This project will trial a new type of fault indicator (Metrysense 5000) which will help locate faults in a shorter time compared to a full line patrol, therefore reducing operational costs, the number of customers off supply and Customer Minutes Lost (CMLs). This will also decrease the time a live conductor could potentially be on the ground, and therefore will reduce the risk to members of the public.
Metrysense 5000 is a fault indicator suitable for the arc suppression coil network arrangement, which can offer detailed information to a DNO’s control centre on the fault location. This has been used successfully in other countries for similar network configurations but at higher voltage levels. This technology has never been tested in the United Kingdom.
Metrysense 5000 will send real time data once integrated into UK Power Networks’ and WPD’s SCADA system. As part of the project, the fault indicator will be tested first at the Power Networks Demonstration Centre (PNDC) in a simulated network environment. If the testing is successful, it will be followed by training of operational staff, integration into the SCADA system, equipment installation and commissioning across five 11kV feeders in EPN and 10 33kV feeders from a Bulk Supply Point (BSP) in the South West.
Objectives
The project aims to:
- Trial the Metrysense 5000 fault indicator
- Demonstrate how this unit can be utilised to improve the fault location in case of ASC earthing configurations, therefore helping to keep Peterson coils network arrangements commissioned safely
- Analyse how reliable, robust and cost effective the new protection/monitoring system is
- Demonstrate how operational costs and CMLs can be reduced on trial feeders if the technology is successful
- Assess the safety improvement following the deployment of the units
Learnings
Outcomes
The main outcomes of this project were:
· The outcome of the tests and simulation at PNDC determined that the sensors could successfully detect 100% of the faults (not achieved by some of the Primary Substation Relay Software), including high impedance faults, which were tested under different scenarios and had secure and reliable communication and connection. MS 5000 sensors could identify Earth Faults up to 10k Ohm.
· Following the successful testing, UK Power Networks carried out familiarisation training with the teams required for the installations. This highlighted the ease of the installation: each sensor was installed with a short stick or a hot glove procedure, and approximately 10 minutes installation time was required for each gateway in accordance with distribution safety regulations and High Voltage live manual.
· Performance of these units is also vital to the long term BaU strategy to continue to employ Arc Suppression Coil (ASC) earthed systems going forward.
· Asset management teams have integrated one set of sensors at Nelson Street substation (used for Live demos in Innovation projects) to assist with systems integration work and monitor the solution which has been proving to detect all faults. All sensors and gateways were installed in the three relevant networks (Harleston primary in Bury St Edmunds, Woodwalton primary in Cambridge and Littleport primary in Kings Lynn – 18 feeders total).
· The results from the Arc Aid trials have significantly exceeded the original scope of the trials which were simply to enable the reliable detection of Faults on Compensated Networks, enable reduced customer minutes lost (CML), enable reduced switching operations and increase safety.
· The trials have also shown that the full range of Fault Data captured by the MetryView software can be used to automatically identify a network's weak spots using Heat Maps functionality of the software and this information could be used to target further CML and System Average Interruption Frequency Index (SAIFI) improvements using Pareto principles.
· Finally, the ability to immediately identify the type of Fault (Overhead line -OHL, PILC, vs Transformer) could also be used to reduce repair times and improve productivity with the right team structures. Further work as set out in internal report would also need to be carried out to gain the full potential benefits available.
Lessons Learnt
- Testing: Real time digital simulation testing can offer high quality information on device performance in a relatively short time period and can provide a good alternative when lacking the ability to install and test sensors.
- Product: Units of this size offer advantages in terms of installation time and techniques available within the distribution safety regulations as both hot glove and short stick methods can be used by operational teams giving more flexibility.
- Communication: It is beneficial to check cellular network at the specific sites, especially for remote areas of installation to ensure reliable communication.
- Installation phase:
o It is important to ensure that the sensor sets, and associated gateways were installed safely on the network: The pole-mounted gateway devices can be left isolated from HV earth provided they are installed a minimum of 3.7m above ground level.
o Determine a consistent sign convention for power flow prior to the sensor installations. This is relatively straightforward for networks with radial feeders; however, the NGED St. Austell 33kV network is meshed with several 33kV rings. The orientation of the sensors on the network was aligned with the policy requirements for substation measurement transducers, which always has positive power flows shown as flowing out of the substation busbar.
- Trial:
o An issue was identified with the 4G modem in one gateway causing loss of comms to the sensors on the OHL. The functionality to shift sensor sets onto an adjacent gateway unit could reduce sensor downtime due to a gateway fault. This was successfully demonstrated in this learning point.
- Integration:
o UK Power Networks' Secondary Polling requirements were not fully understood at the start of the DMS integration work and so MetryView's communication protocols had to be re-written to meet this requirement which had evolved from communication with a large range of independent devices. A key learning point is to have all requirements documented at an earlier stage as soon as the decision to integrate the MetryView outputs into DMS had been made.
- Stakeholder Engagement: given the technical complexity of the project, specialist resources should be engaged as early as possible to ensure the avoidance of any delay related to personnel availability.
