System Operability Framework (SOF)

Power quality in the GB transmission network

Power quality is critical to the performance of the plant and equipment connected to the power network. Poor power quality can reduce efficiency, cause excessive heating, or even damage the assets. Driven by the net zero targets, the penetration of inverter-based resources (IBR) will continue to increase, reducing the system strength in certain areas of the network.

There is a direct correlation between system strength, traditionally measured by the short circuit levels (SCL), and some power quality aspects, including harmonics, voltage unbalance, and voltage flicker. This report discusses the main aspects of power quality in the future GB transmission network.

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Provision of short circuit level data

This paper explores options for defining and referencing the short circuit level (SCL) for new and existing connections to the GB electricity system. As more non-synchronous generations connect to the electricity system, a reduction in traditional synchronous generators impacts system stability. We describe why the short circuit level is important and explore several options for defining its requirements for new and existing generation. We are also seeking industry feedback on which of these options provides the optimal solution for defining short circuit level.

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Removing barriers to flexibility on the grid: interconnection

By 2025, interconnectors will become a key source of flexibility and constitute a significant portion of the overall generation mix. Accessing flexibility and ancillary services on interconnectors will become key for system operability, and an important pillar in our ambition for competition everywhere. Following the publication of the BEIS Smart Systems and Flexibility plan, we’ve been looking into the barriers to interconnector participation in the dynamic containment market. Our report outlines those barriers and what mitigating actions could be taken.

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National trends and insights

The UK’s transition to a low carbon economy brings many new challenges and opportunities to how NESO operates the GB electricity system, with flexibility becoming an increasingly valuable characteristic. At NESO, we continuously work with industry stakeholders to transform our operations and deliver the right market solutions at the right time to benefit the end consumer. This document takes the output of our ETYS and NOA processes in 2020, and looks further into the technical issues that may need addressing to operate a low carbon electricity system successfully.

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Low demand - operability challenges from COVID-19 (spring and summer 2020)

The COVID-19 pandemic led to partial or total lock downs in Great Britain in the spring of 2020, which in turn caused a reduction in electricity demand. This low demand, combined with large renewable output at times, resulted in a high penetration of non-synchronous machines on the system. This combination led to challenges with demand forecasting and maintaining flexibility for system integrity, voltage profiles, and system stability. This paper provides a brief on the challenges of 2020 which ESO faced, the measures applied to tackle the challenges, and the work we will look to carry out to improve the system operability in the future.

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The potential operability benefits of virtual synchronous machines and related technologies

At NESO, we are always looking at ways to enable new technologies to connect to the network safely, securely and efficiently. This report discusses how new technologies can support system stability by adopting virtual synchronous machine (VSM) technologies and associated control approaches, enabling the transition to a zero carbon system.

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More reports

Past SOF documents