Design Of Intelligent Operating Mechanism For SF₆ High Voltage Circuit Breaker

SF6 high voltage circuit breaker?HVCB?is an important switch equipment in power system with the task of controlling and protecting the circuit.The safety of the power system partly depends on the function of HVCB.For SF6 HVCB,the operating mechanism should have fast response and high opening and closing speed.Hydraulic mechanism and spring mechanism are widely used nowadays,which are composed of complicated mechanism assembly with characteristics of more parts,complex actuating mechanism,higher requirements for manufacturing technique,and uncontrolled moving procedure.So,it is necessary for researching on an operating mechanism with fewer parts,more simple construction,and controlled moving procedure to improve the intelligent operating of circuit breaker.This thesis presents a permanent magnet brushless DC motor?BLDCM?operating mechanism and the academic analysis is carried on at the same time as the design on the motor of the SF6 HVCB is accomplished in this thesis.According to the design requirement of the motor operating mechanism for the SF6 HVCB,the design on motor operating mechanism of LW8B₄0.5kV SF6 HVCB is accomplished through the theoretical calculation and test analysis,and the systemic design theory is established,thus meeting the operating demands.Firstly,the correlated properties of operating mechanism is put forward in this thesis and a boundary-phase circuit breaker operating mechanism scheme based on the performance requirements of operating mechanism.The thesis also focuses on the mechanical properties of the circuit breaker motor operating mechanism especially the opening process and closing process.Dynamic simulation and optimization is carried out for some parameters affecting the moving contact speed for matching the load characteristics of the circuit breaker with the motor operating mechanism output force characteristics.Through the mechanism dynamics analysis,the paper reduces the haul cycle,the force characteristic and motion quality.etc,which is as a basis to determine motor electromagnetic parameters and performance index.Because permanent magnet BLDCM is at starting and braking status,dynamic math model of motor should be analyzed through finite element method.The dynamic process of motor is calculated,and the relationship of current,speed,displacement and time is obtained to verify the reasonableness of the motor structure design.The capacitor charging opening and closing experiment is carried out in this thesis and an optimal design has been made on vital unit.Comparing the performance before and after being optimized to verify the correctness of the optimization method,this way provides theoretical guidance for the operating mechanism design.Combining with EDA technology and the trait of large programmable logic device,this paper puts forward a project of intelligently designing the whole interface based on FPGA?Field Programmable Gate Array?:The theory of synchronous switching technology is introduced in this thesis.The relative theory of wavelet transform and principle of wavelet de-noising are first introduced in this paper,focusing on the wavelet threshold de-noising algorithm based on the hard threshold function and soft threshold function,then improved the threshold function.Based on the characteristic of PSD?Power Spectrum Density?restraining white noise and bi-spectrum restraining Gaussian noise,the PSD method and bi-spectrum estimation is used to analyze the composition of field noise,which shows that there is much of non-Gaussian noise in CB?Circuit Breaker?field signal;Concerning the problems of much resource consumption and low processing speed by using the traditional distributed arithmetic,a new method of implementing high order FIR filters targeted FPGA is proposed.Designing examples show that our method can implement FIR filters with smaller resource usage and higher speed.Finally,the mechanical linkage experiment is carried out to the improved motor mechanism.Through the analysis of the test data,comparing the past field data and using the existing motor to drive three-phase?two-phase?linkage breaker,the opening and closing operation can be achieved,their characteristics can be guaranteed and the synchronization is better than before.The results show that the design of permanent magnet BLDCM actuator performance is reliable and able to meet the performance requirements of SF6 HVCB operating mechanism.A better theory of the design and optimization for SF6 HVCB motor operating mechanism is established in this thesis and the thesis has the significance for further research and development of the mechanism in the area.