A Standalone Photovoltaic Power Generation System With a Hybrid Maximum Power Point Tracking Strategy and Dual-Input Power Conversion

This paper proposes a standalone photovoltaic (PV) power generation system for off-grid applications, integrating a dual-input power converter, a five-level multilevel inverter, and a coordinated control architecture to improve system stability, power quality, and energy utilization efficiency. The proposed dual-input converter can simultaneously interface with PV modules and lithium battery packs, enabling coordinated energy management through a simplified power coordination mechanism and avoiding the high complexity and computational burden associated with conventional multi-stage conversion architectures. In addition, a PV-voltage-based maximum power point (MPP) region detection method is incorporated into a low-complexity hybrid maximum power point tracking (MPPT) framework to achieve a balance between computational efficiency and tracking performance. Experimental results demonstrate that the proposed hybrid MPPT framework successfully tracks the maximum power point, achieving output powers of 198 W and 99 W under solar irradiance conditions of 1000 W/m2 and 500 W/m2, respectively, corresponding to a tracking efficiency of approximately 99%. Regarding output power quality, the proposed standalone PV system incorporates a five-level multilevel inverter, a multi-carrier pulse-width modulation (MC-PWM) strategy, and an LC output filter to effectively mitigate harmonic distortion. The measured voltage total harmonic distortion (VTHD) is reduced from 21.24% at the inverter output stage to 4.5% after LC filtering, demonstrating effective harmonic suppression and improved output waveform quality. Moreover, the overall system maintains a stable 65 V DC-link voltage under high-irradiance, low-irradiance, and nighttime operating conditions, demonstrating stable and reliable operation. Owing to its high efficiency, modular design, and operational flexibility, the proposed system is well suited for applications such as remote-area electrification, off-grid residential systems, agricultural power facilities, and green microgrids.