Situational awareness helps integrate renewables and slash carbon
How California’s transmission grid operator CAISO increased complexity to simplify the rise of renewables.
The California Independent System Operator (ISO) recently implemented a new energy management system that offers more functionality to meet the challenges of integrating higher levels of renewable energy, by accommodating new energy technologies in support of the state’s goal to decarbonize the grid.
By Justin Gerdes
“If you can't solve a problem, enlarge it.” The aphorism, attributed to former U.S. President Dwight Eisenhower, is an apt description of how California’s electric grid operator resolved an emerging operational challenge. Ambitious state policies have made California a global clean energy leader. By law, the state is to have a carbon-free power grid by 2045. At the end of 2019, 36 percent of the state’s electricity came from renewable sources, including 6,000 megawatts (MW) of wind and 12,000 MW of solar PV.
Because the Western EIM participants are located in nine states, the geographical diversity create efficiencies.Hani Alarian, Executive Director Power System Technology Operations of California ISO
About a decade ago, when these variable sources of renewable energy started to account for an increasingly large share of the new electricity capacity, the California ISO, the entity charged with maintaining reliability on the high voltage transmission system, began to grapple with how to integrate higher levels of renewables into the grid. Emissions reductions required under state law precluded reliance on conventional sources of grid balancing such as new coal- or gas-fired power plants. At midday, when California’s growing fleet of utility-scale solar farms generate power at peak capacity, grid operators sometimes resort to curtailment – ratcheting down the output of individual solar power plants – to maintain a balance between supply and demand on the system.
A real-time wholesale energy market…
The California ISO created a market to transfer power not just inside California but across the western United States. What came to be called the Western Energy Imbalance Market (EIM) launched in 2014. The real-time wholesale energy market made it possible to avoid curtailment by using the lowest-cost energy resources, which often are renewable energy resources, to be traded across the West. After the new members who are scheduled to join the market come online over the next two years, the Western EIM will encompass 82 percent of Western Electric Coordinating Council’s (WECC) total load.
“Because the Western EIM participants are located in nine states, the geographical diversity create efficiencies,” Hani Alarian, Executive Director Power System Technology Operations of California ISO, said in an interview. “The Western EIM’s participants export and import in real-time, so when an entity has a lower cost energy resource – like solar -- that they don’t need to meet demand, they can transfer it to another balancing authority which saves the utility money and avoids having to curtail renewable energy generation.”
Since its launch in 2014, the Western EIM has provided $1.18 billion in economic benefits to participating utilities. By making it easier to transfer carbon-free electricity that might otherwise have been curtailed, cumulative CO2 emissions have been reduced by a total of 586,553 metric tons. During the past five years, the Western EIM’s participants have used 1.3 gigawatt hours (GWh) of renewable energy that would have otherwise been curtailed.
… and a sophisticated energy management system
Several years after the launch of the Western EIM, the California ISO assumed the role of grid reliability coordinator for more than 40 electricity balancing authorities across 14 western states and northern Mexico in 2019. The ISO’s reliability coordinator, RC West, provides members with grid reliability services in accordance with federal and regional standards such as outage coordination, day-ahead planning, real-time assessment, monitoring, and analysis, as well as system restoration coordination.
California needed a scalable grid operating system built to handle its expanding geographic reach. After five years of study, competitive bidding, design, and implementation, the new energy management system, Siemens Spectrum Power 7, launched in October 2019. RC West went live the next month.
The California ISO now has a sophisticated energy management system with the functionality needed to meet the needs of an evolving grid.Hani Alarian, executive director, power system technology operations, California ISO
“The California ISO now has a sophisticated energy management system with the functionality needed to meet the needs of an evolving grid,” Alarian said. “The system offers more details and improved data accuracy which provides our operators with the information they need to make decisions.”
“The sizing went five times as big, going from only California to the entire West,” added Alarian. “And as the Western EIM continues to expand, we add more details and more accuracy to the model.”
Another critical improvement offered by the new EMS, Alarian said, was building data access layer architecture into the system. “This improvement gives operators the ability to have an interface that can present data from any application on the same display in the EMS.” He went on, “That gives operators a powerful presentation because now they can see market data on top of one line diagram, on top of geographical spatial data, and all in one display.”
Real-time visibility into weather patterns
California ISO’s original EMS did not include geospatial information; the new system now offers features that enhance operations. As more variable renewable energy generation came online within its territory and beyond, the California ISO’s grid operators needed real-time weather information. “If you have a clear day versus scattered clouds versus overcast, it's going to affect generation,” said Alarian. “It’s important for operators to know about cloud coverage, and wind speed and direction to respond quickly to renewable generation output.”
It’s important for operators to know about cloud coverage, and wind speed and direction to respond quickly to renewable generation output.Hani Alarian, Executive Director Power System Technology Operations of California ISO
Beyond weather, grid operators must also account for wildfires in California and the West. “Fires near major transmission lines create many challenges for operations. Operators must know the fire’s proximity to transmission lines to respond the risk,” Alarian said. Real-time visibility into weather patterns, fire danger, and other environmental factors helps control room operators make better decisions and maintain grid reliability.
“With a sophisticated energy management system, our operators’ situational awareness has improved,” said Alarian. “We try to provide as much information as quickly as possible using data, pictures and video of issues.”
Up to 10,000 contingencies each run
To maintain reliability, grid operators must constantly balance supply and demand. Arm the control room with richer data, updated at shorter intervals, and operators make better-informed decisions. Towards that end, future improvements to the EMS, Alarian said, will focus on performance and speed. “Performance” in this context refers to how fast the state estimator and real-time contingency analysis runs.
“You want the most recent data telemetry state estimator results,” he said. “The faster you can run it and the more often you can run it, the closer to reality the solution is.”
“The new system can process around 10,000 contingencies every three-and-a-half minutes. I wouldn’t be surprised if in the future we might want to go up to 15,000 or even 20,000.”Hani Alarian, Executive Director Power System Technology Operations of California ISO
Run more contingencies and you have a more reliable grid
The California ISO’s new EMS has significantly increased capacity to solve for contingencies each day. The old system was limited to just 2,000 contingencies, updated every 10 minutes.
“In the new system, we’re running contingencies every three-and-a-half minutes. And we would like to even get it down to every two minutes,” said Alarian. "The new system can process around 10,000 contingencies per run. I wouldn’t be surprised that in the future we might want to go up to 15,000 or even 20,000,” he added.
The California Independent System Operator (ISO) maintains reliability on one of the largest and most modern power grids in the world, and operates a transparent, accessible wholesale energy market. The organization works diligently around the clock to meet the electricity needs of consumers, while increasing the amount of renewable energy to usher in the clean, green grid of the future.
May 3, 2021
Author: Justin Gerdes is an award-winning energy journalist based in the San Francisco Bay Area and U.S. Senior Correspondent for Energy Monitor, an online publication on the global clean energy transition.
Picture credits: California Independent System Operator Corporation, Getty Images, Siemens AG
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