基于SF_6分解产物的GIS设备放电类型与位置的诊断方法

针对目前工作中监测SF_6中SO_2、H_2S的浓度无法有效指导放电故障诊断的问题,首先,从SF_6在放电状况下分解的机制出发,分析不同放电类型下不同放电位置SF_6中可能产生的分解产物;提出利用特征值和特征物质种类诊断GIS设备放电类型和位置的方法,并在实际案例中得到验证。

Analysis of the Molecules Structure and Vertical Electron Affinity of Organic Gas Impact on Electric Strength

It is necessary to find an efficient selection method to pre-analyze the gas electric strength from the perspective of molecule structure and the properties for finding the alternative gases to sulphur hexafluoride （SF6）. As the properties of gas are determined by the gas molecule structure, the research on the relationship between the gas molecule structure and the electric strength can contribute to the gas pre-screening and new gas development. In this paper, we calculated the vertical electron affinity, molecule orbits distribution and orbits energy of gas molecules by the means of density functional theory （DFT） for the typical structures of organic gases and compared their electric strengths. By this method, we find part of the key properties of the molecule which are related to the electric strength, including the vertical electron affinity, the lowest unoccupied molecule orbit （LUMO） energy, molecule orbits distribution and negativeion system energy. We also listed some molecule groups such as unsaturated carbons double bonds （C=C） and carbonitrile bonds （C=N） which have high electric strength theoretically by this method.

Insulation characteristics of triple mixtures of c-C_4F_8/N_2/CO_2 under lightning impulse voltage

This paper has researched the insulation characteristics of 10% c-C4F8/N2/CO2 mixtures under lightning impulse voltage by experiment. It is shown that the positive and negative lightning impulse breakdown voltages of 10%c-C4F8/N2/CO2 gas mixtures rise linearly as the electrode gap distance and gas pressure increase and under the same conditions, the positive lightning impulse breakdown voltage of the gas mixtures is always higher than the negative lightning impulse breakdown voltage. As the gas mixtures have a little higher liquefied temperature than SF6 and the comprehensive GWP is about 5% of SF6, and the positive and negative lightning impulse breakdown voltages can both reach 60% of SF6, 10%c-C4F8/N2/CO2 gas mixtures can be applied as insulation gas in electrical equipment such as C-GIS, GIT, GIL and so on.

Study of partial discharge characteristics in HFO-1234ze(E)/N2 mixtures

HFO-1234 ze(E)(trans-1,3,3,3-tetrafluoropropene,chemical formula:C3H2F4)is an extremely environmentally friendly SF6 alternative gas with high electrical strength.In this paper,the partial discharge(PD)characteristics of HFO-1234 ze(E)/N2 mixtures were studied using the gas insulation test platform.The PD inception voltage of insulating gas under positive and negative half cycles of power frequency was tested.Using SF6/N2 mixtures as a control group,the effects of electrode spacing,mixing ratio and pressure on the insulation performance of HFO-1234 ze(E)/N2 mixtures were explored.The test results show that the PD inception voltage of the negative half-cycle of pure HFO-1234 ze(E)under short electrode spacing can reach 0.96-1.04 times of pure SF6 under different pressures;the PD inception voltage of40%HFO-1234 ze(E)/60%N2 mixtures at 0.3 MPa is 0.67-0.89 times that of SF6/N2 mixtures under the same conditions,which has great application prospect.

单壁碳纳米管气体传感器在GIS局部放电检测中的应用(英文)

This paper describes a realizable fabrication method to manufacture chemical gas sensors by using singlewalled carbon nanotubes(SWCNTs).The sensors were tested for the monitoring of SF_6 decomposition gas produced by partial discharge(PD) in GIS tank.The results showed a superior sensitivity,favorable reliability and good reproducibility. For further clarifying the relativity between sensor response and partial discharge activity,the discharge in GIS tank was monitored simultaneously through conventional pulse current method and a SWCNTs gas sensor,and the measurement results were put together for comparative analysis in this paper.The sensor response showed a great dependence on partial discharge characteristics.The sensor response increased nearly linearly with limits when the energy of discharge was persistently accumulated.Partial discharge power had a great influence on the response rate and the time delay.With the increase of partial discharge power,the response rate augmented almost in proportion while the time delay gradually becomes shorter with limits.The results were quite favorable to assess the partial discharge intensity and duration to some extent.Compared with pulse current method,the sensor was predominant to detect partial discharge exposed to constantly high levels of noise.It was capable of detecting partial discharge which was too weak to be detected with pulse current method.However,the sensor response didn't show much dependency on the apparent discharge of partial discharge.

浅论六氟化硫组合开关安装的管理

随着国民经济的发展需要,高压配电SF6的装置广泛应用于水电站、城区变电站。做好SF6的安装、维护,能保证电力系统的安全运行。

Estimation of the Type of Low Energy Discharge in GIS Adopting Characteristic Gas

In order to guarantee safe operations, low energy discharge within gas insulated switchgear （GIS） should be detected as soon as possible before they develop severely and cause final breakdown failures. This paper aims to present a GIS discharge diagnosis technique adopting gaseous decompositions. To reach this aim, needle-plate electrode and the sphere-plate electrode with metallic particles on the plate are designed to simulate two kinds of low energy discharge, namely, corona discharge and spark discharge, respectively. After sampling and analyzing the gases, different yields of gaseous by-products under different types of low energy discharge are obtained. Based on the decomposition mechanisms reported by previous researches and the experiment results, it can be concluded that S2OF10, SO2F2 , and SO2 can be used as the characteristic gas to identify low energy discharge; the increment of S2OF10 can indicate the occurrence of low energy discharges while the volume ratio between SO2F2 and SO2 can define the type of low energy discharge.