+44 (0) 151 347 2313

Foresight Report


  • 22 July 2021

  • EA Technology

2021

Northern Powergrid has worked with EA Technology to develop and test novel, low cost pre-fault detection and location techniques. These techniques have been proven to detect and locate developing faults in LV circuits before a loss of supply event. The project has utilised this technology on different types of LV network and cable types and the data collected is being used to develop a process that aims to predict when faults will occur and provide a level of prioritisation in terms of proactively dealing with faults before a loss of supply occurs.

Image

To find out more download our full report on the right hand side and see our full description and story below. 

Full Description

Foresight - LV Network Visibility and Fault Recognition

The Foresight project outlines a new approach to LV fault management using innovative, ground-breaking low-cost technology that can not only detect gestating faults but can successfully locate them before a loss of supply occurs. It will also provide an indication as to whether the fault is imminent or not so that operational resource can be targeted in the most effective way. This type of approach will require a whole new paradigm shift in operational culture within electricity distribution companies to be effective and avoiding these faults would deliver significant quality of supply benefits.

Electricity Regulators continue to focus on increased availability and reliability of networks. Many Electricity Network Operators have improved the performance of High Voltage networks and consequently a significant proportion of customer interruptions and customer minutes lost now result from Low Voltage (LV) faults. In addition, Low Carbon Technologies, such as electric vehicles, heat pumps and distributed generation are increasingly being connected to the LV network, changing power flows, voltage profiles and increasing stresses on the network.

Due to an ageing network, much of which is over 50 years old, LV fault management is becoming increasingly difficult. Restoration times can be lengthy, as most of the LV network is neither comprehensively monitored nor controlled automatically. Responses to faults tend to be reactive as the condition of LV cable systems at any point in time is unknown and there is no capability of predicting the timing and location of faults before the event occurs.

The Foresight project involves using a range of LV network monitoring equipment in combination with automated switching devices. The aim of the project is to recognise LV pre-fault signals and then use low cost monitoring devices to identify and locate developing faults before supply outages occur. This enables pro-active deployment of reclosing devices and pro-active cable repair before fault. Planned interventions rather than post fault repair on cables produces both financial and customer service benefits.

Traditionally, LV cable replacement has been driven by the reliability history of cable sections, however, the Foresight project has provided the opportunity to radically change this strategy to incorporate condition based information to guide replacement decisions. This is especially important as the age of the LV cable asset base advances towards the end of its design life where there is a need for cost effective asset replacement.

Northern Powergrid has worked with EA Technology to develop and test novel, low cost pre-fault detection and location techniques. These techniques have been proven to detect and locate developing faults in LV circuits before a loss of supply event. The project has utilised this technology on different types of LV network and cable types and the data collected is being used to develop  a process that aims to predict when faults will occur and provide a level of prioritisation in terms of proactively dealing with faults before a loss of supply occurs.

Story

Back in 1974 when EA Technology was the Electricity Distribution Research Centre, some work was started on the recognition of “transitory faults” on the Low Voltage network.  One of the collaborating electricity companies was Yorkshire Electricity.  These events were observed to occur as dips or notches in the voltage waveforms measured by, at the time, expensive equipment at substations. They were found to be due to degradation of the cable insulation at a particular location which, following a short passage of current, self-healed before fuses blew and therefore before customers lost supplies.  In 2017 the same companies, now called EA Technology and Northern Powergrid, collaborated again to further research these phenomenon.

At the start of the Foresight Project in 2017, the project team wondered whether these events (now named pre-fault events) could be used to enable a brand new way of managing LV underground cable faults.  At the end of the project in 2021, we had discovered that they could.  The Foresight Final Report  charts the journey between those two dates and presents the equipment, systems and methods used to move away from reactive fault management to management based on proactive action. 

This comes at a critical time in the UK and elsewhere in the world.  While electricity networks are being looked at as a critical ally in the transition to zero carbon and move away from fossil fuels, they are also aging, most being over 50 years old.  Increasing probability of faults at the same time as increased reliance upon it for the connected customers is an unwelcome combination and calls for a step change in way network performance is managed.

The Foresight Project has demonstrated through trial that the equipment, system and methods proposed will enable a proportion of developing faults to be detected, located and proactively mitigated in the early of development, drastically reducing unplanned off-supplies in comparison with present methods. The presented proactive method of managing LV faults uses new low-cost/ quick-deploy monitoring equipment (Guards) designed for widespread deployment. Signatures from the data from that equipment create a measured cable condition data set. This data set has been used for two purposes.  In the operational timeframe (months, weeks) it is used to recognise circuits that are accelerating toward failure.  These are prioritised for proactive intervention to mitigate the impact of the developing fault. The intervention trialled involved targeted deployment of fault management equipment (Reclosers) and new techniques to pin-point the location of the developing fault with the ultimate goal of being able to Find and Fix these faults whilst they are still in the early stages of development and before they Fail.  In network investment timescales (years), the same cable condition data set has also been used to provide previously unavailable circuit condition data. This has been integrated into a LV Cable Asset Management Model (EA Technology’s CNAIM model) capable of providing strategic insight into movements on the health indices of this significant asset group.

In a demonstration of the proactive management methodology described in the report, a developing fault was located, customers informed and was repaired as planned work.  Not only was the (obviously) damaged component removed from the system whilst it was (surprisingly) still capable of providing supplies (see figure below), a seemingly healthy adjacent joint of similar type and age also removed and sent for forensic examination.  Although visually healthy, the forensic investigation showed indications of accelerated aging judged to be consistent with an expectation of failure within 5 years.  LV Cable networks, to which the majority of customers are connected and are becoming increasingly reliant, are not getting any younger.

Download our Foresight Final Report

Please download here

Download here