There’s a lot of efficiency to be squeezed out of today’s distribution grids in wasted voltage. Volt/VAR optimization (VVO), conservation voltage reduction (CVR) and other such smart grid projects have proven they can save 2 percent to 6 percent on overall power use, simply by lowering distribution grid voltages in a way that keeps them humming within operating boundaries, but at slightly lower voltages -- a tiny reduction that adds up quickly when multiplied across millions of customers.
But there’s a cost for that efficiency. CVR and VVO schemes need constant feedback from sensors or smart meters down the line to keep themselves within the boundaries required by regulations, as well as by physics. Even with that data, they face the inherent instability that comes from trying to control an entire network’s power quality from only a few central points, such as substation or feeder line voltage regulators.
Wouldn’t it be better if utilities could just drop a bunch of devices on their most troublesome lines, and let them balance voltages all by themselves? That’s the idea behind ENGO (for “Edge of Network Grid Optimization”), a new volt/VAR control and monitoring device launched Monday by Varentec, a Menlo Park, Calif.-based startup backed by ARPA-E and Khosla Ventures.
“The best VVO schemes today are extremely complex,” involving line sensors or smart meter power quality data, devices like voltage regulators, and central control software, according to Deepak Divan, Varentec president and CTO. Today’s centralized systems also have trouble keeping voltages “flat” at the far ends of a distribution feeder line or circuit, since voltages tend to drop the farther you get from the substation.
Varentec’s ENGO combines a line sensor -- easy to deploy by a utility worker using a “hot stick” to hang it on a power line -- with the capability to actually alter line voltages, using some power electronics and analytics that constitute the core of Varentec’s intellectual property.
“They have a very smart way of injecting the right amount of VARs at the right place, at the right time,” is how Divan described the devices’ function. Because each one is a sensor, a network of ENGO devices can send back lots of power quality data for a traditional distribution management system (DMS) to use, he said. At the same time, each device is programmed to make autonomous decisions on how to affect the voltage on the line it sits on, he said.
That means that it can respond “extremely fast” at the local level, as compared to centralized systems, which may need to be alerted to local problems by sensors or alerts before they can be corrected. It can also help flatten voltages along those far-off sections of distribution line, all while managing “dynamic fluctuations” like solar panels rising and falling in power output as clouds pass overhead, he said.
Varentec, which landed a $2.2 million Department of Energy grant in 2010, a $5 million ARPA-E grant in 2011, and a $7.7 million Series A round from investors including Khosla Ventures in early 2012, is focused on applying digital power electronics to help manage power in more discrete and variable ways. While today’s grid is an analog, magnets and wire affair, new technologies such as solid-state transformers, advanced inverters and other power electronics gear could also allow grid power to be directed and transformed in a more “digital” fashion.
As distribution grids become more and more unstable with the introduction of on-again, off-again wind andsolarpower and other distributed generation resources, these kinds of devices may start to find uses that justify their high cost and experimental nature. The ENGO network can work on its own in an automated fashion, but it can also be integrated into existing DMS platforms to add their rich power quality data into those systems’ models, Divan noted.
Right now, Varentec is working with three major utilities, two of them in the United States, Andrew Dillon, vice president of business development and marketing, said last week. While he didn’t name the utilities involved, Varentec’s ENGO press material includes some accolades from executives at big Southeastern utility Southern Co. and the National Rural Electric Cooperative Association (NRECA), as well as Mexican state-owned utility Comisión Federal de Electricidad.
As for pricing, Varentec isn't releasing specific figures, but Dillon said the entire system should be “quite competitive” to the alternative of adding sensors, communications, software and upgrades to control assets that would be needed for modern VVO schemes, he said.
It will be interesting to see how Varentec’s gear might compete with -- or play a cooperative role in -- the growth of distribution grid voltage management, which offers utilities a fairly fast and reliable payback on the investment, according to recent projects. Grid giants like ABB, General Electric, Siemens and Schneider Electric, as well as a host of other mid-tier and up-and-coming companies like Utilidata, are all involved in projects around the country. Stay tuned for more related news from this week’s DistribuTECH conference in San Diego, where smart grid investments that utilities can actually control are all the rage.