DC Fault Protection in Shipboard Power Systems using Z-Source Breakers

DC faults may cause severe disruptions in continuity of service to vital loads in a shipboard integrated power system, hence detection, isolation and protection against dc faults must be incorporated in both medium-voltage dc and low-voltage dc systems. A standard z-source breaker can identify and de-energize a faulty dc load on both buses quickly. However, until now, provisions for re-energizing have not been described. In this paper, a new z-source breaker is designed and control and detection techniques to identify the fault duration as well as to re-energize the load efficiently once the fault is cleared are developed. Dc fault characteristics on both mediumand low-voltage dc buses in a complete model of the allelectric-ship are demonstrated and the effective use of the new z-source breaker for the reenergizing process in protecting and restoring the continuity of ship service with a minimal effect is investigated.