Project Summary
As the share of inverter-based resources including renewable generation increases, lower system strength can lead to uncontrolled voltage changes which can escalate to instability and risk widescale customer disconnections. To secure the net-zero grid, network operators urgently need to monitor system strength conditions to implement the most effective and economic mitigations. At present, neither the requirements for system strength monitoring nor the possible hardware and digital solutions are well defined. The SYSMET project brings together leading experts who will create the pathway to confident implementation of measurementbased tools that provide comprehensive visibility of system strength status for
operational decision making.
Innovation Justification
Network owners have poor visibility of the power system strength status because of the rapid growth of IBRs, connected to the grid by converter technology. Neither the requirements for system strength monitoring nor the possible solutions are fully understood. This challenge cannot be met within business-as-usual activities as it goes beyond incremental extension of existing monitoring. This challenge is visualised in Appendix_Q3-Figure_1 and Figure_2.
The state-of-the-art of system strength assessment is summarised by a lack of standardisation. Various versions of the short circuit ratio (SCR), defined fundamentally as the fault level divided by nominal active power, have been proposed and trialled. However, the results don't necessarily provide consistent conclusions for network operation, and fault level monitoring is not yet universally available. Moreover, there is a consensus that metrics based on fault levels alone are not a sufficient predictor for the range of problems arising from low system strength.
The core innovation of the proposed SYSMET project is a pathway to the implementation of measurement-based tools that provide visibility of system strength for operational decision-making. The three technical work packages scope out the challenge of achieving system strength visibility to ensure the reliability of an IRB-dominated power system, fully aligned with the SIF Discovery Phase both in scale and technical risk. The project will expand to testing and development of identified novel solutions in Alpha and Beta, see Appendix_Q3-Figure_2.
The SYSMET project will consider additional candidate indicators such as small and large signal impedance under investigation in the NIA project 'Strength to Connect' concluding March-2024.
For the most suitable indicators, measurement requirements and approaches will be identified leveraging existing measurement techniques through the application of machine learning and AI.
The project will utilise the learnings of the 'Real-time Fault Level Monitoring' project to assess if existing commercial offerings trialled in distribution networks can be applied to transmission.
We are aware of high CRL system strength tools available, but these have not been adapted/proven in the UK. These and other novel SYSMET solutions for different system strength indicators are at low CRL for the UK market. TRL progression planned:
- Current: TRL2/3 relevant processes understood in other applications.
- Alpha: TRL4/5 is targeted through proof-of-concept validation.
- Beta: TRL6/7 achieved through prototype demonstration in the field.
Currently IRL2, it is expected to reach IRL3-4 in Alpha by mapping the compatibility with other system monitoring tools, and IRL6-7 in Beta through demonstrated integration with operational systems.
Appendix Q3 - SYSMET.pdf (opens in a new window)(/application/10102960/form/question/36580/forminput/99771/file/630500/download).
Impacts and Benefits
Current Position
Power system strength status indicators are poorly defined and ill-understood. Whilst there are monitoring tools and digital solutions available in the UK and internationally, they are immature in the UK system where fault level is used which is inadequate for IBRs. Adopting a standardised approach to system strength monitoring enables manufacturers of grid monitoring systems to develop new and innovative devices that are fit-for-purpose and industrially relevant. It also provides network owners with a set of requirements that can be issued to prospective monitoring tool providers who must demonstrate compliance with functionality and measurement accuracy requirements.
Reliable, widespread, and consistent monitoring of system strength indicators will enable network owners to address problems arising from lower system strength to ensure the availability of the power system. Furthermore, greater knowledge of real-time or near real-time system stability will allow better decision-making when disturbances occur so mitigating actions minimise the overall cost and impact on customers.
The qualitative high-level net benefits are:
a) Reducing constraints and costs for renewable generation customers,
b) Increasing system resilience due to improved system stability, thereby reducing the risk of severe disruption,
c) Optimising network operating costs and reducing consumer bills.
Financial- future reductions in network operational costs
Accurate quantification and measurement of the strength of the network allows efficient and targeted real-time deployment of stability services. Low system strength can cause issues with network stability and the default countermeasure is constraining generation and implementing stability services to increase the fault level or inertia of the system. These reactive actions can have high operational costs (£millions/annum); a consumer cost.
Environmental- carbon reduction - direct CO2 savings/annum against a business-as-usual counterfactual
Improvements in the management of grid stability build operational confidence in the stability of the network, allowing increased system capacity for renewable generation, and reducing CO2 emissions if it avoids the need to use synchronous fossil generation for system strength.
New to market - products
SYSMET defines a new way to measure system strength, measurement requirements, and test methods. These requirements and test methods will feed into standards development and pave the way for developing new monitoring products. Standards play a pivotal role in power grids, ensuring consistency, reliability, and efficiency in electrical measurements. SYSMET will build the foundation for a standardised methodology to measure system strength promoting confidence for manufacturers, with several UK vendors already identified, and offers comparability across system owners and networks.
