硅橡胶电树枝的引发与生长过程

交联聚乙烯电力电缆的应用日渐广泛,但电缆附件的电树枝击穿故障时有发生,电缆附件材料硅橡胶的电树枝引发和生长过程尚缺乏深入研究。为此,通过材料的测试分析与计算等手段,定量描述了硅橡胶材料微观结构,测试、分析了电树枝引发期的电树枝通道特征和局部放电特性。研究结果表明:硅橡胶中同时存在主链上的化学交联以及通过氢键吸附形成的物理交联;在交流场强下物理交联破坏使得材料中的微裂纹逐渐扩大,最终导致电树枝引发;硅橡胶电树枝通道呈现良好的绝缘特性,电树枝生长主要依靠局部放电下气体受热膨胀或电磁力产生的撕裂作用;增强机械性能尤其是撕裂特性可以提高材料的抗电树枝老化性能。研究硅橡胶材料的电树枝引发和生长过程为其在电缆附件中的合理使用提供了理论依据。     

800kV等级高压隔离开关的交、直流电场仿真计算

隔离开关的电场计算对于校核和优化开关结构,控制隔离开关的电晕损耗、可听噪声及无线电干扰水平低于限值具有重要的工程价值.因此利用分布式并行ANSYS计算平台,仿真得到交、直流电场条件下隔离开关所在空间的电场分布,并确定出最大场强及其位置.其中,交流场计算基于静电场理论,而直流场计算首先采用恒定传导电流场理论计算开关表面的...     

交直流复合电压油纸绝缘的沿面局部放电特性(英文)

The valve side windings of converter transformers bear AC, DC, impulse, and reversal-polarity voltages during operation, which could result in serious insulation problems of the equipment. By performing experiments with surface discharge model of oil-paper insula- tion at 80 ℃ under combined AC-DC voltage for 200 h, we studied the spectrums and statistical parameters of partial discharges at different discharge stages. Furthermore, some fingerprint parameters were calculated in order to estimate the development situation of par- tial discharge, while the characteristic gases dissolved in the transformer oil were measured by gas chromatography. The surface discharges in the experiments were observed using a high speed camera, and a full discharge process could be marked off into four stages as follows. ①The elementary stage. When a partial discharge occurs near electrodes, electrical charges are injected into the region near electrodes and causing bubble generation. ②Due to their high resistivity and low dielectric constant, the bubbles would bare the major part of the voltage applied to samples. Therefore, discharge happens inside the small bubbles, and it emits a lot of light. ③Micromolecules of gas are produced in discharge, and further ionization in the transformer oil takes place simultaneously when high-energy electrons collide with oil molecules. ④The carrier charge moves forward to electrodes driven by the applied electric field, till they neutralize with the charge from electrodes, and hence discharge channels are formed subsequently.     

直流局部放电检测系统研制与应用(英文)

Direct current (DC) partial discharge (PD) test has drawn extensive attention from world-wide electric power research institutes in recent years. However, presently, no DC PD detection device on the market has the statistical function. Thus, we developed a test system for PD detection under DC voltage, which is characterized by strong anti-jamming capability, continuous high-speed real-time data acquisi- tion and effective, complete detection of DC PD signals. The DC PD mechanism, as well as the measuring principles, software system, and hardware design of the test equipment were introduced. Adopting typical electrode pairs, we tested the statistical spectrum of PD under DC voltage. The main difference in statistical spectrums between parallel plate electrodes and needle-plate electrodes was that the time interval between two consecutive discharges for needle-plate electrodes has obviously larger variation range than that for parallel plate electrodes, which could be the convincing proof for distinguishing the type of electrodes under DC PD. Practical results indicate that the proposed sys- tem can measure time domain signals of DC PD of oil-paper insulation effectively and promptly, and it can be used to determine and detect defects in DC power transmission equipment.     

气泡及气隙裂纹缺陷对硅橡胶电树枝起始特性的影响

超高压电缆附件用硅橡胶的电树枝化严重制约了电力电缆的长期安全稳定运行。为此,采用针板电极结构,在硅橡胶试品的针尖处模拟了气泡和气隙裂纹两种缺陷,在工频电压下测量其电树枝起始电压,并通过数字显微观测系统记录电树枝形态,研究缺陷对硅橡胶电树枝起始特性的影响。结果表明,试品存在气泡缺陷时,电树枝起始电压比无缺陷时有小幅下降,起始阶段松枝状电树枝与树枝状电树枝出现的比例分别为65%和35%,与无缺陷产品相比不同电树枝形态出现的比率变化不大;而存在气隙裂纹缺陷的试品,电树枝起始电压则大幅下降,电树枝形态仅为树枝状。分析表明,硅橡胶具有优异的抗氧化性能使得缺陷中的氧对其电树枝起始特性影响较小;气隙裂纹导致的机械损伤和应力集中,是引起电树枝起始电压大幅下降的根本原因。     

纳米TiO2等离子体放电催化空气净化技术的研究

提出了空气净化的新方法——纳米二氧化钛等离子体放电催化空气净化技术,该技术是空气净化技术中最有前景的技术之一。进行了纳米二氧化钛等离子体放电催化降解甲醛的试验和杀灭芽孢杆菌的试验,取得了令人满意的结果。     

随机参数对同塔双回输电线路雷击跳闸过程的影响

同塔双回输电线路较之电压等级相同的单回输电线路具有导线数量多、杆塔高度高等结构特点,更易发生雷击故障。为了深入研究同塔双回输电线路雷击跳闸机理,结合忻州地区实际线路数据,基于Monte Carlo法这一随机数学方法建立了适用于同塔双回输电线路的雷击跳闸率仿真流程,并对其随机参数产生的影响进行了深入探讨,比较分析了单、双回输电线路雷击跳闸率受随机参数影响的敏感程度。结果表明,较之同电压等级下单回输电线路,双回输电线路对雷击部位更为敏感,其绕击跳闸率随地面倾角增加而增加的幅度更大;在考虑工频叠加电压后,单、双回输电线路反击跳闸率均有显著提高,地面倾角较大的情况下单回输电线绕击跳闸率略微减小,而双回输电线路绕击跳闸率则有明显增大。     

交直流复合电压下变压器油中电弧放电及产气特性

换流变压器是直流输电工程重要设备之一,其阀侧绕组承受的电压较为复杂,包括直流、交流、交直流叠加以及极性反转等多种电压形式。因此在构建交直流复合电压系统的基础上,采用典型针板电极模型,对变压器油在交流、直流和交直流复合电压条件下的电弧放电和产气特性进行研究。试验表明变压器油在交直流复合电场和直流电场下的绝缘性能较交流电压下差。交直流复合电压下油隙的击穿电压与其纹波因数有关,纹波因数越小击穿电压越低。引入小桥理论的极化过程很好地解释了这一物理现象。同时,不同类型的电压作用下放电产生的油中溶解气体体积分数（每种气体与总气体的体积比）一致,说明判断交流变压器的改良三比值法故障类型判断方法对交直流叠加电压和直流电压下的电弧放电故障仍然适用。但是由于直流和含有直流分量的电压更容易产生油中放电,换流变压器的油中溶解气体体积分数（换算后每升油中所溶解气体的体积）的注意值和气体增长率注意值应有别于传统交流变压器。     

工频电压对输电线路雷击跳闸率的影响

为研究工频电压对输电线路反击跳闸率和绕击跳闸率产生的影响,验证目前的试验结果,从工频叠加影响机理、蒙特卡罗法实例计算两个方面进行了计算和分析。结果显示,工频叠加影响机理分析和蒙特卡罗法实例计算的结论一致:工频电压主要提高了输电线路的反击跳闸率,而对绕击跳闸率影响不大。     

废易拉罐铝合金料的除漆熔化技术

介绍废易拉罐铝合金料重熔再生生产线的基本组成,并着重介绍废易拉罐的除漆熔化技术,指出除漆熔化是废易拉罐重熔再生的核心技术。