US5227713A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vernier control system for subsynchronous resonance mitigation
Assignee: Electric Power Research Institute
•
Filing: 1992-05-15
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Granted: 1993-07-13
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Expires: 2012-05-15
Abstract
Abstract A subsynchronous resonance mitigation system, including a method and apparatus, for damping undesirable subsynchronous resonance oscillations in a generator, which, if left unchecked, may damage the shafts of a turbine-generator set. A remote coupling apparatus, such as a thyristor controlled series capacitor (TCSC) system, a sourced inverter device, or a static phase shifter, is coupled to the generator by a transmission line. In response to a firing command, the coupling apparatus introduces subsynchronous resonance mitigating currents into the transmission line. Sensors monitor power line parameters and/or the generator speed, and in response thereto, a higher-level controller generates a voltage command. A vernier controller responds to the monitored power line parameters and the voltage command to provide the firing command to the coupling apparatus.
Inventors
- 👤 Colin E. J. Bowler
- 👤 Einar V. Larsen
- 👤 Daniel H. Baker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:32
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/14; G05F1/16; G05F1/20; H; H02; H02J; H02J3/00; H02J3/001; H02J3/0014; H02J3/18; H02J3/1807; H02J3/1814; H02J3/1878; H02P; H02P13/00; H02P13/06; H02P9/00; H02P9/10; H02P9/105; Y; Y02; Y02E; Y02E40/00; Y02E40/10; Y02E40/30
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
86 words
A subsynchronous resonance mitigation system for damping subsynchronous resonance oscillations occurring in a generator from a transmission line coupled to the generator, comprising: a coupling apparatus for coupling to the transmission line, the coupling apparatus responsive to a firing command to introduce subsynchronous resonance mitigating currents into the transmission line; a higher-level controller having a generator speed monitoring device and producing in response thereto a voltage command; and a firing time controller responsive to the voltage command for providing the firing command to the coupling apparatus.
Claim 2
Dependent Claim
86 words
A subsynchronous resonance mitigation system for damping subsynchronous resonance oscillations occurring in a generator from a transmission line coupled to the generator, comprising: a coupling apparatus for coupling to the transmission line, the coupling apparatus responsive to a firing command to introduce subsynchronous resonance mitigating currents into the transmission line; a higher-level controller having a generator speed monitoring device and producing in response thereto a voltage command; and a firing time controller responsive to the voltage command for providing the firing command to the coupling apparatus.
Claim 3
Dependent Claim
20 words
A subsynchronous resonance mitigation system according to claim 1 wherein the coupling apparatus comprises a thyristor controlled series capacitor system.
Claim 4
Dependent Claim
56 words
A subsynchronous resonance mitigation system according to claim 2 wherein the thyristor controlled series capacitor system comprises a capacitor in series with the transmission line, and a thyristor switched inductive commutating circuit in parallel with the capacitor, the commutating circuit having a thyristor valve responsive to the firing command to conduct a thyristor current pulse therethrough.
Claim 5
Dependent Claim
20 words
A subsynchronous resonance mitigation system according to claim 1 wherein the coupling apparatus comprises a voltage source inverter coupling apparatus.
Claim 6
Dependent Claim
44 words
A subsynchronous resonance mitigation system according to claim 4 wherein the voltage source inverter coupling apparatus comprises: a voltage source inverter; a coupling transformer coupling the voltage source inverter to the transmission line; and an energy storing device coupled to the voltage source inverter.
Claim 7
Dependent Claim
20 words
A subsynchronous resonance mitigation system according to claim 1 wherein the coupling apparatus comprises a current source inverter coupling apparatus.
Claim 8
Dependent Claim
44 words
A subsynchronous resonance mitigation system according to claim 6 wherein the current source inverter coupling apparatus comprises: a current source inverter; a coupling transformer coupling the current source inverter to the transmission line; and an energy storing inductor coupled to the current source inverter.
Claim 9
Dependent Claim
18 words
A subsynchronous resonance mitigation system according to claim 1 wherein the coupling apparatus comprises a static phase shifter.
Claim 10
Dependent Claim
121 words
A subsynchronous resonance mitigation system according to claim 8 wherein the static phase shifter comprises: a series transformer with mutually magnetically coupled series and excited windings, the series winding for coupling in series with the transmission line; a regulating transformer with mutually magnetically coupled exciting and regulating windings, the exciting winding for receiving power from the transmission line; a switching network coupling together the regulating winding of the regulating transformer with the excited winding of the series transformer, the switching network responsive to the firing command for establishing a nominal voltage level on the series transformer series winding; and a modulator responsive to the firing command for modulating the voltage of the series transformer series winding about the nominal voltage level.
Claim 11
Dependent Claim
26 words
A subsynchronous resonance mitigation system according to claim 1 wherein the coupling apparatus is coupled to the transmission line at a location remote from the generator.
Claim 12
Dependent Claim
45 words
A subsynchronous resonance mitigation system according to claim 1 wherein: the system further includes a transmission line sensor monitoring a parameter of the power flowing through the transmission line; and the firing time controller provides the firing command in response to the transmission line sensor.
Claim 13
Dependent Claim
27 words
A subsynchronous resonance mitigation system according to claim 11 wherein the transmission line sensor is coupled to the transmission line at a location remote from the generator.
Claim 14
Dependent Claim
60 words
A subsynchronous resonance mitigation system according to claim 11 wherein: the transmission line sensor comprises a current sensor monitoring a line current flowing through the transmission line, and a first voltage sensor monitoring a line to neutral voltage of the transmission line; and the higher-level controller generates the voltage command in response to the current sensor and first voltage sensor.
Claim 15
Dependent Claim
39 words
A subsynchronous resonance mitigation system according to claim 13 wherein the higher-level controller includes a velocity transducer responsive to the current sensor and first voltage sensor, and a conditioner responsive to the velocity transducer for providing the voltage command.
Claim 16
Dependent Claim
48 words
A subsynchronous resonance mitigation system according to claim 13 wherein: the transmission line sensor comprises a second voltage sensor monitoring a transmission line voltage across the coupling apparatus; and the firing time controller provides the firing command in response to the current sensor and the second voltage sensor.
Claim 17
Dependent Claim
39 words
A subsynchronous resonance mitigation system according to claim 15 wherein at least one of the current sensor, the first voltage sensor, and the second voltage sensor is coupled to the transmission line at a location remote from the generator.
Claim 18
Dependent Claim
19 words
A subsynchronous resonance mitigation system according to claim 1 wherein the generator speed monitoring device comprises a velocity transducer.
Claim 19
Dependent Claim
42 words
A subsynchronous resonance mitigation system according to claim 17 wherein: the velocity transducer includes a reference frame transformation device and a velocity synthesizer responsive thereto; and the higher-level controller includes a conditioner responsive to the velocity synthesizer for generating the voltage command.
Claim 20
Dependent Claim
112 words
A subsynchronous resonance mitigation system according to claim 17 wherein: the velocity transducer includes a reference frame transformation device for transforming the line current and the line to neutral voltage into a direct current signal, a quadrature current signal, a direct voltage signal, and a quadrature voltage signal representing respective direct current, quadrature current, direct voltage, and quadrature voltage at the generator; the velocity transducer includes a velocity synthesizer responsive to the direct current signal, quadrature current signal, direct voltage signal, and quadrature voltage signal for generating a synthesized generator velocity signal; and the higher-level controller includes a conditioner for generating the voltage command in response to the synthesized generator velocity signal.
Claim 21
Dependent Claim
32 words
A subsynchronous resonance mitigation system according to claim 1 wherein the generator speed monitoring device synthesizes the generator speed based on a synchronously rotating reference frame rotating at a fundamental system frequency.
Claim 22
Dependent Claim
53 words
A subsynchronous resonance mitigation system according to claim 1 wherein: the system further includes a transmission line sensor monitoring a parameter of the power flowing through the transmission line; and the generator speed monitoring device determines the transmission line impedance in response to the transmission line power sensor for synthesizing the generator speed.
Claim 23
Dependent Claim
30 words
A subsynchronous resonance mitigation system according to claim 1 wherein the generator speed monitoring device synthesizes the generator speed based on transmission line characteristics stored within an impedance memory device.
Claim 24
Dependent Claim
28 words
A subsynchronous resonance mitigation system according to claim 1 wherein the higher-level controller includes a conditioner responsive to the generator speed monitoring device for producing the voltage command.
Claim 25
Dependent Claim
40 words
A subsynchronous resonance mitigation system according to claim 23 wherein the conditioner includes a first order wash-out stage responsive to the generator speed monitoring device, a phase compensation device, and a limiter coupled in series to the phase compensation device.
Claim 26
Dependent Claim
41 words
A subsynchronous resonance mitigation system according to claim 24 wherein the phase compensation device includes a first order lead/lag stage coupled to the first order wash-out stage, and a complex second order lead/lag stage coupled to the first order lead/lag stage.
Claim 27
Dependent Claim
63 words
A subsynchronous resonance mitigation system according to claim 1 wherein: the generator speed monitoring device comprises a telemetering generator speed sensor for measuring the generator speed at a location local to the generator, and for transmitting the measured generator speed to the higher-level controller; and the higher-level controller includes a conditioner responsive to the transmitted measured generator speed for generating the voltage command.
Claim 28
Dependent Claim
91 words
A subsynchronous resonance mitigation system for damping subsynchronous resonance oscillations occurring in a generator from a transmission line coupled to the generator, comprising: a coupling apparatus for coupling to the transmission line, the coupling apparatus responsive to a firing command to introduce subsynchronous resonance mitigating currents into the transmission line; a higher-level controller for synthesizing the generator speed based on a rotating reference frame, and producing in response thereto a voltage command; and a firing time controller responsive to the voltage command for providing the firing command to the coupling apparatus.
Claim 29
Dependent Claim
91 words
A subsynchronous resonance mitigation system for damping subsynchronous resonance oscillations occurring in a generator from a transmission line coupled to the generator, comprising: a coupling apparatus for coupling to the transmission line, the coupling apparatus responsive to a firing command to introduce subsynchronous resonance mitigating currents into the transmission line; a higher-level controller for synthesizing the generator speed based on a rotating reference frame, and producing in response thereto a voltage command; and a firing time controller responsive to the voltage command for providing the firing command to the coupling apparatus.
Claim 30
Dependent Claim
24 words
A subsynchronous resonance mitigation system according to claim 27 wherein the rotating reference frame rotates synchronously at the fundamental frequency of the transmission line.
Claim 31
Dependent Claim
26 words
A subsynchronous resonance mitigation system according to claim 27 wherein the coupling apparatus is coupled to the transmission line at a location remote from the generator.
Claim 32
Independent Claim
96 words
A method of damping subsynchronous resonance oscillations occurring in a generator from a coupling apparatus coupled to the generator by a transmission line, the coupling apparatus responsive to a firing command, the method comprising the steps of: determining a speed of the generator; generating a voltage command in response to the determined generator speed; generating a firing command signal in response to the voltage command and the monitored parameter of power flowing through the transmission line; and introducing subsynchronous resonance mitigating currents into the transmission line through the coupling apparatus in response to the firing command.
Claim 33
Independent Claim
96 words
A method of damping subsynchronous resonance oscillations occurring in a generator from a coupling apparatus coupled to the generator by a transmission line, the coupling apparatus responsive to a firing command, the method comprising the steps of: determining a speed of the generator; generating a voltage command in response to the determined generator speed; generating a firing command signal in response to the voltage command and the monitored parameter of power flowing through the transmission line; and introducing subsynchronous resonance mitigating currents into the transmission line through the coupling apparatus in response to the firing command.
Claim 34
Dependent Claim
37 words
A method of damping subsynchronous resonance oscillations according to claim 30 wherein the determining step comprises measuring the generator speed at a location local to the generator, and transmitting the measured generator speed to the higher-level controller.
Claim 35
Dependent Claim
26 words
A method of damping subsynchronous resonance oscillations according to claim 30 wherein the determining step comprises synthesizing the generator speed based on a rotating reference frame.
Claim 36
Dependent Claim
53 words
A method of damping subsynchronous resonance oscillations according to claim 30 wherein: the method further includes the step of monitoring a parameter of the power flowing through the transmission line; and the generating step comprises generating the firing command signal in response to the monitored parameter of power flowing through the transmission line.
Claim 37
Dependent Claim
40 words
A method of damping subsynchronous resonance oscillations according to claim 33 wherein the step of monitoring comprises the steps of: monitoring a line current flowing through the transmission line; and monitoring a line to neutral voltage of the transmission line.
Claim 38
Dependent Claim
46 words
A method of damping subsynchronous resonance oscillations according to claim 34 wherein the step of determining a generator speed comprises the steps of synthesizing a remote generator speed in response to the monitored line current and the monitored line to neutral voltage of the transmission line.
Claim 39
Dependent Claim
45 words
A method of damping subsynchronous resonance oscillations according to claim 35 wherein the step of generating a voltage command comprises the steps of phase conditioning and gain conditioning the synthesized generator speed signal with a broad-band transfer function comprising first and second order transfer functions.
Claim 40
Dependent Claim
62 words
A method of damping subsynchronous resonance oscillations according to claim 30 wherein: the method further includes the step of predicting an upcoming firing time for issuing the voltage command; and the step of generating a firing command signal comprises generating a synchronized firing command signal at the predicted upcoming firing time in response to the voltage command and the monitored line current.
Claim 41
Dependent Claim
102 words
A method of damping subsynchronous resonance oscillations according to claim 30 wherein the step of generating a voltage command comprises the steps of: transforming the monitored line current and the monitored line to neutral voltage into a direct current signal, a quadrature current signal, a direct voltage signal, and a quadrature voltage signal representing respective direct current, quadrature current, direct voltage, and quadrature voltage at the generator; generating a synthesized generator speed signal in response to the direct current signal, quadrature current signal, direct voltage signal, and quadrature voltage signal; and generating the voltage command by conditioning the synthesized generator speed signal.
Claim 42
Dependent Claim
60 words
A method of damping subsynchronous resonance oscillations according to claim 30 wherein: the method includes the steps of monitoring a transmission line voltage across the coupling apparatus and predicting therefrom an upcoming firing time; and the step of generating the synchronized firing command signal comprises the step of generating the synchronized firing command signal at the predicted upcoming firing time.
Claim 43
Dependent Claim
99 words
A higher-level controller for a subsynchronous resonance mitigation system for damping subsynchronous resonance oscillations occurring in a generator from a transmission line coupled to the generator, the subsynchronous resonance mitigation system including a coupling apparatus in series with the transmission line and responsive to a firing command for introducing subsynchronous resonance mitigating currents into the transmission line, and a firing time controller responsive to a voltage command for providing the firing command to the coupling apparatus, higher-level controller comprising a generator speed monitoring device, and a conditioner responsive to the generator speed monitoring device for generating the voltage command.
Claim 44
Dependent Claim
99 words
A higher-level controller for a subsynchronous resonance mitigation system for damping subsynchronous resonance oscillations occurring in a generator from a transmission line coupled to the generator, the subsynchronous resonance mitigation system including a coupling apparatus in series with the transmission line and responsive to a firing command for introducing subsynchronous resonance mitigating currents into the transmission line, and a firing time controller responsive to a voltage command for providing the firing command to the coupling apparatus, higher-level controller comprising a generator speed monitoring device, and a conditioner responsive to the generator speed monitoring device for generating the voltage command.
Claim 45
Dependent Claim
39 words
A higher-level controller according to claim 40 wherein the generator speed monitoring device comprises a velocity transducer including a reference frame transformation device, and a velocity synthesizer coupled in series between the reference frame transformation device and the conditioner.
Claim 46
Dependent Claim
42 words
A higher-level controller according to claim 40 wherein the generator speed monitoring device comprises a telemetering generator speed sensor for measuring the generator speed at a location local to the generator, and for transmitting the measured generator speed to the higher-level controller.
Claim 47
Dependent Claim
23 words
A higher-level controller according to claim 40 wherein the generator speed monitoring device synthesizes the generator speed based on a rotating reference frame.
Claim 48
Dependent Claim
185 words
A vernier firing time controller for driving a coupling apparatus of a subsynchronous resonance mitigation system for remotely damping subsynchronous resonance oscillations occurring in a generator coupled thereto by a transmission line, the coupling apparatus responsive to a firing command, a transmission line sensor monitoring a parameter of the power flowing through the transmission line, and a higher-level controller having a generator speed monitoring device and producing in response thereto a voltage command, the vernier firing time controller comprising: a coupling apparatus predictor responsive to the transmission line sensor for predicting an initial voltage; a limiter for limiting the initial voltage and the voltage command received from the higher-level controller to provide a limited final voltage; a storage device for determining a predicted firing angle from the limited final voltage and the predicted initial voltage; a synchronizer for generating a first timing signal in response to the monitored line current; and a firing time computer responsive to the first timing signal and the predicted firing angle for generating the firing command to introduce subsynchronous resonance mitigating currents into the transmission line through the coupling apparatus.
Claim 49
Dependent Claim
185 words
A vernier firing time controller for driving a coupling apparatus of a subsynchronous resonance mitigation system for remotely damping subsynchronous resonance oscillations occurring in a generator coupled thereto by a transmission line, the coupling apparatus responsive to a firing command, a transmission line sensor monitoring a parameter of the power flowing through the transmission line, and a higher-level controller having a generator speed monitoring device and producing in response thereto a voltage command, the vernier firing time controller comprising: a coupling apparatus predictor responsive to the transmission line sensor for predicting an initial voltage; a limiter for limiting the initial voltage and the voltage command received from the higher-level controller to provide a limited final voltage; a storage device for determining a predicted firing angle from the limited final voltage and the predicted initial voltage; a synchronizer for generating a first timing signal in response to the monitored line current; and a firing time computer responsive to the first timing signal and the predicted firing angle for generating the firing command to introduce subsynchronous resonance mitigating currents into the transmission line through the coupling apparatus.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-07-12 | 1997-01-11 | 1997-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-07-12 | 2001-01-11 | 2001-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-07-12 | 2005-01-11 | 2005-07-13 | $7700.00 | Window Closed / Lapsed |