Control strategy of the full-bridge based hybrid DC breaker

A reliable, fast and low conduction losses DC breaker plays an significant role in the development of the DC grid. This paper presents the control strategy of the hybrid DC breaker based on series combination of full bridge Sub-modules (FBSM). The topology and operation principle of the full-bridge based hybrid DC breaker is illustrated. Compared with the topology that utilize directly IGBTs in series connection, the voltage balance is easier to achieve for connecting FBSM in series. For a DC line fault close to the DC switchyard, the fault current could rise to a large value in a short time. In order to get a quick response to the DC grid fault, the rapid fault detection method and the pre-transferring strategy are introduced. A low voltage physical dynamic model has been built to verify the operation and control strategy.