World’s first mobile STATCOM: When grid stabilization gets wheels
In a rapidly changing energy world, grid operators need a quick solution to address volatility when power plants shut down or renewables are added. Now Siemens Energy and US grid operator Dominion Energy have developed a mobile reactive power compensator that can do just that, providing fast grid support where and when it’s most needed – even in emergencies.
by Rhea Wessel
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Sometimes great ideas lurk in plain sight. Dave Roop, Director of Electric Transmission at Dominion Energy, recognized such an idea in an “aha” moment while visiting a Siemens plant in 2015. There he saw an SVC PLUS being built in a container for a different customer.
At that time, Dominion Energy, one of the largest power producers and transmission system operators in the USA, had been using noncontainerized STATCOMs for years to provide dynamic load compensation for its transmission system.
Roop thought to himself, “If a STATCOM can go in a container, then that container could also go on wheels, right?” Aha. And the idea was born for a space-saving reactive power compensator multi-tool for grids.
Some 18 months after the start of discussions on a mobile STATCOM for utilities, Dominion Energy became the first customer worldwide to receive delivery of an SVC PLUS on wheels. SVC PLUS, a member of the Flexible AC transmission system (FACTS) devices, is an advanced STATCOM (static synchronous compensator) based on modular multilevel converter (MMC) technology that offers an innovative and universally applicable solution for grid enhancement.
This is an exciting time for our industry. The grid is changing very quickly, and we’ve got to morph the transmission network to the new environment.Dave Roop, Director of Electric Transmission at Dominion Energy
Creative use cases for Dominion Energy’s STATCOMs
Over the years, the way Dominion Energy has used STATCOM has evolved as the company gained experience with the technology. That’s why it seems fitting that it was Dominion Energy together with Siemens Energy who came up with the idea to put a STATCOM on wheels.
“First, we wanted SVCs for a dynamic stability problem in the eastern part of the USA,” Roop says. “Then we saw that it resolved voltage issues in the short term and soon after that it helped us with generation, too. Our engineering staff guided us to change the way we use our STATCOMs. We actually put four in service and then realized we had enough capability to change the control algorithm to help us with steady state voltage control – and still enough in reserve to handle the dynamic issue. When the last big storm hit, our customers’ lights came on faster than in previous events since we could control voltage in the initial light load conditions.”
Based in Virginia, Dominion Energy serves a number of large, important customers, including data centers and government facilities. It is increasingly faced with a potentially unstable grid, given the rate at which renewables are being added to Dominion Energy’s energy mix and the speed at which power plants are being shut down.
Dominion Energy and other providers are required to compensate for the load when plants are shut down, which can occur within months of announcement in the USA. For these reasons, the mobile SVC PLUS solution, with multilevel Voltage-Source Converter (VSC) technology, is critical for Dominion Energy. Roop says that when the first mobile STATCOM is placed into service in June 2018, it will initially be used to compensate for network shutdowns.
Typically, when major changes are made to the grid, substation infrastructure must be built on site, which can take years of planning to get the required authorizations. That substation infrastructure would also usually take up the size of a football field, but the mobile STATCOM comes in three trailers of equipment that utilities can easily maneuver. With tools that can be moved where they’re most needed, energy providers now have much more flexibility to react quickly to the demands of the network and to limit the impact of changes on customers.
Mirko Düsel, CEO Siemens Energy Management Transmission Solutions, says, “If you want to extend your grid and you have difficulty with the stability of your voltage, people are not so willing to undergo extensions. But if you have a temporary solution, then the population is more open to grid renewal.”
As Dominion Energy developed the idea of a mobile STATCOM together with Siemens Energy, it went back to its case records to find out if such a solution would be helpful in the future. “We studied projects where we had to take elements out of the grid or to build or rebuild lines,” Roop says, “for instance to upgrade them. Just in normal construction, where we were trying to reinforce our infrastructure, we saw that there are multiple projects where mobile STATCOMs would help us harden our grid.”
How to schlep a substation
Once it was clear that the infrastructure could be made mobile, Siemens Energy and Dominion Energy set out to find the right trailers for hauling the equipment and began working with trailer engineering specialist Gfoellner Fahrzeugbau und Containertechnik GmbH near Linz, Austria.
“The transport issue is one that had us concerned,” Roop says, “considering the type of turning radiuses we would need to get into a substation environment. But Siemens was able to work through these concerns and make sure that the containers could be shipped. Siemens and its trailer partner came up with some creative ideas, from mounting the IGBTs (insulated-gate bipolar transistors) so they could be moved down the highway to installing air conditioners, which are critical to keep the transistors cool.”
Looking forward, Roop sees additional uses for more mobile STATCOMs in Dominion Energy’s network, including rapid restoration after storms, line rework and the integration of renewables. He also sees a need for more and more standard equipment to become mobile, such as mobile gas-insulated switchgear and mobile transmission transformers. “This is an exciting time for our industry,” he says. “The grid is changing very quickly, and we’ve got to morph the transmission network to the new environment.”
Roop isn’t alone in thinking this. He has already fielded calls from other energy providers in the USA who face similar challenges. And though he’s not considering leasing out his new equipment, he’s not keeping it a secret either. “We’re very open with other utilities when it comes to our technology. Our view is that we’re all in this together.”
Rhea Wessel is a freelance writer based near Frankfurt, Germany
Picture credits: Siemens