Model-predictive direct power control of grid-connected inverters for PV systems

Based on the instantaneous power theory, photovoltaic grid connected inverter power predictive model in d-q rotating coordinates was established. After sampling grid current, output active power and reactive power of the grid-connected can be directly predicted by using the predictive model. The model predictive direct power control strategy of photovoltaic grid connected inverter was designed. According to the power predictive model and cost function, the optimal space voltage vector was selected. The proposed control strategy does not need PWM modulation module and the inner current control. It has low computational complexity and easy to be implemented. The control system performance was simulated in different light intensity conditions. The results show that the grid-connected inverter can track illumination change and output power with good dynamic and static performance, which validate the effectiveness of proposed control strategy.