A Multi-functional Utility Interface of BIPV Systems Based on Cascade Multilevel Converter

Building integrated photovoltaic (BIPV) systems bring forward many requirements to grid-tied inverters in these aspects such as generating efficiency, shading effects, harmonic & reactive current compensation and quick economical payback, etc.. This paper presents a multi-functional utility interface of BIPV systems based on cascade multilevel converter. It has two operating modes: one is operated as grid-tied inverter at normal insolation level and the other is operated as active power filter (APF) at very low insolation level or at nighttime. Compared with traditional inverters, cascade multilevel converter is much more efficient and suitable for utility interface of BIPV system because it has the merits of high efficiency, minimum switching frequency, low switching stress and EMI, approximate sinusoidal waveform voltage output with low total harmonic distortion (THD), modular structure and good dynamic stability. Simulation and experimental results have verified its feasibility and advantage.