Researches On The Motion Parameters Detection Of Operating Mechanism Based On LabVIEW

Vacuum circuit breaker is one of the most important equipment for control and protection in power system.Its performance determines the safety of power grid operation.It is urgent to study basic theory and related technology of VCB,especially in the field of high voltage and high current.The motion of the contact in the vacuum interrupter is driven by operating mechanism.Arc will be produced inevitably during the opening process,how to control the arc effectively and extinguished arc successfully is the key.Therefore,it is of great significance to study the basic theory of arc control to realize the application of VCB in different fields.The arc characteristics include static and dynamic characteristics.The dynamic characteristics have an important effect on the comprehensive performance of the VCB.Because of the particularity of vacuum interrupter,it brings great challenge to the research of dynamic characteristics.On the one hand,the motion parameters of operating mechanism have the characteristics of fast speed and short running time,which make the diagnosis difficult.The existing diagnosis technology has the limitations of low installation accuracy and easy to be disturbed.On the other hand,vacuum arc is produced in shielding case,which makes it difficult to collect arc images.In order to study the dynamic characteristics of the arc,it is necessary to detect the motion parameters of operating mechanism with high precision firstly.At the same time,it is the key to collect arc images under the action of the operating mechanism.Based on this,the glass vacuum interrupter without shielding case is used for arc experiment,and CMOS high-speed camera is used to collect arc sequence images.The arc images are processed based on IMAQ Vision module in LabVIEW.In the pretreatment,RGB weighted averaging method is used to gray the image,and median filtering is used to remove the noise.Then the edges of the arc can be detected and the contact position can be located accurately based on straight edge search method in IMAQ Vision module.Because of the very short running time,the average velocity can be replaced by instantaneous velocity.Calculate the displacement s of contact between adjacent sequence images,and the opening velocity can be calculated by formula v=s/t.In chapter 5 the area of arc is detected by LabVIEW.Based on the parameters of opening velocity,arc area and current,the evolution of arc shape and the influence of opening velocity on arc shape are analyzed.The experimental results show that the method of which efficiency is high and program is simple can detect the opening velocity effectively.Compared with the traditional methods,the detection precision is improved by 9.1%.The opening velocity has an important influence on the arc dynamic characteristics through the analysis of the arc shape.