Design Of The Single Stable Permanent Magnetic Actuator

In recent years,the development of power system,especially the development of strong smart grid based on UHV puts forward higher requirements for the rapidity,reliability and intelligence of the high voltage switch.As the most important high voltage switchgear,circuit breaker plays an important role in the control,regulation and protection of electric power system,and its reliability has a great influence on the stability of electric power system.The operating actuator is the core component of circuit breaker,and its working performance and quality play an important role in the performance and reliability of circuit breaker.Therefore,the study of the operating actuator is an ongoing issue.This thesis introduces the development and present situation of vacuum circuit breaker and permanent magnetic actuator.A comprehensive comparative analysis of three common types of permanent magnetic actuator is made.It is decided that the circular single stable permanent magnetic actuator is chosen as the research object of this thesis.Then this thesis summarizes the design methods for each part of the circular single stable permanent magnetic actuator of 12kV vacuum circuit breaker,and gives a systematized design flow.Based on the transmission ratio of the transmission mechanism of the circuit breaker,three different permanent magnetic actuators are designed for the transmission mechanism of the three different transmission ratios.The force analysis and mass conversion of the arc extinguishing chamber are carried out,and the motion characteristic of the opening process of the vacuum circuit breaker is analyzed by using Newton's law of motion and the law of conservation of angular momentum.The structural parameters of each permanent magnetic actuator are obtained by the theoretical calculation.Using Ansoft Maxwell software to simulate the three actuators,the characteristic curves of the relevant parameters in the process of closing process are obtained.Through comparison and analysis,it is concluded that the three kinds of permanent magnetic actuators designed according to three kinds of transmission ratios have their own advantages.Suggestions for selection under different application conditions are given.In the flexible DC power transmission system based on the modular multilevel converter(MMC),when a fault occurs to the MMC sub module,the switch needs to close within 3ms to bypass the faulty MMC sub module to ensure that the system can continue to run.Two kinds of fast closing single stable permanent magnetic actuators are designed for the bypass vacuum circuit breaker.The mechanism of 1000N permanent magnetic retaining force is suitable for vacuum arc extinguishing chamber with rated contact pressure of 100N.The mechanism of 2000N permanent magnetic retaining force is suitable for vacuum arc extinguishing chamber with rated contact pressure of 100N-600N.It uses Ansoft Maxwell for modeling in order to simulate the closing process of two permanent magnetic actuators.The closing time of two mechanisms are less than 2.5ms,thus meeting the design requirement.