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Reference Number NIA_NGTO022
Title High Frequency Earthing and its Impact on the Transmission System
Status Completed
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 November 2018
End Date 31 July 2021
Duration ENA months
Total Grant Value £411,000
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 plc (0.000%)
Web Site
Objectives The project will involve extensive modelling and experimental testing in the HV laboratory at Cardiff University and at the universitys outdoor earthing test site in Llanrumney. Furthermore, measurements and tests at selected sites where high frequency rods are installed will be performed.Modelling investigations will include test electrodes at Llanrumney and practical high frequency electrodes installed at selected National Grid substation sites. CDEGS-HIFREQ software will be utilised to construct the electrode geometries and analyse their performance. Such numerical modelling predictions will be compared to measurements at the test sites. Furthermore, the comparative performance of overlaid insulated conductors will be introduced to evaluate its merits compared to HF rods.The experimental work will involve (i) preparatory and calibration laboratory tests for measurement equipment, (ii) establishing earth grid with vertical rods and insulated overlaid horizontal conductors at Llanrumney test site, and carrying full characterisation of the various electrodes: grid, and vertical and horizontal electrodes and their combinations. The tests will involve variable frequency sources as well as impulse injections. In addition to the electrodes, above ground arrangements of down leads will be set up and investigated. In particular, the effect of bends will be quantified, and testing equipment will be purchased for this part of the project, (iii) on-site testing of existing HF electrodes. This project will address the safety issues and the effectiveness of high frequency earth electrodes with particular emphasis on high frequency rods when subjected to fault and surge conditions. Alternative high frequency/surge mitigations will be investigated and trialled to ascertain their effectiveness and potential cost-efficiency. Collaboration with a world-leading manufacturer of earth measurement apparatus will allow a better assessment of the performance of such electrodes under injected high frequency and surge currents. The main objectives of this project are to:Fully quantify any added benefit of the so-called High Frequency rod and assess its cost benefits.Fully quantify the earthing down lead geometries and arrangements on the effectiveness of the earth electrode and earth potential rise under high frequency fault currents and surges on the system.Further develop, refine and quantify the benefits of the Cardiff University proposed alternative method of overlaid insulated horizontal conductors for reducing earth impedance, improving the effective area of earthing systems and enhancing the high frequency earthing performance. Furthermore, establish the relative merit of this technique compared to HF rods.Trial and validate test new techniques for earth impedance measurements under high frequency and surge conditions.
Abstract Given that High Frequency (HF) rods are more susceptible to installation difficulties and higher costs, there would be strong saving benefits if the need for HF rods can be avoided. Furthermore, early research at Cardiff demonstrated the superiority of HF performance of partially insulated electrode configurations overlaid on existing earth grids. Such a solution, if adopted, can help mitigate the effect of high frequency and surge currents more effectively and with associated cost savings on installation and maintenance. This project will involve extensive modelling and experimental testing to investigate the safety issues and the effectiveness of high frequency earth electrodes with various earthing methods.
Publications (none)
Final Report (none)
Added to Database 09/11/22