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US3886330A
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Security monitoring system and method for an electric power system employing a fast on-line loadflow computer arrangement
Assignee: Westinghouse Electric Corp
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Filing: 1971-08-26
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Granted: 1975-05-27
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Expires: 1991-08-26
Abstract
Abstract A security monitoring system for an electric power system includes a data acquisition system and a hybrid loadflow computer arrangement. The hybrid loadflow computer in turn includes an analog network simulator and a digital computer which processes and operates upon acquired on-line data and operator data related to the power system loadflow problem. The analog simulator includes modular circuits representative of power system busses and lines and the interface between the digital computer and the analog network simulator is provided by analog-to-digital and digital-to-analog converters and by line outage contact closure outputs. The hybrid arrangement operates iteratively to provide loadflow solutions, with the analog network simulator providing a bus voltage solution for a set of network simultaneous equations and the digital computer providing bus load and generation injection current calculations and convergence steering control. Because loadflow solutions are generated cyclically and contingency case loadflow solutions are generated with the use of basecase data modified to reflect the contingencies. Modifications are also made in the analog simulator to reflect the contingencies.
Inventors
- 👤 David M Egelston
- 👤 Jerry C Russell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:39
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/48; G06G7/62; G06G7/63; G06J; G06J1/00
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
332 words
A security monitoring system for an electric power system comprising a security loadflow computer including an analog network simulator and a programmed digital computer, means for generating signals representing predetermined on-line system data including at least some unit generator and tieline power values and at least some bus voltage values, means for applying said data signals to said digital computer, said digitial computer including means for storing said predetermined on-line data, said analog simulator including a plurality of bus DC circuits and line DC circuits interconnected to correspond to the AC network, said digital computer including means for geneRating representations of bus generation and load currents as a function of predetermined parameters including stored bus power and voltage data, an analog output system, said digital computer further including means for causing said output system to generate phasor current signals representative of the digital computer determined bus generation and load currents, means for applying the phasor bus generation and load current signals to the corresponding bus DC circuits, each of said bus DC circuits including means for responding to line phasor current and bus generation and load phasor input current signals and for generating an output bus voltage phasor signal, each of said line DC circuits including means for responding to the difference between applied bus voltage phasor signals and generating an output line phasor current signal in accordance at least with a representation of the equivalent series branch line impedance, said digital computer further including means for generating representations of bus voltage phasor signals after the generation and load phasor current signals are applied to said DC bus circuits, means for generating representations of bus generation and load current values in successive iterations after a startup iteration as a function of bus voltage values determined in the next preceding iteration, means for converging the iterative process to a solution and for sensing when a solution is reached and means for monitoring representations of predetermined solution parameters and generating alarms under predetermined conditions.
Claim 2
Dependent Claim
332 words
A security monitoring system for an electric power system comprising a security loadflow computer including an analog network simulator and a programmed digital computer, means for generating signals representing predetermined on-line system data including at least some unit generator and tieline power values and at least some bus voltage values, means for applying said data signals to said digital computer, said digitial computer including means for storing said predetermined on-line data, said analog simulator including a plurality of bus DC circuits and line DC circuits interconnected to correspond to the AC network, said digital computer including means for geneRating representations of bus generation and load currents as a function of predetermined parameters including stored bus power and voltage data, an analog output system, said digital computer further including means for causing said output system to generate phasor current signals representative of the digital computer determined bus generation and load currents, means for applying the phasor bus generation and load current signals to the corresponding bus DC circuits, each of said bus DC circuits including means for responding to line phasor current and bus generation and load phasor input current signals and for generating an output bus voltage phasor signal, each of said line DC circuits including means for responding to the difference between applied bus voltage phasor signals and generating an output line phasor current signal in accordance at least with a representation of the equivalent series branch line impedance, said digital computer further including means for generating representations of bus voltage phasor signals after the generation and load phasor current signals are applied to said DC bus circuits, means for generating representations of bus generation and load current values in successive iterations after a startup iteration as a function of bus voltage values determined in the next preceding iteration, means for converging the iterative process to a solution and for sensing when a solution is reached and means for monitoring representations of predetermined solution parameters and generating alarms under predetermined conditions.
Claim 3
Dependent Claim
40 words
A security monitoring system as set forth in claim 1 wherein means are included in said digital computer for providing on-line basecase loadflow solutions cyclically and for providing contingency case loadflow solutions in the time periods between on-line loadflow solutions.
Claim 4
Dependent Claim
39 words
A security monitoring system as set forth in claim 2 wherein means are included in said digital computer for determining and running contingency cases in accordance with predetermined rules applied to the results of next preceding basecase loadflow solution.
Claim 5
Dependent Claim
64 words
A security monitoring system as set forth in claim 3 wherein means are included in said digital computer for receiving operator specified contingency cases and for generating contingency case data for the contingency case loadflow solutions on the basis of data employed in the next preceding basecase solution and on the basis of the specified contingency events in the contingency case to be run.
Claim 6
Dependent Claim
45 words
A security monitoring system as set forth in claim 2 wherein one set of contingency events includable in contingency cases are line outages, and means are included in said digital computer for determining line outages and for disconnecting determined outage lines from said analog simulator.
Claim 7
Dependent Claim
57 words
A security monitoring system as set forth in claim 2 wherein means are included in said digital computer for generating contingency case data for the contingency case loadflow solutions on the basis of data employed in the next preceding basecase solution and on the basis of the specified contingency events in the contingency case to be run.
Claim 8
Dependent Claim
36 words
A security monitoring system as set forth in claim 6 wherein means are included in said computer for modifying basecase data for generation unit losses in accordance with a predetermined basis for allocation of lost power.
Claim 9
Dependent Claim
36 words
A security monitoring system as set forth in claim 6 wherein means are included in said digital computer for modifying basecase data for tieline losses in accordance with a predetermined basis for allocation of lost power.
Claim 10
Dependent Claim
176 words
An automated method for monitoring the security of an electric power system comprising the steps of sensing at least some on-line parameter values including at least some on-line unit generation power and bus voltage values for the system, applying said sensed on-line values to an input of a digital computer and storing representations of said on-line vlaues therein, operating the digital Computer to determine bus generation and load current values as a function of stored bus power and voltage data, applying phasor signals corresponding to the bus generation and load current values in said computer to an analog network simulator which includes DC bus circuits and DC line circuits interconnected to simulate the power system, operating the analog simulator to cause the bus circuits to generate solution bus voltage phasor signals, and operating the digital computer to determine new bus generation and load current values as a function of the stored data and the solution bus voltage phasor signals, and operating said digital computer to monitor predetermined solution parameters and to generate alarms under predetermined conditions.
Claim 11
Dependent Claim
176 words
An automated method for monitoring the security of an electric power system comprising the steps of sensing at least some on-line parameter values including at least some on-line unit generation power and bus voltage values for the system, applying said sensed on-line values to an input of a digital computer and storing representations of said on-line vlaues therein, operating the digital Computer to determine bus generation and load current values as a function of stored bus power and voltage data, applying phasor signals corresponding to the bus generation and load current values in said computer to an analog network simulator which includes DC bus circuits and DC line circuits interconnected to simulate the power system, operating the analog simulator to cause the bus circuits to generate solution bus voltage phasor signals, and operating the digital computer to determine new bus generation and load current values as a function of the stored data and the solution bus voltage phasor signals, and operating said digital computer to monitor predetermined solution parameters and to generate alarms under predetermined conditions.
Claim 12
Dependent Claim
39 words
A method as set forth in claim 9 wherein the steps further comprise operating said digital computer to provide on-line basecase loadflow solutions cyclically and to provide contingency case loadflow solutions in the time periods between on-line loadflow solutions.
Claim 13
Dependent Claim
92 words
A method as set forth in claim 9 wherein the steps further comprise operating said digital computer to generate contingency case data for the contingency case loadflow solutions on the basis of data employed in the next preceding basecase solution and on the basis of the specified contingency events in the contingency case to be run, operating said digital computer to determine and run contingency cases in accordance with predetermined rules applied to the results of next preceding basecase loadflow solution, and operating said digital computer to accept operator specified contingency cases.
Claim 14
Dependent Claim
33 words
A method as set forth in claim 9 wherein the steps further comprise operating said digital computer to modify basecase data for contingency power losses in accordance with a predetermined basis of allocation.
Claim 15
Dependent Claim
96 words
An automated method for monitoring the security of an electric power system comprising the steps of sensing at least some on-line power and bus voltage values for the system, storing said sensed on-line values in loadflow computer, operating the computer to determine loadflow solution parameters including line currents and bus voltages as a function of stored bus power and voltage data, operating the computer to monitor and alarm predetermined solution parameters, operating the computer to provide on-line base-case loadflow solutions cyclically and to provide contingency case loadflow solutions in the time periods between on-line loadflow solutions.
Claim 16
Dependent Claim
96 words
An automated method for monitoring the security of an electric power system comprising the steps of sensing at least some on-line power and bus voltage values for the system, storing said sensed on-line values in loadflow computer, operating the computer to determine loadflow solution parameters including line currents and bus voltages as a function of stored bus power and voltage data, operating the computer to monitor and alarm predetermined solution parameters, operating the computer to provide on-line base-case loadflow solutions cyclically and to provide contingency case loadflow solutions in the time periods between on-line loadflow solutions.
Claim 17
Dependent Claim
95 words
A method for monitoring the security of an electric power system as set forth in claim 13 wherein the method steps further comprise operating said computer to determine and run contingency cases in accordance with predetermined rules applied to the results of the next preceding basecase loadflow solution, and to accept operator specified contingency cases, and to generate contingency case data for the contingency case loadflow solutions on the basis of data employed in the next preceding basecase solution and on the basis of the specified contingency events in the contingency case to be run.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |