摘要:
A synchronous condenser is provided on an AC bus line which is connected to an AC power system via a circuit breaker. The AC bus line and a DC bus line are connected via a power converter system. In such a system, if three conditions: the breaker is opened; the synchronous condenser is under operation; and the power converter operates as an inverter, are met, the power converter is driven into a zero power factor operation, i.e., an operation to cancel a capacitive reactive power on the AC bus line including AC filters in order to prevent the synchronous condenser self-excitation.
摘要:
A protection system for a thyristor valve composed of a plurality of thyristors connected in series. The protection system includes a forward voltage detection circuit for generating a forward voltage signal, a first reverse voltage detection circuit for detecting that a reverse voltage in excess of a first reverse voltage level is applied to the thyristor to generate a first reverse voltage signal, and a second reverse voltage detection circuit for detecting that a reverse voltage in excess of a second reverse voltage level larger than the first reverse voltage level is applied to the thyristor to generate a second reverse voltage signal. The protection system further includes a protection circuit for detecting a first time period during when the first reverse voltage signal is outputted and a second time period during when the first reverse voltage signal is outputted and the second reverse voltage signal is not outputted, for adding the first and the second time periods to generate an addition signal, for generating a decision signal when the addition signal is smaller than a second predetermined value, and for generating a protection gate pulse based on the decision signal when the forward voltage is applied to the thyristor. The protection gate pulse is applied to all of the thyristors.
摘要:
A device for controlling a thyristor converter including series connected thyristors. The device includes a plurality of forward voltage detection circuits, each of which detects forward voltage of one of the thyristors and generates a forward voltage signal based on the detected forward voltage, respectively. The device includes a first circuit for generating a conduction command signal which commands the thyristor converter to conduct, and a second circuit for generating a plurality of light gate signals and a gate monitoring signal based on a plurality of modified forward voltage signals and the conduction command signal. Each of the light gate signals is applied to one of the thyristors to turn ON thereof, respectively. The device includes a first delay circuit connected to receive the gate monitoring signal for delaying the gate monitoring signal by a first predetermined time to produce a first delayed signal. The device further includes a processing circuit connected to receive the first delayed signal and a plurality of the forward voltage signals for detecting whether or not any of the plurality of forward voltage detection circuits is in a failure, for distinguishing the forward voltage detection circuit in a failure and for generating a plurality of the modified forward voltage signals based on the result of the failure detection and the distinction, thereby inhibiting the forward voltage signal of the forward voltage detection circuit in a failure from transmitting to said second circuit.