Over the past decade, a new class of digital power electronics has emerged that can shape, shift and control the flow of electricity on the power grid in ways never before seen. But the providers of such technologies have faced challenges moving past pilot projects and into real-world utility deployments.
One of the things limiting these technologies, at least in the United States, is that most utilities don't yet face high enough penetrations of wind and solar to make them necessary.
Perhaps the U.K., which has set far more ambitious clean-energy goals for its island grid, may be a better fit.
That’s the proposition behind tests launched this month by two of the U.K.’s biggest power grid operators, which are seeking to apply next-generation power electronics to two different scales of grid control.
National Grid and Smart Wires target transmission
The first project involves National Grid and Smart Wires, an Oakland, Calif.-based startup that has developed devices that can alter the flow of power through high-voltage transmission lines. Last month, the two announced a five-year framework agreement to increase the capacity of the nationwide transmission network run by National Grid to “quickly reduce the congestion that limits renewable generation, with minimal impact on communities and the environment.”
Smart Wires has piloted its technology with the federal Tennessee Valley Authority and Southern Company subsidiary Georgia Power, as well as Irish transmission system operator EirGrid. In simple terms, its line-mounted devices increase impedance on transmission lines to increase flows on alternative circuits, allowing operators more flexibility in avoiding congestion that can otherwise drive up prices or force curtailment of excess renewable energy.
National Grid plans at least five Smart Wires installations in 2020, with the goal of a 1.5-gigawatt increase in capacity of its network to carry power from one region of the country to another. That will include power transfers of up to 500 megawatts from Scotland, rich in wind power, to England, home to most of Great Britain's electricity demand.
The U.K. has been struggling for years to integrate its rising share of onshore and offshore wind into its transmission system, including work with technology providers such as Smarter Grid Solutions to tap the flexibility of distributed energy resources (DERs) to balance this rising share of intermittent supply. This summer’s massive power outage, caused by a lightning strike on a transmission circuit north of London, has drawn public attention to the reliability of the grid as well.
SP Energy taps Ermco, GridBridge
The second new project is between SP Energy Networks and Ermco, a Tennessee-based company that owns technology developed by startup GridBridge for use on the low-voltage distribution network. This project is aimed squarely at the grid edge, and in particular, on a direct current (DC)-based network for linking solar PV, batteries and other DERs.
Under the deal announced this week, Ermco will supply its GridBridge "smart transformer solution" for SP’s LV Engine project. This £8.3 million ($10.9 million) project is one of many government-backed projects aimed at easing the challenges of interconnecting and integrating DERs at the distribution grid level, including others that are looking at DC-based solutions.
SP Energy Networks, part of Iberdrola's Scottish Power, is the distribution network operator for much of Scotland and northern England.
The pilots indicated that the line-mounted devices were capable of stabilizing circuits to reduce voltages and save energy, which could make them useful for utility conservation voltage reduction and volt/VAR optimization programs. They’re also capable of adjusting individual circuits that may be experiencing heavy solar generation, electric vehicle charging loads or other effects of high DER penetration.
That’s the technology, rebranded as a smart transformer, that SP Energy plans to use in its LV Engine project.
According to the company’s project website, the devices will connect medium- and low-voltage networks and adjust conditions based on feedback from smart meters and DERs. It will also allow for powering DC devices such as EV chargers and LED streetlights without wasteful conversion from alternating current and back again.