Study on Power Feedforward Control Strategy for PWM Rectifier

Abstract

With the increasing proportion of renewable energy and DC load, there are more and more occasions for both new energy generation and power grid to supply power to DC load. In this paper, when photovoltaic and mains power supply DC load at the same time, the grid stabilizes the DC side voltage through AC/DC. When the illumination changes greatly, the traditional double closed-loop control shows a certain degree of hysteresis, which leads to the DC side voltage cannot be adjusted in time, and the whole system dynamic performance is not ideal. To improve the DC bus voltage control dynamics, this paper introduces the load power and photovoltaic output power into the model prediction direct power control loop. Based on simulation results, the variation of DC voltage of the proposed control strategy is smaller than that of the former when the illumination changes sharply. After that, the Fourier analysis of the grid side current also shows that the proposed strategy makes the grid side harmonic content less, which verifies the effectiveness and superiority of the strategy.