What does The National Grid of the future look like?
Professor Campbell Booth explores what’s on the horizon for electrical power and energy systems in the UK
National Grid Electricity System Operator (ESO), in its latest set of Future Energy Scenarios publications, highlights how at least 3GW of wind and 1.4GW of solar must be built every year between 2020 and 2050 to meet “net zero” carbon targets. This is a massive undertaking: as future energy systems increasingly encompass multiple vectors – not just electricity – they are experiencing unprecedented changes and challenges. And these challenges will only continue to grow.
Already, significant and well-documented changes in electricity system structure, behaviour and operability are being witnessed. Twenty years ago there were a relatively small number of large-scale generation sources meeting overall system demand. In Q1 of 2020, renewable energy capacity was 47.4GW against a maximum overall electricity demand of approximately 60GW, representing an increase of around 7%, or 3 GW, on the previous year, which is considerably less than the requirement to build 4.4GW per year stated earlier.
Additionally, National Grid estimates that there will be over 11 million electric vehicles in the UK by 2030, with more than 30 million by 2040 in the “most stretching net zero scenarios.” By 2025, up to 45% of homes may be offering up to 38GW of “flexible” electricity (controllable supply and/or demand) to assist in operating and balancing the system.
What could this mean for the power system sector?
The electrical power system is effectively being turned upside down – with more power being generated from the bottom up as opposed to the top down. This, coupled with the electrification of transport and other changes, means that power systems will be structured and will behave very differently in the future.
In the past, power was generated from a relatively low number of large-scale, transmission-connected, relatively predictable and controllable sources of power with well-understood behaviour and characteristics (e.g. provision of fault level and inertia) facilitating stable operation of power systems.
Now, and even more so in the future, power will be provided by a relatively huge number of small-scale, relatively unpredictable and perhaps non-controllable sources of power, that do not necessarily possess the stability-enhancing features of large-scale traditional generators. Although some renewable energy will be generated at scale (e.g. offshore wind), this may be interfaced to the system using DC/AC interfaces, and again, these do not inherently possess the attractive features of large-scale synchronous generators.
From an electrical system perspective, the impact of reductions in inertia and reliance on distributed energy resources are already being witnessed. For example, the events in the UK on August 9th 2019, where the system experienced a sequence of faults and loss of generation, resulting in the loss of supply to more than 1.1 million consumers, led to concerns throughout the industry and its stakeholders, with various investigations and reports being commissioned.
Although the system operator performed well against all expectations, it was noted that a number of changes and reviews would be required, for example to “reduce the risk of inadvertent tripping and disconnection of embedded generation, as GB moves to ever increasing levels of embedded generation”.
How can the power sector respond to these challenges? It has been stated by National Grid that “the events of August 9th highlighted that improvements to system stability should be made” and that “the system is becoming less stable. This results in faster system frequency changes, less voltage and fault ride-through stability, and makes it more difficult for both synchronous and non-synchronous generators to operate safely.”
It is also indicated that there is a need to “understand the behaviour of new technologies and their impact on the system, e.g. virtual synchronous machines” and also that there is a need to “improve our understanding of how the system behaves in extremely low levels of inertia”.
The ESO Innovation Strategy document identifies a number of macro trends, including coordination between transmission and distribution system operators, mathematical, digital and analytical tools to deal with increased system complexity, and an investigation of alternative tools/technologies to support the system. Furthermore, it is also stated that, “The Energy Data Taskforce has made clear recommendations that industry needs to work together quickly to make data more accessible.”
To gain understanding of and to effectively operate future power systems, comprehensive amounts of high-quality data will be required, ideally in a synchronised fashion, given the fast-changing and dynamic nature of electrical power systems, and this data must be secure. Solutions now exist, from companies such as Synaptec, that offer real-time synchronous data collection and analysis.
This type of data will be critical to understanding system behaviour and trends in how this behaviour is evolving over the longer term to inform strategy and long-term planning, and for real-time and near-real-time applications to assist with the secure operation, control, protection and monitoring of future power systems operating in a context of increased volatility and uncertainty.
Campbell Booth is co-founder of Synaptec and a professor at the University of Strathclude