Back in 2003, when the Institute of Electrical and Electronics Engineers (IEEE) put out its first standard designed to guide electric utilities and equipment manufacturers in connecting distributed energy resources (DER) with the conventional electric grid, co-op engineers and other experts agreed that fuel cells were the wave of the future.
“The new technologies gaining attention then were microturbines and fuel cells,” a November 2016 background report from NRECA’s Business & Technology Strategies (BTS) group says, “with the latter to exploit the ‘hydrogen economy’ that was the futuristic fad du jour.”
That “futuristic fad” fizzled, but the need to organize DER interconnections, especially solar arrays, only grew. Since 2014, IEEE has been working to overhaul and update its Standard 1547 on DER interconnection. By late spring of this year, a working group of about 120 equipment manufacturers, utility representatives, integrators, and other interested parties had developed a comprehensive rewrite of the 2003 version.
“This is a large and complex standard,” says Robert W. Harris, NRECA’s senior principal for transmission & distribution engineering and the association’s lead organizer of the electric co-op response to the proposal. “It really does require anybody who has the time and expertise to get down in the weeds with it.”
The weeds are pretty thick this time around, but with Harris’s encouragement, about 20 co-op engineers joined the “balloting pool” of 389 interested parties qualified to participate in a vote, which surprisingly closed on June 18. Harris says he and many other participants fully expected the measure would be disapproved on first ballot, leaving room to negotiate changes before a second round.
“There were literally hundreds of formal concerns registered on the standard, and we thought we were in for the long haul in hammering this out,” he says. “Co-ops have several issues we want to see changes on, and most of us were stunned that it managed to get a narrow majority in favor on the first ballot.”
Harris says the working group announced after the vote that it would work with all parties to try and satisfy their concerns. The group plans to hold a second ballot in early September. A final draft must go to the IEEE Standards Association in early October in order to have a chance of being adopted this year.
“They already have the acceptance vote, so they’re not technically under any obligation to answer people’s concerns, but they know it’s better for everyone if they get a stronger margin on this,” Harris notes. “I’m hopeful they’ll do what they need to and improve the standard in the process.”
'Safety is at Stake'
The original Standard 1547 was focused almost entirely on safety, for linemen and the public. At the time, few believed DER would provide more than minimal capacity, so a 10-megavolt ampere (MVA) applicability limit was set. Since then however, DER capacity has soared, and many individual plants now provide well over 10 MVA to distribution systems. Because of this, the limit has been removed in the draft standard and a co-op would need to determine how much DER capacity they can safely handle when a developer applies to install a system. The new standard would also require DER owners to coordinate some control functions with the utility, including voltage and frequency settings.
Much of the need for an updated standard stems from an explosion of solar power, driven by both reduced costs for the technology and increasing regulatory and consumer interest.
The 350-member working group that put together IEEE’s original Standard 1547 knew, of course, that sunlight could be turned into electric power. They just didn’t think it would ever amount to much, according to the BTS report.
“Photovoltaic [PV] DER existed but was not a major portion of DER,” the BTS report explains. “And the common view then was that PV was too expensive and would never be a big factor. Needless to say, much has changed since 2003.”
“We’ve got something like 400 PV installations,” says Kent Davenport, vice president of engineering at
Delta-Montrose Electric Association, a co-op serving some 33,000 meters from headquarters in Montrose, Colorado.
He says solar is not the only DER on his lines.
“Several years ago, we also interconnected to a coalbed methane unit; it’s 3 megawatts, and we’re actually wheeling that power to Holy Cross Energy,” another Colorado co-op. “They in turn sell it to Aspen Ski Corporation. Then we built two of our own hydroelectric facilities, let’s say 7 megawatts combined. That was in 2013.
“In 2015, we connected two more run-of-canal facilities, and those two plants are also somewhere around 7 megawatts,” Davenport continues. “Last year, we interconnected another hydro unit, and it runs just over 2 megawatts. And we have two community solar array sites, one that’s 20 kilowatts right outside our Read Service Center, and the other site has a 150-kilowatt and a 20-kilowatt array directly connected to our system near our headquarters building.”
Davenport says the need has grown dramatically for an accepted and widely used uniform standard for linking all those dispersed energy sources to the conventional power plants, transmission lines, and distribution feeders that make up the core of the grid. Voltage and frequency variations between DER and conventional energy sources mean that the safety of utility consumers and crews, as well as the reliability of the grid, are all at stake.
Germany got an object lesson in all of this about a decade ago, Harris says. Rapid and extensive deployment of wind generation nearly crashed the country’s entire grid when too much wind energy on the system pushed that source past the frequency “set point,” the trigger for shutting down the turbines.
“The frequency kept creeping up toward the set point,” Harris says. “It finally hit it, and dropped all those wind generators off. That in turn dumped all the load on conventional generation, but that generation couldn’t carry it. The outage just mushroomed.”
North American Electric Reliability Corporation (NERC) was watching closely, he says.
“That got NERC’s attention, so they began looking at the root cause, which led them to interconnection standards. They realized there is a problem built into the system which would only get worse if not addressed. NERC doesn’t usually pay attention to distribution standards, but this forced them to.”
In addition to limitations of the standard itself, other problems have indeed crept deep into the system, as documented by a survey by
Advanced Energy (NRECA Associate Member), a North Carolina-based utility consulting operation. In 2014, the same year IEEE was gearing up to strengthen its DER interconnection standard, Advanced Energy inspected 15 customer-owned PV installations. The units ranged in size from 250 kW to 2 MW.
Among the findings was that the actual installation scheme did not match the interconnection plan at 60 percent of the units, meaning that the utility serving the site would be operating with incomplete or insufficient information when recovering from an interruption.
IEEE’s revised standard is meant to address shortcomings of the current standard, but problems such as those documented by Advanced Energy point to the need for continued diligence following the initial installation, Harris says.
“The assumption is that there’s going to be a continued proliferation in distributed generation across the country,” he says. “The fear is that we could be building in what NERC calls common-mode failure, and it ends up creating a much bigger problem than whatever it was meant to fix.”
At Delta-Montrose Electric in southwestern Colorado, that assumed proliferation has already proven to be correct. And the co-op’s board is all for it, Davenport says.
“Our board’s been very supportive in encouraging and responding to our strong member interest for DER interconnections,” he says. “They want to do it safely and reliably, but they want to encourage it. All you have to do is look at the utility landscape, and you know that the pressure will be there to integrate these resources and to do it well.”
Davenport and his staff have managed to largely avoid interconnection problems with the co-op’s ballooning DER deployments.
“We do system-impact studies for every one of them,” he says. “Each of the larger units have a direct-transfer trip, and we saw to that with the system-impact study. If they trip, we try to make sure we know why.”
An industry-wide standard like IEEE’s revised 1547 will help guide the co-op’s approach going forward, Davenport adds. Safe utility operations, he says, must be a guiding principle.
“It definitely needs to be addressed, for customer safety as well as lineworkers’ safety,” he says. “DER does add a level of complexity to the distribution system that was not there before. That’s just a fact. But I do think it’s doable.”
The NRECA report on Standard 1547 notes that the latest revision comes at a critical juncture.
“DER will continue to grow in penetration and play an increasing role in distribution systems everywhere. As the national DER standard, IEEE 1547 will directly affect the capabilities and flexibility of DER equipment and will define how these sources will be integrated into the distribution systems. This can have an impact on the way co-op distribution systems need to be designed and operated well into the future.
“With the increase of DER across the nation’s power grid, they will have an effect on bulk system security and reliability. DER [that is] connected now will be around for a long time. A retrofit program to make DER compatible with grid needs long after it is installed would be an administrative and legal nightmare.”
‘What Were We Thinking?'
It should come as no surprise that, with all of the new ground it had to cover, the revised standard grew to 116 pages by the time it went before industry experts for the May–June ballot. The 2003 version was 16 pages.
“After 14 years in the life of DER systems, there’s been a lot of changes,” NRECA’s Harris says. “I’d say we’re getting most of it right based on what we can predict today. But if history’s any indicator, there’ll be some parts of it that are right and some parts we’ll be saying, ‘What were we thinking when we came up with that one?’ Then it all starts over again.”
In the run-up to the May–June ballot, Davenport was still making up his mind on how to vote on 1547.
“It’s a lot like a political election, I guess,” he says. “I’ve been reaching out to folks who are knowledgeable on it, getting their thoughts, making sure I’m aware of what’s in it. You do your due diligence and make your decision.”
He doubts, though, that deciding to wait out the DER revolution will be an option.
“I do think that distributed energy resources are the future,” Davenport says. “It’s coming at us, and we need to be knowledgeable. It’s very important for co-op engineers to know about the standard. It will guide electric utilities for years to come.”