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Method for controlling a H.V.D.C. power transmission plant and a control means embodying the method

  • US 4,672,519 A
  • Filed: 01/27/1986
  • Issued: 06/09/1987
  • Est. Priority Date: 02/04/1985
  • Status: Expired due to Fees
First Claim
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1. A method for control of a high voltage direct current power transmission plant, the plant having first and second converter stations, one of the stations operating as a rectifier station and the other of the stations operating as an inverter station, said two stations being interconnected by a d.c. power transmission line, the plant further having a telecommunication link for the transmission of control information between the two stations, at least the first station having at least two a.c./d.c. converters which are parallel-connected on their d.c. sides, the plant furthermore having means for the protective blocking of one of these converters upon a fault arising in that converter;

  • wherein, for maintaining the operation of the plant in case of protective blocking of a faulty converter in said first station when the telecommunication link is not available, the method comprising the step of;

    temporarily reducing the voltage in that part of the plant operating as the rectifier station to a low value; and

    wherein in the second station, where no protective blocking has occurred, the method further comprising the steps of;

    sensing the d.c. voltage of the transmission line during a first predetermined time interval and, if the thus-sensed value is lower than a first predetermined low value, increasing the minimum value for the control angle of the converters of the second station from its normal value to a predetermined value chosen in dependence on whether the second station is operating as a rectifier or as an inverter,after termination of the voltage reduction of the rectifier station, measuring the current in the transmission line and setting the current order in the second station in accordance with the measured line current value, andthereafter, reducing the minimum value of the control angle to its normal value.

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