Suppression strategy for the inrush current of a solid-state transformer caused by the reclosing process

Abstract

Abstract The automatic reclosing strategy is an effective measure to improve the reliability of a distribution network. It can quickly clear instantaneous faults in the grid. The traditional transformer has proven to be reliable and robust during the reclosing process. However, the influence of the reclosing process on the operational characteristics and reliability of solid-state transformers (SST) is still unclear. The reclosing action may generate a huge inrush current, resulting in shutdown and even damage of the SST. To address this problem, this paper proposes an inrush current suppression strategy. First, the operational performance of the SST under a reclosing process is discussed, and the inrush current generation mechanism is analyzed in detail. Then, considering the controllability of distributed generation (DG), a novel DG-supported inrush current suppression strategy is proposed. The suppression ability of the DG on inrush current in different initial conditions is analyzed. Finally, the effectiveness of the proposed strategy is verified by simulation and experiment. These show that the proposed strategy can help to enhance the FRT capability of the SST, as well as support the SST to maintain continuous power supply and physical integrity during grid faults.