POWER METERING AND MERGING UNIT CAPABILITIES IN A SINGLE IED

• US 20100153036A1
• Filed: 12/12/2008
• Published: 06/17/2010
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Elwarry, Basem, Tuckey, David T.
• Granted Patent: US 8,560,255 B2
• Time in Patent Office: Days
• US Class Current: 702/62
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 22/063 related to remote communication

Abstract

An intelligent electronic device (IED) integrating a power metering unit (PMU) and a merging unit that combines signals from both analog transformers and digital transformers into a set of merged digital samples. Analog current/voltage signals from analog CTs/PTs are received at the IED'"'"'s analog inputs and converted to digitized samples. Digital current/voltage samples from digital CTs/PTs are received via point-to-point connections at digital inputs of the IED. A tagging unit applies metadata tags to the digitized and digital samples. The metadata tags include the transformer providing the input signal, sampling rate, primary and/or secondary timestamps, scaling values, calibration values, and/or the location of the IED in the electrical system. The PMU performs metering and/or power quality calculations on the samples, and the calculation results are formatted and transmitted via a master-slave protocol to a requesting master. A grouping unit groups the merged samples into default or custom groupings, which are formatted and transmitted over a network via a publish-subscribe mechanism.

Claims

1. An intelligent electronic device (IED), comprising:

a housing;

a plurality of inputs received at the housing and receiving representations of current or voltage signals from corresponding first current transformers or potential transformers;

a power metering unit disposed within the housing, the power metering unit calculating a function that includes a representation of any of the current or voltage signals;

a merging unit disposed within the housing, the merging unit being configured to combine digital representations of the current or voltage signals into a single set of merged digital samples;

a memory disposed within the housing, the memory storing the single set of merged digital samples; and

a microcontroller coupled to the memory.

2. The device of claim 1, wherein the plurality of inputs includes a plurality of analog inputs, and wherein at least some of the first current transformers or potential transformers are analog transformers that each outputs an analog representation of an analog current or voltage sensed by respective ones of the at least some transformers, the device further comprising:

a digital conversion unit disposed within the housing, the digital conversion unit converting the analog current or voltage signals from the analog inputs into corresponding digitized current or voltage samples.

3. The device of claim 1, wherein the plurality of inputs include a plurality of digital inputs, and wherein the representations of current or voltage signals are digital samples representing the current or voltage signals, wherein at least some of the first current transformers or potential transformers are digital transformers that each outputs a digital representation of an analog current or voltage sensed by respective ones of the at least some transformers.

4. The device of claim 1, wherein the first current transformers or potential transformers include protection current transformers.

5. The device of claim 1, wherein the first current transformers or potential transformers include measurement current transformers.

6. The device of claim 1, wherein the first current transformers or potential transformers include protection current transformers and measurement current transformers.

7. The device of claim 1, further comprising a tagging unit that applies a metadata tag to at least some of the digital representations of the current or voltage signals.

8. The device of claim 7, wherein the first current or potential transformers include protection current transformers and measurement current transformers, and wherein the merging unit is configured to combine the digital representations of the current or voltage signals associated with the protection transformers with the digital representations of the current or voltage signals associated with the measurement transformers into the set of merged digital samples.

9. The device of claim 7, wherein the metadata tag further includes an indication, for each of the plurality of inputs and, of the physical transformer from which each of the current or voltage signals originated.

10. The device of claim 7, wherein the metadata tag further includes sampling rates, each of the sampling rates representing a rate at which respective ones of the digital representations of the current or voltage signals were digitally sampled.

11. The device of claim 7, wherein the metadata tag further includes scaling values corresponding to a ratio of a maximum primary to secondary current associated with respective ones of at least some of the first transformers.

12. The device of claim 7, wherein the metadata tag further includes calibration values corresponding to a calibration of respective ones of at least some of the first transformers.

13. The device of claim 7, wherein the memory stores a representation of a physical location of the IED in an electrical system relative to all other IEDs in the electrical system, and wherein the metadata tag further includes the representation of the physical location.

14. The device of claim 1, further comprising a first communications interface for communicating a formatted representation of the single set of merged digital samples over a first communications network to a subscriber device.

15. The device of claim 14, wherein the formatted representation is expressed according to a Sampled Measured Values (SMV) format.

16. The device of claim 14, wherein the first communications interface communicates the formatted representation of the single set of merged digital samples via a publish-subscribe messaging protocol.

17. The device of claim 14, wherein the publish-subscribe messaging protocol is defined by the International Electrotechnical Commission (IEC) 61850-9 standard.

18. The device of claim 14, wherein the subscriber device is a relay, a controller, a remote terminal unit (RTU), or a power meter.

19. The device of claim 1, wherein the function calculated via the power metering unit produces metering data, the device further comprising a second communications interface for communicating a formatted representation of the metering data over a second communications network to a remote computer system.

20. The device of claim 19, wherein the remote computer system is a Supervisory Control and Data Acquisition (SCADA) system.

21. The device of claim 19, wherein the formatted representation of the metering data is communicated over the second communications network according to an Ethernet protocol.

22. The device of claim 14, wherein the function calculated via the power metering unit produces metering data, the device further comprising a second communications interface for communicating a formatted representation of the metering data over the first communications network to a remote computer system.

23. The device of claim 2, wherein the microcontroller is programmed to apply primary timestamps to the digitized current or voltage samples, each of the primary timestamps representing a unique time that each of the digitized samples occurred on a primary side of respective ones of the first transformers.

24. The device of claim 23, further comprising a tagging unit that applies metadata tags to at least some of the digitized current or voltage samples, each of the metadata tags including respective ones of the primary timestamps associated with respective ones of the digitized samples.

25. The device of claim 3, wherein the plurality of digital inputs are configured to receive corresponding primary timestamps for each of the digital samples, each of the primary timestamps representing a unique time that each of the digital samples occurred on a primary side of respective ones of the first transformers, and wherein the microcontroller is programmed to apply secondary timestamps to at least some of the digital samples, each of the secondary timestamps representing a unique time that each of the digital samples was received at respective ones of the digital inputs.

26. The device of claim 25, further comprising a tagging unit that applies metadata tags to the digital current or voltage samples, each of the metadata tags including respective ones of the primary timestamps and the second timestamps associated with respective ones of the digital samples.

27. The device of claim 26, wherein the microcontroller is programmed to apply primary timestamps to the digitized current or voltage samples, each of the primary timestamps representing a unique time that each of the digitized samples occurred on a primary side of respective ones of the first transformers, and wherein each of the metadata tags further includes respective ones of the primary timestamps associated with respective ones of the digitized samples.