HOLYOKE, Mass.--In between power plants and the plug on the wall is this thing called the grid, an engineering marvel that's largely invisible and impenetrably complex to most of us.
If you follow the grid network backwards behind the wall socket, the meter, and the utility poles on your street, you eventually get to a building called a grid operations center, where megawatts of energy flow from state to state and specially trained operators make split-second decisions that can mean the difference between blackouts or business as usual.
To get a better feel for how the grid works, I visited ISO New England here last week, one of several grid operators called independent system operators (ISOs) or regional transmission organizations (RTOs), which work behind the scenes to ensure delivery of electricity across the country.
The term "smart grid" often refers to smart meters on homes and businesses, but ISO New England is on the front lines of modernizing the wholesale grid, where energy is purchased and dispatched in bulk. It's involved in a Department of Energy project to add high-speed sensors, called synchrophasors, to make the grid more reliable. And it's on the cutting edge of using efficiency technology called demand response to keep the grid in balance when power plants can't keep up with supply.
Long before you plug in to charge your cell phone, energy is purchased by auction through an RTO. Every day, ISO New England, for example, creates a forecast of the next day's projected energy demand based on historical data and weather forecasts. It then holds an auction where power plant generators--there are 350 of these in New England--place bids to supply that energy. Electricity delivery companies, also known as utilities, do the buying.
Bids for the day-ahead market need to be in by noon. But what if it's hotter than expected and the demand exceeds the forecast? There's another "real-time market" where RTOs can fill those gaps and dispatch the energy to those places that need it. Bulk energy purchasing represents between $5 billion and $11 billion of business per year in New England.
Inside the control room, though, job one is reliability. ISO New England is staffed with a team of six grid operators who monitor several screens at once at different desks--transmission security, dispatching power, forecasting--to avoid problems. They sit below a giant screen about the size of a tennis court which displays all of the major "assets" on the New England grid, including power generators, substations, and pumped storage. In addition to directing bulk power, grid operators call on power generators to maintain a steady frequency and keep "spinning reserves" available in as little as 10 minutes.
Increasingly, operators need to be aware of grids outside their own region, which is a response to the 2003 blackout that started in Cleveland but caused a massive blackout that reached all the way from upper Ontario to New York City. The operators need to have the right psychological profile and stay calm under pressure; many in ISO New England previously worked on nuclear submarines.
"The training for these operators is rigorous because when events unfold, they happen very quickly," explained Vamsi Chadalavada, the chief operating officer at ISO New England. "You may be monitoring screens for several hours and in a few moments, it can be complete chaos."
A classic example of thinking on your feet happened during a very hot day earlier this summer, when there were forced outages at a few power plants on the New England grid. Rather than purchase energy on the real-time market at very high prices, operators decided to call on what are called "demand-side resources." The flow of energy on the grid needs to remain in a steady balance. But ratcheting down demand, or reducing the electrical load, is effectively the same as bringing more power online.
ISO New England on June 24 successfully called on demand-response companies to reduce the load by 670 megawatts--that's on the order of what a single power plant can produce and enough to power thousands of homes. It called on aggregators, such as EnerNoc and Comverge, which have contracts with their customers to reduce electricity use during peak times across thousands of locations. For consumers, this can mean adjusting the air conditioner thermostat for a few hours or dimming the lighting in a store.
During the August heat wave, another grid operator, PJM, also called in demand-side reductions to weather the supply crunch during peak hours. Efficiency introduces more competition into the power supply market and is increasingly a part of the pool of resources that grid operators rely on. In the New England area, demand response providers will "supply" almost 10 percent of projected power capacity in 2013.
Synchrophasors, not smart meters
A greater reliance on efficiency complicates matters significantly for the people who run the wholesale grid. Until recently, they needed to keep tabs on 350 power generators, compared to the 5,000 demand-side resources they now oversee. But life is only going to get more complicated for grid operators as more renewable energy and storage comes online, which is why grid operation centers need more real-time information.
ISO New England is undergoing a three-year, $18 million project to use synchrophasors, essentially high-speed sensors, which will be placed on 30 to 35 major substations in the region. These home appliance-size boxes will gather electrical data, such as current, voltage, and the phase angle, at a far higher volume than now. Rather than report once every four seconds, these phasor measurement units will gather data 30 times a second, which is then synchronized with a GPS clock.
More data means that grid operators have a far better idea of whether problems may be brewing, rather than finding out only a few moments before impact. Going forward, better system awareness paves the way for more wind and solar power, said Chadalavada.
"If we have these perturbations because of the intermittent nature of renewables, we would like to know about it ASAP and not have to wait even four or eight seconds because that's a whole dispatch cycle for us," he said. "Instantaneous rebalancing is much better done with these sensors."
If, for example, the wind kicks up more than expected, the energy dispatch system could tell a power producer to scale back. Or if the wind dies down, operators could dispatch energy storage. Right now, managing wind is not a big difficulty because it's such a small portion of the total mix. Although it's not sure to be built, 3,000 megawatts' worth of wind power is projected to be added to the New England grid in the next three years, which would be about 10 percent of the total capacity.
Hand in hand with the grid operators is a crew of IT professionals who man a data center at ISO New England and manage the private network. One of the biggest challenges the industry faces is making sense of the mountains of data collected from sensors and other sources in a way that makes sense to the operators, Chadalavada said.
"We would like tools that allow us to simulate the next two or three hours of real time and give us a set of options," he said. "Today's limitation is the next 15 minutes, which is itself a complex scenario. We want to take that one step further."
Editor's note: This is the second part of a two-day look at how technology is changing how electricity is used. See part one on home energy here.