High-Speed Numeral Filter in Impulse Voltage Measurement

Since the CPU of embed system has some limitation in operating speed, a new filter was put forward which implemented mountain template convolution by performing rectangle template convolution two times. It can obtain time and frequency localization with computational complexity greatly reduced. This algorithm was applied to lightning waveforms (include chopped waveforms) parameter calculation. It simplifies the computation and the results pretreated by this algorithm are in accord with IEC1083-2 completely. It was applied in embed system successfully. Its capability in frequency restraining was researched. The validity of the algorithm was proved in theory when processing lightning waves. The standard sources and the processing results are consistent completely.

Research on Influence of Electromagnetic Interference on X-Ray Digital Detection

X-ray digital imaging technology has found wide application owing to its advantages of real-time, visualization and rapid imaging. In substations the substantial electromagnetic interference has some influence on the live detection by the X-ray digital imaging technology, hindering the promotion of the technology in the detection of electric equipment. Based on a large number of field tests, the author carded out a series of researches on electromagnetic interference protection measures, image de-noising, and image enhancement algorithms.

Defects and failure types of solid insulation in gas‐insulated switchgear:In situ study and case analysis

The gas‐insulated switchgear(GIS)has been widely used in modern ultra‐high voltage systems.However,once it fails,its fully enclosed feature brings challenges in its diagnosis and maintenance.As the failure rate of GIS due to insulator failure has been increasing in recent years,it is necessary and important to understand the commonly existing defects presented in the insulator.First,the manufacturing process of GIS insulators is intro-duced here.The defect types commonly existing in the insulator are categorised.The failure of GIS due to insulator defects that occurred in recent years are reviewed and discussed.The content in this study is useful for engineers and scientists to study on the GIS solid insulation defects and their failure mechanisms.

Study on the influence mechanism of ambient humidity on the temperature rise of decay-like composite insulators

At present,observing the temperature rise of composite insulators is an effective method for the detection of decay-like defects.However,ambient humidity will affect the temperature rise of composite insulators,which will cause problems in screening the decaylike composite insulators.Therefore,it is urgent to study the temperature rise principle of decay-like insulators and find out the influence mechanism of humidity on temperature rise.In this study,a four-electrode system is designed to measure the surface current,volume current and interface current of the decay-like short sample and the intact short sample under different humidity.Then the equivalent circuit models of short samples and the 500 kV full-size decay-like composite insulator are built to analyse the contribution rates of leakage conductance loss and polarisation loss to temperature rise.The results show that the contribution rates of the polarisation loss to the temperature rise of two samples are 35.8%and 23.6%in low humidity,while they are 98.3%and 64.4%in high humidity.For the full-size decay-like composite insulator,the contribution rates of polarisation loss to its temperature rise in high or low humidity are more than 99%.In addition,the proportion of polarisation loss increases at first and then decreases with the increase of the length of the decay-like section.The conclusions of this study provide a theoretical basis for further understanding the corresponding relationship between decaylike defects and temperature rise and improve the detection rate of decay-like insulators.