Multi-field Coupling Of Double Moving Self-Energized Interrupter And Dynamic Characteristics Of Transmission System For Extra-high-Voltage Circuit Breaker

Operational stability and reliabilityof the lhigh voltage power system is one of the key factors to support the development of national economy and guarantee the social stability.High-voltage circuit breaker is not only one of the most important and complex electrical equipment,but also the most important control and protection equipment in power system.While switching off the circuit with short-circuit fault,high-temperature and high-voltage arc will be existedin the interrupter of the circuit breaker.Hereafter,it has to experience attack of the transient over-voltage after the arc is extinguished.During the breaking of circuit breaker,there is a complex multi-coupling physical process with multi-field coupling of air flow,temperature and electromagnetic fields in the interior of the interrupter.In addition,due to the requirement of short opening and closing time(within 100ms),mechanical failures on transmitting system of circuit breaker,such as mechanical wear and pin cracking,are likely occurred under the action of transient impact load.Therefore,more efforts are required in design of interrupter and transmitting system.In this paper,the multi-field coupling model for double-moving self-energized interrupter of extra-high-voltage(EHV)circuit breaker(CB)and the dynamic model for transmitting system are both investigated.An integrated system of”design-modeling-analysis-trial producing-verification" is utilized as the research method.This paper improves the design theory of the circuit breaker with double-moving self-energized interrupter,as well as its overall performance.As a result,a breakthrough from high\oltage to extra high voltage is achieved.The main contents of this paper are as follows:1.Multi-field coupling model for double-moving self-energized interrupter is established,and the multi-field coupling characteristics of the interrupter is investigated.By analyzing the structure and moving parameters of core elements for double-moving self-energized interrupter,a physical model for the interrupter is established.Based on the assumption of the mathematical model for the arc,the mathematical model and simulating model for gas-temperature-electromagnetic multi-field coupling are established.So as to obtain the changing rules of the key parametersin load and unload conditionsduring CB’Opening process,e.g.pressure,temperature and flow rate.2.Based on multi-field coupling characteristic research on double-moving self-energized interrupter,the parameter optimization of the interrupter structure is carried out.The influencing factors on the breaking performance of double-moving self-energized interrupter are analyzed.The arc resistance at 200ns before current zero is taken as the breaking capacity evaluation index,and the nozzle throat diameter and line length and the expansion chamber volume are taken as the optimization parameters.Simulation optimizing scheme for interrupter structure is developed based on orthogonal test method.The design method of double-moving self-energized interrupter is perfected by optimizing the interrupter structure through multi-field coupling model.3.The rigid dynamic model for transmitting system of double-moving interrupter is established,and the dynamic response of transmitting system is researched.Based on analytical mechanics theory,and using of Lagrangian quadratic equation and Newton’s second law,the transmitting system’s rigid dynamic model and non-linear dynamic model that considers the gap and friction coefficient are established respectively.The dynamic response of the system is obtained by numerical solution.The influences of gap,friction coefficient and excitation on the opening and closing characteristics of transmitting system are revealed.4.Flexible dynamic model for the transmitting system of double-moving self-energized interrupter is established to calculate the kinematic and dynamic responses of the transmitting system in service.Based on related theory of elastic and contacting mechanics,a flexible dynamic model for the transmitting system is established while considering the influence of friction,contacting,elastic deformation,hinge clearance and preload on the transmitting system.The stress concentration prediction of key components such as linkage,pin shaft and fixed contact fingers of interrupter and the rule of dynamic response of the travel,speed and acceleration of moving and fixed contact of interrupter are obtained.5.Prototype development and performance testingof420kV low operating power circuit breaker with double-moving self-energized interrupter are implemented.The overall scheme for 420kV low operating power circuit breaker with double-moving self-energized interrupter is designed based on the simulating results of multi-field coupling model for the interrupter and dynamic model for the transmitting system.Thereafter,the prototype of circuit breaker is manufactured.Short-circuit breaking and mechanical tests are performed based on GB1984 and GB11022.The results validate the rationality of the design scheme for the circuit breaker interrupter and transmitting system.The multi-field coupling characteristics and dynamic response during short-circuit breaking of EHV circuit breaker with double-moving self-energized interrupter are investigated in this paper.The key factors that affect the operating characteristics of the circuit breaker is revealed.The design method of double-moving self-energized interrupter is improved.The results strongly support the successful development of first 420kV low operating power circuit breaker with self-energized interrupter in China,and provide a technical base for developing double-breaks 800kV self-energized interrupter circuit breaker.