The expected growth of US electricity demand as data centres expand and transportation and buildings electrify, paired with the influx of new renewable energy generation, means that the country’s US electricity grid has to expand and modernise.
Implementing HVDC transmission is a viable method to increase the capacity, reliability, and resilience of the system, but, as it has not been widely adopted, there is a lack of relevant standards.
In the first stage of the joint industry project a high-level survey was conducted to identify the standards and codes needed to implement HVDC transmission systems in the US. Four types of standards emerged as priorities: Performance/Grid Code; Manuals for regional transmission organization (RTO) and independent system operators (ISO); Utility Interconnection Manuals; and Offshore Design Requirements.
Some functionalities, such as active power control, reactive power control, fault ride-through, dynamic voltage control, and frequency control, have been at least partially addressed in the existing US Grid Code (for example, IEEE 2800-2022, FERC LGIA, NERC RSBES, and relevant OATT). However, several other functionalities, including control modes, islanded operation, and adaptive control are not covered. Even for those functionalities that are included in the US Grid Code, there remain significant gaps.
Over the next three years DNV and JIP partners, which include Atlantic Shores Offshore Wind, EDF Renewables, Equinor, Invenergy, National Grid Ventures, Ocean Winds, PPL TransLink WindGrid, RWE, Shell and TotalEnergies, will delve deeper into the identified gaps, focusing primarily on the first three types of standards.
These standards focus on setting formal electrical standards or rule makings for RTOs and utilities. This work will consist of three distinct phases, each roughly a year in length. During the first year, DNV, JIP participants, and an advisory committee will conduct a granular HVDC standards gap analysis and prioritise the relative importance of the identified gaps.
In 2025 and 2026, study participants will establish and implement a plan to address the identified gaps. These recommendations will likely include proposals to initiate NERC SAR or IEEE PAR proceedings and updates to RTO rules and offshore wind solicitation requirements.
“The speed at which we can bring about the transition to clean energy depends very much on the modernisation of the US transmission grid” said Richard S. Barnes, region president, Energy Systems North America at DNV. “Incorporating HVDC will increase the reliability and capacity of the transmission system, and it is essential that the current US Grid Code has performance standards that will ensure the safe and effective operations.”
The timely setting of performance standards for HVDC transmission is imperative given the expected growth in both electricity demand and renewable energy generation.
According to DNV’s 2023 Energy Transition Outlook North America, the grid must increase its capacity 2.5 times by 2050 to be able to support the projected influx of renewable energy resources.
Currently 98 percent of transmission lines in North America are HVAC, but the report forecasts that the share of HVDC lines will increase to 10 percent, given the lower expense and ability to transmit high capacity at low levels of loss, especially undersea cables connecting offshore wind. Codifying performance standards will enable this projected expansion of HVDC transmission lines in the US and beyond.
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