Revenue class power meter with frequency rejection

• US 7,962,298 B2
• Filed: 08/15/2006
• Issued: 06/14/2011
• Est. Priority Date: 09/16/2005
• Status: Active Grant

• Current Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Original Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Inventors: Law, Robert M., Przydatek, Piotr B., Loewen, Daniel N., McPhalen, Erin C., Bandsmer, Michael D., Marr, Darrin G.
• Primary Examiner(s): Raymond; Edward
• Application Number:
  US11/504,269
• Publication Number:
  US 20070067121A1
• Time in Patent Office: 1,764 Days
• Field of Search: 702/61, 702/64, 702182-185
• US Class Current: 702/61
• CPC Class Codes: G01R 22/06 by electronic methods
• CPC Class Codes: G01R 22/065 related to mechanical aspects

Abstract

A power meter for measuring power parameters on one or more electrical power lines/loads is configured to include a revenue class metering module and a power quality metering module. The revenue class metering module and the power quality metering module may use the same measured voltage and current signals to generate revenue accurate power consumption information and power quality information, respectively. The power meter may also include a plurality of filters configured to attenuate high frequency signals included in the voltage and current signals. Each of the filters may be configured with a corner frequency, gain and signal propagation delay that is substantially equal. The filtered current and voltage signals may be received and processed by the revenue class metering module, and the power quality metering module to generate revenue accurate power consumption information and power quality information, respectively. Alternatively, the filtered current and voltage signals may be received and processed by the power quality metering module to generate power quality information, and unfiltered current and voltage signals may be received and processed by the revenue class metering module to generate revenue accurate power consumption information.

Claims

1. A revenue class power meter comprising;

a plurality of sensors configured to be coupled with a plurality of corresponding power conductors, wherein each of the sensors are operative to sense a power parameter of electrical energy present in the corresponding power conductors and generate respective input signals representative of a respective sensed power parameter;

a plurality of transducers coupled with the respective sensors, the transducers operative to generate a voltage representation of the respective sensed power parameter;

a plurality of filters coupled with the respective transducers, the filters operative to attenuate high frequency signal components about 1 kHz greater than the highest frequency desired to be measured , wherein each of the filters are configured to provide a predetermined signal propagation delay, signal gain and corner frequency that are substantially the same for all of the filters;

a revenue class metering module configured to receive the input signals, wherein the revenue class metering module is operative to generate revenue accurate power consumption information based on the received input signals; and

a power quality metering module coupled with the filters and configured to receive the filtered input signals, wherein the power quality metering module is operative to generate power quality information based on the received filtered input signals.

2. The revenue class power meter of claim 1, wherein the revenue class metering module is configured to receive the input signals that have been filtered with the filters.

3. The revenue class power meter of claim 1, wherein the revenue class metering module is configured to receive the input signals prior to the input signals being filtered with the filters.

4. The revenue class power meter of claim 1, wherein each of the filters are analog filters that comprise an integrated filter circuit, and are operative to reject the high frequency signals on said input signals.

5. The revenue class power meter of claim 4, wherein the integrated filter circuit is a switched capacitor integrated circuit filter.

6. The revenue class power meter of claim 4, wherein the integrated filter circuit is a continuous time integrated circuit filter.

7. The revenue class power meter of claim 1, wherein the filters are each configured to have substantially the same predetermined signal propagation delay, and are operative to substantially equally shift the phase of the input signals filtered by each of the respective filters.

8. The revenue class power meter of claim 7, further comprising a common clock, wherein the signal propagation delay, signal gain and corner frequency for all the filters is operative in accordance with a common clock signal generated with the common clock.

9. The revenue class power meter of claim 8, wherein the common clock signal is a digital signal generated with an integrated circuit.

10. The revenue class power meter of claim 8, wherein the common clock signal is an analog signal generated with passive components.

11. The revenue class power meter of claim 8, wherein the common clock signal is an analog signal generated with a crystal oscillator.

12. The revenue class power meter of claim 1, further comprising a processor and memory with instructions stored therein, the instructions executable by the processor to adjust a phase of the filtered input signal based on a predetermined signal propagation delay of the filter.

13. The revenue class power meter of claim 1, wherein each of the filters includes a digital filter that comprises a processor and memory with instructions stored therein, the instructions executable by the processor to reject high frequency noise in a frequency domain.

14. The revenue class power meter of claim 1, wherein the input signals are representative of one of voltage or current present on the power conductor.

15. The revenue class power meter of claim 1, wherein the revenue class meter includes an external master reset button operable to delete stored power parameter data and revenue accurate power consumption information.

16. The revenue class power meter of claim 15, wherein the master reset button is configurable as a tamper proof button.

17. The revenue class power meter of claim 1, wherein the revenue class meter includes an external test mode button operable to toggle the revenue class power meter between an operational mode and a test mode.

18. The revenue class power meter of claim 1, wherein the revenue class power meter includes at least one infrared communication port operable to transmit and receive data.

19. The revenue class power meter of claim 18, wherein the at least one infrared communication port includes a magnetic optical communications coupler.

20. The revenue class power meter of claim 18, wherein the at least one infrared communication port is operable with a communication protocol that conforms with International Electrotechnical Commission standard number 61107.

21. The revenue class power meter of claim 18, wherein the at least one infrared communication port is operable with a communication protocol that conforms with American National Standards Institute standard number C.12.18.

22. A revenue class power meter comprising:

a circuit operative as an analog filter stage to filter an input signal, the input signal representative of a measurable power parameter presentable on a power conductor;

a processor coupled with the circuit;

a memory coupled with the processor, wherein the memory comprises a plurality of instructions, the processor operative to execute instructions to form a digital filter stage to digitally filter the input signal;

wherein the digital filter stage in combination with the analog filter stage are operative as a multi-stage low pass filter to reject high frequency signal components included in the input signal;

a revenue class metering module configured to also receive the input signal, wherein the revenue class metering module is operative to generate revenue accurate power consumption information based on the input signal; and

a power quality metering module configured to receive the input signal, wherein the power quality metering module is operative to generate power quality information based on the received input signal.

23. The revenue class power meter of claim 22, wherein the analog filter stage comprises a continuous time integrated circuit filter.

24. The revenue class power meter of claim 22, wherein the analog filter stage comprises a switched capacitor integrated circuit filter.

25. The revenue class power meter of claim 22, wherein the analog filter stage comprises a discrete component continuous time filter.

26. The revenue class power meter of claim 22, wherein the analog filter stage is operative as an anti-aliasing filter.

27. The revenue class power meter of claim 22, wherein the revenue class metering module is configured to receive the input signal prior to being filtered, and the power quality metering module is configured to receive the filtered input signal.

28. The revenue class power meter of claim 22, wherein the revenue class metering module and the power quality metering module are configured to both receive the filtered input signal.

29. The revenue class power meter of claim 22, further comprising an analog to digital converter operative to sample the input signal at greater than one million samples per second to generate a digital representation of the input signal that has been filtered by the analog filter stage, the digital representation operative to be filtered by the digital filter stage.

30. The revenue class power meter of claim 22, wherein the digital filter stage is configured with a plurality of passbands, to pass at least two determined frequency ranges of the input signal.

31. The revenue class power meter of claim 30, wherein the revenue class metering module is configured to receive a first filtered input signal from a first passband and the power quality metering module is configured to receive a second filtered input signal from a second passband.

32. The revenue class power meter of claim 22, wherein the digital filter stage in combination with the analog filter stage are operative to reject high frequency signal components that are about 1 kHz greater than the highest frequency to be measured.

33. The revenue class power meter of claim 22, wherein the digital filter stage is configured to attenuate frequencies about 1 kHz greater than the highest frequency to be measured that were not attenuated by the analog filter stage.

34. The revenue class power meter of claim 22, wherein the revenue class metering module is configured to adjust a phase of the filtered input signal based on a signal propagation delay of the analog filter stage and the digital filter stage.

35. The revenue class power meter of claim 22, wherein the digital filter stage is operative as an anti-aliasing filter.

36. The revenue class power meter of claim 22, wherein the revenue class power meter is a rack mounted meter.

37. The revenue class power meter of claim 36, wherein the revenue class power meter comprises a removable options module configured to provide additional power quality related functionality.

38. A method of filtering in a revenue class power meter, the method comprising:

providing a first input signal on a first channel and a second input signal on a second channel;

filtering the first input signal with a first filter included in the first channel and filtering the second input signal with a second filter included in the second channel;

maintaining a non-linear constant phase shift of the filtered first input signal and a non-linear constant phase shift of the filtered second input signal to be about the same;

generating a revenue quality power consumption measurement with a revenue class metering module based on the first input signal and the second input signal; and

generating power quality information with a power quality metering module based on the first filtered input signal and the second filtered input signal.

39. The method of claim 38, wherein maintaining a non-linear constant phase shift further comprises during filtering, maintaining a signal propagation delay between the first filtered input signal and the second filtered input signal as substantially equal so that a non-linear phase shift of the first input signal and the second input signal will be about the same.

40. The method of claim 39, wherein maintaining a non-linear constant phase shift further comprises setting a corner frequency and a gain of the first filter and the second filter to be substantially equal so that a non-linear phase shift of the first input signal and the second input signal will be about the same.

41. The method of claim 39, wherein the step of filtering further comprises filtering with a first analog filter and a second analog filter in the time domain and the step of maintaining a signal propagation delay further comprises matching operational performance of a plurality of electrical components included in the first filter with operational performance of a plurality of electrical components included in the second filter.

42. The method of claim 38, wherein the step of achieving a non-linear phase shift further comprises, after filtering, digitally compensating the phase of at least one of the first filtered signal and the second filtered signal to make a magnitude of the phase shift of the first filtered signal about the same as a magnitude of the phase shift of the second filtered signal.

43. The method of claim 38, wherein the step of generating a revenue quality power consumption measurement comprises processing the filtered first input signal and the filtered second input signal with the revenue class metering module.

44. The method of claim 38, wherein the step of generating a revenue quality power consumption measurement comprises processing the first input signal that is unfiltered and the second input signal that is unfiltered with the revenue class metering module.

45. The method of claim 38, wherein the step of filtering comprising attenuating a high frequency signal component included in the first input signal and the second input signal that is greater than about 3 kHz.