The Investigation On Optical And Passive Measuring Technology Of Insulator Leakage Current

Smart grid is an important direction for the development of China's power grid and ensuring the stable operation of transmission lines is one of the key tasks of smart grids.In the operation and maintenance of transmission lines,online monitoring of insulator contamination has received much attention.By monitoring the contamination state during the operation of the insulator string,the efficiency of the insulator string cleaning work can be improved and the possibility of pollution flashover can be reduced.Leakage current is an important monitoring object of transmission lines.At present,the measurement of the leakage current of the insulator string is mainly based on electronic measurement and wireless public network transmission and the data security,transmission stability and long-term effective power supply to the measuring device are not guaranteed.Therefore,research on a passive,anti-electromagnetic interference insulator string leakage current monitoring technology has a high application value.In this paper,based on the three optical signal transmission technologies of phase modulation,intensity modulation and optical fiber sensing,the measurement principle,system model and implementation of the leakage current of the insulator string have been studied.Three optical leakage current measurement schemes are designed,simulated and tested separately.Based on the fiber grating-based leakage current measurement scheme,a set of highly feasible leakage current measurement system is realized.The experiment shows that the measured current data and the current sensor for calibration have high consistency.The main research work and achievements are as follows:1.A leakage current measurement scheme based on phase modulator is designed.The designed scheme is simulated by MATLAB and VPI.The temperature characteristics of the phase modulator are tested and analyzed.2.A leakage current measurement scheme based on intensity modulator is designed,and the designed scheme is simulated by VPI.The signal-to-noise ratio of a single fiber transmission system and a dual fiber transmission system is compared by building an actual link.The range and accuracy of the measured current of the experimental link are measured and the temperature characteristics of the intensity modulator are tested and analyzed.A leakage current measurement scheme based on Bragg grating is designed and a set of leakage current measurement system was realized.3.Measurement experiments are carried out in the laboratory environment and the artificial fog chamber of CHINA ELECTRIC POWER RESEARCH INSTITUTE.The experiment shows that the system has high feasibility in monitoring the leakage current of the insulator string.