Seamless Operation and Improved Control of a Standalone Solar-Wind-BES Driven 3P4W System Designed for Remote Onshore Island Applications

Remote onshore island-based power systems require necessity of neutral point due to presence of single-phase loads. Moreover, existence of nonlinear loads overloads neutral wire of wind system transformer, especially in remote systems driven by wind generators, making them more prone to heating and failure. This work presents a novel configuration of a three phase four-wire islanded doubly fed induction generator (DFIG)-based wind energy conversion system (WECS) tied to a local grid formed by a local grid-forming converter (LGFC), supported at DC link by a battery energy storage (BES) and a solar photovoltaic (SPV) array. System utilizes fourth leg of LGFC to compensate for load neutral current demand, ensuring reactive power and harmonic current compensation for unity power factor (UP F) operation of WECS. Rotor end converter (REC) ensures maximum power point tracking (MPPT) of wind turbine and supplements machine reactive power requirement. Suboptimal wind speeds and maintenance require disconnection of DFIG stator without interrupting power flow to loads. Reactive, negative sequence, and harmonic current requirements of connected loads is compensated by LGFC. This enables smooth power exchange among sources and ensures continuous power flow to loads, regardless of DFIG power generation. A seamless adaptation strategy is presented for smooth disconnection/ reconnection of DFIG stator. This seamless control strategy enables uninterrupted transitions. To mitigate power quality issues arising from loads, an improved generalized robust logarithmic family least absolute difference (IGRLF-LAD) control is implemented to enhance PCC voltage and stator current quality. Simulation results demonstrate alignment of system operation with IEEE std. 1547.