A Voltage Oriented Control Method for PV - Grid Interfaced Inverter by Using Advanced MPPT Algorithm

The output power of PV module varies with module temperature, solar irradiation and loads. And in order to quickly and accurately track the sun, it is necessary to track the maximum power point (MPP) all the time. An improved maximum power point tracking (MPPT) with better performance based on voltage-oriented control (VOC) is proposed to solve a fast changing irradiation problem. In VOC, a cascaded control structure with an outer dc link voltage control loop and an inner current control loop is used. The MPPT controller is applied to the reference of the outer loop control dc voltage photovoltaic (PV). In this project, the main component of the single-stage grid connected PV system is the three-phase voltage source inverter (VSI). The voltage-oriented control (VOC) method used for VSI employs an outer dc link voltage control loop and an inner current control loop to achieve fast dynamic response. The performance of the power flow depends largely on the quality of the applied current control strategy. In this project, the current control has been implemented in a rotating synchronous reference frame d, q because the controller can eliminate a steady-state error and has fast transient response by decoupling control. The robust tracking capability under rapidly increasing and decreasing irradiance is verified in simulations. Simulation results on a large-scale grid-connected PV system show the effectiveness of the proposed control scheme in terms of delivering maximum power into the grid under variable conditions