Projects

Started

Applied Research and Development

ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering)

Not Cross-cutting

Project Contact
National Grid Electricity Transmission

Network Innovation Allowance

Ofgem

01 November 2025

30 November 2026

ENA months

£264,000

Power

London

Network Innovation Allowance

Project Contact, National Grid Electricity Transmission

Project Contact, National Grid Electricity Transmission

Comprehensive review and testing provide certainty that restoration plans will work effectively when needed. It allows for the identification of potential issues, refinement of procedures, and validation of new strategies tailored to high-IBR penetration scenarios. By conducting a thorough assessment and simulations, power system operators can gain confidence in their ability to restore power safely and efficiently. The proposed method includes:Model Development: Creation of positive sequence and electromagnetic transient (EMT) models for selected restoration paths, incorporating detailed transformer and system configurations, including cables, synchronous generators, and inverter-based resources (IBRs).Scenario Definition: Identify credible ESR configurations through consultation with NGETs control centre, NESO restoration teams, and DNO planners.Simulation & Risk Assessment: Conduct time-domain and frequency-domain simulations to assess transient overvoltages (TOVs), voltage dips, negative sequence levels, and protection stability.Mitigation Testing: Demonstrate and evaluate mitigation methods such as point-on-wave switching, pre-insertion resistors, and soft energisation. Special cases that failed the success criteria will be selected for further analysis to highlight the effectiveness of mitigation methods.Parametric Studies: Assess sensitivity to equipment characteristics and network topology to identify boundary conditions for safe operation.Data Quality Statement (DQS):?The project will be delivered under the NIA framework in line with OFGEM, ENA?and NGGT / NGET internal policy. Data produced as part of this project will be?subject to quality assurance to ensure that the information produced with each?deliverable is accurate to the best of our knowledge and sources of information?are appropriately documented. All deliverables and project outputs will be stored?on our internal?sharepoint?platform ensuring access control, backup and version?management. Relevant project documentation and reports will also be made?available on the ENA Smarter Networks Portal and dissemination material will be?shared with the relevant stakeholders.??Measurement Quality Statement (MQS):??The methodology used in this project will be subject to our suppliers own quality?assurance regime. Quality assurance processes and?the source of data, measurement processes and equipment as well as data?processing will be clearly documented and verifiable. The measurements, designs?and economic assessments will also be clearly documented in the relevant?deliverables and final project report and will be made available for review.In line with the ENA's ENIP document, the risk rating is scored Low (6).TRL Steps = 2 (3 TRL steps)Cost = 1 (~264k)Suppliers = 1 (1 Supplier)Data Assumption = 2 (Assumptions known but will be defined within the project) This project focuses on assessing and mitigating the risks associated with transformer energisation during Electricity System Restoration (ESR), particularly under weak system conditions and high inverter-based resource (IBR) penetration. The project will focus on the GB electricity transmission system, particularly in England and Wales. It will:Develop detailed EMT and phasor models of restoration paths to simulate energisation events.Assess transformer energisation risks during restoration.Develop a risk map and mitigation guidelines.Provide technoeconomic assessments of mitigation options.Deliver EMT modelling guidelines forrestoration studies.Deliverables:Developed model, model description, and guidance for modelling.Technical report with risk maps and mitigation strategies.Simulation analysis and testing report. Disseminate key results of the project and learnings via final dissemination workshop. The primary objectives of this project are to:1) Identify and mitigate transformer energisation risks during network restoration.Identify high-risk transformer energisation configurations during system restoration across representative GB network scenarios.Quantify technical risks such as transient overvoltages (TOVs), voltage dips, and negative phase sequences using detailed EMT and phasor-domain simulationsCreate a transformer energisation risk map to rank scenarios based on severity and likelihood, supporting operational decision-making.2) Provide tools and insights to improve restoration planning and execution.Develop and validate mitigation strategies (e.g. point-on-wave switching, pre-insertion resistors, soft energisation) to reduce energisation risk.Produce modelling guidelines for ESR studies, including best practices for EMT modelling of transformers, lines, and IBRs. These outcomes will support TOs and NESO in compliance with ESR standards by 2026, enabling safe, reliable, and low-carbon system restoration.

Energising large power transformers during the early stages of Electricity System Restoration (ESR), when the network is weak and fragmented into isolated Power Islands, is challenging and leads to a variety of technical issues. With new ESR standards and increasing use of inverter-based resources, there is an urgent need for innovative tools to assess critical configurations, guide operational decisions, and identify necessary investments, while addressing modelling challenges in the EMT domain. Through this project, National Grid Electricity Transmission (NGET) will collaborate with Electric Power Research Institute (EPRI) to carry out fundamental research to identify the critical configurations for transformer energisation on the GB network during ESR, assess associated risks, define acceptable operational limits, and evaluate which configurations can be managed through operational measures.

24/04/26