| 摘要 |
PURPOSE:To secure a stable supply of electric power by continuing the operation of a synchronous rotary phase modifier without increasing the rotational speed of the phase modifier up to a dangerous area when a power transmission line is opened and then restarting the power transmission as soon as the transmission line is closed after a trouble of the transmission line is recovered. CONSTITUTION:When an AC line has a trouble, a breaker 2 opens instantaneously a power transmission line to get rid of the trouble. After the breaker is opened, electric power is supplied wholely to a synchronous rotary phase modifier 8 even of the output of a converter 4 is minimized, and the rotational speed of the modifier 8 is increased rapidly. Here a rotational speed detector 10 is provided to the modifier 8 together with the frequency upper and lower limit detectors 11 and 12. The set values of both detectors 11 and 12 are given sufficient margines to the set values of excess and deficient rotational speed protecting relays of the modifier 8. Thus it is possible to prevent such a case where a breaker 9 is opened owing to the function of said relay and the modifier 8 is stopped, in a normal operation mode.
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