| 摘要 |
PURPOSE:To restrain an overvoltage in an AC system upon and after removing a trouble by a method wherein the title controller is equipped with a circuit, generating an ignition pulse in the thyristor of a thyristor bulb when the trouble is generated in the AC system connected to a converter. CONSTITUTION:When a trouble is generated in an AC system 1 and an AC voltage is reduced, an undervoltage relay 5 detects it and '1' is established in the output or a trouble generating signal 17. Accordingly, the output of an AND circuit 7, which is '0' at all times upon stationary time, becomes '1' at every times when a forward voltage is applied on respective thyristor bulbs of a thyristor bridge. In this case, correction such as providing the bias of several percent of a stationary voltage as a forward detecting voltage if necessary or the delay of several degree of igniting angle is effected in order to effect sure commutation. According to this method, the AC converter 3, connected to the AC system of the side of the trouble, continues the operation thereof while igniting immediately after the application of the forward voltage on respective thyristors or with a slight delay after the application of the same when the trouble is generated. |
