A Novel Unified Controller for Grid-Connected and Islanded Operation of PV-Fed Single-Stage Inverter

 Abstract

A Novel Unified Controller for Grid-Connected and Islanded Operation of PV-Fed Single-Stage Inverter In this paper, a novel robust current droop controller (RCDC) using a single droop loop is proposed. The controller supports dual modes of operation for micro-grids (MGs), including grid connected mode (GCM) and islanded mode (ISM), while ensuring seamless transition between the two modes with proportional power sharing maintained. An improved maximum power point tracking (MPPT) technique is also incorporated for the parallel operation of single-stage inverters fed by multi-string PV array topology. Additionally, an improved phase-locked-loop-less (PLL-less) method is presented for the self-synchronization strategy of the parallel operation of PV-inverters with the main grid while maintaining the full capabilities of the unified control architecture, obviating the usage of conventional PLLs. The performance of the proposed control scheme is validated through real-time simulations (RTS) using dSPACE MicroLabBox.

Keywords

Smart Grid, Distributed Generation,Unified Droop Controller,Self-Synchronization, MPPT