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Transmission line power flow controller with unequal advancement and retardation of transmission angle

  • US 5,469,044 A
  • Filed: 01/05/1995
  • Issued: 11/21/1995
  • Est. Priority Date: 01/05/1995
  • Status: Expired due to Term
First Claim
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1. A power flow controller for controlling the flow of electric power flowing between two ends of an alternating current transmission line carrying alternating current at a selected transmission line voltage and a fundamental frequency, said controller comprising:

  • switching power converter means generating a controllable alternating voltage at said fundamental frequency of said alternating current with a controllable magnitude and phase angle relative to said transmission line voltage;

    bias voltage generating means generating an alternating bias voltage at said fundamental frequency of said alternating current and at a predetermined phase angle with respect to said transmission line voltage, said alternating bias voltage having a predetermined amplitude;

    coupling means vectorially summing said controllable alternating voltage and said alternating bias voltage to generate a combined voltage, and injecting said combined voltage into said transmission line in series with said transmission line voltage; and

    control means controlling the controllable magnitude and phase angle of the controllable alternating voltage generated by said switching power converter means at said fundamental frequency to a magnitude and any phase angle relative to said transmission line voltage to selectively adjust, in combination with said bias voltage, individually and in coordination, effective impedance of said transmission line, effective phase angle between voltages at said two ends of said transmission line, and transmission line voltage magnitude to control power flow in said transmission line between unequal maximum power flow control limits.

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