Please find examples of projects performed by STRI in the following listing. Process industry
Power grid companies:
Reduced insulation levels
Insulation co-ordination of future Swedish 145 kV substations with considerably reduced insulation levels.
Dimensioning of overvoltage protection for a GIC limiting resistor in the ground connection of a 400 kV transformer.
Insulation dimensioning of transmission lines
Parametric study for optimization of air clearances on 400 kV transmission lines, including effects of ice, pollution and overvoltages by lightning and switching.
Comparison of loading capability and reliability
Comparison of loading capability and reliability of underground cables in comparison with overhead lines at sub-transmission voltage.
Reliability of compact substations
Reliability studies of future compact substations.
Insulation co-ordination of portable protective gap for live-line work.
Power losses in earthing system
Calculation of power losses in the shield/earth wires on 400 kV transmission lines.
Application of conductive concrete in the construction of ground electrodes.
Earthing and lightning protection
Earthing and lightning protection of 130 kV power lines.
HVDC ground electrode
Investigation of a deep-hole test electrode for an HVDC connection.
New compact 400 kV transmission line
Development of a new compact 400 kV transmission line where the shield wires are replaced by surge arresters in the top phase.
Second generation compact 400 kV transmission line
Development of a second generation compact 400 kV transmission line including a newly developed line post insulator.
New compact 220 kV transmission line
Development of a new compact 220 kV transmission line based on the second-generation 400 kV line concept.
Compact towers for overhead line to cable transition
Conceptual design studies of compact towers for overhead line to cable transition at 400 kV.
Dynamic current rating of transmission lines
The objective was to investigate the usefulness of a forecast dynamic rating from a weather model for a transmission line. The line chosen was a 300 kV line between Sweden and Norway, where measurements were made to compare the predicted (from weather forecast) and actual sag of the conductors. A significant possibility for uprating using this method was found.
Current loadability of breakers, disconnectors and current transformers
The aim of the project has been to develop thermal models and test results that can be used to load substation equipment above rated current under certain conditions by using a weather-dependent rating. Tests on apparatuses have been carried out and thermal models have been refined and developed. A program which can be used in a network control room has also been developed.
Measurement of hoarfrost corona losses
In order to assess the effect of voltage changes on the corona loss level with hoar- frost, measurements have been made using STRI's climate hall as a corona cage. Losses on both duplex and triplex conductors have been measured using test methodology developed at STRI for depositing frost on a test conductor surface.
Measurement of corona losses on test span
In order to confirm the results obtained in STRI's climate hall, corona loss measurements have also been performed on STRI's 400 kV test span during the winter of 2001-2002. The results show that both hoar-frost and wet snow are significant for winter time corona losses.
Development of bare-hand method
Charges for non-delivered energy in Norway have increased the need for changing insulators on the 130 kV grid using live-line methods. Together with ELTEL Services, STRI has developed a methodology using the bare-hands method for performing this work. STRI has been responsible for risk assessment, EMF and health issues and the training of linemen. The methodology developed is now being adapted for use at 300 kV and 400 kV.
Line joints diagnostics
Failure of conductor joints at the 400 kV level has caused significant problems for network operators in Scandinavia. Thus, a project was carried out in 2002 and 2003 to examine the suitability of different diagnostic methods for assessing the condition of line joints. This work will continue with mechanical tests on line joints and the preparation of an application guide for diagnostic inspections and the use of results obtained.
An extensive Reliability Centred Maintenance study has been performed for Vattenfall on a substation in northern Sweden. The study focused on the maintenance of disconnectors. The results showed that changing the maintenance schedule for disconnectors can improve availability as well as reduce costs.
Compact switchgear modules
Software tool for dimensioning of air clearances in compact switchgear modules 145 kV to 300 kV.
Influence of series capacitors
Studies of switching overvoltage levels on 400 kV lines before and after installation of series capacitors.
Reliability of simplified busbar configurations
Reliability studies of simplified busbar configurations in transmission and sub-transmission substations.
Changeover from BT to AT system
Several studies concerning the changeover from BT system (booster transformer) to AT system (auto transformer) in Sweden.
Comparing studies of feeding systems in Norway
Comparisons of the BTRR, BTRC and the AT Traction feeding systems in Norway.
Hungarian AT system
A large number of studies have been performed concerning the Hungarian AT supply system.
Airport express in Malaysia
Technical consultancy for the airport express in Kuala Lumpur, Malaysia.
Iron ore mine
Insulation co-ordination of power supply to a major iron ore mine, comprising voltage levels 0,4 kV to 145 kV.
Studies and measurements of lightning and switching overvoltages in a 145 kV GIS feeding a paper mill.