Three-phase enclosed gas insulated substation technology up to 245 kV and its impact for improved power system reliability

Three phase enclosed GIS has been installed on the market for voltage levels up to 170 kV for more than 30 years. The presented 245 kV GIS was developed to utilize the advantages of the three phase enclosed GIS for voltage levels up to 245 kV. 245 kV three-phase GIS provides the functionality and characteristics needed for users of Substation technology. The size and volume is reduced compared to similarly rated singlephase GIS allowing economical Substation designs with minimized environmental impact. Reduced SF6 volume of the technology also addresses growing global warming concerns. The technology of 3-phase encapsulated design variant also shows technical benefits in increasing the substations and power systems reliability. This conclusion is supported by the latest CIGRE survey for reliability of GIS. According to the report conclusions, reduced materials and compact design of 3-phase GIS gives less room for faults in comparison to single-phase GIS. This paper also reviews some concerns in IEEE and CIGRE standards related to the short circuit faults in 3-phase GIS and its impact on power system stability.