Study On Nonlinear Dynamic Characteristics And Fault Mechanism Of High Voltage Circuit Breaker Mechanical System

Along with our country put forward the construction of "strong smart grid" development goal,the demand for high voltage circuit breaker is more urgent,and higher requirements of its safety,stability and reliability are put forward.High voltage circuit breaker is the most important equipment for controlling and protecting high voltage transmission system distribution network in power system.It has many characteristics such as complex structure,big breaking current,quick responses of controlling,short operating time,strong impact and vibration and high reliability.Moreover,with the existence of clearance joints and mechanical structural flexibility,the wide-band nonlinear dynamic characteristics due to high power pulse in mechanical system were showed up.According to statistics,the mechanical faults occupy the first place in all kinds of faults of high voltage circuit breaker.And the operating mechanism,as the most important execution unit of high voltage circuit breaker,directly determines the mechanical reliability of product.In order to improve the mechanical performance and the reliability of high voltage circuit breaker,forming a set of systematic,comprehensive and scientific evaluation system and research method of dynamic analysis is the urgent problem to be solved by international and domestic academics and journalists.Based on the typical mechanical faults cases of high voltage circuit breaker in practical engineering and during experiment,a spring operating mechanism(SOM)for high voltage circuit breaker is used as an example in this paper.Using theory analysis,numeral calculating and testing study,the wide-band nonlinear dynamics characteristics and failure mechanism of operating mechanism for high voltage circuit breaker are investigated and discussed comprehensively,deeply and systematically.The main research content of this paper is as follows:Firstly,the other characteristics of high voltage circuit breaker such as operation performance,compact structure,small space and airtight requirement are considered,the experimental test system for mechanical characteristics of SOM and stress relaxation of spring is designed and constructed.It is used to collect real-time testing signals of the high voltage circuit breaker such as displacement,velocity,stress,vibration and spring creep parameters.And the signals are analyzed to eliminate the influence of measuring error furthest.In addition,high voltage circuit Refusing operation fault based experimental test system are established,the mechanical fault feature and fault cause are obtained.Moreover,through online testing system some mechanical fault signals are collected,which provides a reliable data source for subsequent numerical simulation.Secondly,based on the vector model of planar revolute clearance joint,the dynamic characteristics of various contact models are compared and analyzed.Then,a spring operating mechanism(SOM)for high voltage circuit breaker is used as an example.The normal contact model is described on the improved nonlinear continuous contact model.And the tangential contact model is represented using modified Coulomb friction law.Moreover,elastic modes are obtained by using modified Craig-Bampton restrained mode synthesis method.Finally,a planar flexible multi-linkage mechanism with multiple clearances for high voltage circuit breakers is established.The effect of nonlinear factors such as clearance joint,friction force on the kinematic and dynamic characteristics of the mechanical system is investigated.In addition,the influence rules of clearance size,clearance joint number,flexible body number and friction coefficient on dynamic responses of multibody system are studied and analyzed also.Thirdly,the multi-features finite element information parametric model,the fatigue life prediction model and the creep model of the elastic-plastic spring operating mechanism for high voltage circuit breaker with three dimensional revolution clearance joints is established based on considering the coupling interaction of multiple nonlinear factors such as large deformation,impact and collision,contact and friction and so.And the reliability and accuracy of the model is proved by experimental test and energy equilibrium theory.The wide-band nonlinear dynamic characteristics due to high power pulse in mechanical system are studied.Moreover,the dynamic behavior and fault mechanism of extrusion deformation,stress concentration,structural failure and creep relaxation of key components are investigated and analyzed.Fourthly,based on the multi-features finite element information parametric simulation platform,six typical mechanical fault simulation models of SOM for high voltage circuit breaker is established by setting the key parameters.The faults including spring failure,clearance error,lock catch failure,cam eccentricity,mechanical jam and over the dead point.The mechanical fault characteristics and corresponding fault mechanism are investigated and analyzed.Moreover,the critical threshold of key parameters induced corresponding faults is obtained.In addition,the intelligent model for fault diagnosis is established,the signal feature extraction and intelligent diagnosis are realized based faults sample database generated by simulation model.The nonlinear dynamic characteristics and fault mechanism of the whole mechanical system for high voltage circuit breaker is studied and analyzed for the first time by using modeling and numerical simulation.The key parameters on the mechanical characteristics of high voltage circuit breaker are investigated.Moreover,the critical threshold of key parameters induced corresponding faults is obtained.In addition,building dynamic simulation platform has a wide range of application,which provides a scientific method for the dynamic analysis,design optimization and reliability improvement of mechanical system.