Measuring Phase Angle Change in Power Lines

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OPEN 2012
Berkeley, California
Project Term:
03/01/2013 - 06/30/2018

Critical Need:

Today, power generally flows in one direction along the grid: from the generation source to the end user. In the power grid of the future, many electricity generators—including home solar power arrays and wind turbines—will cause power to flow in multiple directions along distribution lines. As the grid matures and expands in complexity to accommodate multi-directional power flow, new technologies are needed to monitor the direction of power flow along the distribution lines to ensure grid stability and reliability.

Project Innovation + Advantages:

The University of California, Berkeley (UC Berkeley) is developing a device to monitor and measure electric power data from the grid’s distribution system. The new instrument—known as a micro-phasor measurement unit (µPMU)—is designed to measure critical parameters such as voltage and phase angle at different locations, and correlate them in time via extremely precise GPS clocks. The amount of phase angle difference provides information about the stability and direction of power flow. Data collected from a network of these µPMUs would facilitate better monitoring and control of grid power flow—a critical element for integrating intermittent and renewable resources, such as rooftop solar and wind energy, and other technologies such as electric vehicles and distributed storage.

Potential Impact:

If successful, utilities will be able to use UC Berkeley’s µPMU micro-synchrophasor data to enhance grid reliability and transform the electric power industry by providing new information about grid stability at local, regional, and system-wide levels.


This project could contribute to a smarter, more reliable, more advanced, and secure electric grid.


Enabling more renewable energy sources—such as wind and solar—would reduce the need for coal-fired power plants for electricity generation, reducing the harmful emissions that come from these plants.


Improving local management of energy resources and increasing deployment of renewable generation could position the U.S. as the technological and economic leader in developing and deploying advanced energy technologies.


ARPA-E Program Director:
Dr. Kory Hedman
Project Contact:
Dr. Alexandra von Meier
Press and General Inquiries Email:
Project Contact Email:


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