Kalman-filter Based Maximum Power Point Tracking for a Single-Stage Grid-Connected Photovoltaic System

This paper presents a Kalman-filter based maximum power point tracking (KF-MPPT) in a single-stage photovoltaic (PV) system that is connected to the AC grid. In the proposed KF-MPPT method, there isn’t any current sensor on the DC side, so the output power of the PV array isn’t measured directly. This MPPT method uses the d-component of AC current for calculating the maximum powerpoint. The photovoltaic array is connected directly to the power system via a voltage-source inverter (VSI). Hence, the MPPT algorithm must be done by direct controlling of the VSI. For this, an improved voltage-oriented control (VOC) scheme is used, which contains an outer voltage control loop and an inner current control loop. The MPPT algorithm determines the reference voltage of the outer voltage control loop. The inner current control loop is controlled as the system works at the maximum power point, as well as the reactive injected power set to be zero. The performance of the proposed system is validated by using computer simulations and is compared with the improved Perturb and Observe (P&O) method. Simulations results show that the proposed KF-MPPT method provides effective and fast response under rapidly irradiance changes, as well as no oscillation at steady-state.