Analysis of the DC side sudden short circuit of three-phase/twelve-phase synchronous generator system

As a compact, light, cheap, reliable and high quality power source, the hybrid AC/DC power supply generator (HADPSG) has been developing quickly in the mobile power systems. The most common fault in these systems is the short circuit in the DC load side. Research on the short circuit current peak amplitude and peak instant is carried out to provide safe protection for the generator. The multi-loop method is used to establish the mathematical model of the system, and the transient process of the short circuit is analyzed theoretically. The analytical expression of the short circuit current is obtained, and the experimental results are compared with the theoretical calculations and computer simulations. The phase current of the AC winding after the short circuit fault is less than the normal load value. The peak amplitude of the DC load current is determined by the AC and DC load before the short circuit. The peak instant of the DC load current is shifted before half cycle of the power frequency.