Advanced Discrete Control of Three-Phase Grid-Connected Inverter Using Improved Dead-Beat Compensator

Grid-connected inverters, recognized as one of the key elements in distributed generation systems, have been widely used in modern power systems. In recent literature, many research focuses have been put on the compensation of discrete-time delay grid-connected inverters for better steady-state operation. Even though observer-based methods have shown impressive performance for delay compensation, the existence of model uncertainties has degraded their estimation accuracy and thus has affected the overall control performance. Therefore, based on the modified inverter model, a one-beat delay compensator using an improved Kalman observer is proposed in this article. According to mathematical analysis, the proposed method can provide an accurate estimation of state variables under system uncertainties and can effectively perform discrete-time delay compensation. The effectiveness of the proposed control algorithm is verified by performance comparison with a conventional control method on an experimental inverter prototype. The results have verified that the proposed method can provide stable regulation of the voltages and currents under 1.5- and even 2.5-beat time delay conditions in grid-connected inverters.