector-wise modified droop coefficient adjustment control is proposed which ensures enhanced loading operation of individual converters while maintaining the VR constraints. This article also proposes an optimal droop coefficient, enhancing current distribution, which ultimately decreases circulating current and conduction losses. The proposed control method is simulated in PSIM and experimentally validated in 1.5 kW, 48 V extra low voltage dc (ELVdc) Microgrid Set-Up.