Waveform capturing arrangement in a distributed power network

• US 5,233,538 A
• Filed: 12/05/1990
• Issued: 08/03/1993
• Est. Priority Date: 04/02/1990
• Status: Expired due to Term

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Wallis, Lee D.
• Primary Examiner(s): Cosimano, Edward R.
• Assistant Examiner(s): Ramirez, Ellis B.
• Application Number:
  US07/622,432
• Time in Patent Office: 972 Days
• Field of Search: 364/483, 364/492, 324/117 R, 324/126, 324/127, 324/142, 324/133, 340/870.38, 341/122, 341/123
• US Class Current: 702/62
• CPC Class Codes: G01R 13/06 Modifications for recording transient disturbances, e.g. by starting or accelerating a recording medium
• CPC Class Codes: G01R 31/088 Aspects of digital computing
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 13/00016 using a wired telecommunication network or a data transmission bus
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/30 State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge
• CPC Class Codes: Y04S 40/124 using wired telecommunication networks or data transmission busses

Abstract

A circuit monitoring system for a distributed power network employs waveform capturing techniques for efficient and highly accurate monitoring. The system includes a plurality of circuit monitors and a control station, which is coupled to each of the circuit monitors via a multi-drop communications link. Each of the circuit monitors is disposed adjacent an associated one of the branches in the network for sensing power parameters in the branches and for generating and transmitting data representing the power parameters to the control station. The control station is used for generating monitoring commands to each of the circuit monitors to provide the system with full system control and evaluation capability. The system is capable of simultaneously sensing the waveform at each branch and sampling the waveforms for a predetermined number of sample points over an integral number of cycles so as to provide an efficient yet accurate implementation.

Claims

1. A circuit monitoring arrangement for monitoring power lines in a distributed power network, carrying power-related waveform, the arrangement comprising:

a plurality of circuit monitors which are adjacent at various points along the power line, each said circuit monitor having;

a sensor, disposed adjacent the power line, for sensing power-related parameters associated with the power-related waveform;

sampling means, responsive to a control signal generated from a control center, for sampling the power-related waveform at a time prescribed by the control signal; and

generation means, responsive to said sampling means, for generating data representative of said sampled points; and

said control center being remotely coupled to receive said representative data from said plurality of circuit monitors and to send the control signal to said plurality of circuit monitors so that each of said plurality of circuit monitors samples the power-related waveform approximately simultaneously.

2. A circuit monitoring arrangement, according to claim 1, further including detection means for sensing zero-crossings of the power-related waveform.

3. A circuit monitoring arrangement, according to claim 2, further including means, responsive to said detection means, for determining the time between successive ones of said zero-crossings.

4. A circuit monitoring arrangement, according to claim 3, wherein said detection means and said generation means are implemented using a microcomputer.

5. A circuit monitoring arrangement, according to claim 1, wherein the control signal is used to command each of said plurality of circuit monitors to sample the power-related waveform at a prescribed future point in time.

6. A circuit monitoring arrangement, according to claim 1, wherein said sampling means is implemented using a microcomputer.

7. A circuit monitoring arrangement, according to claim 6, wherein the control signal is used to preprogram said plurality of circuit monitors to sample the power-related waveform at a prescribed future point in time.

8. A circuit monitoring system for a distributed power network, wherein power-related waveforms are passed through a multitude of associated network branches and wherein zero-crossings of the waveforms define their respective cycles, the system comprising:

a plurality of monitoring means, each of which is disposed adjacent an associated one of the branches, for sensing power-related parameter associated with the power-related waveforms and for generating and transmitting data representative thereof, each of said monitoring means including detection means for sensing the zero-crossing of the waveform and sampling means for sampling the power-related waveform over a plurality of integral cycles for a predetermined number of sample points; and

a control station, remotely communicatively coupled to each of the monitoring means, for receiving and evaluating the data transmitted therefrom and for generating sampling commands to command each of said plurality of monitoring means to sample the power-related waveform at a prescribed future point in time wherein said control station remotely instructs each of said plurality of monitoring means to sense the power-related parameters simultaneously.

9. A circuit monitoring system, according to claim 8 wherein said sampling means includes means for commencing said sampling based on one of the sensed zero-crossings.

10. A circuit monitoring system, according to claim 8, further including a microcomputer, coupled to said sampling means, which is programmed to receive at least one of said sampling commands and to instruct said sampling at said prescribed point in time.

11. For use in a monitoring arrangement which is controlled by a user-operated control station and which monitor power lines carrying a power-related waveform in a distributed power network, a circuit monitor comprising:

a sensor circuit, disposed adjacent the power line, for sensing a plurality of power-related parameters associated with the power-related waveform;

a sampling circuit including;

a first microcomputer,

a multiplexer, responsive to the first microcomputer and to the sensor circuit, for sampling the power-related parameters and providing a plurality of output signals therefrom, and

an analog to digital converter circuit which converts the multiplexer output signals,

wherein the first microcomputer receives the converted power-related waveform samples to detect zero crossings therein and to perform power-related computations; and

a second microcomputer, receptive of the power-related computations, which communicates with the user-operated control station.

12. A circuit monitor, according to claim 11, wherein the first microcomputer controls the multiplexer to capture a predetermined number of samples on a continuous basis.

13. A circuit monitor, according to claim 12, wherein the predetermined number of samples is 256.

14. A circuit monitor, according to claim 11, wherein the zero crossings define cycles in the power-related waveform and wherein the power-related waveform is automatically sampled over a plurality of integral cycles for a predetermined number of sample points.

15. A circuit monitor, according to claim 11, further including a two-way data latch arranged to couple data between the first and second microcomputers.

16. A circuit monitoring arrangement for monitoring power lines in a distributed power network, wherein the power lines carry a power-selected waveform, the arrangement comprising:

a plurality of circuit monitors which are situated adjacent at various points along the power line, each said circuit monitor having;

a sensor, disposed adjacent the power line, for sensing power-related parameters associated with the power-related waveform;

a sampling circuit, responsive to a control signal generated from a control center, for sampling the power-related waveform at a time prescribed by the control signal, said sampling circuit including;

a first microcomputer,

a multiplexer, responsive to the first microcomputer and to the sensor circuit, for sampling the power-related waveform, and

an analog to digital converter circuit which converts the power-related waveform samples from the multiplexer,

wherein the first microcomputer receives the converted power-related waveforms samples to detect zero crossings therein and to perform power-related computations; and

a second microcomputer, receptive of the power-related computations, which communicates with the user-operated control station;

said control center being remotely coupled to receive data representative of the power-related waveform samples from said plurality of circuit monitors and to send the control signal to said plurality of circuit monitors so that each of said plurality of circuit monitors samples the power-related waveform approximately simultaneously.

17. A circuit monitoring arrangement, according to claim 16 wherein the first microcomputer controls the multiplexer to capture a predetermined number of samples on a continuous basis.

18. A circuit monitoring arrangement, according to claim 16, wherein the predetermined number of samples if 256 and wherein the timing-related signal is used to preprogram said plurality of circuit monitors to sample the power-related waveform at a prescribed future point in time.

19. A circuit monitoring arrangement, according to claim 16, wherein the zero crossings define cycles in the power-related waveform and wherein the power-related waveform is automatically sampled over a plurality of integral cycles for 256 sample points.

20. A circuit monitoring arrangement, according to claim 19, wherein the control signal is used to preprogram said plurality of circuit monitors to sample the power-related waveform at a prescribed future point in time.

21. For use in a circuit monitoring arrangement which is controlled by a user-operated control station and which monitors power distributed to a plurality of powered equipment, wherein a power-related waveform passes from a non-residential loadcenter to each of the powered equipment through a power line, a circuit monitor comprising:

a sensor circuit, disposed adjacent the power line and between the non-residential loadcenter and at least one of the powered equipment, for sensing a plurality of power-related parameters associated with the power-related waveform;

sampling means, responsive to a control signal generated from the control station, for sampling the power-related waveform at a time prescribed by the control signal;

generation means, responsive to said sampling means, for generating data representative of the power-related waveform; and

receiving means, coupled to said sampling means, for receiving the control signal from the control station for instructing said circuit monitor to sample the power-related waveform at a prescribed future point in time wherefrom said generation means determines power-related information of the power line between the non-residential loadcenter and the powered equipment.

22. A circuit monitor, according to claim 21, wherein zero-crossings of the waveform define cycles of the power-related waveform and wherein the power-related waveform is automatically sampled over a plurality of integral cycles for a predetermined number of sample points.

23. A circuit monitor, according to claim 21, wherein said sampling means comprises:

a first microcomputer;

a multiplexer, responsive to the first microcomputer and to the sensor circuit, for sampling the power-related waveform;

an analog to digital converter circuit which converts the power-related waveform samples from the multiplexer; and

wherein the first microcomputer receives the converted power-related waveforms samples to detect zero crossings therein and to perform power-related computations.

24. A circuit monitor, according to claim 23, wherein said generation means and said receiving means are implemented using a second microcomputer.