Study Of Condition Assessment And Condition-based Maintenance Strategy For Gis

Compared with other general electronic apparatus, the Gas Insulated Switchgear (GIS) is characterized by less occupancy of space, lowness of noise, inexistence of fire, long maintenance cycle, as well as safe and reliable operation. Therefore, GIS has gradually replaced switchgear to become the mainstream varieties. However, due to the following reasons:firstly, GIS is complex with highly requirements of quality, and complicate manufacturing and maintenance process; secondly, although GIS has less fault, in case of breakdown, it will lead to serious consequences; thirdly, the maintenance of GIS is rather complicated and time consuming. At some time, power cut may relate to other non-fault components, thus its repairing request is very fine, even slight mistake may cause quality problem. The current mode of periodic maintenance for GIS equipment may cause over-maintenance or less maintenance, which will reduce the GIS equipment availability factor, thereby affecting the reliability and economy of the power grid. Therefore, it is very important and urgent to assess and study the state of GIS equipment and its optimal maintenance scheme.As a result, this paper studies the state assessment of GIS equipment and explores optimal strategies for its maintenance. Main tasks are as follows:Firstly, through the study of the internal structure of GIS equipment and its mechanism of operation, the author tries to find and analyze characteristic quantity which reflects the health status of the GIS equipment. As the uncertainty of GIS parameters for the healthy operation, combing with vague impact of the assessment factors on the result, the author attempts to adopt mathematical fuzzy theory to establish the evaluation index system, model and method for maintenance of GIS equipment.Secondly, after evaluation of the condition of GIS equipment, the result is used to assess the risk of the GIS equipment. At first, based on binary regression analysis, historical data is analyzed to gain the functional relationship between risk degree and failure rate of the equipment, then the consequences of equipment failure is divided into two parts, that is, loss of asset value for the device and loss for the power system, meanwhile, the severity of damage is measured by semi-quantitative analysis. Finally, risk assessment model and method is established for GIS equipment maintenance.Thirdly, the author proposes assessment methods and related indicators of which the risk degree of GIS equipment impacts on the reliability and economy of the power network. He also develops strategies for the operation of GIS-based risk assessment model system from perspectives of improving reliability and economy of the power network. As for the GIS equipment requiring for maintenance, based on engineering economics, the author has established the best GIS equipment maintenance model which is taken into account of the annual investment costs, annual operating costs, losses and other factors, while as for the GIS equipment not requiring for maintenance, the author also works out specific programs for its state monitoring and inspection.