NOVI — Think of the electric grid as a big water pipe with a bunch of smaller hoses running out of it.

You always want to keep the pipe full so all the smaller hoses have water available to them. You plan how much water to put in the pipe, based on what the people using the smaller hoses tell you they need. But it doesn’t always work out as planned — meaning the hose can get too full, or the water can start moving around in ways you didn’t want it to, meaning there might be a breakdown.

What you need is equipment that can respond quickly to changes in flow, to keep things flowing as planned.

Well, two giant transformers in Marysville, on the St. Mary’s River just south of Port Huron, will do just that for the electric grid that serves Michigan, the Midwest and Ontario, making the grid more efficient and reliable.

Novi-based ITC Holdings Corp., which owns much of the power grid in Michigan and significant chunks of it in other places around the country, spent nearly $50 million on the transformers, called phase angle regulators. Rather than change the voltage of electricity, these transformers will control the magnitude and direction of power flow on the grid.

“They’re used as a tool by our system operators to control power flows to match what the scheduled energy flow is supposed to be,” said Beth Howell, vice president of operations at ITC Holdings. “Loop flow is what we want to prevent. Loop flow is unscheduled energy, a result of a difference between energy scheduled to flow along a path and what actually happens to the system. Electricity flows along the path of least resistance, you can’t tell it where to go, physics dictates where it will go.”

The transformers will reduce what ITC says is a large volume of unscheduled power flow around Lake Erie, which takes up volume on the transmission system. That power flow makes the system more expensive to operate, and in a worst-case scenario can result in brownouts or blackouts.

“The operators of the transmission grid have to operate the system so the energy flow is within equipment limits,” Howell said. “Loop flow can be quite high, therefore operators must take action to ensure operations within system limits or ratings. They might curtail energy transactions, redispatch energy generation, or worst case, shedding customer load. And that’s what we never want to do.”

Added Gregory Ioanidis, president of ITC Michigan: “Think of the transmission system as an interstate highway. Congestion means a traffic jam on the expressway. It’s like not being able to move power where you want it to.”

Ioanidis said the installation represents “quite a milestone for us.” The equipment has been proposed since 2001, he said.

There will be two of the transformers on the U.S. side of the Midwest-Ontario grid and three on the Canadian side. The U.S. transformers will be maintained by ITC but operated by the Midwest Independent Transmission System Operator, a regional transmission organization responsible for the independent planning and operation of the transmission grid and wholesale energy market across 12 states.

Each of the two Michigan PARs weighs approximately 1.7 million pounds and is approximately 30 feet tall with a footprint of approximately 43 feet by 41 feet — about the size of a 1,800 square foot home.


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