Mode of short-circuit state operation in 24-pulse uncontrolled bridge rectifier

Electrical Supply Substations (ESS) in modern railway DC systems are widely equipped with 24-pulse rectifiers, because such a converter provides a good promise between dc-side voltage ripple and ac-side current harmonic content. Accurate determination of transient dc-side short-circuit current is important for design of protection devices and power equipment. Firstly, the mode of short-circuit operation in 24-pulse converter is analyzed; then, the general method to calculate the short-circuit current is obtained by combining both the impedance calculation and short-circuit current formula in short-circuit state; finally, this method is simulated to compare with the transient and steady-state short-circuit currents with its own parameters of the transformer in Matlab. The figure shows that two curves are overlapping, so it proves that the method in this paper is correct.