Voltage Interaction and Thermal Dynamics of Tertiary Connection

Completed

Other Power and Storage Technologies(Electricity transmission and distribution)
Other Power and Storage Technologies(Energy storage)

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 April 2023

31 July 2025

ENA months

£590,000

Power

London

Network Innovation Allowance

Project Contact, National Grid Electricity Transmission

"The project will develop appropriate modelling methodologies for assessing the dynamic thermal performance and voltage interactions of grid transformers with active usage of tertiary connections. It will develop dynamic models of voltage control systems for identifying the conditions under which undesired system performance occurs. It will also develop a dynamic thermal model of the transformer with representation of the three windings, cooler control, and tap-changer control. Finally, a methodology for combined assessment of system voltage and thermal impacts of grid transformer tertiary connections will be carried out to understand the interactions between voltage control and the dynamic thermal performance of the transformer, as well as and risks to asset health. 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 the 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.Risk Assessment: TRL Change = 1Cost = 2Supplier = 1Data = 2Total risk score = 6 Low (L) " "WP1: System Voltage Control InteractionsDevelop appropriate dynamic models of voltage control systems (for tertiary connected equipment and transformer tap-changers) which are appropriate for a variety of general substation configurations.Identify worst case transformer dynamic loading conditions for WP2 modelling.Assess impacts on voltage control interactions for active tertiary connections against various scenarios.Identify conditions and configurations where the tertiary connected equipment can be used to improve the voltage performance through appropriate control.WP2: Dynamic Thermal Modelling and AssessmentDevelop a dynamic thermal model to accommodate requirements of three windings, dual-temperature cooling modes and tap changers.Conduct Computational Fluid Dynamics (CFD) based modelling to understand transformer thermal performance under unbalanced loading scenariosIdentify suitable thermal parameters or equations to improve the three-winding dynamic thermal model developed.Apply the dynamic thermal model under critical scenarios identified from WP1 to assess the impact of tertiary connections on the health condition and lifetime reduction of transformers.WP3: Combined Voltage and Thermal AssessmentsThrough population analysis, identify weak tertiary connection points by consideration of system performance and transformer asset condition.Propose a scheme (e.g. protection and controlsettings, operational parameters) that allows dynamic control of the transformer tertiary connected load with consideration of both transformer voltage control and cooling control for maximising the utilisation of tertiary connected assets without comprising the lifetime and operational reliability of the transformer." "The objectives of the project are as follows:Develop appropriate dynamic models of voltage control systems for tertiary connected equipment and transformer tap-changers.Develop a dynamic thermal model with good representation of three windings, dual-temperature cooling modes and tap changersUnderstand the impacts on voltage control and dynamic thermal performance of super grid transformer with active tertiary connections. Propose a scheme that allows dynamic control of the transformer tertiary connected load for maximising the utilisation of tertiary connected assets."

Tertiary windings of super grid transformers in transmission networks provide a cost-effective and efficient connection solution for BESS (Battery Energy Storage Systems). Numerous connections to BESS and small-scale renewable generation projects are planned. This could result in flows of active and reactive power through the transformers that were not anticipated or planned for in the original system design. This project will develop appropriate modelling methodologies for assessing the dynamic thermal performance and voltage interactions of grid transformers with active usage of tertiary connections. A methodology for combined assessment of system and thermal impacts of grid transformer tertiary connections will be completed to understand the voltage control interactions as well as the dynamic thermal performance of the transformer and risks to asset health.

18/10/23