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The short circuit current in DC (Direct Current) supply system will rise to a risk value within a few milliseconds. The current limiter must detect this fault on microsecond level to restrict the amplitude of short circuit current more effectively. For the existing method, the shunt is always employed for such fault detection, where the time to detect the fault current is relative long and hard for the rapid detection. In this paper, a novel method based on the flexible Rogowski coil is proposed, where the differential signal and the integral signal of the Rogowski coil are combined to perform the relay protection function. The design method of the coil, the relative experiments and the simulation result of the relay protection system are all discussed in sequence. Firstly, the equivalent circuit of the Rogowski coil is established, in which the distributed parameters of the coil are calculated with the Finite Element Method. Secondly, the frequency response of the coil is calculated and validated experimentally. The parameters of the Rogowski coil can be adjusted and designed according to the simulation result. Finally, the simulation of the relay protection system is performed, which shows that the demand of short current protection in ship DC distribution system can be satisfied and the method proposed in this paper is verified.
Date of Conference: 23-27 Oct. 2011