Research On Detection Technology Of The Closing Status Of GIS Disconnectors Based On Bus-transfer Current

Gas insulated switchgear is widely used in the field of high-voltage system and ultrahigh-voltage system due to the development of social economy and the shortage of land resources with the benefits of its small footprint,compact structure,safety,reliability and strong adaptability.Due to the full closure of the GIS structure,the operating personnel in the operation of circuit breaker,can only determine the status of the circuit breaker through breaker identification and background signal,which is not reliable.In order to improve the level of equipment operation and maintenance and control the risk of power system operation,Guangdong Power Grid requires technological means to research and develop monitoring system to monitor circuit breaker on-off status.In this paper,a series of theoretical research and project design are carried out for the reliability of disconnector during the operation of hot bus-bar switching.1.The calculation model of bus-bar switching current is established.And its example analysis based on the actual parameters of the substation is conducted.The influence of the contact resistance of disconnector on the bus-bar switching current is evaluated.The setting process of the on-off status criterion is studied.Moreover the application process of the bus-bar switching current criterion and its blind spots are analyzed.2.The model of air-core transformer which is influenced by the loop current of GIS case and the model of loop current method are studied.And example analysis of he loop current of GIS case is conducted.3.The technical project of setting loop current ring inside the short circuit is proposed to reduce bad influence of induced current of GIS case.4.The scheme of non-invasive and portable current detection of GIS is designed based on the current measuring device using flexible current probe which is based on Rogwski coil principle.5.Portable detection terminal which is able to detect the on-off status of hot bus-bar switching is developed and applied to substations.The bus-bar switching current is the direct electrical quantity criterion,which is more reliable and effective than other indirect criterion.The bus-bar switching current,which has high engineering applicability,not only can be applied directly to new substation,but also can be applied to upgrade GIS disconnector of the old substation.Due to the opportunity of GIS equipments evaluation of 220 k V Banqiao substation of Dongguan Power Company,the field tests of bus-bar switching current criterion and non-invasive detection device are conducted.The test results showed that bus-bar switching current criterion and non-invasive detection device can accurately detect the on-off status of GIS disconnector,which have significant application and popularization value.