Contamination Depositing Characteristics And Contamination Condition Monitoring Method Of Insulators

The pollution flashover of electric power equipment is a great threat to the safe operation of power system. It is considerably important to master the contamination condition and discharge status of insulator timely for effective making of pollution severity, reasonable configuration of external insulation and active implementing of contamination online monitoring and warning. This paper has discussed the characteristics of natural contamination with different types insulators, impacting factors of leakage current(LC) about suspension insulators and post insulators, on-line monitoring method of contaminantion condition and contamination discharge, and so on.In order to summary natural contamination deposit law about XP-70suspention insulators, XP-70insulators coated with RTV, glass insulators, composite insulatos, anti-pollution post insulator and common post insulator, the contamination characteristic has been systematically observed for3years at168line suspension insulators contamination point,65comparison measuring points of different types suspension insulators and50substations measuring points. In the result that the influencing factors of contamination characteristics are analyzed under condition of different contamination periods, different types such as power or no power, then the energy coefficient, saturation coefficient and the insulators types coefficient, which can be a quantitative basis data for the coefficient’s choice of pollution classification for electric power system, was obtained finally.A comprehensive contamination observatory for power system has been independently developed for the on-line monitoring of insulator-contamination condition, which can monitor environmental temperature, humidity, wind speed, wind direction, atmospheric pressure and rainfall, et al.9meteorological elements and acquire complete LC waveforms. The functions of data acquisition, serial communication, wireless transmission, database administration and data query were realized, that implement the synchronous all-weather real-time monitor of six substations in ShenZhen area. During2years stable operation, a lot of LC and meteorological data had been obtained.This paper has deeply analyzed the relationship between LC and meteorological data and changing features of every day and month based on the field data of six substations in ShenZhen. It has emphasizes the relationship between LC and temperature and humidity under condition of rain and no rain, puts forward that LC changes in random affected by the rain under condition of no rain and there was a significant correlation between LC and humidity under rain condition in the Shenzhen region. It is said that the LC and humidity can well satisfy with the exponential relation by using linear and nonlinear regression of fitting LC and environment humidity data under no rain condition.In order to study the relationship between LC and impact factors of LC in unsaturated humidity environment, a lot of research were carried out on suspension insulators and post insulators in multi-factors environmental chamber in the laboratory. The result showed that the equivalent salt deposit density(ESDD), non-soluble deposit density(NSDD) and relative humidity had little effect on LC when the relative humility was below70%, and when the relative humidity was above70%, ESDD and NSDD affected the LC amplitude significantly. The relationship between LC and RH, creepage distance, voltage gradient, the ESDD, NSDD and types of insoluble was discussed on the basis of the quantitative relationship expression between insulator LC amplitude and ESDD, NSDD and humidity, which was established in this paper. Then mathematical model was proposed for quantitative prediction of the insulator surface contamination degrees, ESDD, NSDD based on the LC and the relative humidity, which can provide a theoretical basis for real-time monitoring of the contamination status based on the LC of the insulator.For analyzing the relationship between polluted insulator LC waveform and the surface discharge status, a large number of experiments were carried out, which are artificial pollution test of long strings of XP-70porcelain insulators in the heavy fog environment by the high speed photography and LC waveform synchronous observation. This paper has given a detailed analysis of varistion and relationship between kinds of typical LC and the characteristic quantity of the waveform, and get the characteristic of Pro-flashover LC. It is proposed that LC waveforms with the characteristics of high-amplitude, low harmonic content, small phase difference between the fundamental current and the voltage should be focused on, and finds that the good relationship between the discharge strength and LC waveform. It is suggested that the method of identifying different types of current waveform by the LC amplitude, total harmonic distortion rate, current and voltage phase difference and the amplitude positive and negative half-wave, which provides a new idea about the state of the polluted insulator discharge state real-time monitoring.