Monitoring electrical assets for fault and efficiency correction

• US 20070059986A1
• Filed: 09/13/2006
• Published: 03/15/2007
• Est. Priority Date: 09/13/2005
• Status: Active Grant

• Current Assignee: Aclara Technologies LLC (Hubbell, Inc.)
• Original Assignee: Daniel Rockwell
• Inventors: Rockwell, Daniel
• Granted Patent: US 7,714,735 B2
• Time in Patent Office: Days
• US Class Current: 439/638
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G01R 31/086 in power transmission or distribution networks, i.e. with interconnected conductors
• CPC Class Codes: G01R 31/088 Aspects of digital computing
• CPC Class Codes: G01R 31/50 Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections testing of sparking plugs H01T13/58
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02H 7/28 for meshed systems

Abstract

A system and method of monitoring a plurality of electrical assets comprise an electricity distribution infrastructure, including a plurality of electrical asset sensors coupled to the electrical assets for monitoring an operating condition of the electrical assets as well as any fault conditions. The sensors may include a current transformer for obtaining a current waveform, a GPS receiver for applying a synchronized time-stamp to the waveform data, and a mesh network radio for transmitting the time-stamped waveform data. Data from the plurality of sensors may be encrypted and transmitted over a mesh network to one or more gateways that are in communication with a central command processor. In response to an abnormal operating condition of any electrical asset, the central command processor may determine a probable fault location, a probable fault type, and a fault response.

Claims

1. An apparatus for monitoring an electrical asset in an electrical infrastructure, the apparatus comprising:

a sensor coupled to the electrical asset for obtaining data corresponding to at least one of a voltage, current, and phase angle waveforms;

a globally synchronized timer for time-stamping the data with a globally synchronized time;

a mesh network radio for communicating at least one gateway and for relaying communications between one or more other electrical asset monitors and the at least one gateway; and

a power supply for extracting and storing energy from the electrical asset and supplying power to at least the sensor, the timer, and the radio.

2. The apparatus of claim 1, further comprising a processor for detecting one of a normal condition or an abnormal condition of the electrical asset based on the data, wherein the processor is coupled to the globally synchronized timer for time-stamping the data and to the mesh network radio for transmitting the time-stamped data corresponding to the normal or abnormal condition.

3. The apparatus of claim 2, further comprising a memory coupled to the processor for storing a plurality of fault type signatures, wherein the processor correlates the data to each one of the plurality of fault type signatures to identify a fault type and transmits the fault type to the at least one gateway.

4. The apparatus of claim 1, further comprising a processor for detecting a fault of the electrical asset based on the data and encrypting an indication of the fault according to a predetermined encryption scheme, wherein the processor is coupled to the globally synchronized timer for time-stamping the indication and to the mesh network radio for transmitting the encrypted, time-stamped indication.

5. The apparatus of claim 4, further comprising a memory coupled to the processor for storing a plurality of fault type signatures, wherein the processor correlates the data to each one of the plurality of fault type signatures to identify a fault type and encrypts and transmits the fault type to the at least one gateway.

6. The apparatus of claim 1, wherein the globally synchronized timer includes a global positioning system (GPS) receiver for receiving the globally synchronized time and a plurality of coordinates corresponding to a location of the apparatus.

7. The apparatus of claim 1, further comprising a memory for storing the time-stamped data.

8. The apparatus of claim 1, wherein the mesh network radio is one of a Zigbee radio, a Wi-Max radio or a Wi-Fi radio.

9. The apparatus of claim 1, wherein the sensor includes:

at least one of a current transformer, a Rogowski coil, a Hall effect sensor, a potential transformer, a divider network, or an optoelectronic or fiber optic sensor including a Kerr cell, a Pockels cell, or a Faraday effect sensor, coupled to the electrical asset to provide a signal representing at least one of a voltage, a current or a phase;

a conditioning circuit coupled to the sensor output for filtering high-frequency noise and scaling the measurement signal; and

an analog-to-digital converter coupled to the conditioning circuit for digitizing the filtered current signal to provide at least a portion of the data.

10. The apparatus of claim 1, wherein the sensor includes at least one of a Hall effect sensor, a potential transformer, or an optoelectronic sensor.

11. The apparatus of claim 1, wherein the power supply includes:

a current transformer coupled to extract energy from the electrical line;

a voltage regulator coupled to the current transformer for maintaining a desired supply voltage; and

a capacitor coupled to the current transformer and the voltage regulator for storing energy and delivering the stored energy to the apparatus during a power failure.

12. A system for monitoring a plurality of electrical assets defining an electrical infrastructure, the system comprising:

a plurality of electrical asset monitors coupled to respective ones of the electrical assets, each monitor including a sensor coupled to the electrical asset for obtaining data corresponding to at least one of a voltage, current, and phase angle waveforms, a globally synchronized timer, a mesh network radio, a power supply, and a power storage device;

one or more gateways, each gateway including a gateway mesh network radio for communicating with the plurality of electrical asset monitors and a network interface for communicating with a central command center via a network distinct from the mesh network;

the central command center including a further network interface for communicating with the one or more gateways, a memory for storing a database of fault signatures, a second memory for storing the sensed data, and a processor for analyzing the sensed data to identify a probable fault type, a probable fault location, and a fault response; and

a mesh network for routing communications among the plurality of electrical asset monitors and the one or more gateways, whereby the mesh network coordinates efficient communication paths among the plurality of electrical asset monitors and the one or more gateways.

13. The system of claim 12, wherein each one of the plurality of electrical asset monitors include a processor configured to implement an encryption scheme to encrypt the data before it is communicated by the mesh network radio.

14. The system of claim 13, wherein each one of the one or more gateways includes a processor configured to implement the encryption scheme to decrypt the data from the plurality of electrical asset monitors and to encrypt the data according to a further encryption scheme before it is communicated by the network interface.

15. The system of claim 13, wherein:

the encryption scheme is one of a tree group Diffie-Hellman protocol, an RSA protocol, and an elliptic-curve cryptography protocol;

the encryption processor is configured to encrypt communications with the one or more gateways according to an advanced encryption standard (AES), data encryption standard (DES), Blowfish, Twofish, or triple DES; and

the central command center processor is configured to decrypt communications originating from the plurality of electrical asset monitors.

16. The system of claim 12, wherein the mesh network is configured according to a ZigBee protocol.

17. The system of claim 12, wherein the mesh network is configured according to an ad-hoc Wi-Fi protocol and efficient communication paths are coordinated according to an ad-hoc on-demand distance vector (AODV) algorithm.

18. The system of claim 12, wherein the central command center processor is configured to correlate the data to the database of fault signatures to identify the probable fault type.

19. The system of claim 18, wherein the response processor is configured to generate a fault warning, wherein the fault warning includes the probable fault location and the probable fault type.

20. The system of claim 19, wherein the fault warning is at least one of a fax, an e-mail, a pager message, an audiovisual warning, a network alert, an SMS message, and a Simple Object Access Protocol (SOAP) message.

21. The system of claim 12, wherein the fault is an unbalanced power factor and the response processor is configured to initiate one or more predetermined power factor correction algorithms.

22. The system of claim 12, wherein the fault is an electrical asset failure and the response processor is configured to initiate one or more predetermined electrical asset isolation algorithms.

23. The system of claim 12, wherein the fault is an electrical asset overload and the response processor is configured to initiate one or more predetermined electrical asset bypass algorithms.

24. The system of claim 12, wherein each monitor of the plurality of electrical asset monitors further includes a GPS receiver for synchronizing the globally synchronized timer and obtaining a plurality of coordinates corresponding to a location of the monitor.

25. A method of monitoring an electrical asset in an electrical infrastructure, the method comprising the steps of:

sensing, by a monitoring element, one or more of a current, voltage, and phase angle waveforms of an electrical asset;

digitizing the sensed waveforms into a digital signal;

encrypting the digital signal;

transmitting the encrypted digital signal through a mesh network, the transmission being routed to a gateway based on a most efficient path between the monitoring element and the gateway; and

relaying, to the gateway, one or more other encrypted digital signals from one or more other monitoring elements monitoring one or more other electrical assets.

26. A method according to claim 25, further comprising the step of extracting and storing operational power from the electrical asset.

27. A method according to claim 25, further comprising the step of receiving a globally synchronized time and a plurality of coordinates corresponding to a position.

28. A method according to claim 27, further including the step of time-stamping the sensed waveforms according to the globally synchronized time.

29. A method according to claim 27, further including the steps of encrypting the position and transmitting the encrypted position through the mesh network according to the most efficient path.

30. A method of managing one or more electrical assets defining an electrical infrastructure, the method comprising the steps of:

receiving, from one or more gateways, encrypted data collected by a plurality of electrical asset sensors;

decrypting the encrypted data to obtain a plurality of sensed waveforms, wherein each one of the sensed waveforms is synchronized according to a globally synchronized timer and includes a plurality of coordinates identifying a source location of the waveform; and

determining, based on the plurality of sensed waveforms and respective source locations, one or more of an abnormal condition and a normal condition.

31. The method of claim 30, wherein the decrypting step decrypts the encrypted data according to an advanced encryption standard (AES).

32. The method of claim 30, further comprising the steps of:

receiving, from the one or more gateways, measured metering data collected by a plurality of electricity meters;

calculating, based on the plurality of sensed waveforms corresponding to the normal condition and respective source locations, calculated metering data corresponding to the plurality of electricity meters; and

determining, based on one or more of the calculated and measured metering data, a plurality of time of use bills, each time of use bill corresponding to respective ones of the plurality of electricity meters.

33. The method of claim 32, further comprising the steps of:

comparing the calculated metering data and the measured metering data to determine whether an error exists at any of the plurality of electricity meters and to determine a magnitude of any determined error; and

if an error is determined to exist, alerting a theft monitor if the magnitude of the determined error is higher than a predetermined threshold.

34. The method of claim 30, the method further comprising the steps of:

calculating, based on the plurality of sensed waveforms, the respective source locations, and an electrical asset parameters database, a probable fault type and a probable fault location, if the abnormal condition is determined;

assigning, based on the probable fault type and the probable fault location, a fault response; and

initiating the fault response.

35. The method of claim 34, wherein the determining step determines the probable fault type by correlating the plurality of sensed waveforms to a database of fault signatures, wherein a fault having the fault signature with a highest correlation to the sensed waveforms is the probable fault type.

36. The method of claim 34, wherein the assigning step assigns a fault warning for at least one of a momentary fault, a temporary fault, and an incipient fault.

37. The method of claim 36, wherein the initiating step generates the fault warning including the fault location and the probable fault type, the method further including the step of transmitting the fault warning to a Simple Object Access Protocol (SOAP) notification interface.

38. The method of claim 34, wherein the assigning step assigns a power factor correction algorithm when the probable fault type is an unbalanced power factor fault.

39. The method of claim 34, wherein the assigning step assigns an electrical asset isolation algorithm when the probable fault type is an electrical asset failure fault.

40. The method of claim 34, wherein the assigning step assigns an electrical asset bypass algorithm when the probable fault type is an electrical asset overload fault.

41. An apparatus for controlling electric assets comprising:

an ad-hoc MESH radio configured for use with sensors and gateway, and a processor having analog and digital input and output ports wherein the input ports are configured to receive signal data from at least one electric asset and the output ports are configured to control the at least one electrical asset.

42. A method of load-balancing a plurality of electrical assets in an electrical infrastructure, the method comprising the steps of:

sensing, by each of a plurality of monitoring elements, one or more of a current, voltage, and phase angle waveforms of an electrical asset;

digitizing the sensed waveforms into a digital signal;

transmitting the digital signals via a plurality of ad-hoc mesh radios through a mesh network, the transmission being routed to a plurality of gateways based on a most efficient path between the monitoring element and each of the gateways; and

relaying, to the gateways, one or more other digital signals from one or more other monitoring elements monitoring one or more other electrical assets;

Wherein the system further includes at least one algorithm that operates to equalize a number of ad-hoc mesh radios that cluster to any one gateway; and

to globally coordinate network traffic among the gateways.

43. A system for monitoring a plurality of electrical assets defining an electrical infrastructure for pin pointing fault locations the system comprising:

a plurality of electrical asset monitors coupled to respective ones of the electrical assets, each monitor including a sensor coupled to the electrical asset for obtaining data corresponding to at least ones of a voltage, current, or a phase angle waveform, a globally synchronized timer to time stamp the data, to measure time and to provide position information, a mesh network radio, a power supply, and a power storage device;

one or more gateways, each gateway including a gateway mesh network radio for communicating with the plurality of electrical asset monitors and a network interface for communicating with a central command center via a network distinct from the mesh network;

the central command center including a further network interface for communicating with the one or more gateways, a memory for storing a database of fault signatures, a second memory for storing the sensed data, a third memory for storing fixed asset information that includes at least one of cable type, cable propagation velocity, cable segment length, or asset type and asset electrical impedance, and a processor for analyzing the sensed data to identify a probable fault type, a probable fault location, and a fault response;

where

a system is configured to calculate a fault location from the globally synchronized times and at least one of respective arrival times of the fault signal from multiple ones of the plurality of electrical asset monitors, asset monitor position, fault signal propagation, and cable segment lengths.