Examination of the existing switchgear in the national electricity transmission system and new switchgear design

Electricity transmission system switchgear that require high-cost investments and long time period for their construction have important contributions to the national economy. In an electricity transmission system, there are a lot of power stations called as transformer substation to be able to control power flows and voltage levels in the system. Switchgear in substations is located on both the high voltage and the low voltage side of power transformers. Switchgear consists of circuit breakers that are able to interrupt fault currents and disconnectors that are necessary for the isolation of the some sections in the switchgear and some other similar electrical equipment.For transmission levels of voltage over 36 kV, most switchgear is mounted outdoors and insulated by air that makes it necessary to find a large amount of space for installation of it. But sometimes, if it is necessary to save space, gas insulated switchgear is preferred to use although it has a higher equipment cost. In any case, system design engineers have the purpose of providing most reliable electrical energy at the lowest cost.In this study, the existing switchgear in the national electricity transmission system has been examined and new switchgear designs have been proposed. An example study is run fort the 380/154kV Hisar case for using the criteria based on investment cost, reliability, flexibility, and environmental effects. Finally, the results from the Multi-Criteria Analysis technique has been discussed.