This project will investigate the feasibility of using Digital Twin (DT) technology to support local network restoration plans and the implementation of adaptive protection systems to address challenges associated with high penetration of Inverter Based Generation (IBG) within a power network. Conceptual development will be carried out to model power networks and essential equipment, and build a virtual “twin” system to digitally simulate the live operation. A Real Time Digital Simulator (RTDS) will be deployed with live data fed from Phasor Measurement Units (PMUs) for on-line decision-making and off-line testing/analyses. The project will showcase the use of such a DT system to support the local network restoration plan, in addition to adaptive protection capabilities to eliminate the risks of maloperation.
Benefits
The project aims to investigate the feasibility of using Digital Twin (DT) methodology to assist network restoration and implement adaptive protection. The project will design a virtual twin system to digitally simulate the live operation of a power network with essential power network component representations. The conceptually designed DT system will enable the capability of “playing ahead of the game” and providing real-time decision-making assistance to network controllers for network restoration and allow for the adaptive adjustment of protection settings. The benefits are calculated based on improved efficiency of network restoration from the completion of the project till the end of 2044/45. Based on our cost benefit analysis, the estimated benefit in NPV terms can reach around £146m if the project is successful.
Learnings
Outcomes
2023/2024
· DL 1-1A review survey of the DT technology has been undertaken. It was found that a DT system can assist network restoration assessment in selecting the best restoration route to reduce restoration time and predict system performance in network restoration.
A comprehensive review of the existing network restoration plans all over the world in terms of methodologies and best practices from industry, international organisation regulations, and academia have been conducted. One of the findings is that fixed parameters in protection and control are not suitable for all black start conditions. Potential solutions can be applying adaptive protection and control systems where parameters are automatically reconfigured. A real blackout event has been analysed. In particular, the root cause of blackout and restoration procedures has been reviewed. It was found that unforeseen protection operation or inappropriate operational decisions can be the root cause of cascading outages, leading to wide area blackouts. Inadequate protection configurations can hinder and delay the restoration of a power network. The protection relay settings are usually calculated and proposed for the normal power system configuration including limited credible contingencies, while the system configuration may change and demonstrate different characteristics during the restoration process. Thus, protection settings under this circumstance may not be valid anymore meaning that protection maloperation or mis operation may occur during network restoration.
A conceptional design of the LJRP analysis tool has been developed. This resilience analysis framework can be used to assess a network resilience level under given LJRP and demonstrate the recovery capability of the LJRP. The framework will be used to analyse the resilience of the studied network in the later scope of work.
2024/2025
The modelling of the test system and the development of online functions and offline analysis modules for the DT system have been completed.
Three test models designed for network restoration analysis were created using RSCAD, the graphical user interface of RTDS. These models incorporate essential grid components, including conventional and renewable energy sources, HVDC and Flexible AC Transmission Systems (FACTS) equipment, and protection and control devices. Each of the three test systems features a different primary black start unit: a traditional synchronous generator, a grid-forming (GFM) controlled wind farm, and GFM controlled HVDC interconnectors. Test results indicate that all three primary black start units successfully restore the network.
For the online functionalities and offline analysis of the DT system, three functional modules were developed using RTDS models. The first module, the Network Restoration Study Toolbox, simulates the network restoration process and evaluates various system parameters to identify potential issues. This toolbox includes power flow analysis, voltage assessments (temporary overvoltage compliance, rapid voltage change compliance, and voltage deviation checks), frequency assessments, resynchronisation assessments, and circuit breaker transient recovery voltage assessments.
The second module, the Adaptive Protection Toolbox, detects system topology through online calculations of short-circuit levels and inertia, adjusting protection settings to prevent relay maloperation. The third module, the Online Decision-Making Support System, utilizes the analysis results from the first two modules to quantify the resilience of different restoration routes and provide recommendations for operators.
Recommendations for further work
Future work can focus on finding suitable networks in the GB grid for a site trial, processing and analysing the measured data from a real grid, and further exploring the feasibility of using the DT technology to support real-world network restoration scenarios.
Lessons Learnt
2024/2025
During the network restoration process, the inrush current caused by transformer energisation is a key issue that needs to be mitigated using methods such as low-voltage starting.
Dissemination
One journal paper has been published based on the work done:- ‘Review of methodology and best practice of power system restoration plan’. Energy Internet, 1(2), 123-140. https://doi.org/10.1049/ein2.12022.
