Distributed electricity metering system

• US 9,134,348 B2
• Filed: 11/21/2011
• Issued: 09/15/2015
• 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
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): DICKINSON, DUSTIN R
• Application Number:
  US13/301,453
• Publication Number:
  US 20120062249A1
• Time in Patent Office: 1,394 Days
• Field of Search: 324126-128, 324/764.01
• US Class Current: 1/1
• 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: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 13/00022 using wireless data transmission
• 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 AC power line a primary winding of the current transformer, the at least one analog section for harvesting energy from a secondary winding wound around 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 a value respective of at least an analog signal responsive to the alternating current in the AC power line by the sense resistor, and a time synchronization signal, the time synchronization signal configured to account for an internal drift of a clock of the microcontroller to be smaller than an allowed error in a current to voltage phase measurement;

a memory coupled to the microcontroller; and

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

the at least the value, or the time synchronization signal;

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 and correction thereof respective of the time synchronization signal.

2. The apparatus of claim 1, wherein the time synchronization signal is provided respective of at least one of:

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

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

an RMS value, a peak value, an average value, an RMS squared value, a representative average value, or 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 the time synchronization signal.

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 an SPPS clock and a clock of the receiver, current, phase shift between voltage and current, real power, apparent power, reactive power, power factor, distortion factor, or 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 the secondary winding of the current transformer.

8. The apparatus of claim 1, further comprising:

a real-time clock that generates a synchronization signal.

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 connected 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.