具有反步预测的双三相四桥臂多电平逆变器用于不平衡低压电网

Wind and solar renewable energy sources (RES) have been fundamental in reducing carbon emissions in electrical energy systems. However, when integrated into low voltage grids, some problems can arise due to the high number of single-phase loads. This situation often leads to unbalanced loads, which can result in increased losses or even under- or over-voltages in one of the phases. This issue is even more critical in the context of isolated microgrids. Therefore, this paper introduces a novel control system for a grid-connected photovoltaic (PV) generation with storage setup based on a dual three-phase four-leg multilevel inverter. This power converter topology, comprising two four-leg two-level three-phase inverters, connects two PV arrays to a three-phase transformer with four wires which in turn connects to a grid. This arrangement is designed to inject PV-generated power into the low voltage (LV) grid, providing support for unbalanced loads. A new backstepping method including the delay simplified dynamics is derived to estimate the optimum converter voltage and near optimum vector to control the load currents, while balancing the capacitor DC voltages. As only one voltage estimate is needed, a fast controller is obtained even if the converter has a high number of voltage vectors. The backstepping method increases the speed of choosing the converter vector, allowing the control of the grid currents injected under both balanced and unbalanced conditions, while also maintaining balance of the capacitor DC voltages in RES. Experimental tests were conducted using a laboratory prototype to evaluate the backstepping performance applied to the proposed PV generation system.