Research On Temperature Rise Characteristics And Ultrasonic Fault Locationtechnology Of UHV GIL

Su-tong Project is the first pipe gallery(tunnel)project to apply UHV GIL in the world.The project uses two(6-phase)UHV GIL equipment laid in the tunnel to cross the Yangtze River.The GIL is insulated with pure SF6,with a total length of about 35km.The ultra-long-distance GIL project with the highest voltage level and largest transmission capacity in the world.Before the localization of UHV GIL,the high-voltage GIL technology was basically mastered by several companies such as ABB,Siemens and AZZ in the United States.my country has not mastered the core key technology of UHV and above voltage level GIL.For UHV GIL,due to the length of a single gas chamber and various types of structural units,it has very high requirements to withstand the undulations and settlements of tunnels,thermal expansion and contraction,and it is very difficult to install and maintain.For UHV GIL,the two most critical technologies for UHV GIL operation and maintenance are to discover abnormal conditions in operation and to achieve accurate fault location.Based on the large transmission capacity of UHV GIL,high current-carrying level,and many internal electrical connections,the problem of temperature rise effect is more prominent.Temperature rise is one of the most intuitive and important indicators for judging the normal operation of GIL.An important means of whether there is abnormality in the GIL.Due to the long length of UHV GIL and various structural units,once an internal fault occurs during operation,it will cause great hidden dangers to the safe operation of the power grid.Quickly and accurately finding the fault location for maintenance and replacement has the advantages of reducing power outage time and ensuring power grid security.Significance.In order to ensure the safe and reliable operation of the UHV GIL in Su-tong Project,this topic takes the development process of UHV GIL localization as the background,from the perspective of UHV engineering GIL operation and maintenance,with the GIL temperature rise characteristics and fault location technology as the core of the research,carry out Research on the temperature rise characteristics of UHV GIL and ultrasonic fault location technology,build a live assessment platform for UHV GIL,study the temperature rise characteristics of UHV GIL,carry out experimental research on temperature rise characteristics,put forward key measures for the operation and maintenance of Su-tong project,and study the use of ultrasonic waves in UHV Propagation characteristics in GIL,carry out UHV GIL ultrasonic fault location real-type test research,and carry out application verification of Su-tong project.The main contents are as follows:Built the UHV GIL live assessment platform,studied the site selection,power supply configuration,and measurement system scheme of the platform,studied the type and layout of the assessment GIL unit,carried out the GIL installation and handover test,and had the UHV GIL insulation,temperature rise,fault location,mechanical,thermal and vibration characteristics research test capabilities,provide platform support for the research on temperature rise characteristics and fault location technology under UHV GIL operating conditions.The temperature rise characteristics of the UHV GIL are studied,and the simulation calculation of the thermal balance of the UHV GIL,the loss of the expansion joint and the overall thermal field of the typical linear unit are carried out,and the relevant factors affecting the temperature rise of the UHV GIL shell are obtained.According to the loss characteristics and temperature rise distribution law,the internal flow velocity of the GIL cavity was obtained,and the reason was analyzed.The UHV GIL temperature rise test research was carried out,the UHV GIL temperature rise test platform was built,and the live test of the UHV GIL shell surface temperature rise and expansion joint temperature distribution under operating conditions was carried out,and the UHV GIL shell and expansion joint temperature distribution were obtained.The maximum temperature of the node surface was verified,the results of the simulation calculation were verified,the temperature rise difference between the type test and the live test was compared and analyzed,and the GIL installation and operation and maintenance suggestions in the project were put forward.The mechanism of ultrasonic signal generation of GIL breakdown discharge was studied,the calculation model of ultrasonic propagation path was established,the simulation calculation of ultrasonic propagation characteristics in UHV GIL was carried out,and the propagation path and attenuation characteristics of ultrasonic wave in UHV GIL were studied.The propagation speed of ultrasonic waves along the UHV GIL is obtained,and the attenuation law of ultrasonic waves passing through the GIL linear unit,gas separation basin and expansion joints is obtained,and the simulation data is compared and analyzed.Carry out UHV GIL ultrasonic fault location test and engineering application research,study the GIL fault location test plan,develop a fault discharge unit that simulates the internal breakdown of the GIL,carry out the fault location test test,and systematically analyze the location error,The composition of the ultrasonic fault location system of the Su-tong project was studied,and the arrangement method of the ultrasonic sensors with different GIL gas chamber structures was studied.The test application of ultrasonic fault location was carried out in the debugging link of the Su-tong project.According to the amplitude and attenuation of the received signal by the sensor The situation verifies the accuracy of fault location,analyzes the range of fault location error,and verifies the arrangement method of ultrasonic sensor according to the type probability of GIL breakdown fault.