Electricity must be consumed as it is produced. What goes out into motors, air conditioners, and lights, must equal what comes in from power plants—whether coal, nuclear, or solar—every second.
Keeping this system operating is a moment-by-moment challenge. As with everywhere that real-time situational awareness is necessary, the Internet of Things is increasingly playing a role. Consumers are familiar with smart meters, but less-visible advances such as synchrophasors promise to enable a deep and detailed view of the grid.
Anyone who works in the field of power transmission knows IoT is nothing new. The industry has been working on developing its smart grid, based on machine-to-machine (M2M) communication, for years, and, in fact, its experience can inform other industrial IoT efforts.
“We are a system of purpose-built electrical things,” says Alison Silverstein, project manager for the North American Synchrophasor Initiative (NASPI), who sees IoT as an extension of that system that will integrate non-purpose-built devices.
But a lot of the underlying issues and challenges will be the same, she says.
The grid’s challenges
Like a lot of the nation’s infrastructure, the power grid is aging. Seventy percent of transmission lines and transformers are now over 25 years old. This leads to increased outages due to weather – and the number of severe weather events is increasing.
Growth in peak demand has exceeded growth in transmission capacity by 25 percent every year since 1982. The United States grid loses power 285 percent more often than it did in 1984, when record keeping began. Power outages cost businesses in the U.S. as much as $180 billion per year, according to the Electric Research Power Institute (EPRI).
Add in the increasing use of distributed and variable power sources such as wind, solar, and fuel cells in a grid designed for a small number of central power generators, and it’s clear why the system is under stress.
What is needed to effectively manage the grid is situational awareness, in real-time.
A system in darkness
Despite the fact that you can see the wires outside your window, from the point of view of a control room, a lot of the network is in darkness. In many areas, the only way a utility knows of an outage is if someone calls in to report it. And finding the cause requires physical investigation, and can take quite some time.
The advent of smart meters and other sensors is changing this—though more slowly and less completely than is sometimes claimed. Achieving situational awareness will be a long process.
In many IoT applications, it is the consumer-facing devices that get most of the attention, and in power transmission, that is the smart meter, which records consumption at short time intervals and transmits that information wirelessly. Aside from their advantages in automated meter reading and consumption management for homeowners, smart meters supply situational awareness from the consumption side. Previously, it was impossible to see the details of consumption beyond the substation.
But smart meters have also experienced a lot of consumer pushback, focused on RF radiation and privacy concerns. While it might be possible for a smart meter to communicate with smart household devices to reduce consumption at times the grid is unable to supply all the power demanded, this is as yet far off.
Synchrophasors and PMUs
Current technology observes the network roughly every four seconds—which is too slow to respond to many of the events that can affect the system. There has recently been a great deal of innovation in this area, driven by ARRA funding and other support, financial and technical, by the DOE and other agencies.
A synchrophasor is a power system measurement made many times per second, and time-stamped in a way that means that measurements can be synchronized and the shape of any event in space and time can be understood. It can monitor key components of the power system, like voltages, currents, frequency, and rates of change. Synchrophasors are the measurement, and the device that provides them is a Phasor Measurement Unit (PMU).
In the 1990s, PMUs were an interesting research device. Then came the Northeast blackout of 2003, and the realization by investigators that it was impossible to work out the exact sequence of events that had caused the blackout, because the clocks of the various sensors and circuits were not synchronized. Since then, a lot of money and effort has been poured into improving and deploying PMUs to provide a synchronous view.
But if PMUs seem to be technically mature, why are they not yet integral to the real-time operation of the grid?
“Originally we thought all we had to do was to put in the PMUs, and the magic would happen,” says Alison Silverstein, NASPI project manager. “Then you get the devices out there and you realize that communications and data quality are a lot harder than you thought. And then there is the matter of acceptance in the control room of a critical application. We won’t get widespread acceptance in control rooms until we earn it.”
You need more than data
The lesson? Even superb data is not enough on its own. It must feed into a system that accepts it, understands it, and finds the proper use for it. The lessons learned in the course of increasing the intelligence of the smart grid will be useful for other large-scaled IoT implementations.