A DAB-Based DC Transformer for Multiterminal HVdc Dynamic Simulation Platform With Short Circuit Tolerance

The dc transformer (DCT) can be used to achieve a direct connection between various dc bus voltages. A multiwinding dual active bridge (DAB) structure is proposed to be used in that occasion for a dynamic simulation platform. For high voltage side, automatic voltage balance and power-sharing balance can be achieved automatically without mandatory power sharing control. To deal with wide voltage conversion gain application, a multimode modulation with peak current value optimization is proposed. It has the tolerance for the short circuit operation under dc fault. The power transmission can be suppressed rather low during the fault. A 1 kV/1.6 kV 10 kW DCT has been fabricated and applied in a dynamic simulation platform. The bidirectional power flow capability together with the short circuit fault tolerance has been verified through the test.