Development of an Efficient Integrated Test Circuit for Overcurrent and Short Circuit Current Testing of the MMC-Based MVDC Valve

This paper proposes an integrated fault current testing circuit capable of IGBT(Insulated Gate Bipolar Transistor) overcurrent turn-off test and short circuit current test for valves used in modular multilevel converter-based medium voltage direct current systems. Conventional fault current test circuits require separate test circuits for each type of fault current, and conventional synthetic circuits, having a structure wherein two circuits are physically merged, have had disadvantages in terms of reliability, efficiency and cost. In contrast, the integrated test circuit propose in this paper can perform carry out IGBT(Insulated Gate Bipolar Transistor) overcurrent turn-off tests and short circuit current tests based on the operation of a circuit breaker within the circuit, addressing a disadvantage of conventional test circuits. Fault tree analysis is used to test the reliability of the proposed test circuit, yielding a failure rate of 0.565058 Failures/10(6)Hour, a lower than that of conventional circuits. Further, using the PLECS simulation tool, generation of current with a 2 A/mu s overcurrent slope, 1557 A short current peak and 29.1 kA(2) energy accumulation is confirmed, verifying conformity with the design equation and the design parameter values.