A Double Closed-Loop Steady-State Error Compensation Strategy for Grid-Forming Converters Using the Deadbeat Predictive Control Technique
The deadbeat predictive control (DPC) method has received increasing research interest in the grid-forming converter control strategy, due to its advantages of fast response in emergency grid scenarios and great potential in utilizing a system multi-time-step predictive optimization strategy. However, the voltage–current double-loop DPC of a grid-forming converter is sensitive to the filter inductance and capacitance parameters, resulting in a steady-state tracking error under parameter mismatch conditions. To address this issue, this manuscript proposes a double closed-loop steady-state error compensation strategy for grid-forming converters using double-loop DPC. Based on an analysis of the DPC algorithm and the mechanism of performance degradation caused by parameter mismatch, compensation terms are designed for the inner current loop and outer voltage loop respectively. The compensation terms are constructed from the feedback errors, effectively and rapidly suppressing the performance degradation caused by parameter mismatch, without introducing complex observers that may degrade the system dynamic response speed. A simulation model, which includes both the physical model of the electrical circuit and the discrete-time controller with sample-and-hold characteristics, is established to verify the proposed control strategy under different operating conditions, including load transient and inductor parameter mismatch. The results demonstrate that the proposed compensation method significantly reduces the steady-state tracking error caused by parameter mismatch while preserving the fast dynamic response characteristic of DPC, thereby substantially improving the accuracy of active power output and enhancing the system’s robustness against parameter deviations.