Impact of Synchronous Generator Deexcitation Dynamics on the Protection in Marine DC Power Distribution Networks

This article presents the characteristics of power supply protection in dc shipboard power systems utilizing the deexcitation of a synchronous generator, which has been used to achieve a breakerless protection scheme. From state-of-the-art analyses on the deexcitation and the dc ship protection, the analytical expressions of a dc short-circuit fault are introduced with the consideration of the generator dynamics and the deexcitation. The rectifier protection, based on the analytical expression, is examined in terms of the peak fault current (or peak nonrepetitive surge current) and the overloading capability (or limiting load integral) of the rectifier diodes. Finally, experimental dc short-circuit tests are conducted with the rectifier-generator system rated of 10 kW and 500 V_dc. With the test results, the analytical expression derived in the article is verified, and more importantly, the characteristics of the dc fault behaviors are discussed for different fault resistance, dc-link capacitance, and exciter response.