Research And Development Of 800kV SF6 Circuit Breaker

Electrical power industry is very important to the development of national economy, and the development of national economy promotes electrical power industry greatly. Because of the long distance between regions of power generation and power consumption, the electrical power network construction layout in China is schemed to be larger generator groups,superhigh voltage and electrical network combination. High voltage switchgears are the key equipments to protect electrical power system running safely. Electrical power network in northwest of China has applied 750kV power transmission line in 2005 and nowdays the research of 1000kV power transmission technology has already begun, so it's very important to develope 800kV switchgears independently.Development of high voltage switchgear involves many subjects such as mechanism,heat,gas flow,eletricity and magnetism, so it is very profound. In this dissertation, based on deep research of its associated theory, applying the method of imported software with self-programming, the softwares integrating by pressure characteristic and movement characteristic coupling, gas flow computation, electric field computation and interrupted criteria were formed, which are very useful in the developing process of circuit breaker. Using the softewares, 800kV SF₆ high voltaege circuit breaker which is one of the very key items of the tenth five-year plans was developed successfully.Based on the laws of mass conservation, energy conservaion and newton 2nd law, the coupling computation method of pressure characteristic and mechanism characteristic of SF₆ high voltage circuit breaker was built and its validity was proved. Associating with noload operation and T100s test duty the gas pressure characteristic of cylinder and mechanism characteristic of operation mechanism of 800kV SF₆ circuit breaker were coupling computated; The influences of interrupted arc and key structures on the gas pressure characteristic, to the mass and enthalpy flow characteristic and the stroke of operation mechanism were compared. The chamber structure of 800kV SF₆ circuit breaker was optimized and determined.Based on the laws of gas mass conservation,energy conservation and momentum conservation, the mathmatics model of gas flow field computing method was built. Applying zone decomposition theory and moving grid technique, the complex path problem and field-changing problem were solved; Finite volumn discretization theory was applied to solve the built mathmatics model. After its validity being proved, the gas flow fields of 800kV SF₆ circuit breaker were computed and analysed associating with its noload operation and T100s test duty. The region where the gas insulation strenghth was relatively weaker was determined.Regarding to the real service situation and dielectric type tests, taking the capacity property and resistance property of medium into account, the electric field computing mathematics model under power voltage and transient voltage was built on the basis of static electric field computing method. Associating with its power frequency voltage withstand test, switching impulse voltage withstand test and lightning impulse voltage withstand test and TRV during the interrupting process, the static and dynamic insulation characteristics of 800kV SF₆ circuit breaker were computed and analyzed in detail. Its insulation structure was optimized and determined.Regarding to the criteria founded on the gas discharge theory, the interruption performance of T100s test duty of 800kV SF₆ circuit breaker were evaluated.The 800kV SF₆ circuit breaker sample has passed its dielectric tests including the power frequency voltage withstand test, the switching impulse voltage withstand test and lightning impulse voltage withstand test regulated to the national standards DL/T593-2006 in Shenyang High Voltage Apparatus Quality Test Co.,Ltd in Jananury 2007. It has also passed the short circuit breaking and making tests including the terminal fault test,the short line fault test regulated to the national standards DL/T402-2007 in Xi'an High Voltage Apparatus Quality Test Co.,Ltd in June 2007 successfully. The tested results proved the theories and methods in this dissertation are reasonable, and the pricision and the credibility of the evaluation criteria were proved as well.