Series compensator inserting real and reactive impedance into electric power system for damping power oscillations
First Claim
1. Apparatus for providing series line compensation with enhanced capability to dampen oscillations in an electric power transmission line carrying ac current at a selected transmission line voltage and fundamental frequency, said apparatus comprising:
- compensation means coupled in series with said transmission line injecting into said transmission line a compensation voltage at said fundamental frequency with controllable magnitude and phase angle relative to said ac current in said transmission line;
power exchange means selectively connected to said transmission line only through said compensation means; and
control means controlling the controllable magnitude and phase angle of said compensation voltage to insert selected reactive and virtual real impedance into said transmission line to dampen said oscillations, and selectively connecting said power exchange means to said compensation means to enable said compensation means to provide said virtual real impedance.
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0 Petitions
Accused Products
Abstract
A series compensator for damping power oscillations in an electric power transmission system includes a switching power converter which injects a voltage into the transmission line having a phase angle relative to transmission line current which is controlled to provide reactive compensation and to inject virtual real impedance into the line. The switching power converter is a dc to ac converter which is capable of injecting virtual real impedance into the transmission line by virtue of the fact that it has a power exchange device connected to its dc terminals. Where the power exchange device is a resistor, the switching power converter is capable of absorbing real power during surges in power on the line. Alternatively, the power exchange device is a storage device such as a battery bank or a super conducting magnet, in which case the switching power converter can provide both virtual positive and negative real impedance.
74 Citations
28 Claims
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1. Apparatus for providing series line compensation with enhanced capability to dampen oscillations in an electric power transmission line carrying ac current at a selected transmission line voltage and fundamental frequency, said apparatus comprising:
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compensation means coupled in series with said transmission line injecting into said transmission line a compensation voltage at said fundamental frequency with controllable magnitude and phase angle relative to said ac current in said transmission line; power exchange means selectively connected to said transmission line only through said compensation means; and control means controlling the controllable magnitude and phase angle of said compensation voltage to insert selected reactive and virtual real impedance into said transmission line to dampen said oscillations, and selectively connecting said power exchange means to said compensation means to enable said compensation means to provide said virtual real impedance. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for providing series line compensation with enhanced capability to dampen oscillations in an electric power transmission line carrying ac current at a selected transmission line voltage and fundamental frequency, said apparatus comprising:
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switching power converter means coupled in series with said transmission line injecting into said transmission line a compensation voltage at said fundamental frequency with controllable magnitude and phase angle relative to said ac current in said transmission line; power exchange means including at least positive real impedance means; and control means controlling the controllable magnitude and phase angle of said compensation voltage to insert selected reactive and virtual real impedance into said transmission line to dampen said oscillations, said virtual real impedance being supported by said power exchange means and said reactive impedance being generated within said switching power converter means. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for providing series line compensation with enhanced capability to dampen oscillations in an electric power transmission line carrying ac current at a selected transmission line voltage and fundamental frequency, said method comprising the steps of:
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coupling compensation means in series with said transmission line to inject into said transmission line a compensation voltage at said fundamental frequency with controllable magnitude and phase angle relative to said ac current in said transmission line; selectively connecting power exchange means to said transmission line only through said compensation means; and controlling the controllable magnitude and phase angle of said compensation voltage to insert selected reactive and virtual real impedance into said transmission line to dampen said oscillations, and selectively connecting said power exchange means to said compensation means to enable said compensation means to provide said virtual real impedance. - View Dependent Claims (15, 16)
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17. A method of providing series line compensation with enhanced capability to dampen oscillations in an electric power transmission line carrying ac current at a selected transmission line voltage and fundamental frequency, said method comprising the steps of:
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coupling switching power converter means in series with said transmission line to inject into said transmission line a compensation voltage at said fundamental frequency with controllable magnitude and phase angle relative to said ac current in said transmission line; providing power exchange means including positive real impedance means; and controlling the controllable magnitude in phase angle of said compensation voltage to insert selected reactive and virtual real impedance into said transmission line to dampen said oscillations, said virtual real impedance being supported by said power exchange means and said reactive impedance being generated within said switching power converter means. - View Dependent Claims (18)
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19. An apparatus for providing series line compensation with enhanced capability to dampen oscillations in an electric power transmission line carrying ac current at a selected transmission line voltage and fundamental frequency, said apparatus comprising:
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compensation means coupled in series with said transmission line and being adapted to inject into said transmission line two ac voltage components with controllable magnitude at the said fundamental frequency, a first one of said voltage components being in quadrature with said transmission line current and a second one of said voltage components being in-phase with said transmission line current; and control means for coordinately controlling said controllable magnitude of said first and second voltage components in response to transmission line voltage and current conditions, said first voltage component being controlled to adjust the steady-state and dynamic flow of electric power in said transmission line and said second voltage component being controlled to temporarily supply or absorb from said transmission line electric power in order to effectively dampen the oscillation of power flow in said transmission line. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. A method for providing series line compensation with enhanced capability to dampen oscillations in an electric power transmission line carrying ac current at a selected transmission line voltage and fundamental frequency, said method comprising the steps of:
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coupling a compensation means in series with said transmission line to inject into said transmission line two ac voltage components with controllable magnitude at the said fundamental frequency, a first one of said voltage components being in quadrature with said transmission line current and a second one of said voltage components being in-phase with said transmission line current; and coordinately controlling said controllable magnitude of said first and second voltage components from said compensation means in response to transmission line voltage and current conditions, said first voltage component being controlled to adjust the steady-state and dynamic flow of electric power in said transmission line and said second voltage component being controlled to temporarily supply or absorb from said transmission line electric power in order to effectively dampen the oscillation of power flow in said transmission line. - View Dependent Claims (28)
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Specification