Conversion of 230 kV Switchyard to Gas-Insulated Substation in a Gas Plant

Frequent failures and increased maintenance in a 30-year old 230 kV air-insulated switchyard (AIS) of a large gas plant caused the existing installation to be unreliable to provide uninterrupted power supply to critical plant operations. The replacement parts from original equipment manufacturers became scarce and expensive. The maintenance activities in severe and extremely hot middle-east weather conditions were cumbersome and time-consuming. A planned plant expansion with considerable incremental load to the facility provided an opportunity for a review of the complete electrical system. After a thorough review, it was decided to convert the main outdoor AIS to an indoor gas-insulated switchgear (GIS) substation to support the existing and new facilities. However, a total loss of power to the continuous operation of this critical gas facility was unacceptable. The existing switchyard with an energized 230 kV open bus system had limited space to safely perform the demolition and construction activities for the new GIS. Detailed analysis of the installation options, construction techniques, safety requirements, and logistical methods was performed to eliminate potential for any total loss of power. The construction activity involved interfacing with two separate redundant power supply sources, with separate transmission line protection systems and equipment. The parties involved worked together in reaching an agreement on engineering, procurement, installation, testing, and commissioning activities that would successfully implement this transition without any loss of power to the gas production facilities.