A Novel Control Strategy for a Single-phase Grid-connected Power Injection System

In this paper, a novel and simple control strategy, based on state feedback method is suggested to control the power injection system (PIS). The considered PIS is composed of, a DC voltage source, a voltage source inverter (VSI) and a L-C-L filter. The DC source includes the battery source with boosted voltage. The battery can be charged with photovoltaic cells. Since, the grid voltage acts as a disturbance, so, the state space model is modified to reject the disturbance. In the proposed method, for the power injection requirement, the minimum input DC voltage, is calculated. Moreover, to avoid measurement problems such as noise and cost, an observer is also designed. The major problem of the single-phase PISs is the injection of somewhat DC current together with AC current. We show that the proposed controller not only implements nearly perfect tracking, but also eliminates the injected DC current to the grid. In addition, a Proportional-Resonant (PR) is also designed and applied to PIS. Simulation results show that the proposed method has significant advantages versus PR such as simple realization and application, low overshoot, no DC offset at the output current and fast response. The simulations are performed on average and accurate models. The accurate model encompasses practical conditions.