Sep 2012
Electricity Transmission
Transient and Clearances in the Future Electrical Transmission Systems (ICASE Award)
Sep 2012
Jun 2016
National Grid Electricity Transmission
Chris Land
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Network Innovation Allowance
Substations and Conductors
An ICASE award has been set up by National Grid to investigate transient and clearance levels in the future transmission electrical system.

The objectives of the project include:

  • A review of the following areas to produce an overview of the current ‘state of the art’ and the areas with the highest priority for further work:
    • The existing insulation coordination methodology within National Grid
    • The historical background behind the definition of the existing safety clearances and the guidance of standardisation bodies such as IEC and CIGRE in this area
    • The differing clearance requirements for standard substation working and live line working
    • The different methodologies employed across global transmission systems to manage overvoltage levels
    • The impact of new technologies on overvoltage levels
  • A review of the capabilities offered by modern simulation packages (to include EMTP, EMTDC and Digsilent) to make a recommendation on which is best suited to carry out insulation coordination studies as judged on the basis of technical capability and ease of integration with existing National Grid models.
  • The development of a simplified National Grid system model capable of being used for a range of overvoltage studies within the chosen simulation package. This model should represent a section of the actual transmission system and have the capability to include new technologies (the connection of offshore HVDC for example).
The success criteria of the project will be:

  • The delivery of a report that critically examines the safety clearances applied to the high voltage system and those which are applied in the case of live line working both on overhead lines and within substations.

  • A model of part of the National Grid system delivered in such a way that electromagnetic transient studies can be quickly / easily run by National Grid staff in the future

  • A report highlighting the opportunities and/or threats that could be derived from a modification to the existing insulation
coordination methodology within National Grid including a change to the overvoltage levels stated in technical specifications and the use of different forms of protective devices