Electrical power line and substation monitoring apparatus and systems

• US 4,758,962 A
• Filed: 05/05/1986
• Issued: 07/19/1988
• Est. Priority Date: 04/13/1983
• Status: Expired due to Term

• Current Assignee: Undersground Systems, Inc.
• Original Assignee: Roosevelt A. Fernandes
• Inventors: Fernandes, Roosevelt A.
• Primary Examiner(s): Gruber, Felix D.
• Assistant Examiner(s): Teska, Kevin J.
• Application Number:
  US06/859,496
• Time in Patent Office: 806 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: 702/62
• 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: G01R 15/26 using modulation of waves other than light, e.g. radio or acoustic waves
• CPC Class Codes: G01R 23/16 Spectrum analysis; Fourier analysis
• CPC Class Codes: H01J 13/00 Discharge tubes with liquid-pool cathodes, e.g. metal-vapour rectifying tubes
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 13/00022 using wireless data transmission
• CPC Class Codes: H02J 13/00024 by means of mobile telephony
• CPC Class Codes: H02J 13/00026 involving a local wireless network, e.g. Wi-Fi, ZigBee or Bluetooth
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: H02J 13/0004 involved in a protection system
• 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 40/126 using wireless data transmission

Abstract

An electrical power monitoring and control system including individual sensor modules for mounting directly upon energized electrical power conductors and systems employing such modules, with principal emphasis upon the provision of both data transmitting and receiving means in each sensor module and at an associated ground station. The modules sense the instantaneous values of all parameters necessary to perform complete metering functions and, in one embodiment, are synchronized by a signal transmitted from the ground station and received by all modules so that the values are measured simultaneously on all conductors at a substation. The signals are transmitted by the modules in a time-synchronized manner and are in a condition for use directly by the ground station microprocessor. In another embodiment, data transmissions by a plurality of modules is synchronized to avoid data collisions by self-contained means within each module, requiring no synchronizing signal from the ground station. The modules preferably include a reliable battery back-up system, requiring essentially no removal and/or replacement of batteries for recharging, for providing power to the module electronics when there is little or no current flowing through the associated conductor.

Claims

1. A system for monitoring a plurality of parameters associated with each of a plurality of energized electrical power conductors, one of said parameters being conductor voltage, on power system circuits operable over a load range between predetermined minimum and maximum conductor currents in either direction for complete installation and removal while said conductors are energized, said system comprising:

(a) a plurality of sensor modules each having a metallic housing, one of said modules being mounted upon each of said energized conductors, said housing being conductively isolated from said conductor at least for frequencies below the highest frequency of conductor voltage to be measured, whereby the surface of said housing continuously collects the charging current due to the electrostatic field associated with said conductor;

(b) means connected between said conductor and said housing for measurement of conductor voltage from said charging current;

(c) means contained within said housing for continuously sensing the current through said conductor over said entire loan range;

(d) means carried by each of said modules for establishing the phase relationship between said sensed values of conductor voltage and conductor current;

(e) means carried by each of said modules for identifying, processing and storing said sensed values of conductor voltage and conductor current and said established phase relationship;

(f) means carried by each of said modules for transmitting a sequence of encoded signals commensurate with each of said sensed values and including said established phase relationship and sensor module identification; and

(g) means remote from said modules for receiving said signals from each of said plurality of sensor modules, decoding said signals and calculating voltage, current and power factor of each of said conductors.

2. The invention according to claim 1 wherein said remote means includes means for calculating power and energy quantities from said readings of voltage, current and phase over said entire load range.

3. The invention according to claim 1 and further including means for measuring the frequency of voltage and current on said conductors.

4. The invention according to claim 1 and further including means for sensing parameters other than voltage, current and phase.

5. The invention according to claim 1 wherein said conductor voltage and current contain harmonic and transient components and said remote means includes means for calculating the harmonic and transient components of voltage, current and power.

6. The invention according to claim 1 wherein said housing is conductively isolated from said conductor by a relatively thin layer of insulation interposed therebetween.

7. The invention according to claim 1 wherein said housing is conductively isolated from said conductor by a capacitance having a value providing a relatively high impedance at said frequencies below the highest frequency of conductor voltage to be measured and appearing as a short circuit between said housing and conductor above said highest frequency, thereby permitting said charging current to flow through said conductor voltage measurement means at said frequencies below the highest frequency of conductor voltage to be measured.

8. The invention according to claim 1 wherein said means for establishing phase relationship include means for detecting zero-crossings of conductor current and voltage, and said data transmitting means includes means to transmit a message of predetermined duration in synchronization with said voltage zero crossings.

9. The invention according to claim 1 and further including energy storage means carried by said sensor modules for powering said transmitting means when current flow through the associated power conductor is below a predetermined threshold value.

10. The invention according to claim 9 and further including means for charging said energy storage means from the electromagnetic field associated with said conductor.

11. The invention according to claim 9 and further including means for charging said energy storage means from the electromagnetic and electrostatic field associated with said conductor and said metallic housing.

12. The invention according to claim 11 and further including means carried by each of said sensor modules for generating an indicating signal when current flow through the associated conductor is below said threshold value.

13. The invention according to claim 12 wherein said transmitting means includes an RF transmitter and means for regulating the frequency of transmissions.

14. The invention according to claim 13 and further including means responsive to the presence of said indicating signal for a predetermined, continuous period of time to reduce said frequency of transmissions.

15. The invention according to claim 14 and further including means carried by each of said modules for sensing voltage on said associated power conductor with no current in said associated power conductor and for providing a signal indicating the no current condition.

16. The invention according to claim 15 including means for electrostatically charging said battery when no current is flowing through said power conductor and data is not being transmitted from said device.

17. The invention according to claim 1 and further including means carried by each of said sensor modules for deriving electrical power from the electromagnetic field associated with current flow through said power conductor for powering all sensor module electronics.

18. The invention according to claim 1 and further including conductor temperature measurement means carried by each of said modules and including a temperature probe having a portion in direct contact with the associated conductor to measure the temperature thereof and means for avoiding any influence on said temperature measurement due to heat from said sensor module and solar sources.

19. The invention according to claim 18 and further including means carried by each of said sensor modules for measuring ambient temperature of the air immediately adjacent the associated conductor.

20. The invention according to claim 19 wherein said avoiding means comprise a protective shroud surrounding at least a portion of said temperature probe.

21. A system for monitoring a plurality of parameters associated with each of a plurality of energized electrical power conductors for complete installation and removal while said conductors are energized, said system comprising:

(a) a plurality of sensor modules, 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; and

(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.

22. The invention according to claim 21 wherein said controlling means of each of said modules establishes said starting times for beginning transmission by said transmitting means in relation to a reference point on the voltage waveform which is chosen to be the same for all modules on conductors connected to the same phase of a common three-phase bus.

23. The invention according to claim 22 wherein said reference point is the zero crossing of the voltage on one phase of said common bus, said times for beginning transmissions by the modules on adjacent phases of each three-phase circuit is displaced by the successive zero crossings of each phase, and said duration of transmission by each module is less that the time between successive zero crossings of adjacent phases.

24. The invention according to claim 23 wherein predetermined times for successive transmissions from each module are an integral multiple of elapsed voltage cycles.

25. The invention according to claim 24 wherein said integral multiple is different for each of said modules and does not have a common denominator with said integral multiple of any other module.

26. The invention according to claim 21 and further including an RF transmitter and antenna for transmitting signals on a second frequency from a location remote from said modules, and an RF receiver and antenna carried by each of said modules for receiving signals at said second frequency.

27. The invention according to claim 26 wherein said signals transmitted on said second frequency are encoded to provide an address unique to each of said modules including its assigned time slot for transmitting said sequence of signals on said first frequency.

28. The invention according to claim 21 wherein said controlling means includes means for detecting zero-crossings of conductor current and voltage, said data transmitting means includes means to transmit a message of predetermined duration in synchronization with said voltage zero crossing.