Renewable energy | Ecotrope

The No. 1 rule of power management

Ecotrope | July 20, 2011 9:53 a.m. | Updated: Feb. 19, 2013 1:36 p.m.

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I’ve found myself asking a lot of questions lately about how the Northwest power grid works. Oregon is aiming to meet a goal of 25 percent renewable energy by 2025, and has provided incentives for renewable energy development to meet that goal.

“Electricity has to be generated exactly in the same time that it’s being produced in the system. In order for the system to work, power supply and demand have to match exactly.” —Jon Kaake, CEO ColumbiaGrid

But it’s becoming more and more clear that adding renewables makes grid management more complicated. Somehow, in this obscure world of high-voltage wires, hydropower manager Bonneville Power Administration says it has to choose between protecting salmon and delivering wind energy.

There were two big developments on this front yesterday:

  • 15 Northwest utilities are moving to intra-hour scheduling – that’s buying, selling and managing power in 30-minute intervals instead of every 60 minutes. It’s a big step toward accommodating the hard-to-predict changes in renewable power supply – especially wind energy. Renewable energy advocates say it’s good for overall grid efficiency, too.
  • The Bonneville Power Administration, a quasi-federal agency that manages 75 percent of the Northwest power grid, shot down accusations from the wind industry and others that the agency is abusing its power over the grid by choosing to shut off wind turbines and sell hydropower produced by its own dams. BPA argues it has the right to substitute hydropower for wind power (without paying damages to wind farm owners) in the spring when there’s so much water it floods the power market and threatens to kill salmon if it’s spilled over dams.

After a long talk with Jon Kaake, the CEO of the non-profit Northwest grid analyst group ColumbiaGrid, I learned that to understand all things grid-related, it’s important to know the No. 1 rule of power management: That all the power produced at any given time must be equal to the amount of power being used at that very moment.

If it doesn’t – if there’s too much or too little power at any point – safety protections built into the grid to prevent fires will shut down the system, and lights will go out.

A map of all the grid managers or "balancing authorities" in the western network. They make sure all power produced equals the power being consumed in their area at all times. The No. 1 rule of power management: Power in = power out. Making both sides equal is trickier with variable wind and solar power.

A map of all the grid managers or “balancing authorities” in the western network. They make sure all power produced equals the power being consumed in their area at all times. The No. 1 rule of power management: Power in = power out. Making both sides equal is trickier with variable wind and solar power.

Traditional power sources like coal and gas-fired power plants can be easily adjusted to produce more or less power depending on how much power is needed, Kaake said. New, renewable power sources – mostly wind turbines and solar panels – are variable and less predictable.

Grid managers have to make sure the power in equals power out at all times. They’re also called “balancing authorities” because they have to balance the power load for their section of the grid (see the map of grid managers above). The more variable power sources you have, the more the more balancing is needed on the supply side of the equation. Hydropower and/or natural gas plants, for example, can be adjusted to balance out surges or drops in the wind.

Kaake has been in the power management business for 40 years. Transmission is something people tend to take for granted, he said, and it probably wasn’t considered when state and federal governments approved renewable energy incentives. But it ultimately explains why the wind industry is fighting with hydropower managers, and why everybody from the Oregon Public Utility Commission to Save Our Wild Salmon is taking sides in the case.

Here’s how Kaake explains some basics of the grid, including:

Uh…what is it?

“When we talk about the grid we’re usually talking about the high-voltage transmission system. The big wires you see on towers crossing highways that march off into the distance (not the small ones that come directly to your house).

This is how huge amounts of electricity are moved around the system – usually from a generator off in the distance. Almost all the generation we have comes in on high-voltage transmission – even if we’re just moving it from eastern Oregon to western.

The thing to know about this is it’s a network. It’s integrated. Tied together. It doesn’t matter whether lines belong to Bonneville Power Administration or PacifiCorp, Portland General Electric. They’re interconnected at points of interconnection, but from a power flow basis, meaning the way the electrons flow, it’s on one massive network.

When PGE is generating power at Boardman, the power goes into the grid, into the network. It flows its way over here on any number of paths that may not even be directly owned by PGE and comes back here through the grid. You’re basically consuming whatever flows into the distribution system in your house.

It’s not possible in this network to specifically state you want your electrons from Boardman or wind power. You’re almost certainly getting electrons from elsewhere.”

How is it affected by renewable power sources?

“In the olden days, we would build steam plants and hydro-generators and load those up, and they would perform almost always exactly as you’d want them to. Now, with the introduction of renewable power in the system – almost all in the form of wind, though there’s some small solar – there are a couple of other aspects that we are beginning to look at.

As wind varies you have two-part problem: That generator is not responding exactly as you expected because the wind is changing. You also have to have another generator to compensate for that (wind-power) generator.

Electricity has to be generated exactly in the same time that it’s being produced in the system. As loads come on and you flip on and off switches, generation is responding to those demands. In order for the system to work, power supply and demand have to match exactly.

As you now introduce more variable generation into the system like wind, and it’s fluctuating, you have to have generation elsewhere in the system that can respond to that. And wind doesn’t respond to directed signals to drop or increase load. So, somewhere else on the system you’ve got coal-fired or gas-turbine or hydro that are responding to the changes in demand and changes in other generation.

While the industry has always had to deal with changes in loads — which are actually very predictable – it now has this new aspect of variable generation.

All the resources have to be precisely in balance. That’s a critical thing to know and understand because it’s what’s driving a lot of the problems.

When a utility steps up to be a balancing authority, it takes on a huge responsibility for reliability in the network. They’re the ones giving the directed signals to the compensating generator.”

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