Indirect Measure And Calculation Of Switch Cabinet Contact Temperature And Contact Resistance And Development Of Temperature Measurement System

As an important electrical equipment in the power system,switch cabinet play the role of relay protection,connecting and breaking power equipment.The contact resistance between the contacts increase due to the air oxidation,wear and other reasons.When the flow is large,it will produce a large amount of heat.Because the contact of the switch cabinet is closed and the cooling effect is not good,the contact temperature is increased.Excessive temperature may cause burning loss,explosion and other accidents.It is difficult to directly monitor the contact temperature of the switch cabinet due to the limited structure,and the contact resistance of contact is not easy to measure directly.In view of the above problems,the research and development of indirect measure and calculation of contact temperature and resistance are carried out in this paper.First of all,based on heat transfer theory,the tempefature field and its distribution in the switch cabinet are analyzed.A heat transfer model of switchgear with bus bar and control equation of the model and boundary conditions are built.After,the ANSYS simulation software is used to mode,mesh and apply load,and the simulation calculation of typical switchgear temperature field is made.Various situations of good contact and bad contact are analysed,and a strong correlation between the contact temperature and bus temperature is showed.Then,the least squares support vector machine(SVM)algorithm is used to calculate the contact temperature and contact resistance indirectly,the feasibility and effectiveness of the method are tested by a large number of sample.At last,the on-line infrared temperature measurement system of switch cabinet is developed.Based on the analysis of the infrared temperature measurement technology,choice of sensor and the communication protocol,the data acquisition module and communication converge module are designed emphatically.Through the joint debugging of software and hardware,the basic work performance of infrared temperature measurement system is tested.The foundation for the accurate measurement of the contact temperature and resistance of the switch cabinet are laid from the research and development of this paper,and the development platform is also provided.