A/B/C phase determination and synchrophasor measurement using common electric smart meters and wireless communications

A method of determining phase relationship among power meters, the method comprising:

• collecting count stamped messages transmitted between nodes in a network including at least two power meters, the messages including zero crossing measurements of a power signal sensed at a corresponding power meter;
• from the count stamped messages, determining relative timing among clocks within the power meters;
• from the relative timing and zero crossing measurements, determining relative phases between the power meters;
• wherein the zero crossing measurements within a first power meter, and the count-stamping of a message by said first power meter, are made relative to a common clock within the first power meter.

A power meter comprising:

• a metrology unit for measuring zero crossing of a power signal;
• and
• a communication unit, in communication with the metrology unit, for collecting zero crossing measurements, and communicating count stamped messages including the collected zero crossing measurements to a remote node for determining relative phase between the power meter and another power meter;
• wherein the communication unit is in communication with a local clock for count-stamping messages upon receipt or transmission.

A system comprising:

• a node for collecting count stamped messages transmitted between nodes in a network, the nodes including at least first and second power meters, the count stamped messages including zero crossing measurements of a power signal sensed at the first power meter, and including count stamped zero crossing measurements of a power signal sensed at the second power meter;
• a node for determining relative timing among clocks within the network nodes from the count stamped messages;
• and
• a node for determining relative phases between the network nodes from the relative timing and zero crossing measurements.

A metrology unit for coupling to a power distribution network, comprising:

• a zero-crossing detector;
• a free-running counter;
• and
• circuitry that outputs a value from the free-running counter when the detector senses a zero-crossing;
• wherein the communication unit is in communication with a local clock for count-stamping messages upon receipt or transmission.