| Along with the development of national Large Grid project,the requirement of collar equipment for high voltage lines continues to increase.As one of the most significant controlling and protecting device,the performance of high voltage circuit breaker directly affect the reliability of high voltage lines.Compared with low and middle level voltage circuit breaker,high voltage circuit breaker requires higher power of hydraulic operating mechanism and arc extinguish chamber with complex structure leading to high load and transient strong impact which is barely observed in low and middle level voltage circuit breaker.These nonlinear characteristics directly influence the performance of high voltage circuit breaker and finally affect the reliability of high voltage lines.How to take the coupling affection of mechanism system-hydraulic system-arc extinguish chamber system into consideration becomes the major concern of both engineering and academic community.Based on the nonlinear phenomenon existing in engineering test of high voltage circuit breaker,the generation mechanisms have been concluded.Theoretical models and simulation models have been accomplished with verification of test data concerning on the nonlinear characteristics of high voltage circuit breaker.Finally the hydraulic-mechanism-pneumatic coupling simulation model has been implemented to further study the nonlinear characteristics of high voltage circuit breaker.The main research contents are as follows:1、Based on the structure characteristics and working principle of high voltage circuit breaker,engineering test concerning the nonlinear characteristics has been conducted.Reasonable test scheme has been carried out to reduce the influence of environment with breaking the original structure to the minimum extent.By scientific data analysis and processing,the main measurement error has been eliminated.The test results show the key factor causing the nonlinear characteristics of high voltage circuit breaker is the hydraulic impact in working cylinder,flow filed in the arc extinguish chamber and flexible mechanism and tolerance which are set as the main research contents.The test data also is provided to compare with subsequent theory and simulation calculation.2、Taking working cylinder in high voltage circuit breaker as research object,the lumped parameter model and hydraulic system model based on theory of cushion and CFD model based on six degree of freedom model has been accomplished.Comparing with the advantages and disadvantages of three simulation models,the hydraulic system model has proper accuracy and engineering value.Finally,the flow filed distribution of CFD model has been applied to build model of gradual cushion process.Through different mathematical equations and stroke of cylinder piston,the theory of cushion process has been modified to describe the gradual process which proves to have higher accuracy than the original one.3、Through analysis of the principle of arc extinguish process,the arc extinguish chamber system model has been carried out based on the theory of arc extinguish process with proper simplified structure.Then the CFD simulation model has been built to compare with the arc extinguish system model and test data.Finally,the nonlinear characteristics of mechanism system have been concluded as related dynamic characteristics which are served as boundary condition of CFD simulation model.The influence of nonlinear characteristics of mechanism system on flow field in arc extinguish chamber been studied.4、Based on the above study of hydraulic system and the arc extinguish system,the mechanism system has been taken into consideration.With proper system coupling port and compiling platform,the mechanism-hydraulic-pneumatic co-simulation model of high voltage circuit breaker has been accomplished.Through applying the engineering case with coupling simulation model,the similar results have been obtained compared with test data along with some factors difficult to monitor such as response of control valve and pressure fluctuation in oil line.Finally,the influence of key structure parameters of working cylinder on cushion performance and influence of mechanism parameters on arc extinguish performance has been conducted.In this thesis,the nonlinear characteristic and its mechanism under the coupling influence of mechanism system-hydraulic system-arc extinguish system has been studied.In addition,the influence of related key parameters on nonlinear characteristics has been accomplished.The co-simulation model of high voltage circuit breaker provides a set of analytical method to guide the design of high voltage circuit breaker for engineering technicians which has theoretical and practical engineering value. |
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