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Reference Number NIA2_NGET0021
Title New online tools for Assessment of Bushing Condition
Status Started
Energy Categories Other Power and Storage Technologies(Electricity transmission and distribution) 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
National Grid Electricity Transmission
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 July 2022
End Date 30 April 2024
Duration ENA months
Total Grant Value £400,000
Industrial Sectors Power
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , National Grid Electricity Transmission (100.000%)
  Industrial Collaborator Project Contact , National Grid Electricity Transmission (0.000%)
Web Site
Objectives The project will assess the advantages and disadvantages of relative and absolute power factor measurements, as well as the practicalities of installing the additional equipment required for a voltage reference. Additionally, consideration will be given to the benefits of permanently installed systems versus the concept of installing the necessary sensors and safety box, and using a portable system to acquire data for a limited time period i.e. a week or month. In the latter case, reproducibility of results will be a key consideration.An adapter will be attached to the bushing tap (Bushing Tap Adapter or BTA) to measure the leakage current from which the capacitance and relative power factors can be determined.To measure true power factor, a voltage reference is required from the VT connected to the bushing. Hardwiring this across a substation, from the VT to the monitor, can be disruptive and time consuming. The project will develop a prototype wireless phase reference to negate the need for hardwiring. Although wireless data transmission is well proven within a substation environment, the accuracy of the measurements will be challenging and will require GPS clock precision to detect the very small differences in phase angle between the measurements at the VT and the bushing tap. Such a development would reduce installation time, eliminate the lifting of trench covers and/or digging, and reduce the area impacted during the installation; combined these factors would reduce the cost of installation.Since a large proportion of the ERIP bushings of interest are connected to the LV side of the transformer, for a true power factor measurement the transformer is now part of the measurement circuit and will influence the result obtained for the LV bushing tap; changes in tap position will also affect the measurement. The project will investigate these effects and determine if these can be eliminated algorithmically.The BTA can also be used to detect PD signals and the project will be able to assess the potential advantages of both asynchronous and simultaneous PD monitoring along with the capacitance measurements.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.Risk AssessmentTRL Steps = 2 Cost = 1Suppliers = 1Data Assumption = 2 Assessed risk score 6 - Low This project supports development of a condition monitoring strategy for solid statebushings and the use of condition monitoring data in determining a health index for the same assets. The goal will be to demonstrate that bushing replacements can be deferred, in some cases indefinitely. This will reduce the future cost of ET and increase resilience of the network by reducing outage requirements for planned replacement works. Reducing costs and increasing resilience underpin the ambitions for a transition that is fair for all customers and supports greater electrification of energy.Although this project will focus on transformer bushings, the technology may be applied to through wall bushings The objective of this project is to deliver sufficient results from monitoring of bushings at three sites to deliver understanding of the following:Comparison of true and relative power factor measurementsDevelop algorithms to enable calculation of true power factor of bushings on the LV side of transformers taking tap-changers into accountEvaluate the influence of weather conditions on the measurement of condition indicatorsCost benefit analysis of temporary vs. permanent installation of bushing monitors.The relative value of monitoring partial discharge as well as power factor when partial discharges could have an alternative source on the substationDevelopment of an asset health methodology for solid state transformer bushings 
Abstract This project will consider the available options for monitoring bushings and, through trials and data analysis, determine both the optimum monitoring strategy and the most efficient way to collect the data. The advantages and disadvantages of relative and absolute measurements of power factor and tan delta will be investigated. More efficient monitoring installation using a wireless voltage reference will be investigated and a new algorithm will be developed to determine true power factor on the LV side of a transformer.Analysis of the data collected during the project will be used in the development of a new asset health index system for solid-state bushings to support a transition from age-based to condition-based asset replacement.
Publications (none)
Final Report (none)
Added to Database 14/10/22