A Power Balance Control Strategy for The Photovoltaic Cascaded Multilevel Inverter

The photovoltaic cascaded multilevel inverter (PV-CMI) can realize the component-level maximum power point tracking (MPPT) and the multilevel output voltage, worth investigating in the field of photovoltaic power generation. However, when the powers of photovoltaic modules connected to H-bridge units (HBs) are unbalanced, it is easy to cause over-modulation problems of partial HBs, which will deteriorate the quality of the grid-connected current and further lead to instability. To solve this problem, considering the background harmonic of the power grid, a power balance control strategy based on the harmonic compensation and suppression is proposed to further expand the linear modulation range of the H-bridge unit (HB). It can not only maintain the stability of the system but also improve the quality of the grid-connected current. Finally, the effectiveness of the proposed strategy is verified by the simulation.