Hawaiian Electric Co. is assessing a wide variety of technologies to help manage the challenges that come with a lot of rooftop solar on the edges of its grid -- from demand response and energy storage, to smart inverters and grid-edge power electronics.
This week, HECO announced its latest partner on this front, Santa Clara, Calif.-based startup Varentec. In a new pilot program, the utility will deploy Varentec’s Edge of Network Grid Optimizer (ENGO) devices and Grid Edge Management System (GEMS) software to test their ability to stabilize the voltage fluctuations on a distribution circuit with a high penetration of solar PV.
Varentec’s ENGO units are among a new class of grid-mounted power electronics devices, capable of injecting reactive power into grid circuits to lower or raise voltages. To date, they’ve primarily been tested out as tools to allow utilities to squeeze more efficiency out of volt/VAR optimization (VVO) systems.
In that role, they’re primarily being asked to increase voltages on circuits that would otherwise be pushed below minimum levels by centralized VVO schemes, which in turn can allow for a near-doubling of the overall efficiency gained by the process.
But Varentec CEO Guillaume Dufossé said in an interview late last year that the company has also been demonstrating its ability to manage the voltage effects of rooftop solar PV on distribution circuits.
That requires the ability to reduce over-voltages caused by an excess of distributed solar power, which can trip off rooftop solar systems, damage home appliances, and even endanger utility crews working on the grid, HECO noted in Tuesday’s announcement.
It also requires technology with the flexibility to respond to the moment-by-moment changes in solar output as clouds pass overhead, rather than simply responding to the commands of a central VVO control system. Varentec’s ENGO devices can act autonomously to stabilize voltages, or take orders from its GEMS software platform to act in concert with other utility systems.
"Varentec offers a mature, grid edge volt/VAR Control technology that can be deployed very quickly to help solve the rooftop solar integration problem we are facing,” Colton Ching, HECO’s vice president of energy delivery, said in Tuesday’s statement. “Even though Varentec's technology was not primarily designed for this purpose, our innovative engineers are eager to test this volt/VAR control technology to solve our unique solar challenges."
The fundamental technologies behind Varentec’s ENGO devices have been in fairly wide use at transmission scale for some time now, in the form of static VAR compensators, static synchronous compensators and other flexible alternating current transmission systems (FACTS) devices.
But advances in electric motors, power converters, electric-vehicle drives and other industries have allowed companies like Varentec, Gridco, GridBridge and Smart Wires to shrink these systems to pole-mounted size, manage waste heat without fans or other moving parts, and network and control them at costs low enough to make them a potential alternative for the distribution grid.
GTM Research predicts the U.S. market for these devices will reach $320 million by 2017. That’s based on the business case of solar PV integration alone, since that’s a particularly challenging problem to solve using traditional utility grid equipment and control systems.
This isn’t HECO’s first test of advanced grid-edge power electronics. In a GTM Squared article last month, we covered some of the details of the utility’s pilot project with Gridco, using the startup’s in-line power regulators (IPRs) on a western Oahu circuit that’s undergoing voltage increases and back-feeding from several customer-sited PV systems.
UPDATE: HECO spokesman Peter Rosegg described in a Wednesday email how the two projects differ: "In simple terms, with Varentec, we are looking at optimizing and reducing voltage fluctuations across an entire circuit (from substation to the customer meter). The Gridco project looks at optimizing and reducing voltage fluctuations for a specific cluster of customers." Because Varentec's systems work as a "swarm of shunt-connected (in parallel) power electronic devices," they can potentially "inject reactive power into the circuit to stabilize the voltage and allow for more voltage headroom to interconnect more PV."
Hawaii is a ripe testing ground for these types of technologies, given its challenges integrating the growing amounts of customer-sited PV on its island grids. HECO has a number of distribution circuits that can generate more solar power at midday than is being used by the customers on those lines, leading to back-feeding problems. It’s also seeing load-curve disruptions that HECO grid planners have dubbed the “Nessie curve” -- a more pronounced version of the “duck curve” problems that California is facing.
Technologies like those coming from Varentec and Gridco aren’t the solution to all of HECO’s problems. The utility has developed a broad-ranging set of initiatives to manage its push toward a target of 100 percent renewables by 2045, including a large-scale energy storage procurement, deploying behind-the-meter batteries from Stem and grid-responsive water heaters from Steffes, and engaging the smart inverter capabilities of vendors such as Enphase and SolarCity.
Varentec raised $13 million in Series C funding in January, led by new investor 3M New Ventures, and joined by previous investors Bill Gates and Khosla Ventures. The new round comes on top of $7.7 million raised in 2012 and $8 million in 2013, along with earlier Department of Energy and ARPA-E grants.
Varentec has also signed a contract manufacturing deal with Flex (formerly Flextronics), continued collecting and analyzing data from large-scale pilot projects with utilities such as Southern Company and Duke Energy, and added a new customer, Ontario, Canada-based distribution utility Entegrus, deploying the devices for a conservation voltage reduction pilot.