Transmission line power flow controller with unequal advancement and retardation of transmission angle
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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Abstract
A bias voltage vectorially added to the controllable voltage injected in series with the line voltage of a transmission line reduces the required MVA rating for a unified power flow controller (UPFC) in applications where the power in the transmission line only flows in a single direction, or where the range of the transmission angle is otherwise unequal about zero.
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Citations
17 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A power flow controller for controlling the flow of electric power flowing in a single direction 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;
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switching power converter means generating a controllable alternating voltage at said fundamental frequency of said alternating current with controllable magnitude and phase angle relative to said transmission line voltage; bias voltage generating means generating an alternating bias voltage in quadrature with said transmission line voltage and 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; means providing real power to said switching power converter means; and control means controlling real and reactive power exchange between said transmission line and said switching power converter means by controlling said alternating controllable voltage to a selected magnitude no greater than said predetermined magnitude of said alternating bias voltage and to a selected phase angle between 0° and
360°
to establish a selected transmission line impedance, a selected transmission angle, and a selected transmission line voltage for controlling power flow through said transmission line in said single direction. - View Dependent Claims (16, 17)
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Specification