EirGrid and the System Operator for Northern Ireland (SONI) are the transmission system operators (TSOs) for Ireland and Northern Ireland, respectively. Together the Ireland and Northern Ireland power systems constitute a synchronous system with a peak demand of approximately 7 GW. In 2022, approximately 40% of electricity used on the island of Ireland came from renewable resources, predominantly onshore wind generation.
Policymakers in both jurisdictions have separately set targets to achieve 80% of electricity from renewable sources by 2030. To achieve this, it will be necessary to accommodate unprecedented penetrations of variable non-synchronous renewables such as offshore wind, onshore wind, and solar whilst keeping curtailment (dispatch-down) levels to a minimum.
Over the last decade, EirGrid and SONI have made huge strides in operating the all-island power system with very high levels of variable non-synchronous renewables. However, to deliver on government renewable energy policies in Ireland and Northern Ireland in the period to 2030 will require a significant further evolution of the operation of the power system. EirGrid and SONI will need to deal with unique challenges that will not be faced in larger, more heavily AC interconnected power systems for years to come.
Journey to 75% System Non-Synchronous Penetration
EirGrid and SONI employ a metric called System Non-Synchronous Penetration (SNSP) as a useful proxy for the capability to operate the power system safely, securely and efficiently with high levels of renewables. SNSP is a real-time measure of the percentage of generation that comes from non-synchronous sources, such as wind and solar generation as well as high-voltage DC (HVDC) interconnection, relative to the system demand.
Over the course of the last decade, EirGrid and SONI have increased the allowable SNSP level on the all-island system to 75% from 50% following the successful conclusion of five separate SNSP operational trials undertaken with 5% incremental increases.
EirGrid and SONI’s success in increasing the allowable SNSP level was enabled by the program of activity that was carried out as part of our “Delivering a Secure Sustainable Electricity System (DS3)” Program, which was established in 2011 with the specific aim of meeting the challenges of operating the electricity system in a secure manner while achieving our 40% RES-E (renewable energy source of electricity) targets by 2020.
Some of the key DS3 Program activities included:
- Introducing a range of new and enhanced system services, and greater incentivization for provision of these services
- Making changes to Grid Code standards, including an increase in the Rate of Change of Frequency standard from 0.5 Hz/s to 1 Hz/s, the delivery of which involved a multi-year and multi-stakeholder program of work
- Delivering a suite of new control centre systems and tools including a Look-Ahead Security Assessment tool and a Ramping Margin tool
- Continued undertaking of system studies and analysis as the power system has evolved
Operational Policy Roadmap to 2030
Looking forward to 2030, to deliver the renewable ambitions in Ireland and Northern Ireland, it will be necessary to have the ability to operate the power system with SNSP levels of up to 95% and with significantly reduced numbers of conventional units online. However, operating at such SNSP levels is unprecedented and poses several technical challenges. These technical challenges will drive the need to significantly enhance our system operational capability.
In December 2022, EirGrid and SONI published an Operational Policy Roadmap to 2030 which sets out our plan for evolving operational policy across a range of key metrics such as SNSP, Inertia, and Minimum Number of Large Synchronous Units as well as development of new metrics such as System Strength. This roadmap sets out the context, drivers, timelines, milestones, actions, and stakeholder impacts for each operational policy area, and will be reviewed and updated (if required) every two years.
In addition to the Operational Policy Roadmap, EirGrid and SONI have produced a comprehensive broader roadmap, based on consultation and studies, of the necessary changes spanning transmission infrastructure, stakeholder engagement, power system operation, and electricity markets. The aim is to develop an integrated vision of the 2030 power system and electricity markets for Ireland and Northern Ireland.
The System Operations strand of this Shaping Our Electricity Future roadmap is divided into four main workstreams:
- Operational Policy: Undertake operational studies and analysis and develop operational policies to facilitate renewable ambitions
- Standards and Services: Ensure we have the right operational standards and appropriate system services frameworks to support investment in required capability
- Operational Tools: Identify and oversee the delivery of enhanced and new integrated control centre technologies and tools that are required to operate the system securely and efficiently with increasing levels of variable non-synchronous renewable generation
- Technology Enablement: Facilitate the development and integration of new technologies and innovations on the power system to enable them to operate efficiently and effectively
We are making good progress in these workstreams and the associated changes needed to operate at SNSP levels up to 95% by 2030. For example, in spring 2023, EirGrid and SONI completed a suite of studies to identify the capability to reduce the minimum number of large synchronous units required to be run across the island from eight to seven. The scope of the studies included evaluation of ramping capability, system strength, voltage stability, and dynamic stability of the future power system for operation with seven large synchronous units.
In May 2023, we commenced an operational trial with this operational constraint relaxed from eight to seven; we expect to close out this trial in spring 2024.
Collaboration to Accelerate the Global Energy Transition
While EirGrid and SONI are at the forefront internationally at managing the integration of non-synchronous renewable generation, the targeted operational policy changes are ambitious, and we appreciate that there is much we can learn from other TSOs who are also at the vanguard of tackling the various technical challenges. By working in collaboration with other TSOs through forums such as the European Network of Transmission System Operators for Electricity (ENTSO-E) and the Global Power System Transformation (GPST) initiative, we can share learnings and potential solutions that can collectively accelerate the global energy transition.
Head of Future Operations, EirGrid