Direct power control of an under-damped grid connected boost inverter

This paper presents a simple and direct power control approach to control a single-phase grid-connected boost inverter (GCBI) for renewable energy applications. A DC voltage source and a single-phase single-stage boost inverter that is connected to the grid by an L filter form the power injection system (PIS). Unlike the conventional voltage source inverters (VSIs), the boost inverter can generate an AC output voltage with amplitude larger than the DC input one, only in a single stage. In comparison with multi-stage power conversion systems, the aforementioned inverter has less number of devices and components which results in low cost and higher efficiency. Nevertheless, the boost inverter suffers from undesirable dynamic behavior and extreme fluctuation response that makes it difficult to control. Thus, the proposed power injection control system consists of two parts. First, a proper state-feedback control scheme is designed to increase damping and also improve the stability of the closed-loop system. Then, the direct power control strategy is employed to control and track the desired powers that should be injected into the grid. Simulation results are presented to validate the effectiveness of the proposed control strategy.