Development Of A Device For On-line Monitoring Contaminated Insulators Based On Embedded System

Due to the effects of rain, snow, fog, frost and other climatic condition s, high-voltage transmission line insulators in actual operation may simply be pollut ed by the floating debris in the atmosphere and form a filthy layer on its surface dep osition. Then the insulators may easily occur pollution flashover and seriously affe ct the security and stability of power system operation. In view of this situation, th is paper gives a detailed study of the insulator pollution flashover principle and ch aracteristics of the insulator’s surface leakage current. This paper presents ametho d to dynamically reflect the status of insulator surface contamination by real-time and online monitoring of the insulator surface leakage current, provides an important basis for insulator pollution flashover warning, and effectively improve the safety an d reliability of the insulator.According to the correspondence between leakage current and discharge charact eristics and technical regulations of the State Grid Corporation of on-line monitorin g of the open wire, this paper determines the object and its range of monitoring f or the for the purpose of preventive monitoring. Monitoring device use a slip ring to collect insulator surface leakage current, and put it into the device. The desig n of the device is based on the embedded system formed by the dsPIC30F4011mai n chip, and it contains a collection of functional circuits of the I/V conversion circu it, filter circuit, the voltage comparator circuit, the A/D converter circuit and True R MS conversion circuits, etc., and it can calculate the leakage current in real tim e, quickly, and accurately. Inside the device, the high-performance amplifier chip M AX4304constitute the I/V conversion circuit, the weak current signal can be accuratel y converted to voltage signal, and completely retain the high-frequency pulse curre nt signal, improve the feasibility and accuracy of frequency leakage current rms cal culations and high-frequency pulse count. The True RMS circuit can calculate the po wer frequency leakage current valid value in real time, quickly and accurately, eli minates the need for multi-point sampling of the current signal, the process of data st orage and rms calculations, saves software resources, but also makes the system wi thout the need for memory expansion, simplifies the circuit structure. The filter can improve the overall anti-jamming capability of the device to reduce the noise from th e outside world and the circuit itself. The embedded systems with the dsPIC30F401 1as the core has a simple peripheral circuits, high-efficiency instructions writing a nd easy online debugging, it can control the signal acquisition and processing precis ely. RS-485communication circuit and optocoupler isolation circuit have the charact eristics of anti-jamming ability and stable performance, can transmit data between t he monitoring device and base station safely and reliably.This paper designs test methods for measuring the accuracy of the device, a nalyses the data error, improves the measurement accuracy of the device through m aking the calibration tables for software calibration of measurement errors. The test re sults show that the overall performance of the monitoring device can meet the requir ements of Insulator Leakage Current Monitoring,and provide important and reliable basis for insulators Contamination judgment,the device has a great actual value.