10kV复合外套避雷器大电流冲击耐受能力研究

10 k V复合外套避雷器在电力系统中有着较庞大的应用数量,而大电流耐受能力是制约复合外套避雷器应用的重用因素.对10 kV复合外套避雷器开展整只4/10μs、65 kA大电流冲击耐受试验,并对试验结果进行分析,得出生产工艺与大电流冲击耐受能力存在密切关系,因此在非电阻片因素下对生产工艺进行改进,从而最大程度提高其大电流冲击耐受能力.     

珠江三角洲某地区雷电特征对10kV配网用避雷器故障的影响分析

为了研究和总结10 kV配网用避雷器故障的规律,笔者以珠江三角洲某地区2010年10 kV配网避雷器故障数据为样本,根据避雷器故障部位的不同将避雷器故障分为绝缘筒外表面闪络、电阻片炸裂、绝缘外套爆裂3种故障类型;结合雷电地闪分布、雷电流幅值分布和避雷器本身因素分析造成3种故障类型的原因。其次,引入电气几何模型原理分析造成顶/上相避雷器故障比例最大的原因是顶/上相避雷器最容易遭受大电流雷电冲击且动作频次最高。最后通过建立10 kV架空配电线路杆塔的PSCAD仿真模型,分析不同接地方式对避雷器雷电流的泄放量的影响,为10 kV配网避雷器接地方式的选取提供依据。     

配网避雷器产品国家监督抽查方案建议及可行性分析

近5年避雷器产品质量国家监督抽查合格率稳步提升的同时抽样率下降明显,为了提高产品抽样率使抽查样本具有足够的覆盖力,提出了新的避雷器产品国家监督抽查方案建议。文中通过分析现行避雷器产品国抽过程中暴露出的电阻片产品抽样难、电阻片样品与避雷器中实际电阻片不一致、大电流冲击耐受试验等价性等问题,提出直接在产品流通领域抽取整只避雷器作为样品,并联系产品制造企业对样品进行书面确认的新抽样方式,要求所有检验项目都在整只避雷器上进行。并且从必要性、可行性、预计产生的影响等方面分析了新抽检方法的适用性。新的抽样方式不仅可以增加抽样的灵活性提高抽样率,还可以查处流通领域的假冒产品;整只避雷器样品上进行大电流冲击耐受试验(大电流幅值有待论证)会导致抽检合格率降低,但这一方式可以刺激生产企业严控产品质量,引导企业远离不合理的低成本竞争,对于行业的长期健康发展具有积极促进作用。     

配电网避雷器运行故障原因分析及建议

着重研究了氧化锌避雷器故障类型及原因。避雷器雷电冲击耐受寿命与其内部氧化锌电阻片的参数性能和整体制作工艺密切相关,避雷器整体密封性不良受潮,氧化锌电阻片额定电压过低,承受的较大暂时过电能量过载,避雷器整体耐受雷电冲击能力较差都是造成入网避雷器抗雷击能力和应对外部受潮和系统过电压等外界因素抵抗力不足,频发故障的原因。     

110 kV整只氧化锌避雷器雷电冲击老化特性研究

避雷器在其运行寿命过程中会承受多次雷电冲击过电压,其保护性能的变化值得关注。选取110 kV整只氧化锌避雷器作为试验研究对象,开展了多次连续的雷电冲击电流（8/20 μs, 10 kA）试验,测试了试验过程中避雷器的小电流伏安特性和残压。研究发现了110 kV整只避雷器在多次雷电冲击电流作用下的小电流伏安特性和残压变化规律及发生显著变化时的阈值次数,并解体分析了雷电冲击后避雷器内部电阻片的破坏形式。最后从微观机理上解释了避雷器在多次雷电冲击作用下的老化特征。     

配网线路避雷器阀片90/200微秒冲击电流耐受特性试验

为了试验调查现有线路避雷器阀片在90/200 μs冲击电流下的耐受能力,对标称放电电流为5 kA和10 kA的两种ZnO避雷器阀片分别进行了不同能量等级下放电冲击次数为18次的90/200 μs冲击电流耐受特性试验,并进行了相同能量等级下单次90/200 μs冲击电流与4/10 μs大电流冲击耐受特性对比试验。试验结果表明,相同能量等级下4/10 μs大电流冲击对阀片造成的损伤大于单次90/200 μs冲击电流造成的损伤;5 kA阀片最高可通过约3.5 kA的18次90/200 μs冲击电流耐受特性试验,10 kA阀片最高可通过约7.3 kA的18次90/200 μs冲击电流耐受特性试验;直流1 mA参考电压作为评价避雷器阀片性能判据的敏感度高于标称放电电流残压。     

基于雷击特性的配网避雷器可靠性与经济性研究

为掌握配网避雷器雷击特性并提出经济可靠的改善措施,首先对典型10kV配网工程的配变用避雷器和线路用避雷器的雷击工况进行了归类和仿真计算,得到其残压、放电电流、吸收能量变化规律及数值水平,然后对D3、D4和D5三种电阻片避雷器的吸收雷电冲击能量水平进行了计算,同时结合了已得到的雷击工况下避雷器的电气特征量数据,给出避雷器出现电气过载的雷电流范围和对应避雷器过载概率,进而以南方电网为例对配置不同电阻片避雷器进行了经济性评估,评估结果表明采用D4或D5电阻片避雷器可以降低年均运行成本、提高供电可靠性、减少检修压力。     

包封材料的改进及其对压敏电阻大电流耐受性能的影响

为了满足IEC和国标对避雷器阀片大电流冲击耐受性能指标的要求，通过对环氧树脂配方及工艺的调整，研制了新型环氧包封材料，使环氧树脂与氧化锌瓷体的热膨胀系数更加匹配，大幅度提高氧化锌压敏电阻阀片大电流冲击耐受性能。     

一起110 kV避雷器事故分析及思考

通过对一起110 kV线路终端无间隙复合外套金属氧化物避雷器爆炸事故同批次试品的解体检查试验, 指出整体密封性能较差导致运行受潮 是加速了电阻片老化的主要原因。针对线路终端避雷器运行条件和运行管理的薄弱环节,提出运行管理和试验维护建议。     

再议10kV线路避雷器雷电耐受技术参数的选用

10kV线路避雷器自身运行雷击损坏故障多发,归因为雷电耐受设计参数水平低缺乏充分论证。该文构建了10kV架空线路直击雷过电压瞬态过程计算模型,以冲击大电流幅值耐受超限作为避雷器本体雷击损坏的判据,计算获得线路避雷器故障临界雷电流,采用电气几何模型法统计得到线路避雷器的雷击故障概率,证明了现行技术标准规定的避雷器雷电耐受技术参数能够满足一般雷电强度地区的使用要求。进一步结合我国雷电活动区域分布特征,提出线路避雷器雷电耐受技术参数优化选择建议:用于雷电地闪密度小于4.71次/(km~2·a)的多雷区、中雷区、少雷区的线路,选择8/20μs标称放电电流为5kA、4/10μs大电流冲击为65kA;用于强雷区的线路和雷电地闪密度大于等于4.71次/(km~2·a)的多雷区的重要线路,选择标称放电电流为10kA、大电流冲击为100kA。并建议大电流冲击耐受试验采用整只避雷器本体为试品,促进生产工艺改良,改善线路避雷器产品实际雷电耐受性能与设计指标不匹配问题。     

Review of generator surge coordination including generator breakers

The results of a utility survey on surge protection practices for large generators are presented. The surge environment, 60 Hz withstand test value, designated impulse withstand, arrester protective levels, and insulation breakdown tests on two machines were compared. Factors included in the surge environmental were lightning, faults, HV switching, ferroresonance. opening surges, breaker failure, and system-side resonance. Several topics are identified for further study     

合成套氧化锌限压器的热特性研究──第一部分：限压器热特性研究的有限元法及其散热特性

本文用传热学理论分析了合成套ＺｎＯ限压器的热传导，采用有限元方法（ＦＥＭ）来求解限压器的温度场，分析计算其整体热性能；编写了限压器整体热性能分析计算软件；分析计算了合成套ＺｎＯ限压器的散热性能，合成套限压器的散热时间常数明显低于瓷套限压器的散热时间常数。散热试验表明，计算结果与试验结果吻合较好。     

Development of polymeric surge ZnO arresters for 500-kV compact transmission line

The 500-kV polymeric ZnO surge arresters for compact transmission line against lightning overvoltage were developed and have been put into operation, which consists of arrester unit and series gap. The design of the arrester unit, including structure design, selection of ZnO varistor, parameter determination, polymeric housing design, and mechanical structure design was discussed. The design of the series gap and the determination of the series gap length were presented. The calculated results state the line surge arrester can highly improve the lightning withstand level of the compact transmission line, and the line surge arrester can withstand the effects of lightning.     

Effect of overhead ground wires on reduction of failure rates of surge arresters on power distribution lines

Surge arresters are sometimes damaged by lightning strokes with high energy, in spite of installation of conventional protection methods. In order to reduce the number of failures of surge arresters, we should consider another protection method, such as an increase in the withstand capability of surge arresters and installation of additional overhead ground wires. However, quantitative comparison of these methods for preventing damage to surge arresters against lightning strokes with high energy has never been performed. This paper describes the effects of additional overhead ground wires for preventing damage to surge arresters. The main results are: (1) The failure rate of surge arresters on a distribution line with two overhead ground wires is about one third of that with an overhead ground wire. (2) Installation of a second overhead ground wire six to eight spans from the end of a line reduces the failure rate of a surge arrester at the end as effectively as increasing the withstand capability by a factor of two. © 1998 Scripta Technica. Electr Eng Jpn, 122(2): 12–20, 1998     

1 000 kV大跨越直线塔防雷间隙取值及优化

为评估1000kV交流特高压大跨越线路的耐雷性能,首先依据设计规范要求,计算了直线塔雷电过电压间隙取值,随后利用ATP-EMTP建立仿真模型,研究了大跨越线路的反击及绕击耐雷水平和雷击跳闸率,最后分析了线路避雷器对耐雷性能的影响。研究结果表明：直线塔下相安装避雷器,可显著提高大跨越线路的耐雷性能,使雷击跳闸率降低66%;安装避雷器后,上、中相雷电过电压间隙可减小1.5m,此时雷击无故障时间为99年,这有利于降低塔高、节省塔材。     

Rocket-triggered lightning experiments on zinc oxide arresters and their applications to power transmission lines

In measurements of rocket-triggered lightning current and voltage performed between 1986 and 1995 on the mountain top of Okushishiku in the Kanazawa area, the authors succeeded in artificially inducing winter lightning to arresters. Using the data obtained from those measurements, we analyzed the energy absorption characteristics of surge arresters, such as are installed on every transmission line tower for three phrases, by EMTP. The energy withstand capability of an individual arrester was verified to be approximately the same as the expected value. The analysis results for the energy share of each arrester connected in parallel showed that the usual light duty arresters installed on every tower have the possibility to be able to absorb extreme winter lightning energy even if the lightning hits the power line directly. © 1998 Scripta Technica. Electr Eng Jpn, 122(4): 25–33, 1998     

A Procedure for Estimating the Lifetime of Gapless Metal Oxide Surge Arresters for AC Application

The development of the gapless metal oxide (ZnO) surge arrester has presented the arrester engineer with new materials and an opportunity for new designs. This situation arises because the gapless surge arrester is electrically active throughout its lifetime whereas its predecessor, the silicon carbide arrester, was electrically passive being electrically isolated with gap structures. The prime consideration is one of reliably estimating the lifetime of a gapless ZnO surge arrester under continuous ac stress while maintaining the capability not only to limit surge voltages but also to absorb energy inputs resulting from lightning or switching surges and temporary overvoltages. In this paper we establish a procedure for reliably estimating the lifetime of gapless metal oxide surge arresters for ac application by incorporating the device characteristics into design requirements. This method is illustrated for metal oxide surge arrester elements that exhibit a predictable linear resistive current versus time1/2 behavior as a function of applied voltage and temperature.     

Surge transference through transformers

The article demonstrates the need for secondary surge protection on main utility tie transformers and low-voltage substation transformers. Investments in these surge protection devices are minimal and an insurance against insulation failures. A more elaborate transformer model could be used in EMTP simulations, however, the results based on the simplified transformer inductive/capacitance model are valid for practical purposes. The modeling of surge phenomena on EMTP is complex, and a modeling of all the possible surges of atmospheric origin or generated within a distribution system will be time consuming. The cost of providing secondary surge protection on unit transformers is rather small, though a coordination of the surge arrester characteristics is required. Considerations should be applied to the overvoltage withstand capability of solid-state protective devices, ASDs, and monitoring and control equipment, which is much lower than the insulation levels associated with the power equipment.     

硅和碳化硅二极管在脉冲功率源中的对比研究

碳化硅功率器件近年来发展很快,具有高击穿电压、高热导率等优点。通过仿真和实验研究了碳化硅二极管作为续流二极管应用在脉冲形成网络中的表现,并与硅二极管作对比。实验结果表明,碳化硅二极管在常温下抗浪涌电流能力不如硅二极管。在高温下两者抗浪涌电流能力均有所减弱,但硅超快恢复二极管的抗浪涌电流能力下降更多。可以预见在更高的温度下,碳化硅肖特基二极管的抗浪涌电流能力将超过硅快恢复二极管。     

复合外套避雷器在昌房500kV紧凑型线路的防雷效果分析

５００ ｋＶ昌房紧凑型线路采用线路避雷器后,能较大地提高线路的耐雷水平。紧凑型线路避雷器本体的荷电率取０．９,完全能承受雷击杆塔时的放电电流和放电能量。