Electrical power line parameter measurement apparatus and systems, including compact, line-mounted modules

• US 4,709,339 A
• Filed: 05/05/1986
• Issued: 11/24/1987
• Est. Priority Date: 04/13/1983
• Status: Expired due to Fees

• Current Assignee: Roosevelt A. Fernandes
• Original Assignee: Roosevelt A. Fernandes
• Inventors: Fernandes, Roosevelt A.
• Primary Examiner(s): Gruber, Felix D.
• Assistant Examiner(s): Teska, Kevin J.
• Application Number:
  US06/859,497
• Time in Patent Office: 568 Days
• Field of Search: 364/464, 364/492, 364/483, 324/17, 324/127, 324/133, 340/538, 340/539, 340/657, 340/870.17, 340/870.38
• US Class Current: 700/293
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G01K 1/143 for measuring surface temperatures
• CPC Class Codes: G01R 1/22 Tong testers acting as secondary windings of current transformers
• CPC Class Codes: G01R 15/142 Arrangements for simultaneous measurements of several parameters employing techniques covered by groups G01R15/14 - G01R15/26
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 13/00007 using the power network as support for the transmission
• CPC Class Codes: H02J 13/00012 using an auxiliary transmission line
• CPC Class Codes: H02J 13/00017 using optical fiber
• CPC Class Codes: H02J 13/00019 using optical means
• CPC Class Codes: H02J 13/00022 using wireless data transmission
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/00 Systems supporting electrical power generation, transmission or distribution
• CPC Class Codes: Y04S 10/30 State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission
• CPC Class Codes: Y04S 40/124 using wired telecommunication networks or data transmission busses
• CPC Class Codes: Y04S 40/126 using wireless data transmission

Abstract

The invention is primarily directed to sensor modules for mounting directly upon energized electrical power lines to monitor parameters associated with operation thereof, wherein the modules have a more compact lateral configuration than prior art modules designed for the same purpose. The modules include a first, cylindrical housing portion containing the sensing means and other electronic data processing and transmitting elements, and a second housing portion, affixed to the exterior of the first portion and extending not more than about 150° around the periphery thereof, and enclosing mechanical elements of the module mounting means. The invention also concerns means for improving the accuracy of voltage measurements made by such modules by compensating for effects of adjacent, energized conductors, means for reducing the number of frequency channels required for RF data transmissions by a large number of sensor modules at a substation, means for acquiring time-synchronized data from multiple modules within a substation for accurate post-fault, sequence-of-events analysis, means for performing high speed sampling and comparison of cyclically variable parameters for relaying and harmonic measurement applications, and optical communications links for transmitting data from sensor modules.

Claims

1. A compact system for installation on and removal from energized AC power conductors and accurately measuring the voltage on each of a plurality of AC power conductors, said system comprising:

(a) a plurality of sensing means one of which is mounted upon each of said conductors and including means to measure said conductor voltage simultaneously by all of said sensing means at a plurality of predetermined times;

(b) signal transmitting means associated with each of said sensing means to transmit signals commensurate with said conductor voltage at each of said predetermined times; and

(c) signal receiving and processing means for receiving said transmitted signals and calculating therefrom the tue value of said voltage on each of said conductors after correcting the received signal for any influence of adjacent conductor on said measured voltage.

2. The invention according to claim 1 wherein said sensing means includes a metallic housing mounted in surrounding relation to and conductively isolated from the associated conductor, upon which it is mounted whereby a charging current is present on said housing due to the electrostatic field of said associated conductor, and said conductor voltage is measured by sensing said charging current.

3. The invention according to claim 2 wherein said influence of adjacent conductors comprises the charging current present on said housing of any one of said sensing means as a result of the electrostatic field of any conductors adjacent to said associated conductor.

4. The invention according to claim 3 wherein said energized conductors have at least one adjacent conductor which may be energized or deenergized and said processing means includes scale factor storage means responsive to the state of energization or deenergization of each of said adjacent conductors.

5. A system for monitoring the rate of change of a cyclically variable parameter of an energized electrical power conductor and for actuating ground station control means in response to a predetermined abnormal rate of change of said parameter, said system comprising:

(a) a sensor module for mounting upon and removal from said energized conductor, and carrying means for sampling the value of said parameter at each of a plurality of evenly spaced times within each cycle of said parameter, and for storing the sampled values;

(b) means carried by said module for comparing said stored values with the sampled values at corresponding points in successive cycles of said parameter and determining whether the difference between said sampled values and said stored values indicates said predetermined abnormal rate of change;

(c) means carried by said module for transmitting an alarm signal in response to said abnormal rate of change; and

(d) ground receiver means remote from said module for receiving said alarm signal and actuating said control means in response thereto.

6. The invention according to claim 5 wherein said transmitting means includes means to transmit signals on either of first and second transmission channels, and means responsive to said comparaing means to cause said transmitting means to transmit on said first and second channels when said difference indicates the absence and presence, respectively , of said abnormal rate of change.

7. The invention according to claim 6 wherein said transmitting means comprises an RF transmitter having at least two crystals for respective transmissions on said first and second channels.

8. The invention according to claim 7 wherein said remote means includes means for receiving and processing signals transmitted on each of said first and second channels, and for actuating said control means in response to signals received on said second channel.

9. The invention according to claim 8 and further including means to disable transmission on said first channel, thereby permitting immediate transmission on said second channel, in response to said abnormal condition.

10. The invention according to claim 5 wherein said module further includes means for varying the duration of said evenly spaced times, and thereby the interval of said sampling, to sample at shorter intervals in response to said parameter varying at said predetermined abnormal rate of change.

11. The invention according to claim 10 wherein the number of samples within each cycle is variable in response to a predetermined rate of change of said parameter within a cycle.

12. The invention according to claim 11 wherein the number of samples within each cycle is increased by a predetermined multiple in response to a predetermined increase in the rate of change of said parameter.

13. The invention according to claim 10 wherein said sampling means is constructed and arranged to sample at least one harmonic of said parameter, and said sampling interval is proportionate to the frequency of the harmonic being sampled.

16. The invention according to claim 5 wherein said control means comprises a relay actuable to interrupt the circuit including said power conductor.

17. The invention according to claim 5 wherein said transmitting and receiver means comprise a fiber optic communications link.

14. The invention according to cliam 5 wherein said control means comprises means for actuating operator alarm means.

15. The invention according to claim 14 wherein said operator alarm means comprises a remote telemetering interface for communicating said alarm signal to a location remote from said ground receiver means.

18. A system for wireless sensing of current differential across the primary and secondary windings of a power transformer bank to provide differential relay protection of said power transformer bank, said system comprising:

(a) a sensor module for mounting upon and removal from each of the energized conductors which are connected to said primary and secondary windings, said modules carrying means for measuring the current flowing through its associated conductor;

(b) means for causing said modules to measure the current on its associated conductor simultaneously;

(c) means for transmitting signals from said modules commensurate with the value of current measured thereby;

(d) means remote from said modules for receiving and comparing said signals all within the time contraints required for effective differential relay protection; and

(e) means for operating a differential relay in response to the difference between said compared signals exceeding a predetermined threshold level.

19. The invention according to claim 18 wherein said time constraints comprise a time period not greater than that of 3 successive cycles of said current.

20. The invention according to claim 19 wherein said remote means further includes means for transmitting time-synchronizing signals, and said modules include means for receiving said time-synchronizing signals and for measuring said current and transmitting said signals commensurate with the value of current at times established by said time-synchronizing signals.

21. The invention according to claim 20 wherein said time-synchronizing signals are transmitted through the air.

22. The invention according to claim 20 wherein said means for transmitting said time-synchronizing signals comprise means coupling said remote means with said power conductors and said time-synchronizing signals are transmitted using power line carrier injection.

23. The invention according to claim 20 wherein said means for transmitting and receiving at least one of said time-synchronizing signals and said signals commensurate with the value of current comprise fiber optic communication links.

24. A system for wireless sensing of current differential on first and second pluralities of electrical conductors carrying current to and from, respectively, a singled bus to provide differential relay protection of said bus, said system comprising:

(a) a sensor module mounted upon each of the conductors of said first and second pluralities, said modules carrying means for measuring the current flowing through its associated conductor;

(b) means for causing all of said modules to measure the current on its associated conductor simultaneously;

(c) means for transmitting signals from said modules commensurate with the current measured thereby;

(d) means for receiving and comparing said signals from modules on said first plurality of conductors with signals from modules on said second plurality of conductors; and

(e) means for operating a differential relay in response to the difference between said compared signals exceeding a predetermined threshold level.

25. An integrated system for performing metering functions by both wireless and hard-wired sensing means at an electrical power substation, said system comprising:

(a) a plurality of individual sensor modules each mounted upon one of a first plurality of power conductors at said substation, each of said modules including means for simultaneously measuring each of a plurality of variable parameters, including d voltage and current, associated with operation of said first conductors;

(b) means for time-synchronizing the measurement of said parameters by said plurality of modules, whereby each of said modules measures the value of the same parameter at the same time on its associated conductor;

(c) means for transmitting first metering signals commensurate with the values of said parameters from said modules;

(d) a ground station having means for receiving and processing said signals from said modules;

(e) said ground station further including means for receiving substation analog signals, and conditioning signals from existing current and potential transformers, processing the values of current and voltage on a second plurality of conductors and generating second metering signals in response thereto;

(f) means for multiplexing said second metering signals for processing at said ground station; and

(g) means at said ground station for integrating in a single processor the processing of said first and second metering signals.

26. The invention according to claim 25 wherein said ground station further includes means for monitoring alarm status, sequence-of-events, and performing select-before-operate control functions through interposing relays, pulse control and means for processing non-metering analog and pulse/digital signals.

27. The invention according to claim 25 wherein said ground station further includes means for establishing from said first metering signals whether each of the conductors of said first plurality is energized, and means for selecting an appropriate scale factor to be applied to the voltage reading of each of said sensor modules in accordance with the state of energization of adjacent conductors.

28. A system for monitoring a plurality of parameters associated with each of a plurality of energized electrical power conductors of a power delivery network over the full operating range from minimum to maximum conductor current, said system comprising:

(a) a plurality of sensor modules for complete installation and removal while said conductors are energized, one of said modules being mounted upon each of said energized conductors;

(b) means carried by each of said modules for sensing values of a plurality of parameters of the associated power conductor;

(c) means carried by each of said modules for identifying, processing and storing said sensed values;

(d) means carried by each of said modules for periodically transmitting a sequence of encoded signals in data bursts of predetermined duration from each of said plurality of sensor modules commensurate with each of said sensed values;

(e) means carried by each of said modules for controlling the starting times of said data bursts by said transmitting means of each of said modules to avoid simultaneous transmission, with consequent data collisions, by any two of said modules;

(f) means remote from said modules for receiving said signals from each of said plurality of modules and decoding said signals to provide said parameter values at said remote means, and to derive from said values operational status information, including normal, abnormal and transient operating conditions, about said power conductors; and

(g) means for controlling said power delivery network over said full operating range during all of said normal, abnormal and transient operating conditions, in accordance with said operational status information.

29. A method of monitoring and controlling a power delivery network having a plurality of power conductors over the full operating range from minimum to maximum conductor current, said method comprising:

(a) mounting upon each of said conductors a sensor module;

(b) measuring a plurality of parameters of each of said conductors by the module mounted thereon;

(c) transmitting from each of said modules to a remote receiver a sequence of encoded signals in data bursts of predetermined duration indicating the values of said measured parameters and module identification;

(d) controlling the starting times of said data bursts to avoid simultaneous transmission by any two of said modules;

(e) deriving from said values operational status information, including normal, abnormal and transient operating conditions, about said power conductors; and

(f) controlling said power delivery network over said full operating range during all of said normal, abonormal and transient operation conditions, in accordance with said operational status information.