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Projects: Projects for Investigator
Reference Number NIA_SHET_0022
Title Transmission System Fault Level Monitoring
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
Scottish Hydro Electric Power Distribution plc (SHEPD)
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 June 2017
End Date 01 June 2019
Duration 24 months
Total Grant Value £285,000
Industrial Sectors Power
Region Scotland
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , Scottish Hydro Electric Power Distribution plc (SHEPD) (100.000%)
Web Site http://www.smarternetworks.org/project/NIA_SHET_0022
Objectives 1. Carry out an initial validation exercise to confirm the accuracy of the passive fault level estimation technique against a known active method. Should this have a positive outcome, the project will continue, with the following further objectives: 2. Implement a programme of passive fault level monitoring across the SHE Transmission system at several locations, which delivers measured fault level values collected through seasonal and other variations. 3. Carry out regular off-line calculations based on the SHE Transmission GB system model to cross check against the monitored values, delivering an improved understanding of the range of actual fault levels and the behavior of the system model, and improved confidence in decisions made on the basis of the model. The project will be judged to be a success based on the following criteria: 1. That sufficient evidence is collected to establish the effectiveness of passive fault level monitoring techniques within the transmission system, to enable a decision to be made on long term BAU adoption2. The comparisons of measured data with off-line analysis supports ongoing industry efforts to validate or improve short-circuit calculation methodologies. 3. A specification is developed which can be used for the competitive procurement of further fault level monitoring equipment
Abstract The calculation of accurate fault levels across the transmission system is a vital task to ensure that primary equipment is adequately rated and protection is correctly set and coordinated across the range of system operating conditions. In addition to the foregoing, a good understanding of fault levels is also important as a measure of system strength which is used in creating system equivalents for a range of analysis tasks (e.g. generator grid code compliance assessment, switching studies and control system tuning). System fault levels are calculated by power system planners using models which are setup to reflect the generation background and network configuration appropriate for the system condition being studied. The minimum system fault level typically occurs during summer months due to lower levels of generation and the presence of system maintenance outages; whereas, the winter months lead to the maximum condition when the highest levels of generation are connected to a largely intact system. The GB power system is currently undergoing significant changes as major reinforcements are constructed to support a shift in generation away from synchronous machines to renewable technologies using increasing levels of power electronics which provide a much reduced fault current contribution. Recent work by the System Operator as part of the System Operability Framework has highlighted that the accelerating closure of synchronous machine plant will lead to much lower transmission minimum fault levels. With greater levels of renewables being connected alongside imports via High Voltage Direct Current (HVDC) based interconnectors, the minimum fault levels across the system will drop to an extent which could degrade system power quality. This could make it difficult to calculate satisfactory protection settings and may lead to a requirement to deploy alternative protection schemes from those presently used. There may also be issues with maintaining compliance with voltage step limits and reduced voltage stability margins. This downward trend is of particular interest to SHE Transmission as the system in the North of Scotland already has the lowest fault levels of the three onshore license areas and the resolution of these issues could require significant investment to ensure that the system can continue to operate safely and within planning limits. It is therefore important that the models used by power system planners continue to provide accurate assessments of fault levels - particularly so for minimum fault level conditions. The contribution from power electronic interfaced generation technologies or Voltage Source Converter HVDC is inherently different to that from synchronous machines and its treatment within existing short-circuit calculation methodologies is the subject of ongoing industry review (e.g. the current review of ER G74 by the ENA). It is timely to commence a study based on fault level monitoring while the levels of these technologies are still modest, as it will allow a degree of benchmarking to be made before major trends in fault level physically emerge in the system. SHE Transmission proposes a programme of fault level monitoring using a recently developed technique at strategic locations across the North of Scotland with a view to cross-check the calculated results from the detailed system model. SHE Transmission proposes the following programme of activity to address the problem outlined above: Work package 1: Fault Level Monitoring Method Verification The fault level monitoring technique chosen is a passive method developed by Outram Research Ltd which involves the derivation of a fault level value from observations of changes in measured voltage and current. To date the method has been laboratory tested and trialled at a number of distribution or industrial substations with promising results. It is recognised that this method is only suitable for assessing fault levels within radial networks supplied from a single grid source and thus it cannot be directly applied within an interconnected transmission system. However, to mitigate this issue it is proposed that the devices are installed on the lower voltage side of Grid Supply Point (GSP) transformers and the calculated grid contribution referred back up onto the transmission system to give an estimate at the supplying transmission bus-bar. SHE Transmission intends to perform a verification check on the passive fault level technique by installing the device at a GSP which is electrically close to, and within one voltage transformation of, a Static Var Compensator (SVC) which makes use of an active fault level estimation technique within its control system for gain optimisation. This fault level estimate is available within the SHE Transmission Supervisory Control And Data Acquisition (SCADA) system and will be used to verify the accuracy of the passive technique. This site is relatively close to several large hydro stations which, due to their operating regimes, will provide known step changes in local fault level which will be beneficial to the testing. Work package 2: Fault Level Monitoring Campaign SHE Transmission will identify a further five strategic locations across the North of Scotland which will enable a good assessment to be made of system fault levels at the three transmission voltages (400kV, 275kV and 132kV). Upon the successful completion of work package 1, the fault level monitoring devices will be installed at these locations along with a supporting IT infrastructure and the monitoring programme will commence. This programme will continue for two years with the intention that the hardware and supporting software will remain in service after the completion of the project. The fault level contributions measured by the devices will also be made available to the local DNO SHEPD. Work package 3: Offline Analysis With the monitoring programme underway and gathering data, offline analysis will be conducted at regular intervals to cross-check measured values against those calculated from the system model. This will require that the system model is setup with the same generation, demand and network configuration. The offline analysis programme will be defined to investigate not only min/max values over the last monitoring period, but also times of high/low outputs from various generation technologies. From this work it is planned that a good appreciation of variation in fault level will be obtained over the course of system operation. If necessary this analysis will incorporate any recommendations arising from the review of ER G74.Note : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above
Publications (none)
Final Report (none)
Added to Database 17/12/18