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Title:
BLIND SPOT MITIGATION IN A SENSOR NETWORK
Document Type and Number:
WIPO Patent Application WO/2015/167576
Kind Code:
A1
Abstract:
According to one aspect, embodiments herein provide a system for monitoring a plurality of circuit branches coupled to an input line, the system comprising a plurality of current sensors, each configured to be coupled to at least one of the plurality of circuit branches, a communications bus, a plurality of sensor circuits, wherein each sensor circuit is configured to sample a current signal from one of the plurality of current sensors, a voltage sensor configured to be coupled to the input line and to sample the input voltage from the power source, and means for pipelining the current signal sampling of the plurality of sensor circuits, the input voltage sampling of the voltage sensor, the transmission of input voltage samples to the plurality of sensor circuits, and the calculation, by each sensor circuit, of at least one power parameter of at least one of the plurality of circuit branches.

Inventors:
LINDER, Stephen, Paul (136 Grove St, Medford, MA, MA, US)
ORNER, Bret, Alan (7 Shadow Lane, Wellesley, MA, 02482, US)
Application Number:
US2014/036537
Publication Date:
November 05, 2015
Filing Date:
May 02, 2014
Export Citation:
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Assignee:
SCHNEIDER ELECTRIC IT CORPORATION (132 Fairgrounds Road, West Kingston, RI, 02895, US)
International Classes:
H04L12/26; H02J13/00
Domestic Patent References:
WO2013154563A12013-10-17
Foreign References:
US8321163B22012-11-27
US20100235122A12010-09-16
Attorney, Agent or Firm:
SULLIVAN, Thomas, M. (Lando & Anastasi LLP, Riverfront Office ParkOne Main Street, Suite 110, Cambridge MA, 02142, US)
Download PDF:
Claims:
Claims

1. A system for monitoring a plurality of circuit branches coupled to an input line, the input line configured to receive input voltage from a power source, the input voltage having a waveform including multiple line cycles, the system comprising:

a plurality of current sensors, each configured to be coupled to at least one of the plurality of circuit branches and to produce a current signal having a level related to a current level of the one of the plurality of circuit branches;

a communications bus;

a plurality of sensor circuits, each coupled to an associated one of the plurality of current sensors and configured to be coupled to the communication bus, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during a first line cycle of the input voltage;

a voltage sensor configured to be coupled to the input line and to sample the input voltage from the power source during the first line cycle; and

a controller configured to be coupled to the communication bus and to the voltage sensor, wherein the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the first line cycle, to the plurality of sensor circuits via the communications bus during a second line cycle of the input voltage;

wherein each sensor circuit is further configured to calculate, during a third line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the first line cycle and the at least one input voltage sample received from the controller during the second line cycle.

2. The system of claim 1, wherein each sensor circuit is further configured to transmit the at least one power parameter to the controller via the communication bus during a fourth line cycle of the input voltage.

3. The system of claim 1, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during the second line cycle,

wherein the voltage sensor is further configured to sample the input voltage from the power source during the second line cycle,

wherein the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the second line cycle, to the plurality of sensor circuits via the communications bus during the third line cycle, and

wherein each sensor circuit is further configured to calculate, during a fourth line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the second line cycle and the at least one input voltage sample received from the controller during the third line cycle.

4. The system of claim 3, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during the third line cycle,

wherein the voltage sensor is further configured to sample the input voltage from the power source during the third line cycle,

wherein the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the third line cycle, to the plurality of sensor circuits via the communications bus during the fourth line cycle, and

wherein each sensor circuit is further configured to calculate, during a fifth line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the third line cycle and the at least one input voltage sample received from the controller during the fourth line cycle.

5. The system of claim 4, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during the fourth line cycle,

wherein the voltage sensor is further configured to sample the input voltage from the power source during the fourth line cycle,

wherein the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the fourth line cycle, to the plurality of sensor circuits via the communications bus during the fifth line cycle, and

wherein each sensor circuit is further configured to calculate, during a sixth line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the fourth line cycle and the at least one input voltage sample received from the controller during the fifth line cycle.

6. The system of claim 1, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors a first multiple number of times during the first line cycle. 7. The system of claim 6, wherein the voltage sensor is further configured to sample the input voltage from the power source a second multiple number of times during the first line cycle.

8. The system of claim 7, wherein the at least one power parameter calculated during the third line cycle by each sensor circuit is a dot product of the first number of current signal samples and the second number of voltage samples.

9. The system of claim 1, wherein the communication bus includes a multi-drop bus. 10. A method for monitoring a plurality of circuit branches coupled to an input line, the method comprising acts of:

coupling a current sensor to each one of the plurality of circuit branches;

coupling a plurality of sensor circuits to a communication bus, wherein each of the sensor circuits is coupled to an associated one of the current sensors;

receiving, by the input line from a power source, input power having an input voltage, the input voltage having a waveform including multiple line cycles;

generating, in each current sensor, a current signal having a level related to a current level of one of the plurality of circuit branches;

sampling, with each sensor circuit, the current signal of the associated one of the current sensors;

sampling, with a voltage sensor, the input voltage from the power source;

transmitting at least one input voltage sample from the voltage sensor to each sensor circuit via the communication bus; and

calculating, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal samples and the at least one input voltage samples received from the voltage sensor,

wherein the acts of sampling the current signal, sampling the input voltage, transmitting, and calculating are distributed across the multiple line cycles of the waveform.

11. The method of claim 10, wherein each one of the acts of sampling the current signal, sampling the input voltage, transmitting, and calculating is performed during a different line cycle of the waveform.

12. The method of claim 10, further comprising:

coupling a controller to the communication bus;

wherein the act of transmitting includes transmitting, with the controller, the at least one input voltage sample from the voltage sensor to each sensor circuit via the communication bus.

13. The method of claim 12, wherein sampling the current signal comprises sampling the current signal of the associated one of the current sensors during a first line cycle of the input voltage, and

wherein sampling the input voltage comprises sampling the input voltage from the power source during the first line cycle.

14. The method of claim 13, wherein transmitting comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the first line cycle, from the voltage sensor to each sensor circuit via the communication bus during a second line cycle of the input voltage,

wherein sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the second line cycle, and

wherein sampling the input voltage further comprises sampling the input voltage from the power source during the second line cycle.

15. The method of claim 14, wherein calculating comprises calculating, during a third line cycle of the input voltage, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the first line cycle and the at least one input voltage sample received during the second line cycle,

wherein transmitting further comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the second line cycle, from the voltage sensor to each sensor circuit via the communication bus during the third line cycle, wherein sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the third line cycle, and

wherein sampling the input voltage further comprises sampling the input voltage from the power source during the third line cycle.

16. The method of claim 15, further comprising transmitting, via the communication bus, the at least one power parameter based on the current signal sampled during the first line cycle and the at least one input voltage sample received during the second line cycle to the controller during a fourth line cycle of the input voltage,

wherein calculating further comprises calculating, during the fourth line cycle, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the second line cycle and the at least one input voltage sample received during the third line cycle,

wherein transmitting further comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the third line cycle, from the voltage sensor to each sensor circuit via the communication bus during the fourth line cycle,

wherein sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the fourth line cycle, and

wherein sampling the input voltage further comprises sampling the input voltage from the power source during the fourth line cycle.

17. The method of claim 16, wherein transmitting the at least one power parameter further comprises transmitting, via the communication bus, the at least one power parameter based on the current signal sampled during the second line cycle and the at least one input voltage sample received during the third line cycle to the controller during a fifth line cycle of the input voltage,

wherein calculating further comprises calculating, during the fifth line cycle, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the third line cycle and the at least one input voltage sample received during the fourth line cycle,

wherein transmitting further comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the fourth line cycle, from the voltage sensor to each sensor circuit via the communication bus during the fifth line cycle, wherein sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the fifth line cycle, and

wherein sampling the input voltage further comprises sampling the input voltage from the power source during the fifth line cycle.

18. The method of claim 10, wherein sampling the current signal comprises sampling the current signal of the associated one of the current sensors a first multiple number of times over one of the line cycles of the waveform, and

wherein sampling the input voltage comprises sampling the input voltage from the power source a second multiple number of times over one of the line cycles of the waveform.

19. The method of claim 18, wherein calculating at least one power parameter comprises calculating a dot product of the first number of current signal samples and the second number of input voltage samples.

20. A system for monitoring a plurality of circuit branches coupled to an input line, the system comprising:

a plurality of current sensors, each configured to be coupled to at least one of the plurality of circuit branches and to produce a current signal having a level related to a current level of the one of the plurality of circuit branches;

a communications bus;

a plurality of sensor circuits, each coupled to an associated one of the plurality of current sensors and configured to be coupled to the communication bus, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors;

a voltage sensor configured to be coupled to the input line and to sample the input voltage from the power source; and

means for pipelining the current signal sampling of the plurality of sensor circuits, the input voltage sampling of the voltage sensor, the transmission of input voltage samples to the plurality of sensor circuits, and the calculation, by each sensor circuit, of at least one power parameter of at least one of the plurality of circuit branches.

Description:
BLIND SPOT MITIGATION IN A SENSOR NETWORK

BACKGROUND OF INVENTION

Field of the Invention

At least one example in accordance with the present invention relates generally to distributed sensor networks in a load center.

Discussion of Related Art

A load center or panelboard is a component of an electrical supply system which divides an electrical power feed from a power line into different subsidiary circuit branches. Each subsidiary circuit branch may be connected to a different load. By dividing the electrical power feed into subsidiary circuit branches, the load center may allow a user to individually control and monitor the current, power and energy usage of each load.

A distributed network of current sensors within a load center is commonly used to monitor activity of the load center. For example, Current Transformers (CT) are typically used to monitor current in a subsidiary or main branch of a load center. A CT may be used to measure current in a branch by producing a reduced current signal, proportionate to the current in the branch, which may be further manipulated and measured. For example, a CT coupled to a branch of a load center may produce a reduced current AC signal, proportionate to the magnitude of AC current in the branch. The reduced current AC signal may then be measured. Based on the signal received, the level of current in the subsidiary branch may be determined. Additionally, based on the level of current in the subsidiary branch, the power and/or energy provided to a load coupled to the subsidiary branch may also be determined. SUMMARY OF THE INVENTION

Aspects in accord with the present invention are directed to a system for monitoring a plurality of circuit branches coupled to an input line, the input line configured to receive input voltage from a power source, the input voltage having a waveform including multiple line cycles, the system comprising a plurality of current sensors, each configured to be coupled to at least one of the plurality of circuit branches and to produce a current signal having a level related to a current level of the one of the plurality of circuit branches, a communications bus, a plurality of sensor circuits, each coupled to an associated one of the plurality of current sensors and configured to be coupled to the communication bus, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during a first line cycle of the input voltage, a voltage sensor configured to be coupled to the input line and to sample the input voltage from the power source during the first line cycle, and a controller configured to be coupled to the communication bus and to the voltage sensor, wherein the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the first line cycle, to the plurality of sensor circuits via the communications bus during a second line cycle of the input voltage, wherein each sensor circuit is further configured to calculate, during a third line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the first line cycle and the at least one input voltage sample received from the controller during the second line cycle.

According to one embodiment, each sensor circuit is further configured to transmit the at least one power parameter to the controller via the communication bus during a fourth line cycle of the input voltage. In one embodiment the communication bus includes a multi-drop bus.

According to another embodiment, each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during the second line cycle, the voltage sensor is further configured to sample the input voltage from the power source during the second line cycle, the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the second line cycle, to the plurality of sensor circuits via the communications bus during the third line cycle, and each sensor circuit is further configured to calculate, during a fourth line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the second line cycle and the at least one input voltage sample received from the controller during the third line cycle.

According to one embodiment, each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during the third line cycle, the voltage sensor is further configured to sample the input voltage from the power source during the third line cycle, the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the third line cycle, to the plurality of sensor circuits via the communications bus during the fourth line cycle, and each sensor circuit is further configured to calculate, during a fifth line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the third line cycle and the at least one input voltage sample received from the controller during the fourth line cycle.

According to another embodiment, each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors during the fourth line cycle, the voltage sensor is further configured to sample the input voltage from the power source during the fourth line cycle, the controller is further configured to transmit at least one input voltage sample, sampled by the voltage sensor during the fourth line cycle, to the plurality of sensor circuits via the communications bus during the fifth line cycle, and each sensor circuit is further configured to calculate, during a sixth line cycle of the input voltage, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the fourth line cycle and the at least one input voltage sample received from the controller during the fifth line cycle.

According to one embodiment, each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors a first multiple number of times during the first line cycle. In another embodiment, the voltage sensor is further configured to sample the input voltage from the power source a second multiple number of times during the first line cycle. In one embodiment, the at least one power parameter calculated during the third line cycle by each sensor circuit is a dot product of the first number of current signal samples and the second number of voltage samples.

Another aspect of the invention is directed to a method for monitoring a plurality of circuit branches coupled to an input line, the method comprising acts of coupling a current sensor to each one of the plurality of circuit branches, coupling a plurality of sensor circuits to a communication bus, wherein each of the sensor circuits is coupled to an associated one of the current sensors, receiving, by the input line from a power source, input power having an input voltage, the input voltage having a waveform including multiple line cycles, generating, in each current sensor, a current signal having a level related to a current level of one of the plurality of circuit branches, sampling, with each sensor circuit, the current signal of the associated one of the current sensors, sampling, with a voltage sensor, the input voltage from the power source, transmitting at least one input voltage sample from the voltage sensor to each sensor circuit via the communication bus, and calculating, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal samples and the at least one input voltage samples received from the voltage sensor, wherein the acts of sampling the current signal, sampling the input voltage, transmitting, and calculating are distributed across the multiple line cycles of the waveform.

According to one embodiment, each one of the acts of sampling the current signal, sampling the input voltage, transmitting, and calculating is performed during a different line cycle of the waveform.

According to another embodiment, the method further comprises coupling a controller to the communication bus, and the act of transmitting includes transmitting, with the controller, the at least one input voltage sample from the voltage sensor to each sensor circuit via the communication bus. In one embodiment, sampling the current signal comprises sampling the current signal of the associated one of the current sensors during a first line cycle of the input voltage, and sampling the input voltage comprises sampling the input voltage from the power source during the first line cycle.

According to one embodiment, transmitting comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the first line cycle, from the voltage sensor to each sensor circuit via the communication bus during a second line cycle of the input voltage, sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the second line cycle, and sampling the input voltage further comprises sampling the input voltage from the power source during the second line cycle.

According to another embodiment, calculating comprises calculating, during a third line cycle of the input voltage, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the first line cycle and the at least one input voltage sample received during the second line cycle, transmitting further comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the second line cycle, from the voltage sensor to each sensor circuit via the communication bus during the third line cycle, sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the third line cycle, and sampling the input voltage further comprises sampling the input voltage from the power source during the third line cycle.

According to one embodiment, the method further comprises transmitting, via the communication bus, the at least one power parameter based on the current signal sampled during the first line cycle and the at least one input voltage sample received during the second line cycle to the controller during a fourth line cycle of the input voltage, calculating further comprises calculating, during the fourth line cycle, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the second line cycle and the at least one input voltage sample received during the third line cycle, transmitting further comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the third line cycle, from the voltage sensor to each sensor circuit via the communication bus during the fourth line cycle, sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the fourth line cycle, and sampling the input voltage further comprises sampling the input voltage from the power source during the fourth line cycle.

According to another embodiment, transmitting the at least one power parameter further comprises transmitting, via the communication bus, the at least one power parameter based on the current signal sampled during the second line cycle and the at least one input voltage sample received during the third line cycle to the controller during a fifth line cycle of the input voltage, calculating further comprises calculating, during the fifth line cycle, with each sensor circuit, at least one power parameter of one of the plurality of circuit branches based on the current signal sampled during the third line cycle and the at least one input voltage sample received during the fourth line cycle, transmitting further comprises transmitting the at least one input voltage sample, sampled by the voltage sensor during the fourth line cycle, from the voltage sensor to each sensor circuit via the communication bus during the fifth line cycle, sampling the current signal further comprises sampling the current signal of the associated one of the current sensors during the fifth line cycle, and sampling the input voltage further comprises sampling the input voltage from the power source during the fifth line cycle.

According to one embodiment, sampling the current signal comprises sampling the current signal of the associated one of the current sensors a first multiple number of times over one of the line cycles of the waveform, and sampling the input voltage comprises sampling the input voltage from the power source a second multiple number of times over one of the line cycles of the waveform. In one embodiment, calculating at least one power parameter comprises calculating a dot product of the first number of current signal samples and the second number of input voltage samples.

One aspect of the invention is directed to a system for monitoring a plurality of circuit branches coupled to an input line, the system comprising a plurality of current sensors, each configured to be coupled to at least one of the plurality of circuit branches and to produce a current signal having a level related to a current level of the one of the plurality of circuit branches, a communications bus, a plurality of sensor circuits, each coupled to an associated one of the plurality of current sensors and configured to be coupled to the communication bus, wherein each sensor circuit is further configured to sample the current signal of the associated one of the plurality of current sensors, a voltage sensor configured to be coupled to the input line and to sample the input voltage from the power source, and means for pipelining the current signal sampling of the plurality of sensor circuits, the input voltage sampling of the voltage sensor, the transmission of input voltage samples to the plurality of sensor circuits, and the calculation, by each sensor circuit, of at least one power parameter of at least one of the plurality of circuit branches.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various FIGs. is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

FIG. 1 is a circuit diagram of a load center in accordance with aspects of the present invention;

FIG. 2 is a diagram of a method of operation of a distributed sensor network in accordance with aspects of the present invention; and

FIG. 3 is a block diagram of a system upon which various embodiments of the invention may be implemented.

DETAILED DESCRIPTION

Embodiments of the invention are not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Embodiments of the invention are capable of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having," "containing", "involving", and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

As discussed above, a distributed sensor network may be utilized to monitor circuit branches of a load center and assist in providing efficient energy management. For instance, sensors or meters may be coupled to circuit branches, inside or outside of a load center, to monitor current, power and/or energy consumption in the circuit branches.

In one example, such sensors or meters include dedicated hardware (e.g., analog Integrated Circuits (IC) or custom Application Specific Integrated Circuits (ASIC)). The dedicated hardware typically includes specific high performance components that are configured to continuously sample current and/or voltage of a circuit branch at a high rate. In such a system of high performance sensors, continuous sampling results in only a relatively small amount of the voltage or current waveform on a circuit branch not being monitored (i.e., the sensor has relatively few "blind spots"), making the resulting measurements very accurate. However, due to the continuous sampling and the amount of information being handled by the sensor, the resource requirements (e.g., processing, bandwidth, and latency requirements) of the sensor may be relatively high.

In other examples, where relatively high system resources (e.g., high bandwidth, low latency, or high processing requirements) and/or high performance components are not available or practical (e.g., due to cost constraints or system architecture limitations), sensors or meters coupled to circuit branches of a load center may include general purpose components that are programmed and/or configured to monitor voltage and/or current waveforms of circuit branches with acceptable "blind spots". "Blind spots" are periods of time when part or all of the pertinent information (e.g., voltage, current, frequency, phase) is not measured (or discarded).

For example, in a limited complexity and/or cost distributed sensor network, the limited resources of the distributed sensor network (e.g., limited bandwidth or computing resources) may result in "blind spots" in the measured voltage and/or current waveforms. The "blind spots" in the measured voltage and/or current waveforms of a circuit branch may be acceptable to a user as the measurements are made with a distributed sensor network with reduced power consumption, limited internal communication bandwidth requirements, and limited required computer resources. However, while the acceptance of "blind spots" in a sensor network may limit the complexity and/or cost of the network, it also may compromise the accuracy of measurements made by the sensor and lead to potential inaccuracies in power and energy measurements.

Embodiments described herein provide an accurate energy measurement system that eliminates, or at least reduces, measurement blind spots. According to at least one

embodiment, the energy measurement system described herein utilizes pipeline data acquisition, communication and computation to distribute power calculations over multiple line cycles. By overlapping data acquisition, communication and computation over multiple line cycles, power consumption of a circuit branch may be calculated while minimizing any blind spots.

FIG 1 shows a load center 100 that includes a system for monitoring subsidiary circuit branches 102 of the load center 100 according to one embodiment of the current invention. The load center 100 includes a housing 101. Within the housing 101, the load center 100 includes a first input power line 104, a second input power line 106, a plurality of circuit branches 102, a neutral line 108, and a ground connection 110. The first and second input power lines 104, 106 and the neutral line 108 are each configured to be coupled to an external power source (e.g., a utility power system). Each one of the plurality of circuit branches 102 is configured to be coupled to one of the input power lines 104, 106 and the neutral line 108. Each one of the plurality of circuit branches 102 is also configured to be coupled to an external load (e.g., an appliance, a power outlet, a light etc.).

According to one embodiment, each one of the input power lines 104, 106 includes a circuit breaker 113 coupled between the input power line 104, 106 and circuit branches 102. According to another embodiment, each one of the plurality of circuit branches 102 includes a circuit breaker 115 coupled between the input power line 104, 106 and an external load 112. In one embodiment, the current rating of each of the circuit breakers 113, 115 may be configured based on the power required by the external load 112 to which the circuit breakers 113, 115 associated circuit branch 102 is coupled. The neutral line 108 is coupled to the ground connection 110. According to one embodiment, the neutral line is coupled to the ground connection 110 via a neutral bus bar 116. According to another embodiment, the ground connection 110 is coupled to the neutral line 108 via a ground bus bar 118.

Within the housing 101, the load center 100 also includes a plurality of Current Transformers (CT) 114, a plurality of smart sensor circuits 120, a communication bus 122, a Power/Voltage Module (PVM) 126, and a main controller 124. According to one embodiment, the communication bus 122 includes a plurality of wires. For example, in one embodiment, the communication bus 122 is a ribbon cable including 4 wires (a power line, a return line, D+ differential pair line, D- differential pair line); however, in other embodiments, the

communication bus 122 may include any number and type of wires. Each one of the plurality of CT's 114 is coupled to at least one of the plurality of circuit branches 102. According to one embodiment, CT's 114 may also be coupled to each input line 104, 106. According to one embodiment, each CT 114 encompasses a corresponding circuit branch 102 or input line 104, 106. Each one of the plurality of CT's is also coupled to a corresponding smart sensor circuit 120. Each smart sensor circuit 120 is coupled to the communication bus 122.

According to one embodiment, each smart sensor circuit 120 is connected to the communication bus 122 so that the smart sensor circuit 120 is in electrical communication with the main controller 124. In one embodiment, each smart sensor circuit 120 is clamped onto the communication bus 122. For example, in one embodiment, electrical contacts of a smart sensor circuit 120 are pressed onto the communication bus 122 so that the electrical contacts pierce an insulation layer of the communication bus 122 and become electrically coupled to appropriate conductors within the communication bus 122. In other embodiments, the smart sensor circuits 120 may be coupled differently to the communication bus 122. For example, according to one embodiment, the smart sensor circuits 120 may be coupled to the

communication bus 122 via a bus bar or daisy chained connectors. According to some embodiments, each smart sensor circuit 120 is connected to the communication bus 122 as described in U.S. Patent Application Publication No. US 2012/0268106, entitled "Smart Current Transformers," published October 25, 2012, which is hereby incorporated herein by reference in its entirety.

According to one embodiment, the main controller 124 includes a digital interface 125 and a wireless network interface 128. In one embodiment, the wireless network interface 128 is a Zigbee RF interface; however, in other embodiments, another wireless network interface may be utilized. The communication bus 122 is coupled to the digital interface 125.

According to one embodiment, the PVM 126 is coupled to at least one input power line 104, 106 via at least one branch circuit 102.

The main controller 124 defines the communication and addressing on the

communication bus 122. According to one embodiment, the main controller 125 utilizes the RS-485 physical communication protocol to communicate over the communication bus 122 with the smart sensor circuits 120 and the PVM 126. According to one embodiment, the controller 502 utilizes the Modbus serial communication protocol to define the communication and addressing on the communication bus 122. For example, communication over the communication bus 122 using the Modbus protocol may be performed as described in U.S. Patent Application Serial Number 13/089,686 entitled "SYSTEM AND METHOD FOR

TRANSFERRING DATA IN A MULTI-DROP NETWORK", filed on April 19, 2011, which is herein incorporated by reference in its entirety.

According to one embodiment, AC power is provided from an external source (e.g., a utility power system) to the input lines 104, 106. AC power from the input lines 104, 106 is provided to each of the external loads via the circuit branches 102. The circuit breakers 113 are configured to automatically open and prevent current in an input line 104, 106 if an overload or short circuit is detected in the input line 104, 106. The circuit breakers 115 are configured to automatically open and prevent current in a circuit branch 102 if an overload or short circuit is detected in the circuit branch 102.

The PVM 126 receives AC power from at least one input line 104, 106 and acts as a power source for the main controller 124. According to one embodiment, the PVM 126 may also act as a power source for other components within the housing 101 (e.g., the smart sensor circuits 120). In addition, the PVM 126 measures the AC voltage, frequency and/or phase of the AC power and communicates the measured AC voltage, frequency, and/or phase information to the main controller 124.

The main controller 124 transmits the measured AC voltage, frequency and/or phase information to the smart sensor circuits 120, via the communication bus 122. For example, in one embodiment, the main controller 124 transmits voltage information of the AC power to the smart sensor circuits 120. In another embodiment, the main controller 124 transmits phase information of the AC power to the smart sensor circuits 120 so that the main controller 124 may be synchronized with the smart sensor circuits 120. According to one embodiment, the main controller 124 is synchronized with the smart sensor circuits 120 as described in U.S. Patent Application Publication No. US 2012/0271579, entitled "System and Method to

Calculate RMS Current and True Power in a Multidrop Sensor Network," published October 25, 2012, which is hereby incorporated herein by reference in its entirety. According to one embodiment, the main controller 124 is also capable of being powered by a battery.

AC current passing through a circuit branch 102 or input line 104, 106 induces a proportionate AC current in its associated CT 114 which encompasses the circuit branch 102 or input line 104, 106. In one embodiment, each CT 114 is calibrated to make accurate current measurements. According to one embodiment, where a CT 114 may be coupled to multiple circuit branches 102, an AC current proportionate to the combined current in the multiple circuit branches is induced in the CT 114 which encompasses the multiple circuit branches.

Each smart sensor circuit 120 is configured to operate on the current information received from its associate CT 114. In one embodiment, the smart sensor circuit 120 is configured to convert the received current information into digital signals. In another embodiment, the smart sensor circuit 120 is configured to utilize the received current information from the CT 114 and the received voltage, frequency and/or phase information from the main controller 124 (via the communication bus 122) to calculate power and/or energy parameters such as RMS current, true and apparent power, and power factor of the corresponding circuit branch 102 or input line 104, 106. According to one embodiment, this information may be converted into digital values and sent to the digital interface 125 of the main controller 124 over the communication bus 122. In another embodiment, this information may be transmitted directly to the main controller 124.

According to one embodiment, each smart sensor circuit 120 is also configured to utilize the phase information received from the main controller 124 to synchronize operation with the main controller 124 such that current measurements performed by the smart sensor circuits 120 can by synchronized with voltage measurements made by the main controller 124.

According to one embodiment, upon receiving the power and/or energy information from the smart sensor circuits 120 via the communication bus 122, the main controller 124 transmits the power and/or energy information to an external client (e.g., a web server, in-home display, internet gateway etc.) via the wireless network interface 128 to assist in power management of the load center 100 and to assist in power management and control of a residence or other facility containing the system. The main controller 124 may also transmit the power and/or energy information to an external client via a wired connection or any type of wireless connection.

The system described above in relation to FIG. 1 is configured to utilize pipeline data acquisition, communication and computation to distribute power calculations of each subsidiary circuit branch 102 over multiple line cycles. By overlapping data acquisition, communication and computation over multiple line cycles, power consumption of each branch 102 may be calculated while minimizing any blind spots.

FIG. 2 is a diagram 200 of a method of operation of a distributed sensor network (e.g., as shown in FIG. 1) in accordance with aspects of the present invention. As described above, the PVM 126 is coupled to at least one input line 104, 106 and configured to sense an input AC voltage waveform on the at least one input line 104, 106 over multiple line cycles. In one embodiment, the input AC voltage is a sinusoidal waveform; however, in other embodiments, the input AC voltage may be a non-sinusoidal waveform (e.g., a square wave).

During a first line cycle (L0) 202 of the input AC voltage waveform, the main controller 124 instructs, via the communication bus 122, each smart sensor circuit 120 and the PVM 126 to collect current and voltage data respectively. In one embodiment, each smart sensor circuit 120 is configured to take 64 current samples per line cycle; however, in other embodiments, the smart sensor circuits 120 may be configured to take any number of current samples per line cycle. In one embodiment, the PVM 126 is configured to take 64 voltage samples per line cycle; however, in other embodiments, the PVM 126 may be configured to take any number of voltage samples per line cycle.

During a second line cycle (LI) 204 of the input AC voltage waveform, the main controller 124 transmits the voltage data collected by the PVM 126 during the first line cycle (LO) 202 to each smart sensor circuit 120 via the communication bus 122. Also during the second line cycle (LI) 204, the main controller 124 instructs, via the communication bus 122, each smart sensor circuit 120 and the PVM 126 to collect current and voltage data, respectively.

During a third line cycle (L2) 206 of the input AC voltage waveform, each smart sensor circuit 120 calculates power and/or energy information of its corresponding circuit branch 102 (e.g., as discussed above) utilizing the current samples collected during the first line cycle (L0) 202 and the voltage samples collected by the PVM 126 during the first line cycle (L0) 202 (but received from the PVM 126 during the second line cycle (LI) 204). For example, in one embodiment, each smart sensor circuit 120 stores the current samples of the first line cycle (L0) 202 as a vector C(LO) = [ci, c 2 , c 3 ...c n ] and the voltage measurements of the first line cycle (L0) 202 (received from the PVM 126 during the second line cycle (LI) 204) as a vector V(LO) = [vi, v 2 , v 3 ...v n ], where n is the number of current and voltage samples taken per line cycle. In such an embodiment, each smart sensor circuit 120 calculates the power use of its associated current branch 102 over the first line cycle (L0) 202 by calculating the dot product of the current measurement vector C(LO) and the voltage measurement vector V(LO> The dot product of the current measurement vector C(LO) and the voltage measurement vector V(LO) is

rt i =1

where n is the number of current and voltage samples taken per line cycle (e.g., n = 64).

Also during the third line cycle (L2) 206, the main controller 124 transmits the voltage data collected by the PVM 126 during the second line cycle (LI) 204 to each smart sensor circuit 120 via the communication bus 122. Also during the third line cycle (L2) 206, the main controller 124 instructs, via the communication bus 122, each smart sensor circuit 120 and the

PVM 126 to collect current and voltage data, respectively. During a fourth line cycle (L3) 208 of the input AC voltage waveform, the power information calculated by each smart sensor circuit 102 during the third line cycle (L2) 206 (i.e., the dot product of the current measurement vector C(LO) and the voltage measurement vector V(L0) related to the first line cycle (L0) 202) is transmitted to the main controller 124 via the communication bus. Also during the fourth line cycle (L3) 208, each smart sensor circuit 120 calculates power and/or energy information of its corresponding circuit branch 102 (e.g., as discussed above) utilizing the current and voltage measurements collected during the second line cycle (LI) 204 by the smart sensor circuits 120 and the PVM 126. For example, in one embodiment as discussed above, where each smart sensor circuit 120 stores the current measurements of the second line cycle (LI) 204 as a vector C(LI) = [c \ , c 2 , c 3 ...c n ] and the voltage measurements of the second line cycle (LI) 204 (received from the PVM 126 during the third line cycle (L2) 206) as a vector V(LI) = [vi, v 2 , v 3 ...v n ], where n is the number of current and voltage samples taken per line cycle, each smart sensor circuit 120 calculates the power use of its associated current branch 102 over the second line cycle (LI) 204 by calculating the dot product of the current measurement vector c (L i ) and the voltage

measurement vector V(LI

Also during the fourth line cycle (L3) 208, the main controller 124 transmits the voltage data collected by the PVM 126 during the third line cycle (L2) 206 to each smart sensor circuit 120 via the communication bus 122. Also during the fourth line cycle (L3) 208, the main controller 124 instructs, via the communication bus 122, each smart sensor circuit 120 and the PVM 126 to collect current and voltage data, respectively.

During a fifth line cycle (L4) 210 of the input AC voltage waveform, the power information calculated by each smart sensor circuit 102 during the fourth line cycle (L3) 208 (i.e., the dot product of the current measurement vector C(Li) and the voltage measurement vector V(LI) related to the second line cycle (LI) 204) is transmitted to the main controller 124 via the communication bus. Also during the fifth line cycle (L4) 210, each smart sensor circuit 120 calculates power and/or energy information of its corresponding circuit branch 102 (e.g., as discussed above) utilizing the current and voltage measurements collected during the third line cycle (L2) 206 by the smart sensor circuits 120 and the PVM 126. For example, in one embodiment as discussed above, where each smart sensor circuit 120 stores the current measurements of the third line cycle (L2) 206 as a vector C(L 2 ) = [ci, c 2 , c 3 ...c n ] and the voltage measurements of the third line cycle (L2) 206 (received from the PVM 126 during the fourth line cycle (L3) 208) as a vector V(L 2 ) = [ i, v 2 , v 3 ...v n ], where n is the number of current and voltage samples taken per line cycle, each smart sensor circuit 120 calculates the power use of its associated current branch 102 over the third line cycle (L2) 206 by calculating the dot product of the current measurement vector C(L 2 ) and the voltage measurement vector V(L¾.

Also during the fifth line cycle (L4) 210, the main controller 124 transmits the voltage data collected by the PVM 126 during the fourth line cycle (L3) 208 to each smart sensor circuit 120 via the communication bus 122. Also during the fifth line cycle (L4) 210, the main controller 124 instructs, via the communication bus 122, each smart sensor circuit 120 and the PVM 126 to collect current and voltage data, respectively.

During a sixth line cycle (L5) 212 of the input AC voltage waveform, the power information calculated by each smart sensor circuit 102 during the fifth line cycle (L4) 210 (i.e., the dot product of the current measurement vector C(L¾ and the voltage measurement vector V(L2) related to the third line cycle (L2) 206) is transmitted to the main controller 124 via the communication bus. Also during the sixth line cycle (L5) 212, each smart sensor circuit 120 calculates power and/or energy information of its corresponding circuit branch 102 (e.g., as discussed above) utilizing the current and voltage measurements collected during the fourth line cycle (L3) 208 by the smart sensor circuits 120 and the PVM 126. For example, in one embodiment as discussed above, where each smart sensor circuit 120 stores the current measurements of the fourth line cycle (L3) 208 as a vector C ( o ) = [c \ , c 2 , c 3 ...c n ] and the voltage measurements of the fourth line cycle (L3) 208 (received from the PVM 126 during the fifth line cycle (L4) 210) as a vector V(L¾ = [vi, v 2 , v 3 ...v n ], where n is the number of current and voltage samples taken per line cycle, each smart sensor circuit 120 calculates the power use of its associated current branch 102 over the fourth line cycle (L3) 208 by calculating the dot product of the current measurement vector C(L¾ and the voltage measurement vector V(L 3 Also during the sixth line cycle (L5) 212, the main controller 124 transmits the voltage data collected by the PVM 126 during the fifth line cycle (L4) 210 to each smart sensor circuit 120 via the communication bus 122. Also during the sixth line cycle (L5) 212, the main controller 124 instructs, via the communication bus 122, each smart sensor circuit 120 and the PVM 126 to collect current and voltage data, respectively.

As seen in FIG. 2, four line cycles pass before power information (related to the first line cycle 202) is transmitted from each smart sensor circuit 120 to the main controller 124. Current and voltage related data is acquired during the first line cycle (L0) 202. The voltage data is transmitted to each smart sensor circuit 120 during a second line cycle (LI) 204. Power information, related to the current and voltage data acquired during the first line cycle (L0) 202, is calculated during a third line cycle (L2) 206 and transmitted to the main controller 124 during a fourth line cycle (L3) 208. By pipelining (i.e., distributing across multiple line cycles) data acquisition, communication, and computation functions, real power consumption of a circuit branch 102 may be calculated correctly while minimizing any blind spots.

By pipelining the power consumption measurements in a distributed sensor network and making power calculations at each smart sensor circuit 120 (as discussed above), network traffic on the communication bus 122 may be limited as only voltage data is transmitted from the main controller 120 to each smart sensor circuit 120 and only the calculated power information is transmitted by each smart sensor circuit 120 to the main controller 120. In addition, by reducing the network traffic on the communication bus 122, the power consumption of the system may be reduced.

FIG. 3 illustrates an example block diagram of computing components forming a system 300 which may be configured to implement one or more aspects disclosed herein. For example, the system 300 may be communicatively coupled to a smart sensor circuit, included within a smart sensor circuit, communicatively coupled to a main controller, included within a main controller, and/or configured to make power consumption calculations in a distributed sensor network as discussed above.

The system 300 may include for example a general-purpose computing platform such as those based on Intel PENTIUM-type processor, Motorola PowerPC, Sun UltraSPARC, Texas Instruments-DSP, Hewlett-Packard PA-RISC processors, or any other type of processor. System 300 may include specially-programmed, special-purpose hardware, for example, an application-specific integrated circuit (ASIC). Various aspects of the present disclosure may be implemented as specialized software executing on the system 300 such as that shown in FIG. 3.

The system 300 may include a processor/ASIC 306 connected to one or more memory devices 310, such as a disk drive, memory, flash memory or other device for storing data. For example, in one embodiment, the system 300 includes a Cortex-M4 Processor manufactured by ARM Holdings of Cambridge, UK; however, in other embodiments, other appropriate processors may be utilized.

Memory 310 may be used for storing programs and data during operation of the system

300. Components of the computer system 300 may be coupled by an interconnection mechanism 308, which may include one or more buses (e.g., between components that are integrated within a same machine) and/or a network (e.g., between components that reside on separate machines). The interconnection mechanism 308 enables communications (e.g., data, instructions) to be exchanged between components of the system 300.

The system 300 also includes one or more input devices 304, which may include for example, a keyboard or a touch screen. The system 300 includes one or more output devices 302, which may include for example a display. In addition, the computer system 300 may contain one or more interfaces (not shown) that may connect the computer system 300 to a communication network, in addition or as an alternative to the interconnection mechanism 308.

The system 300 may include a storage system 312, which may include a computer readable and/or writeable nonvolatile medium in which signals may be stored to provide a program to be executed by the processor or to provide information stored on or in the medium to be processed by the program. The medium may, for example, be a disk or flash memory and in some examples may include RAM or other non- volatile memory such as EEPROM. In some embodiments, the processor may cause data to be read from the nonvolatile medium into another memory 310 that allows for faster access to the information by the processor/ASIC than does the medium. This memory 310 may be a volatile, random access memory such as a dynamic random access memory (DRAM) or static memory (SRAM). It may be located in storage system 312 or in memory system 310. The processor 306 may manipulate the data within the integrated circuit memory 310 and then copy the data to the storage 312 after processing is completed. A variety of mechanisms are known for managing data movement between storage 312 and the integrated circuit memory element 310, and the disclosure is not limited thereto. The disclosure is not limited to a particular memory system 310 or a storage system 312.

The system 300 may include a general-purpose computer platform that is

programmable using a high-level computer programming language. The system 300 may be also implemented using specially programmed, special purpose hardware, e.g. an ASIC. The system 300 may include a processor 306, which may be a commercially available processor such as the well-known Pentium class processor available from the Intel Corporation. Many other processors are available. The processor 306 may execute an operating system which may be, for example, a Windows operating system available from the Microsoft Corporation, MAC OS System X available from Apple Computer, the Solaris Operating System available from Sun Microsystems, or UNIX and/or LINUX available from various sources. Many other operating systems may be used. The processor and operating system together may form a computer platform for which application programs in high-level programming languages may be written. It should be understood that the disclosure is not limited to a particular computer system platform, processor, operating system, or network. Also, it should be apparent to those skilled in the art that the present disclosure is not limited to a specific programming language or computer system. Further, it should be appreciated that other appropriate programming languages and other appropriate computer systems could also be used.

As discussed above, the process of measuring power consumption of a circuit branch is spread across four line cycles; however, in other embodiments, the process of measuring power consumption of a circuit branch may be spread across any number of multiple line cycles. As also discussed above, the process of measuring power consumption of a circuit branch is spread across four subsequent line cycles; however, in other embodiment, the process of measuring power consumption of a circuit branch may be spread across non-subsequent line cycles. As also discussed above, the process of measuring power consumption of a circuit branch is spread across four sequential line cycles; however, in other embodiments, the line cycles across which the power consumption measurement process is distributed may not occur sequentially.

In addition, as discussed above, power measurements are distributed over six input voltage line cycles; however, in other embodiments, the process may be operated continuously across any number of input voltage line cycles.

In addition, as discussed above, the process of measuring power consumption of a circuit branch is distributed across multiple segments of an input voltage waveform, the segments corresponding to different line cycles of the input voltage waveform. However, in other embodiments, the segments of the input voltage waveform may not correspond to line cycles of the input voltage waveform and instead may be defined in other ways. For example, each segment can be arbitrarily long. Also, each segment may or may not start at a zero crossing of the input voltage waveform.

As discussed above, the same number of current and voltage samples are taken per line cycle; however, in other embodiments, the number of current samples taken per line cycle may be different than the number of voltage samples taken per line cycle.

As discussed above, current in each circuit branch is measured with a CT; however, in other embodiments, current through a circuit branch may be measure with another type of current sensor (e.g., a Hall Effect sensor or a shunt resistor). As discussed above, power information is determined by calculating the dot product of a current sample related vector and a voltage sample related vector; however, in other embodiments, power information may be calculated differently. For example, in one embodiment, power consumption of a circuit branch is calculated using an average value of the current measurements taken during a line cycle and an average value of the voltage measurements taken during the line cycle.

As described above, voltage samples are taken by the PVM 126 external the main controller 124; however, in other embodiments, the PVM 126 may be located in the main controller 124 or the main controller 124 itself may take voltage samples of the input AC voltage.

The energy measurement system described above is utilized in an RS-485 (master/slave type) multi-drop network; however, in other embodiments, the energy measurement system may be utilized in any distributed sensor network including heterogeneous sensors coupled to a network bus. In at least one embodiment, the energy measurement system described above is also utilized in a distributed sensor network including heterogeneous sensors coupled to a controller via a Local Area Network (LAN).

As described above, the energy measurement system is utilized with a distributed sensor network in a load center; however, in other embodiments, the energy measurement system may be utilized with any distributed sensor network including heterogeneous sensors coupled to a network bus.

Embodiments described herein provide an accurate energy measurement system that eliminates, or at least reduces, measurement blind spots. The energy measurement system described herein utilizes pipeline data acquisition, communication and computation to distribute power calculations over multiple line cycles. By overlapping data acquisition, communication and computation over multiple line cycles, power consumption of a circuit branch may be calculated while minimizing any blind spots.

Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

What is claimed is: