Research On Temperature Monitoring System Of Cable Based On Acoustic Surface Wave

In recent years,the increasing demand for electricity in China,the scale of power system is expanding,and the use of cables is also increasing dramatically,which brings new challenges to the repair and maintenance of cables.A large number of cables are laid in the cable trench with complex environment,and work in high-voltage and large-current environment for a long time,which is easy to cause overloaded operation of cables,or failures such as cable insulation breakdown.These phenomena will cause changes in cable temperature.Cables have been burned due to overheating in power system failures.The large proportion has caused serious losses to power companies and power users.Therefore,tracking the running status of the cable by cable temperature monitoring can avoid serious losses to power companies and power users.The cable is the key equipment of the power system.Based on the analysis of cable faults,the commonly used temperature measurement methods include infrared temperature measurement,fiber grating temperature measurement and so on.The acoustic surface wave sensor has the advantages of small size,strong anti-interference and no need for later maintenance,which makes the development prospect of cable temperature measurement technology based on acoustic surface wave broad.This paper designs a cable temperature monitoring system based on acoustic surface wave to monitor the temperature of cable laid in cable trench.Firstly,this paper studies temperature field by heat transfer,and analyzes the conduction equation and the boundary conditions of different laying environments.In this paper,the simulation software COMSOL Multiphysics is used to build the model of a single-core cable laid in the air for simulation,and to calculat the ampacity of the cable by secant line method? The results of temperature field simulation are analyzed to guide the establishment of simulation experiment platform.According to the actual project,establish a cable trench cable laying model for simulation to determine the location of the temperature measurement sensor and the alarm threshold of the temperature measurement system.Then,By analyzing the influence of contact resistance on the core temperature,building the model of a cable joint.the temperature distribution determines the location of the cable intermediate connector sensor placement,and solves the problem of unable to directly measure the core the temperature puzzle.Secondly,the basic principles of surface acoustic wave sensing technology,the structure,classification and principles of surface acoustic wave temperature sensors are discussed in detail.According to the response characteristics of the surface acoustic wave temperature sensor,the structure of the sensor is improved to measure the temperature of the cable conductor.this paper design a cable surface acoustic wave temperature measuring system.This paper mainly designs the hardware and software of the read-write with strong anti-interference ability and low loss,using surface acoustic wave sensor by Zig Bee technology to realize the distributed acquisition cable temperature information,and through the Zig Bee + GPRS center node to transmit data to monitor host,temperature monitor and alarm.Finally,a simulation test platform is built in combination with the cable and the cable middle connector to test the performance of the designed system.The temperature sensor is installed inside the cable connector to measure the conductor temperature at different currents and compared with the digital temperature measurement system to verify the temperature measurement system Accuracy.