DOE grant gives boost to grid-enhancing technologies on the transmission network

By Jeff Billinton, Director, Transmission Infrastructure Planning | 08/08/2024

Adding transmission capacity to the bulk power system has taken on a greater sense of urgency around much of the nation as the transition to cleaner energy resources continues to accelerate. As a result, policymakers are encouraging a range of alternatives for providing additional capacity and efficiency, including solutions known as grid-enhancing technologies, or GETs.

Just this week, in fact, the U.S. Department of Energy awarded California a $600 million grant that, among other things, includes money for upgrades of up to 100 miles of transmission with grid-enhancing technologies that would improve reliability and deliver clean, affordable energy faster. The grant, which went to a consortium that includes the California Energy Commission, California Public Utilities Commission, California Independent System Operator (ISO), Pacific Gas & Electric, and Southern California Edison, also has funding to enable improvements to the ISO’s interconnection portal, improving transparency and efficiency in the interconnection process.

Earlier this year, the Federal Energy Regulatory Commission in May issued Order No. 1920, which requires that “transmission providers in each transmission planning region … consider more fully the alternative transmission technologies of dynamic line ratings, advanced power flow control devices, advanced conductors, and transmission switching in long-term regional transmission planning ...”

Even before these current efforts, consideration of grid-enhancing technologies has been part of the California ISO’s annual transmission planning process, resulting in several innovative applications.

With the recent interest in GETs, we thought it was an opportune time to explore what these technologies are and what they can achieve.

What are grid enhancing technologies?

Currently, GETs primarily refer to the following:

Advanced conductors – wiring that can operate at higher temperatures for longer periods of time with low sag and increased load-carrying capabilities.
Power Flow Controllers - hardware and software that can push or pull power and help balance overloaded lines and underutilized corridors within the transmission network. These can also be referred to as phase shifters.
Dynamic thermal line ratings – hardware or software that more accurately determines the thermal limits of existing lines based on real-time and forecasted weather conditions.
Topology Optimizations – software technology that finds ways to route electricity around areas of congestion.

The ISO, which leads the transmission expansion planning and interconnection process for systems in its geographic footprint, typically considers the first two types - advanced conductors and power flow controllers – as planning tools, providing an alternative to other capital expenditures.

Other grid-enhancing technologies are more appropriately considered in our real time operations. For example, dynamic thermal line ratings and topology optimizations (e.g. transmission switching or reconfiguration after a contingency or in preparation for a contingency) can increase capacity on the system, which can provide value during an emergency.

While the ISO leads the planning processes for the transmission network in its balancing authority area, it is the transmission owners who are responsible for maintenance programs on the system itself – including like-for-like replacement of equipment that may incidentally increase capacity. The transmission owners are also responsible for all planning and maintenance on sub-transmission systems that are classed as distribution and are not under ISO operational control. As such, advanced conductors have also been employed by participating transmission owners in capital maintenance programs.

Examples of installed or planned projects

Flow controllers have been successfully deployed in the ISO system for some time. Some examples include a phase shifting transformer flow controller installation at the Imperial Valley Substation which went into service in 2016, the Imperial Valley phase shifting transformer, HVDC flow control via two projects under development in San Jose, multiple uses of reactors and Smart Wires technology and devices that utilize modern power electronics to control power flow through alternating current transmission networks.

A list of some projects that include flow controllers, advanced conductors and other grid-enhancing technologies is included starting on page 162 in the ISO’s recently approved 2023-2024 Transmission Plan.

Advanced conductors have also been selected by transmission owners in response to particular challenges, such as Southern California Edison’s (SCE) use to address clearance issues – with minimal tower modifications – on its Big Creek-Ventura 220 kilovolt (kV) network. The ISO then approved upgrades to transmission structures and terminal equipment at SCE’s Magunden and Vestal substations to access incremental capacity. Other uses have occurred, especially in select urban areas, where the higher tension capabilities and low sag characteristics allowed lower towers to be used without having to shorten spacing between them.

Another example of ISO-approved GETs is included in our approved 2022-2023 Transmission Plan in an expansion project with advanced conductors on four circuits of approximately ten miles each that are part of the bigger Lugo-Victor-Kramer 230 kV upgrade project in San Bernardino County.

Important considerations for using GETs

While the ISO will continue to consider advanced conductors and seek their appropriate applications, it is important to highlight some considerations, in addition to costs, that must be taken into account.

Installation: Reconductoring often requires taking circuits out of service to do the work. This presents additional challenges when transmission constraints already exist, or may suggest higher-risk work on live lines.
Line loss: While some advanced conductors show lower line loss savings when run at the same level of loading as existing aluminum-conductor steel reinforced lines typically used in transmission projects, line losses climb exponentially as the loading continues to increase.
Project fit: Some applications of GETs may not be optimal for specific projects. For example, the ISO and Southern California Edison did rebut the proposed use of advanced conductors as an alternative to SCE’s West of Devers transmission project, because the conductors could not provide the needed level of capacity even at the higher temperatures they enabled.

The ISO continues to maintain a focus on safety, reliability, and cost in selecting the best application of grid-enhancing technologies and will consider opportunities for their use in our annual transmission planning process and, in our operations, as a means to manage more extreme weather events.

In addition, Federal Energy Regulatory Commission Order No. 2023 issued last July now requires transmission providers to consider opportunities to deploy GETs in the resource interconnection process, which may result in additional projects.

Grid-enhancing technologies are achieving greater maturity and are an important part of the equation as we continue to seek safe, reliable, and cost-effective strategies to onboard new resources. The ISO will continue to evaluate and tailor specific applications to specific areas in our 2023-2024 Transmission Plan and all future planning efforts. We look forward to the creative engagement of stakeholders to provide input and recommendations as these technologies continue to advance.