Distributed Electricity Metering System

• US 20120062249A1
• Filed: 11/21/2011
• Published: 03/15/2012
• Est. Priority Date: 04/16/2009
• Status: Active Grant

• Current Assignee: Panoramic Power Ltd. (NRG Energy, Inc.)
• Original Assignee: Panoramic Power Ltd. (NRG Energy, Inc.)
• Inventors: Shamir, Adi
• Granted Patent: US 9,134,348 B2
• Time in Patent Office: Days
• US Class Current: 324/679
• CPC Class Codes: G01R 15/18 using inductive devices, e.g. transformers
• CPC Class Codes: G01R 15/186 using current transformers with a core consisting of two or more parts, e.g. clamp-on type G01R15/142 - G01R15/16 take precedence; tong testers G01R1/22
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G01R 21/006 Measuring power factor
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 22/063 related to remote communication
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• 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

Abstract

Apparatus and methods are provided for the measurement of a power factor at points of interest, such as circuit breakers, machines, and the like. Accordingly, means are provided for measurement of a power factor for each electrical sub-network that is controlled by a circuit breaker. Each apparatus is enabled to communicate its respective data, in an environment of a plurality of such apparatuses, to a management unit which is enabled to provide finer granularity power factor profiles.

Claims

1. An apparatus comprising:

at least one analog section having a current transformer with a transformer core configured to mount around an alternating current (AC) power line making the power line a primary winding of the current transformer, the analog section for harvesting energy from a secondary winding wound the transformer core, and storing harvested energy for use by components of the apparatus and for periodically switching to allow sampling of a current flowing through the current transformer by a sense resistor;

a microcontroller coupled to the at least one analog section to receive harvested energy, to determine at least one of;

at least a value respective of the at least an analog signal responsive to the alternating current in the AC power line by the sense resistor, a time stamp;

a memory coupled to the microcontroller; and

a transmitter enabled to periodically transmit, under the control of the microcontroller, information responsive to the power consumption of a load connected to the power line that includes at least one of;

the at least the value, the time stamp;

such that a receiver of the at least the value may use the at least the value for determination of at least an electrical parameter.

2. The apparatus of claim 1, wherein the timestamp is at least one of:

timestamp of the peak of the signal, timestamp of zero crossing, timestamp of a sample in a vector of a plurality of samples.

3. The apparatus of claim 1, wherein the at least one value is at least one of:

RMS value, peak value, average value, RMS squared value, a representative average value, a vector of a plurality of samples of the at least one analog signal.

4. The apparatus of claim 1, wherein the apparatus periodically transmits a timing synchronization message.

5. The apparatus of claim 4, wherein the at least an electrical parameter comprises at least one of:

a timing correction value to account for differences between the SPPS clock and the receiver'"'"'s clock, current, phase shift between voltage and current, real power, apparent power, reactive power, power factor, distortion factor, total harmonic distortion (THD) of the at least an analog signal.

6. The apparatus of claim 1, wherein the switching comprises switching between harvesting and sensing.

7. The apparatus of claim 1, wherein the sense resistor is connected to a secondary winding of the current transformer.

8. The apparatus of claim 1, further comprising:

a real-time clock that generates timestamps.

9. The apparatus of claim 8, wherein the real-time clock is periodically synchronized through reception of a message when the apparatus is in a receive mode.

10. The apparatus of claim 1, further comprising:

a resonance capacitor coupled in parallel to the secondary winding of the current transformer.

11. The apparatus of claim 1, further comprising one of:

a diode bridge coupled in parallel to the secondary winding of the current transformer;

or

a voltage multiplier coupled in parallel to the secondary winding of the current transformer.

12. The apparatus of claim 1, wherein the receiver is at least one of:

a communication bridge, a server.

13. A method comprising:

checking periodically if a reservoir capacitor of a self-powered power sensor (SPPS) is adequately charged for the purpose of switching from a harvesting mode of the SPPS to a sensing mode of the SPPS;

switching to the sensing mode upon determination that the reservoir capacitor is adequately charged;

repeating a plurality of times a sampling at a predetermined rate a plurality of samples of a current of a secondary winding of a current transformer (CT) of the SPPS;

determining at least one of;

at least one value responsive of the current, a time stamp; and

transmitting at least one of;

the at least one value, the time stamp, the time stamp of the peak of the analog signal, so that a receiver may determine at least an electrical parameter.

14. The method of claim 13, wherein the timestamp is at least one of:

timestamp of the peak of the signal, timestamp of zero crossing, timestamp of a sample in a vector of a plurality of samples.

15. The method of claim 13, wherein the at least one value is at least one of:

RMS value, peak value, average value, RMS squared value, a representative average value, a vector of the plurality of samples.

16. The method of claim 15, further comprising:

transmitting periodically a timing synchronization message.

17. The method of claim 18, further comprising:

calculating at least one of;

a timing correction value to account for differences between the SPPS clock and the receiver'"'"'s clock, current, phase shift between voltage and current, real power, apparent power, reactive power, power factor, distortion factor, total harmonic distortion (THD) of the at least an analog signal.

18. The method of claim 13, further comprising:

transmitting periodically to the SPPS a real-time synchronization message.

19. The method of claim 13, further comprising:

receiving periodically a real-time synchronization message by the SPPS.

20. The method of claim 13, further comprising:

transmitting a phase calibration factor.

21. The method of claim 13, wherein the receiver is one of:

a communication bridge, a server.

22. A method comprising:

receiving from a self-powered power sensor (SPPS) a message containing at least a value responsive of a current measured by the SPPS and at least a timestamp associated with at least the value;

receiving a measurement of a voltage corresponding to the current;

determining based on the message and the voltage at least one of;

a timing correction value to account for differences between the SPPS clock and the receiver'"'"'s clock, current, phase shift between voltage and current, real power, apparent power, reactive power, power factor, distortion factor, total harmonic distortion (THD) of the at least an analog signal.

23. The method of claim 22, further comprising:

receiving a phase calibration factor.

24. The method of claim 22, wherein the voltage information is received from at least one of:

a voltage meter connected to a power line supplying at least the current;

a wireless voltage sensor coupled to a circuit supplying the current and adapted to communicate with the communication bridge; and

, a network connected voltage meter.

25. The method of claim 22, further comprising:

receiving a voltage offset value to account for losses between a voltage measurement point and the current measurement point.

26. The method of claim 22, wherein the receiving is performed by a receiver that is one of:

a communication bridge, a server.

27. The method of claim 22, wherein the timestamp is at least one of:

timestamp of the peak of the signal, timestamp of zero crossing, timestamp of a sample in a vector of a plurality of samples.