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Reference Number NIA_NGET0179
Title Travelling Wave Fault Locator Trial
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 February 2016
End Date 01 April 2020
Duration 50 months
Total Grant Value £250,000
Industrial Sectors Power
Region London
Programme Network Innovation Allowance
 
Investigators Principal Investigator Project Contact , National Grid Electricity Transmission (100.000%)
Web Site http://www.smarternetworks.org/project/NIA_NGET0179
Objectives The objectives of this trial are to Reduce the costs associated with faults on a composite or cable only circuits by improving fault location Reduce the costs associated with faults on composite circuits with DAR but no DAR lockout capability Reduce the costs of protections systems for new composite circuits, or existing OHL only circuits that become composite circuits by introducing cable sections. Knowledge gained during this project will allow National Grid to make informed decisions about using Traveling Wave Fault Locators to successfully detect a fault in the appropriate section on a composite circuit; to accurately locate a fault in the cable circuit; and to understand if TWFL will or will not interfere with system stability or other plant functionality. Specifically we will test Travelling Wave Fault Locator capabilities in the following areas: Test for DAR lockout purposes on a composite circuit Test as a fault locator on a cable circuit Test fitness for purpose when used for condition monitoring purposes To gather data of transience occurring on the system
Abstract A number of circuits on the GB electricity transmission network are protected with Delayed Auto Reclose (DAR) protection. This acts by opening the circuit breakers at either end of a circuit when a fault is detected and then automatically recloses the circuit breakers after 10 seconds to restore the circuit into use. The circuit will trip again if the fault is permanent, until the fault is investigated and resolved. However, the DAR is very useful for OverHead Line (OHL) circuits, where transient faults (such as those caused by lightning strikes) are the most commonly occurring fault; it eliminates outage time and increases system stability. The use of DAR on composite circuits, a circuit with both OHL and cable sections has more complex implications. A fault on the cable section of a composite circuit will not be transient. One of the most common causes of fault on cable sections is damage by mechanical excavators, so DAR is not suitable for cable or composite circuits. Reclosing the circuit when there is a permanent fault will result in significantly more damage occurring. Approximately 20% of the circuits on the England & Wales transmission network have cable sections. Currently for a composite circuit, a Cable Fault Detection (CFD) system is constructed at the Cable Sealing End (CSE) compound. This includes Current Transformers (CTs), fibre -optic communications feeding back to substations at either end of the circuit, and block houses being built containing protection relays and power supplies. This allows the protection system to detect whether a fault is in the cable or OHL. If the fault is within the cable section the DAR will be locked out. However, the CSE compounds are expensive to build, they require maintenance, they increase the visual impact at the ends of cable sections of a circuit and they cannot be built for all cable sections in a circuit. Some composite circuits currently have either no DAR, which means that the circuit will remain out of service until after investigation for all trip conditions. Other composite circuits may have no DAR lockout facility, which means for a cable fault there is significant damage to assets. This project seeks to prove the accuracy and reliability of an alternative solution, by trialling the use of a Travelling Wave Fault Locator (TWFL) on composite circuits. A TWFL has been used on OHL only circuits in both the USA and Scotland, for fault-finding purposes, and has been proven to be very accurate. However, this would be the first time a TWFL will be installed on a cable circuit and on a composite circuit. A TWFL eliminates many of the problems associated with a separate CSE compound for DAR lockout purposes. A TWFL can be installed either end of the circuit in the substation. The cost of the equipment is significantly cheaper than building a CSE compound. They will improve the visual impact of the transformation from OHL to cable. There are three ways in which the successful proof of reliability and accuracy in composite circuits could be beneficial: on existing composite circuits with no DAR or cable only circuits, fault location will be as beneficial as it is for OHL only circuits in reducing the time taken to investigate and remedy a fault. Currently, for cable circuits the method for finding faults involves digging large holes, so the time and civil costs in finding a cable fault would be reduced. for existing composite circuits with DAR, but no DAR lockout capability, in addition to benefit 1, there is also likely to be less damage and lower repair costs if the fault is in the cable section. for new composite circuits (either completely new circuits or existing OHL circuits that become composite circuits as a result of work done to reduce visual impact), the cost of the additional DAR lockout capability currently achieve with the equipment at the cable sealing ends can be avoided. A simulation study will be conducted to ensure that a TWFL will still produce accurate results on a composite circuit. This will prove the capability of the TWFL in laboratory conditions. In addition to the laboratory trial, a field trial will be carried out by installing the TWFL on a composite circuit that is prone to faulting as a result of 3rd party excavator strikes. This will provide confidence that a TWFL is still accurate on a composite circuit and on a cable circuit with real-life conditions. This will demonstrate how a TWFL interacts with the whole system, and whether it could be used for protection purposes. Desk-based work will be conducted to analyse the data that is generated from the TWFLs. This will be used to interpret the sensitivity of the TWFL, the quality of the data received and the accuracy of the equipment.Note : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above
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Final Report (none)
Added to Database 17/12/18