A new nonlinear control to improve the efficiency of the PV-SAPF system

Abstract

This research introduces a new integral robust nonlinear backstepping command (IRNBC) approach for managing a photovoltaic (PV) system connected to a distributed power resource (PV-DPR) grid. The control method employs a direct power command (DPC) with space vector pulse width modulation (SVPWM) to command the multifunctional voltage source inverter (MVSI), which links the PV-DPR to the grid. The DPC-IRNBC technique was used to reduce overshoot and enhance performance across all control loops of the PV-DPR grid connection. Both the DC-DC boost converter-based PV-DPR and the MVSI controllers are utilized to simultaneously regulate the maximum power point (MPP) of the PV-DPR and ensure grid energy quality. Initially, the proposed approach focuses on the MPPT, current, and DC voltage command loops of the PV-DPR to maintain a consistent DC voltage at the desired level. This control aids in generating a reference current that facilitates efficient extraction and continuous utilization of MPP from the PV-DPR. Subsequently, the strategy is extended to manage the energies exchanged with the grid, along with the control of MVSI capacitor voltage. This comprehensive approach guarantees precise power management and utilization, even for nonlinear loads, while maintaining high grid quality in terms of harmonics, energy factor, overshoot, robustness, and response time. To validate the efficiency of the designed IRNBC-based PV-DPR grid connection, extensive simulation tests were conducted using Matlab with Sim Power Systems and S-Function. These tests involved a careful comparison with classical controllers, evaluating aspects such as success, performance, robustness, effectiveness, and the controller's ability to respond under varying irradiation conditions and nonlinear load imbalances.