Resonance damping in a smart transformer-based microgrid

Compared with the traditional microgrid, a smart transformer (ST)-based microgrid shows advantages in terms of higher efficiency, increased hosting capacity, and enhanced reliability. However, this novel microgrid presents challenges because of the complex resonances within the system and the interactions between ST and power converter-based distributed energy resources (DERs). Both the ST and DERs might be severely affected by each other and leads to performance degradation and system instability. To solve these problems, this paper first develops equivalent circuits of a ST-based microgrid. Then, the resonance and interaction problems are investigated based on the equivalent circuits. The active damping method is used to fully address the resonance issue and mitigate the coupling effects. To guarantee superior performance, this paper also designs high-performance control strategies for both the ST and DERs. Simulation and experimental results are provided to verify the validity of the proposed control strategy.