Startup Strategy With Constant Peak Transformer Current for Solid-State Transformer in Distribution Network

Solid-state transformer (SST) is widely used in many fields and it plays a key role in the development of energy internet. The startup strategy of SST adopted in distribution network has to be designed elaborately because in this application the requirement of functionality, flexibility, and expandability is very high. A number of researches for the startup process of SST were made and several solutions were proposed. In these solutions, the transformer current in the charging process was unable to be observed or controlled, leading to the lack of analytical basis in a startup strategy design. In order to make the charging process observable and controllable, the authors developed a mathematical model of this process. Based on the model, a new startup strategy is proposed to make the peak transformer current in the charging process a constant value. Cases with different conditions are analyzed, indicating that the strategy is insensitive to initial values. Experimental results are provided to validate the accuracy of the mathematical model and the effectiveness of the presented solution.