US5570007A
Expired / Lapsed
US
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Method and apparatus for static VAR compensator voltage regulation
Assignee: General Electric Co
•
Filing: 1993-11-19
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Granted: 1996-10-29
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Expires: 2013-11-19
Abstract
Abstract A voltage regulator regulates the voltage a static VAR compensator (SVC) supplies to a power supply network. An SVC status detector detects the conducting status of the SVC thyristors and generates the measured SVC susceptance in accordance with that conduction status. A calculator calculates a representative voltage, (i.e. the Thevenin equivalent), of the power supply network based on the measured SVC susceptance, measured SVC voltage, and an estimate of the power supply network's equivalent reactance. An ordered susceptance to be provided by the SVC to maintain the SVC voltage at a desired level is predicted based on the calculated voltage. A firing control unit receives the predicted susceptance value and calculates drive signals for controlling thyristors in the SVC. The equivalent reactance is initially estimated, and thereafter, it is modified automatically to track and compensate for large disturbances in the power transmission network. The modification is determined based on changes in the calculated representative voltage and in the measured SVC susceptance. The equivalent reactance is varied until the changes in the calculated representative voltage and measured SVC susceptance are substantially reduced to zero. This Thevenin-based approach to modelling the power supply network from the perspective of the SVC permits predictive SVC voltage regulation that is sensitive, accurate, and stable.
Inventors
- 👤 Einar V. Larsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:13
CPC Classifications
H; H02; H02J; H02J3/00; H02J3/18; H02J3/1821; H02J3/1835; H02J3/1828; Y; Y02; Y02E; Y02E40/00; Y02E40/10
Claims Analysis
Total Claims: 67
Claim 1
Independent Claim
80 words
A voltage regulator for regulating voltage of a static VAR compensator (SVC) connected to a power supply network, comprising: a calculator for calculating a voltage representative of the power supply network based on measured SVC susceptance, measured SVC voltage, and an estimate of the power supply network's equivalent reactance; and a predictor for predicting a susceptance to be provided by the SVC based on the representative voltage, wherein the voltage regulator regulates the SVC voltage using the predicted susceptance value.
Claim 2
Dependent Claim
80 words
A voltage regulator for regulating voltage of a static VAR compensator (SVC) connected to a power supply network, comprising: a calculator for calculating a voltage representative of the power supply network based on measured SVC susceptance, measured SVC voltage, and an estimate of the power supply network's equivalent reactance; and a predictor for predicting a susceptance to be provided by the SVC based on the representative voltage, wherein the voltage regulator regulates the SVC voltage using the predicted susceptance value.
Claim 3
Dependent Claim
26 words
The voltage regulator according to claim 1, further comprising: means for automatically modifying the estimated equivalent reactance in response to changes in the power supply network.
Claim 4
Dependent Claim
43 words
A voltage regulator as claimed in claim 2, wherein the means for automatic modifying includes: means for correlating the representative voltage and the measured SVC susceptance in a predetermined frequency band, and means for modifying the estimated equivalent reactance based on the correlation.
Claim 5
Dependent Claim
29 words
A voltage regulator as claimed in claim 3, wherein the means for correlating includes first and second bandpass filters for passing signals in the frequency range of 5-20 Hz.
Claim 6
Dependent Claim
36 words
A voltage regulator as claimed in claim 3, further comprising: means for emphasizing the outputs from the first and second bandpass filters to increase the responsiveness of the means for automatically modifying the estimated equivalent reactance.
Claim 7
Dependent Claim
54 words
A voltage regulator as claimed in claim 4, wherein the means for emphasizing includes: a multiplier; means for determining the absolute value of an output of the second bandpass filter; and means for raising an output of the means for determining by an exponent n, where n is a real number greater than zero.
Claim 8
Dependent Claim
36 words
A voltage regulator as claimed in claim 3, further comprising: means for weighting output signals from the first and second bandpass filters to increase the responsiveness of the means for automatically modifying the estimated equivalent reactance.
Claim 9
Dependent Claim
56 words
The voltage regulator according to claim 3, wherein the means for automatically modifying the estimated reactance further includes: a correlator for correlating respective outputs of the first and second bandpass filters; an amplifier for amplifying an output of the combiner; and an integrator for integrating an output of the amplifier to generate the estimated equivalent reactance.
Claim 10
Dependent Claim
34 words
The voltage regulator according to claim 1, wherein the representative voltage is the Thevenin equivalent of the power supply network and the equivalent reactance is the Thevenin equivalent reactance of the power supply network.
Claim 11
Dependent Claim
56 words
The voltage regulator according to claim 1, further comprising: means for measuring SVC voltage; a control unit for calculating gate signals for controlling thyristors in the SVC based on the predicted susceptance value; and detecting means for detecting conduction status of the SVC thyristors and generating the measured SVC susceptance in accordance with the conduction status.
Claim 12
Dependent Claim
45 words
The voltage regulator according to claim 1, wherein the calculator calculates the representative voltage based on the following equation: Vthm=Vm(1-Xthm*Bm) where Vthm is the calculated voltage, Vm is the measured SVC voltage, Xthm is the estimated equivalent reactance, and Bm is the measured SVC susceptance.
Claim 13
Dependent Claim
23 words
The voltage regulator according to claim 11, wherein the predictor predicts the predicted SVC susceptance Bo in accordance with the following equation: Bo=(1-Vth/Vm)/Xthm.
Claim 14
Dependent Claim
119 words
A voltage regulator comprising: a static VAR compensator (SVC) switchably connected to a power supply network at a bus; means for measuring a susceptance delivered by the SVC to the power supply network; means for measuring an SVC voltage at the bus; means for modelling the power supply network at the bus using an equivalent network including an equivalent voltage and an equivalent reactance, the equivalent voltage being determined based on an estimate of the equivalent reactance, the measured SVC susceptance, and the measured SVC bus voltage; means for predicting a desired SVC susceptance based on the equivalent voltage and a reference SVC bus voltage; and means for controlling switching of the SVC based on the predicted SVC susceptance.
Claim 15
Dependent Claim
119 words
A voltage regulator comprising: a static VAR compensator (SVC) switchably connected to a power supply network at a bus; means for measuring a susceptance delivered by the SVC to the power supply network; means for measuring an SVC voltage at the bus; means for modelling the power supply network at the bus using an equivalent network including an equivalent voltage and an equivalent reactance, the equivalent voltage being determined based on an estimate of the equivalent reactance, the measured SVC susceptance, and the measured SVC bus voltage; means for predicting a desired SVC susceptance based on the equivalent voltage and a reference SVC bus voltage; and means for controlling switching of the SVC based on the predicted SVC susceptance.
Claim 16
Dependent Claim
34 words
The voltage regulator according to claim 13, further comprising: means for tracking changes in the equivalent voltage and measured SVC susceptance and automatically modifying the estimate of equivalent reactance in response to those changes.
Claim 17
Dependent Claim
21 words
The voltage regulator according to claim 13, wherein the equivalent network is the Thevenin equivalent circuit of the power supply network.
Claim 18
Dependent Claim
96 words
The voltage regulator according to claim 13, wherein the power supply network includes plural phases of power with each phase including an SVC, further comprising: means for measuring SVC voltages for each phase and averaging the measured SVC phase voltages to provide an average SVC voltage to the calculator Vm, and detecting means for detecting activation status of the SVCs and generating the measured susceptance in accordance with the detected activation status; wherein the means for controlling includes a firing control unit for receiving the predicted SVC susceptance and calculating control pulses for activating an SVC.
Claim 19
Dependent Claim
55 words
The voltage regulator according to claim 16, further comprising: a first filter having an associated predetermined delay and connected to the means for modelling for filtering the average SVC voltage, and a second filter, connected to the means for modelling and having substantially the same delay as the predetermined delay, for filtering the measured susceptance.
Claim 20
Dependent Claim
43 words
The voltage regulator according to claim 13, wherein the means for modelling calculates the equivalent voltage Vthm in accordance with the following equation: Vthm=Vm(1-Xthm*Bm) where Vm is the measured SVC voltage, Xthm is the estimated equivalent reactance, and Bm is the measured susceptance.
Claim 21
Dependent Claim
24 words
The voltage regulator according to claim 18, wherein the means for predicting predicts the predicted susceptance Bo in accordance with the following equation: Bo=(1-Vth/Vm)/Xthm.
Claim 22
Dependent Claim
61 words
The voltage regulator according to claim 13, further comprising: a summer for receiving a reference SVC voltage, and a feedback loop for feeding back the ordered susceptance to the summer through a desensitizing circuit, wherein the summer determines the difference between the reference voltage and an output signal from the desensitizing circuit and provides that difference to the means for predicting.
Claim 23
Dependent Claim
43 words
The voltage regulator according to claim 13, further comprising: a filter for filtering an output of the means for predicting and generating the predicted susceptance, and an SVC status detector for detecting an activation status of the SVC to determine the measured susceptance.
Claim 24
Independent Claim
66 words
A method for regulating the bus voltage of a static VAR compensator (SVC) that supplies reactive power to a power supply network, comprising: determining a power supply network voltage based on reactive power delivered to the network by the SVC, SVC bus voltage, and an estimate of the power supply network's reactance, and regulating the SVC bus voltage based on the determined power supply network voltage.
Claim 25
Independent Claim
66 words
A method for regulating the bus voltage of a static VAR compensator (SVC) that supplies reactive power to a power supply network, comprising: determining a power supply network voltage based on reactive power delivered to the network by the SVC, SVC bus voltage, and an estimate of the power supply network's reactance, and regulating the SVC bus voltage based on the determined power supply network voltage.
Claim 26
Dependent Claim
29 words
The method according to claim 22, the regulating step further comprising: calculating a desired susceptance to be delivered by the SVC based on the determined power supply network voltage.
Claim 27
Dependent Claim
22 words
The method according to claim 22, further comprising: automatically modifying the estimated reactance in response to changes in the power supply network.
Claim 28
Dependent Claim
25 words
A method according to claim 24, wherein the power supply network voltage is determined based also on measured susceptance and measured voltage of the SVC.
Claim 29
Dependent Claim
38 words
A method as claimed in claim 25, wherein the automatic modifying step includes: correlating the power supply network voltage and the measured SVC susceptance in a predetermined frequency band, and modifying the estimated reactance based on the correlation.
Claim 30
Dependent Claim
29 words
The method according to claim 22, the regulating step further comprising: predicting a desired reactance to be delivered by the SVC based on the determined power supply network voltage.
Claim 31
Dependent Claim
66 words
The method according to claim 27, further comprising: measuring the SVC voltage; generating SVC control signals based on the predicted reactance; activating the SVC in accordance with the control signals; detecting the activation status of the SVC; and generating a measured susceptance in accordance with the detected SVC activation status, wherein the measured susceptance is representative of the reactive power delivered to the power supply network.
Claim 32
Dependent Claim
52 words
The method according to claim 27, wherein the power supply network voltage Vthm is based on the following equation: Vthm=Vm(1-Xthm*Bm) where Vm is the SVC bus voltage, Xthm is the estimate of the power supply network reactance, and Bm is a measured susceptance of the SVC representative of the SVC reactive power.
Claim 33
Dependent Claim
16 words
The method according to claim 29, wherein reactance is predicted based on the following equation: Bo=(1-Vth/Vm)/Xthm.
Claim 34
Dependent Claim
42 words
The method according to claim 22, wherein the determined power supply network voltage is the Thevenin equivalent voltage of the power supply network and the estimate of the power supply network's reactance is the Thevenin equivalent reactance of the power supply network.
Claim 35
Dependent Claim
116 words
A power generation system, comprising: a power generator for supplying power to a load via a transmission line; a bus connected to the transmission line; a reactive power compensator connected to the bus for selectively supplying reactive current to the transmission line; means for maintaining voltage at the bus substantially at a reference voltage including: a calculator for calculating a voltage representative of the power generation system based on measured SVC susceptance, measured SVC voltage, and an estimate of the power generation system's equivalent reactance, a predictor for predicting a susceptance to be provided by the reactive power compensator based on the calculated voltage, and means for regulating the bus voltage using the predicted susceptance value.
Claim 36
Dependent Claim
116 words
A power generation system, comprising: a power generator for supplying power to a load via a transmission line; a bus connected to the transmission line; a reactive power compensator connected to the bus for selectively supplying reactive current to the transmission line; means for maintaining voltage at the bus substantially at a reference voltage including: a calculator for calculating a voltage representative of the power generation system based on measured SVC susceptance, measured SVC voltage, and an estimate of the power generation system's equivalent reactance, a predictor for predicting a susceptance to be provided by the reactive power compensator based on the calculated voltage, and means for regulating the bus voltage using the predicted susceptance value.
Claim 37
Dependent Claim
17 words
The system according to claim 32, wherein the reactive power compensator is a static VAR compensator (SVC).
Claim 38
Dependent Claim
34 words
The system according to claim 33, further comprising: means for tracking changes in the calculated voltage and measured SVC susceptance and automatically modifying the estimate of the equivalent reactance in response to those changes.
Claim 39
Dependent Claim
41 words
A system as claimed in claim 34, wherein the means for automatic modifying includes: means for correlating the equivalent voltage and the measured SVC susceptance in a predetermined frequency band, and means for modifying the estimated reactance based on the correlation.
Claim 40
Dependent Claim
28 words
A system as claimed in claim 35, wherein the means for correlating includes first and second bandpass filters for passing signals in the frequency range of 5-20 Hz.
Claim 41
Dependent Claim
34 words
A system as claimed in claim 36, further comprising: means for emphasizing the outputs from the first and second bandpass filters to increase the responsiveness of the means for automatically modifying the estimated reactance.
Claim 42
Dependent Claim
34 words
A system as claimed in claim 36, further comprising: means for weighting output signals from the first and second bandpass filters to increase the responsiveness of the means for automatically modifying the estimated reactance.
Claim 43
Dependent Claim
54 words
The system according to claim 36, wherein the means for automatically modifying the estimated reactance further includes: a correlator for correlating respective outputs of the first and second bandpass filters; an amplifier for amplifying an output of the combiner; and an integrator for integrating an output of the amplifier to generate the estimated reactance.
Claim 44
Dependent Claim
15 words
The system according to claim 33, wherein the SVC includes one or more thyristor-controlled capacitors.
Claim 45
Dependent Claim
20 words
The system according to claim 40, wherein the thyristor-controlled capacitor includes in series a capacitor, an inductor, and antiparallel thyristors.
Claim 46
Dependent Claim
55 words
The system according to claim 33, further comprising: means for measuring SVC voltage; a control unit for calculating gate signals for controlling thyristors in the SVC based on the predicted susceptance value; and detecting means for detecting conduction status of the SVC thyristors and generating the measured SVC susceptance in accordance with the conduction status.
Claim 47
Dependent Claim
94 words
The system according to claim 33, wherein the power generation system includes plural phases of power with each phase including an SVC, further comprising: means for measuring SVC voltages for each phase and averaging the measured SVC phase voltages to provide an average SVC voltage to the calculator, and detecting means for detecting activation status of the SVCs and generating the measured susceptance in accordance with the detected activation status; wherein the means for controlling includes a firing control unit for receiving the predicted SVC susceptance and calculating control pulses for activating an SVC.
Claim 48
Dependent Claim
54 words
The system according to claim 43, further comprising: a first filter having an associated predetermined delay and connected to the means for modelling for filtering the average SVC voltage, and a second filter, connected to the means for modelling and having substantially the same delay as the predetermined delay, for filtering the measured susceptance.
Claim 49
Dependent Claim
60 words
The system according to claim 33, further comprising: a summer for receiving a reference SVC voltage, and a feedback loop for feeding back the ordered susceptance to the summer through a desensitizing circuit, wherein the summer determines the difference between the reference voltage and an output signal from the desensitizing circuit and provides that difference to the means for predicting.
Claim 50
Independent Claim
53 words
A method for controlling the reactive power in a power system using a static VAR compensator (SVC), comprising: estimating an equivalent reactance of the power system; determining an equivalent voltage of the power system based on the estimated reactance; and automatically modifying the estimated reactance in response to changes in the power system.
Claim 51
Independent Claim
53 words
A method for controlling the reactive power in a power system using a static VAR compensator (SVC), comprising: estimating an equivalent reactance of the power system; determining an equivalent voltage of the power system based on the estimated reactance; and automatically modifying the estimated reactance in response to changes in the power system.
Claim 52
Dependent Claim
24 words
A method as claimed in claim 46, wherein the equivalent voltage is determined based also on measured susceptance and measured voltage of the SVC.
Claim 53
Dependent Claim
36 words
A method as claimed in claim 47, wherein the automatic modifying step includes: correlating the equivalent voltage and the measured SVC susceptance in a predetermined frequency band, and modifying the estimated reactance based on the correlation.
Claim 54
Dependent Claim
64 words
An AC power system including a static VAR compensator (SVC) for providing reactive power to the AC power system, comprising: means for estimating an equivalent reactance of the AC power system; means for determining an equivalent voltage of the AC power system based on the estimated reactance; and means for automatically modifying the estimated reactance in response to changes in the AC power system.
Claim 55
Dependent Claim
64 words
An AC power system including a static VAR compensator (SVC) for providing reactive power to the AC power system, comprising: means for estimating an equivalent reactance of the AC power system; means for determining an equivalent voltage of the AC power system based on the estimated reactance; and means for automatically modifying the estimated reactance in response to changes in the AC power system.
Claim 56
Dependent Claim
24 words
A system as claimed in claim 49, wherein the equivalent voltage is determined based also on measured susceptance and measured voltage of the SVC.
Claim 57
Dependent Claim
41 words
A system as claimed in claim 50, wherein the means for automatic modifying includes: means for correlating the equivalent voltage and the measured SVC susceptance in a predetermined frequency band, and means for modifying the estimated reactance based on the correlation.
Claim 58
Dependent Claim
26 words
A system as claimed in claim 51, wherein the means for correlating includes first and second bandpass filters for passing signals in a predetermined frequency range.
Claim 59
Dependent Claim
34 words
A system as claimed in claim 52, further comprising: means for emphasizing output signals from the first and second bandpass filters to increase the responsiveness of the means for automatically modifying the estimated reactance.
Claim 60
Dependent Claim
53 words
A system as claimed in claim 53, wherein the means for emphasizing includes: a multiplier; means for determining the absolute value of an output of the second bandpass filter; and means for raising an output of the means for determining by an exponent n, where n is a real number greater than 0.
Claim 61
Dependent Claim
34 words
A system as claimed in claim 52, further comprising: means for weighting output signals from the first and second bandpass filters to increase the responsiveness of the means for automatically modifying the estimated reactance.
Claim 62
Dependent Claim
54 words
The system according to claim 52, wherein the means for automatically modifying the estimated reactance further includes: a combiner for combining respective outputs of the first and second bandpass filters; an amplifier for amplifying an output of the combiner; and an integrator for integrating an output of the amplifier to generate the estimated reactance.
Claim 63
Dependent Claim
139 words
A power generation system for controlling reactive power comprising: an AC power generator for delivering AC power over a transmission line to a load; a static VAR compensator (SVC) connected at a bus to the transmission line for selectively providing reactive current to the transmission line; a voltage regulator for regulating voltage at the bus in accordance with a reference voltage; a calculator for calculating a voltage equivalent to the power generation system based on measured SVC voltage, measured SVC susceptance, and an estimate of an equivalent reactance for the power generation system; a predictor for predicting a susceptance to be provided by the SVC based on the calculated equivalent voltage; and means for tracking changes in the calculated equivalent voltage and measured SVC susceptance and automatically modifying the estimate of the equivalent reactance in response to those changes.
Claim 64
Dependent Claim
139 words
A power generation system for controlling reactive power comprising: an AC power generator for delivering AC power over a transmission line to a load; a static VAR compensator (SVC) connected at a bus to the transmission line for selectively providing reactive current to the transmission line; a voltage regulator for regulating voltage at the bus in accordance with a reference voltage; a calculator for calculating a voltage equivalent to the power generation system based on measured SVC voltage, measured SVC susceptance, and an estimate of an equivalent reactance for the power generation system; a predictor for predicting a susceptance to be provided by the SVC based on the calculated equivalent voltage; and means for tracking changes in the calculated equivalent voltage and measured SVC susceptance and automatically modifying the estimate of the equivalent reactance in response to those changes.
Claim 65
Dependent Claim
41 words
A system as claimed in claim 57, wherein the means for automatic modifying includes: means for correlating the equivalent voltage and the measured SVC susceptance in a predetermined frequency band, and means for modifying the estimated reactance based on the correlation.
Claim 66
Dependent Claim
54 words
A system as claimed in claim 58, wherein the means for correlating includes first and second bandpass filters for passing signals in a predetermined frequency range and further including: means for emphasizing the outputs from the first and second bandpass filters to increase the responsiveness of the means for automatically modifying the estimated reactance.
Claim 67
Dependent Claim
54 words
The system according to claim 59, wherein the means for automatically modifying the estimated reactance further includes: a combiner for combining respective outputs of the first and second bandpass filters; an amplifier for amplifying an output of the combiner; and an integrator for integrating an output of the amplifier to generate the estimated reactance.
References Cited (Backward Citations)
US4204151A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-10-29 | 2000-04-29 | 2000-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-10-29 | 2004-04-29 | 2004-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-10-29 | 2008-04-29 | 2008-10-29 | $7700.00 | Window Closed / Lapsed |