Dual mode operational control of single stage PV-battery based microgrid

This paper presents a single stage solar photo voltaic (PV)-battery based three-phase microgrid in grid connected and isolated modes. The PV-battery system feeds nonlinear load through a voltage source converter (VSC). The battery energy storage (BES) is connected at the DC-link of the VSC through a bidirectional DC-DC buck-boost converter. The proposed control scheme operates the single stage PV system at maximum power point tracking (MPPT) in grid-connected as well as standalone modes. The dual objectives of battery charging and power quality control is implemented through VSC. An adaptive least mean square (LMS) control is used so that grid currents are always maintained balanced and free of harmonics, as per IEEE 519 standards. BES charging, in case of low state of charge (SOC), is implemented by VSC in grid connected mode by using droop based control. Simple and effective perturb & observe (P&O) control for MPPT is executed through the bidirectional DC-DC converter control. The proposed control algorithm is simulated on MATLAB/Simulink with Simscape toolbox and its satisfactory performance is demonstrated in various scenarios.