System and method for phase load discovery

• US 8,570,023 B2
• Filed: 12/02/2009
• Issued: 10/29/2013
• Est. Priority Date: 12/03/2008
• Status: Active Grant

• Current Assignee: Sensus USA Incorporated (Xylem, Inc.)
• Original Assignee: Sensus USA Incorporated (Xylem, Inc.)
• Inventors: Uram, George, Gallagher, Jeff
• Primary Examiner(s): NATALINI, JEFF WILLIAM
• Application Number:
  US12/629,338
• Publication Number:
  US 20100134089A1
• Time in Patent Office: 1,427 Days
• Field of Search: 324/66
• US Class Current: 324/66
• CPC Class Codes: G01D 2204/47 Methods for determining the topology or arrangement of meters in a network
• CPC Class Codes: G01R 22/063 related to remote communication
• CPC Class Codes: G01R 22/066 Arrangements for avoiding or indicating fraudulent use
• CPC Class Codes: G01R 29/16 Measuring asymmetry of polyphase networks
• CPC Class Codes: G01R 29/18 Indicating phase sequence; Indicating synchronism
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

A system and method for determining the relative phase of each of a plurality of load meters connected to a three-phase power distribution system. The system includes a gateway that communicates information to and from each of the individual load meters. The gateway generates a timing pulse that is received by each of the load meters. Based upon the delay from the receipt of the timing pulse to the next zero crossing of the single phase power supply received by the meter, the utility can determine the phase of the individual meter. The system can include a feeder meter connected to each phase of the electrical supply system to determine the energy consumption for each of the meters connected to a specific phase. The utility can compare the energy consumption information from the feeder meter to all of the load meters connected to the same phase to determine whether any energy theft is occurring.

Claims

1. A method of monitoring a load on a three-phase power supply that provides power to a plurality of load meters each connected to one of three supply lines of the power distribution system, wherein each of the supply lines carries a different one of the three voltage phases, the method comprising the steps of:

connecting a feeder meter to each of the three supply lines, wherein each of the feeder meters is positioned between the power supply and the load meters and wherein the phase of the supply line to which each of the three feeder meters is connected is known;

transmitting a timing pulse;

receiving the timing pulse at each of the three feeder meters;

determining a feeder time delay at each of the feeder meters, the feeder time delay being the delay from the receipt of the timing pulse until a landmark value of the single phase voltage received by the feeder meter;

designating each of the feeder time delays as one of three reference time delays based upon the known phase of the feeder meter

receiving the timing pulse at each of the plurality of load meters;

determining a time delay at each of the load meters, the time delay being a measured time from the receipt of the timing pulse until a landmark value of the single phase voltage received by the load meter;

comparing the determined time delay from each of the plurality of load meters to the three reference time delays, each of the three reference time delays being associated with one of the three phases; and

assigning one of the three phases to each load meter based upon the closest reference time delay to the determined time delay for the load meter.

2. The method of claim 1 wherein the landmark value of the single phase voltage is a zero crossing.

3. The method of claim 1 further comprising the steps of:

transmitting energy consumption data from each of the load meters to an end server; and

aggregating the energy consumption data for the plurality of load meters for each of the three phases based upon the designated phase for the load meter.

4. The method of claim 3 further comprising the step of generating an alarm condition when the aggregated energy consumption on each of the three phases is unbalanced.

5. The method of claim 3 further comprising the steps of:

comparing the aggregated energy consumption for each of the three phases to energy consumption information from each of the three feeder meters; and

generating an alarm when the aggregated energy consumption on any of the three phases is below the energy consumption information from the feeder meter for that phase by more than a threshold value.

6. The method of claim 1 wherein the timing pulse is a wireless signal received by each of the plurality of load meters.

7. A system for determining the load on each phase of a three-phase power supply, comprising:

a plurality of load meters each connected to one phase of the three-phase power supply;

at least three feeder meters each positioned to receive one phase of the three-phase power supply

a wireless transmission device positioned to generate a wireless timing pulse received by each of the plurality of load meters and each of the feeder meters, wherein each of the plurality of load meters is operable to determine a time delay from receipt of the timing pulse until a first zero crossing of the single phase voltage, wherein each of the feeder meters determines a reference time delay from the receipt of the timing pulse at the feeder meter until a zero crossing of the single phase received by the feeder meter, the load meter further including a transmission device to wirelessly transmit the determined time delay; and

an end server operable to receive the determined time delay from each of the load meters and group each of the load meters into one of the three phases based upon a comparison between the determined time delay from each meter and the reference time delays from the feeder meters.

8. A method of monitoring a load on a three-phase power supply that provides power to a plurality of load meter each connected to one of three supply lines of a power distribution system, wherein each of the supply lines carries a different one of three voltage phases, the method comprising the steps of:

connecting a feeder meter to each of the three supply lines, wherein each of the feeder meters is positioned between the power supply and one or more of the load meters, wherein the phase of the supply line to which each of the three meters is connected is known;

transmitting a wireless timing pulse that is received by each of the plurality of load meters and each of the feeder meters;

determining a reference time delay at each of the feeder meters, the referenced time delay being the delay from the receipt of the timing pulse at the feeder meter until a zero crossing of the single phase voltage received by the feeder meter;

determining a time delay at each of the load meters, the time delay being a measured time from the receipt of the timing pulse until a landmark value of the single phase voltage received by the load meter;

comparing the time delay from each of the plurality of load meters to the three reference time delays from the feeder meters;

assigning each of the plurality of load meters to one of the three feeder meters based upon the similarity between the reference time delay from the feeder meters and the determined time delay at each of the load meters;

transmitting energy consumption data from each of the load meters and each of the feeder meters to an end server;

aggregating the energy consumption data for the plurality of load meters for each of the three phases based upon the designated phase for the load meter;

comparing the aggregated energy consumption for each of the three phases to energy consumption information from each of the three feeder meters; and

generating an alarm when the aggregated energy consumption on any of the three phases is below the energy consumption information from the feeder meter for that phase by more than a threshold value.

9. The method of claim 8 wherein the reference time delays are determined prior to determination of the time delay from each of the load meters.