Research On Embedded Intelligent Test Record Technology For Insulation Degradation State

The insulation properties of insulating materials and insulating structures are directly related to the insulation properties of electrical / electrical equipment.Insulation failure is one of the main causes of failure of electrical equipment.Insulation degradation is a progressive stochastic process of long-term stress damage accumulation,which usually takes several years to several decades.In order to obtain the life information of new insulating material or new electrical insulation systems in a short time,the accelerated aging test method is often used.Since the stress of insulation during electrical equipment operation is very complicated,the insulation degradation process is not a linear function of time.The previous study of the aging process of insulation under accelerated aging stress environment can roughly reflect the insulation aging process.However,the change rule of insulation aging process and the change rule of insulation residual life need further exploration under the natural stress environment and especially in the condition that the electrical equipment has been used for a period of time with a certain degree of degradation.The current insulation life assessment mainly adopts the destructive test methods in which under the condition of similar accelerated aging stress,the benchmark pattern and the performance of the test sample are compared to assess the degree of improvement in the performance of the sample.There is also a class of applications that require the use of the characteristic parameters recorded in the running and the use of nondestructive method to estimate the remaining life of the electrical equipment,which requires the establishment of a residual life prediction model.In order to accurately study the deteriorating law of the insulation to obtain the required life information and establish the model of residual life,it is necessary to record life-related and residual life-related characteristics parameters of the entire process in the accelerated aging test life.Even if the accelerated aging life test,it also spends time from several hours to hundreds of hours.Due to the characteristics of insulation deterioration,in addition to partial discharge caused by the sudden jump,the information is slowly changing.The usage of ordinary direct storage method will lead to a waste of storage material.In addition,the partial discharge,edge time and other spike signals require a higher rate data acquisition device.Therefore,aiming at the need of insulation aging experiment,this paper has researched and developed a collection and recording device.Firstly,this paper analyzes the characteristics of the data acquisition signal of the insulation aging experiment,and obtains the acquisition rate,channel bandwidth and storage capacity of the high-speed data acquisition device.Then,in order to reduce the redundancy of data storage,an intelligent compression record algorithm isproposed according to the collected signal characteristics.Finally,an embedded data acquisition and recording device based on Cortex-M7 kernel is developed.The device uses ARM chip as the core in the hardware and uses the task scheduling without operating system as the main structure in the software.The hardware system uses 80 MHz high-speed analog-to-digital converter chip ADC10080 and high-speed digital isolation chip ADuM240/241 to achieve dual-channel isolation signal acquisition circuit to respectively collect the pulse voltage and pulse current of the insulation aging test system.The CPLD is used to generate the channel select signal of the dual channel data and control the source of the ADC data read by the variable memory controller of the ARM.Using the intelligent compression recording algorithm designed in this paper,the collected data is compressed and stored in the external extended Nand Flash memory,and the collected data waveform and related parameters are displayed on the LCD.In the software,the idea of task scheduling is applied to complete the implementation of functional modules and switching.After the hardware and software design is completed,and the prototype is made and debugged,the experiment is carried out on the equivalent capacitance and the insulation resistance hardware platform.The method of compressing the square wave pulse and the loop current is verified by changing the parameters of the square wave and the parameters of the circuit components.And then the device is connected to the insulation aging test system to do experiment with the 0.25 mm polyimide film pre-aging sample until the insulation failure.After the primary test,the data acquisition and recording device can record the experimental parameters of the insulation aging process,and can capture the fast pulse signal and the partial discharge signal.This design could meet the expected goals primarily.