BPA-Garrison-500-kV substation-Central Montana.
It was, quite literally, a dark day for the energy industry: On Aug. 14, 2003, a power failure in Ohio triggered a chain reaction across 600 miles (966 km) of the United States. The cascading outage not only left 50 million people in eight Midwest and Northeast states in the dark, it also raised serious questions about the state of the nation’s electric grid.
A decade after the largest blackout in the country’s history, smart grid devices known as phasor measurement units (PMUs), or synchrophasors, are opening the eyes of grid operators everywhere. But, at the Bonneville Power Administration (BPA), engineers are taking the technology to new levels. The agency now has the largest, most sophisticated synchrophasor network in North America, and it is the only network in the West designed to take split-second automated control actions when it detects a problem on the grid. This is the future of power grid operations.
Old and New
For decades, utilities relied on supervisory control and data acquisition (SCADA) systems, which produced grid readings every 2 seconds to 4 seconds, and none of these measurements were time synchronized. Now, PMUs can crank out precise power system parameters a hundred times faster, providing an unprecedented view of power system dynamics. BPA’s PMUs are set to report power system data 60 times per second. This massive boost in resolution is akin to making the technology leap from black-and-white to 3-D color television.
PMUs take current, frequency and voltage readings and time-stamp them using GPS. These measurements are then transmitted over a high-speed broadband network to BPA’s control centers. The result is a turbocharged feed of power system data that provides grid operators real-time intelligence so they can react more quickly to system disturbances and take actions to avoid a blackout or prevent a disturbance from cascading.
Western Interconnection Synchrophasor Program
In August 2003, grid operators did not realize what was happening until it was too late. Today, BPA and others in the West are making wide-area situational awareness a reality. As part of the Western Interconnection Synchrophasor Program (WISP) led by the Western Electricity Coordinating Council, BPA, along with 18 utility and technology partners, is building a network of more than 600 PMUs across the western grid. BPA and its WISP partners have achieved a true industry game changer that has facilitated a whole new level of cooperation among the energy entities in the West, and it results in a more reliable and secure Western Interconnection.
WISP was partially funded with US$53.9 million by the American Recovery and Reinvestment Act of 2009 stimulus funds and is part of the Department of Energy’s Smart Grid Investment Grant program. The program blends the latest synchrophasor technology with a more robust telecommunications system to give the many transmission operators from Canada to Mexico a much clearer view of the entire transmission system in the West. With all the measurements synchronized to GPS, BPA can see more precisely how all the interconnected power systems in the West are responding to changes or disturbances.
In addition to early detection of equipment failures, the system monitoring and operations from the $108 million network improves the integration of renewable energy, such as wind, and unlocks stability-limited capacity, which translates to more efficient power flow on the grid.
BPA’s work with synchrophasors goes well beyond WISP. In fact, the agency was one of the early adopters of the technology. In the 1980s, it worked with inventors of the technology to optimize the devices for application on the electrical grid. Then, in the 1990s, BPA was the first in the industry to assemble PMUs into a network, stream real-time data from substations to its control center and time-align the multiple data streams. In 2013, BPA completed its build out of an unparalleled synchrophasor network as part of a three-year, $30 million synchrophasor project to enhance the Northwest’s generation and transmission systems.
BPA is now receiving data from 126 PMUs at 50 key substations and large wind-generation sites throughout the Northwest. The agency is initially focusing on using the PMU data to understand system performance issues, set safer operating limits and inform its grid-reinforcement decisions. So far, the agency has integrated the PMU data into displays for its dispatchers.
It also is the only fully redundant synchrophasor network in the West. Because there is a minimum of two PMUs at each site, two streams of data are always available — one at each of the agency’s control centers. On top of that, the two control centers share a link of encrypted data, which provides true operational redundancy. So if a stream is interrupted or erroneous, the system automatically uses the feed from the other control center.