Multisource Grid-Connected DC/AC Hybrid Microgrid Decentralized Control Under Input Sources Variation

Abstract

This article proposes a multisource distributed generation-based dc/ac grid-interactive microgrid providing quality power to a distribution network featured with a constant power load (CPL). The hybrid dc/ac system is a consolidation of a Permanent Magnet Synchronous Generator (PMSG) based wind turbine, Photovoltaic array, and Battery Energy Storage System (BESS) at a common dc-bus. The BESS system ensures continuous power support and takes care of the infrequent nature of photovoltaic and wind. The decentralized control is applied in the proposed grid-interactive configuration during variable wind speed and solar irradiance source disturbance to achieve three goals, namely, regulating the dc-bus voltage, extracting maximum power from distributed generation, and supplying energy-efficient power to the grid. The control strategy combines Maximum Power Point Tracking (MPPT), phase-locked loop (PLL) for the grid-linked synchronization, reduction of harmonic output current control, active/reactive power (P/Q) control, and virtual droop control used simultaneously. Applying virtual dc bus voltage droop control and MPPT can regulate the proper power-sharing among sources in a dc sub-grid. During the switching of the interlinking converter, high-frequency harmonics are created, which are eventually mitigated by LCL filters employed in the ac bus. Simulations are developed in Matlab Simulink, and it is verified using real-time digital simulator OPAL-RT to ratify the effectiveness of the suggested control strategy.