Leakage Current Online Monitoring Of High Voltage Transmission Line Insulators

High voltage transmission line insulators have the dual function for both of electrical insulation and mechanical support. To ensure that the transmission lines can normally operate under the condition of all kinds of overvoltage.Insulators are normal or not, to the safety and reliability of the power system plays a decisive role. Related data have shown that the high voltage transmission line insulator pollution flashover accident damages and economic losses caused by far are more than that of over-voltage and lightning overvoltage. So a new type of insulator leakage current online monitoring system is of great significance and has an important practical value and to improve the security and stability of power system.In the paper, combining with the actual requirement, aiming at high pressure (HV), ultra high voltage (UHV) power transmission polluted line insulators, for the pollution flashover problems caused by the resistance reduction, designed a high voltage transmission line insulator online monitoring system based on leakage current. Current detection unit contains the Ⅰ/Ⅴ conversion circuit, the high and low pass filter circuits, the voltage comparison circuits, the A/D converter circuit and the true RMS converter circuit, met the demands of the leakage current acquisition, processing, computing, etc. In view of the traditional transmission line insulator leakage current sensor measurement of the frequency band are narrow, in order to improve the design and structure of the sensor, and the sensor to measure the leakage current online bandwidth and stability. At the same time, this paper also analyses the error of current sensor and also did in-depth research.To deal with the problem of on-line remote monitoring, the paper uses GSM and GPRS switch communication mode with the monitoring center for data transmission, data processing after the front desk detecting3phase the leakage current of insulator string and its related information, then the diagnosis system of the control center sends message to the control running status of the transmission line. When the monitored value is close to the flashover warning value of the monitoring central computer system alarm information, timely guide staff to insulators for maintenance, to achieve the purpose of preventing large-scale pollution flashover accident.