A Fuse-Isolator-Switch Based Protection Scheme for Shipboard Electrical Distribution Systems with Zonal Configuration

The need for high reliability of modern ships has led to the development of a zonal structure for their electrical distribution systems. One of the most important challenges of the electric distribution systems of modern ships with a zonal structure is their protection in the event of a fault to maintain stability and reliability at an acceptable level. Failure to detect the fault and to isolate the faulty section at the proper time has disastrous consequences for the shipboard electrical system. This paper aims to present an effective protection scheme for all equipment of the hybrid AC/DC distribution system of ships with a zonal structure. In the proposed scheme, protection against single-phase to ground faults is performed using a high-resistance grounding system and timer, while the current of two-phase and three-phase faults is cleared using the fuse-isolator-switches. The use of a high-resistance grounding system allows uninterrupted operation of the ship's electrical system when single-phase to ground faults occur. Due to not using protective relays, the cost of the proposed scheme implementation is low. The proposed protection scheme includes primary and backup protections and does not require communication infrastructure. Also, all equipment of the ship's electrical system including generator, propulsion motor, busbar, feeder, line, load, and direct current system are considered in the proposed scheme. The coordinate operation of the developed protection scheme is assessed on the ETAP simulation model of a test zonal electrical system of the ship.