| 摘要 |
PROBLEM TO BE SOLVED: To suppress the increase of a fault current caused by an arm short- circuit in an AC/DC converter and utilize the current capacity of the semiconductor switch (thyristor) of the AC/DC converter efficiently. SOLUTION: An AC/DC converter 2 which converts AC into DC or inversely converts DC into AC and a converter transformer which transforms an AC voltage value into a value suitable for the AC/DC converter 2 are provided. Current limiters 10-12 whose resistance values are normally almost zero by maintaining a superconducting state and, when currents exceeding the specified critical current are applied by the fault and the superconducting state is transferred to the normal conducting state, are increased are connected between the AC/DC converter 2 and the converter transformer. With this constitution, when an arm short-circuit fault occurs in the AC/DC converter 2, currents larger than the normal current flow and, if the currents exceed the critical current of the current limiters 10-12, the superconducting sate of the current limiters 10-12 is transferred to the normal conducting state and the resistance values of the current limiters 10-12 are increased, so that the increase of the fault currents can be suppressed. |
