MROGI and MPS-P&O MPPT Technique Based Self Reliant SEC-BES System

This paper presents a three-phase, four-wire, grid-integrated, solar photovoltaic energy management system with battery backup. The solar energy conversion-battery energy storage (SEC-BES) system is compatible both in grid-connected mode (GCM) and islanded mode (IM), respectively. The system is self compatible to seamlessly transit between the two modes. In GCM, the system operates using grid-following control as a controlled current source, while in IM, the system operates using grid-forming control as a controlled voltage source. Modified reduced order generalised integrator (MROGI) is incorporated into the control strategy which enables the voltage source converter (VSC) to also operate as a static compensator. As a result, power quality issues at the grid interface get resolved. In grid forming strategy, the VSC adopts a multi-loop control strategy so that a proper sinusoidal supply is available across critical loads. Multiple-power-sampling based perturb and observe maximum power point tracking algorithm has been adopted in this investigation which is compatible especially with slow/rapidly changing environmental conditions. In this paper, seamless transition between IM and GCM is realised in accordance with IEEE-929 and IEEE-1547-2018 by estimating the point of common coupling (PCC) voltage, frequency and phase angle difference range respectively. These parameters get estimated using phase-locked loop strategy based on MROGI. The entire system is realised in a MATLAB environment in a discrete time frame under various operating conditions. The total harmonic distortion of grid current (GCM) and PCC voltage (IM) is observed within 5% in accordance with IEEE-519, 929 and 1547–2018 respectively.