WRITTEN BYKaren Haywood Queen
October 31, 2016
A Virginia company says its technology can tap smart meter data to significantly increase the grid’s capacity to host wind and solar power.
Dominion Voltage Inc.’s new voltage stabilization system greatly increases the ability of utility circuits to handle the voltage fluctuation problems created by variable solar and wind power. That opens the door to a much greater penetration of renewables, DVI executive director Todd Headlee said.
“Our goal is to move solar hosting ability from 20 percent of capacity, or peak daily demand, to 80 percent,” Headlee said.
DVI was founded in 2012 as the grid optimization subsidiary of Dominion Resources Inc. (the parent company of Dominion Virginia Power) in Richmond, Virginia. DVI began offering its optimization software platform, Energy Distribution & Grid Efficiency (EDGE), the same year with voltage optimization for energy efficiency.
Twelve utilities in the United States and Canada currently use or have run pilots of some portion of the four-part software platform. The voltage stabilization system, which was awarded a patent in April, is the newest addition.
“Up until very recently, the cost of solar has been the biggest barrier to widespread adoption,” Headlee said. “Now that costs have come down and we have reached grid parity in some markets, the next greatest barrier to overcome is increasing the grid’s hosting capacity.
“In the future, solar is going to be more prevalent in areas such as Virginia where it’s not yet so common. When that happens, these types of applications are going to become mainstream.”
In markets where renewables are gaining traction, new technology is needed to keep fluctuating voltage within safe, regulated parameters without upgrading grid equipment.
For instance, if clouds are approaching an area with high solar production, “We hedge the voltage high so it doesn’t dip too low,” Headlee said.
Major utilities “have sophisticated weather departments and can forecast weather down to the city and even the block or square kilometer level,” he said.
Instead of model-based optimization software, EDGE uses smart meter readings to control voltage in real time, he said. EDGE requires smart meters and can work with or without smart inverters, he said.
“There are other ways to do what EDGE does that aren’t as sophisticated,” Headlee said. “The game changer for this is AMI (advanced metering infrastructure). Half the country has a smart meter on their home. Using the smart meter data, the utility has visibility and voltage at every meter point.
“It’s the only safe way to do this aggressively. Any other way, you’re guessing at voltage or assuming that the low voltage point is at the end of the feeder. We are truly the only ones who can do it using the AMI data.”
As both solar and smart meters become more widely used, demand will grow for technology such as EDGE, Headlee said. As a side note, Virginia—where DVI is based—to date is not a leader in either area. Just 15 percent of all of Dominion Power’s meters are smart meters and the state ranks 30th nationally in percentage of home solar installed.
Another driver is the EPA’s limits on greenhouse gas emissions, currently on hold as the U.S. Supreme Court considers the issue. But some utilities are proceeding as if those limits will eventually be implemented, he said.
“These goals are over two times the current hosting capacity of most all of the circuit,” Headlee said. “Not all the renewables will be solar; some will be wind. But wind also needs voltage stabilization technology. Energy storage is also part of the solution. But it’s not a substitute for the advanced voltage stabilization technology offered by DVI.”
Such voltage stabilization technology is needed, not just to meet future goals but also to address today’s demand, especially when home solar owners want to save money by exporting excess power back to the utility. In Hawaii, which has the highest percentage of home solar in the United States, the Public Utility Commission has set limits for home solar systems that export power to the grid.
“HECO had to stop all the solar going into some neighborhoods because the voltage was so erratic,” Headlee said.
Not surprisingly, utilities in California and Hawaii have been quick to see potential benefits from EDGE. California utility PG&E is currently in a large, five-year pilot project involving DVI’s voltage stabilization system, Headlee said. HECO has signed a contract to use the voltage stabilization system, he said.
Duck River Electric Membership Corp., based in Shelbyville, Tennessee, has been using the EDGE voltage conservation system since November 2015, said Patrick Jordan, the co-op’s director of operations.
Duck River EMC spent about $1.5 million on the DVI software and additional communication equipment to run EDGE, Jordan said. In the first year, the electric co-op has saved about 8,500 MWh, which would cost $850,000 at the retail electricity rate, he said. Each co-op member customer saves about 35 kWh, or $3-$5, per month, he said.
The co-op offsets about 1.5 MW of demand each month and saves $15,000 a month via the conservation program. Duck River also benefits from an energy savings program with energy supplier TVA, which pays Duck River for each kWh saved using the CVR system, he said.
Before EDGE, Duck River EMC relied on upgraded equipment installed in the 1990s for voltage conservation, Jordan said. The co-op couldn’t adjust voltage as low since the readings weren’t as specific as with EDGE.
“We set up parameters that in general terms let the controller know what the feeders down the line looked like, based on impedance,” he said. “We measured voltage at the head end, calculated line drop and raised or lowered voltage based on that calculation.”
“EDGE gives us the feedback to control it tighter,” Jordan said.
Duck River is squeezing benefit from EDGE with a small number of smart meters as opposed to the full deployment intended by DVI. When the co-op purchased the system, engineers targeted key locations and installed a representative sample for each substation.
“Our engineering department did an analysis on each substation and identified the places we needed to install AMI meters to get low voltage readings,” Jordan said. “We started with 25-30 smart meters per station and have upped it to 50.”
Duck River plans to have full deployment of 73,000 smart meters by July 2019, which will enable the co-op to lower voltage further and save more, he said.
Although Duck River is selling less energy to its members, it deems the program a win.
“Our board and our CEO believe when we save our members money, that’s money that stays in our local economy,” Jordan said. “It’s the right thing to do.”