330kV线路避雷器的开发和应用

介绍了330 kV线路型无间隙金属氧化物避雷器的主要性能参数的确定,以及通过避雷器电位分布的实际测量,优化避雷器的均压结构;对安装在杆塔上的330 kV线路避雷器,采用在避雷器高压端加装直径为1m的均压环,在第一节和第二节避雷器元件间安装均压环的均压措施,使得避雷器的最大电位分布不均匀系数小于或等于13.56%,保证了避雷器的可靠运行;提出了避雷器在不同类型的杆塔上的两种安装及避雷器安装点的选取原则.开发的避雷器已在陕西省多条330 kV线路上应用,取得了显著的防雷效果.     

特高压直流线路避雷器灭弧技术研究

介绍了特高压直流系统避雷器的配置方案,研究了直流避雷器产生电弧的原因,并由此提出了一种直流避雷器灭弧新方案,分析了该方案的理论依据,在现有避雷器在线监测系统的基础上设计了了避雷器灭孤系统,对一步改善避雷器在线监测系统性能提供了一种思路.     

一起66kV金属氧化物避雷器故障分析

对一起66 kV金属氧化物避雷器故障进行了分析,通过对避雷器进行外观、解体检查及故障相分析,发现引起故障的原因是避雷器内部受潮,使避雷器整体绝缘迅速下降。针对此次故障提出了对避雷器进行带电测试,对硅橡胶复合外套避雷器交接验收试验时应进行交流持续运行电压下的泄漏电流、阻性电流测量及避雷器抽检试验,以提高避雷器运行的可靠性。     

输电线路避雷器断串分析与防范

目前采用的线路型避雷器多为绝缘子间隙避雷器。运行单位在安装线路避雷器时主要考虑的是避雷器的电气性能,很少对避雷器的安装形式和运行状态下的受力情况进行分析,以至运行中出现掉串现象。例举了一起线路型避雷器断串缺陷,通过计算分析得出断串的原因,并提出了避雷器安装的防范措施。     

避雷器在线监测系统应用

通过对运行避雷器漏电流及放电次数的在线监测 ,可以有效地检测避雷器内部缺陷 ,及时发现故障 ,避免避雷器爆炸 ,降低事故发生率 ;避雷器在线监测系统使避雷器的监测更及时 ,更准确 ,大大提高了避雷器的运行可靠性。     

氧化锌避雷器在线监测系统研究与设计

氧化锌避雷器是目前电力系统中应用最广泛的避雷器,对其运行状况进行在线监测十分必要。介绍了氧化锌避雷器的基本结构、特性及其等效电路,并对主要的避雷器在线监测方法进行了对比分析。在此基础上,采用谐波分析法设计了一套氧化锌避雷器在线监测系统。相关测试结果表明,设计的避雷器在线监测系统能对氧化锌避雷器的运行状态和综合性能进行实时监测和准确诊断,具有较强的应用价值。     

特高压直流避雷器的技术特点与分析

文章介绍了特高压直流输电工程中所用的各种直流避雷器的作用,特别是±800kV直流换流站内典型的避雷器保护方案;以及不同位置的几种关键的直流避雷器如高压端阀避雷器(V1)、高能中性母线避雷器(E2H)、极母线避雷器(DB)、换流变阀侧避雷器(A1)、平波电抗器避雷器(DR)等所承受的波形;我国直流输电工程用避雷器的情况以及我国自主研发高压直流避雷器的应用进展。讨论了特高压直流避雷器与高压直流避雷器共有的特性参数如持续运行电压、配合电流、能量耐受和功率损耗等参数的变化特点,分析了特高压输电工程所特有的直流避雷器V1、E2H、A1、DR、DB的主要特性和作用,给出了这几种避雷器的几个主要配合参数和极母线避雷器的设计参数,讨论了特高压避雷器设计开发中要注意的电阻片容量和伏安特性、均流技术、污秽技术、均压技术等一系列关键技术。     

±800kV DC换流站避雷器配置与参数选择

基于特高压换流站的特殊性考虑,介绍了两种不同的避雷器配置方案,方案A采用M2避雷器和CB1A避雷器,方案B采用A2避雷器、CB1A和CB1B避雷器。讨论了配置C2避雷器的必要性,分析了CB1B避雷器优化经济性的原因及平抗分置所带来的优势,并根据避雷器直流参考电压的选择原则选择了相应参数,对DC输电工程具有参考作用。     

雷电过电压下避雷器的相互配合

本文对安装于同一变电站的不同的金属氧化物避雷器、普阀式及磁吹避雷器的行波保护问题做了论述;比较了各种避雷器,尤其是金属氧化物避雷器的特性参数;探讨了不同的避雷器动作电流问题;并就保护方案及避雷器选择提出了看法;对避雷器国家标准也提出了具体建议。     

氧化锌避雷器泄漏电流特性分析

氧化锌避雷器被广泛应用于高压电气设备过电压防护。根据观测氧化锌避雷器的泄漏电流,可以有效判断避雷器的健康状态。提出了一种氧化锌避雷器的有限元仿真建模方法,利用该模型分别计算220 kV避雷器在交、直流电压作用下的泄漏电流,并通过对比试验,验证了仿真模型的准确性。利用该模型仿真分析了220 kV避雷器在不同受潮状态下的泄漏电流特性,为避雷器在线监测预警提供了依据。     

一种氧化锌避雷器阻性电流的提取方法

氧化锌避雷器作为电力输变电系统的一个核心保护设备,必须进行在线状态监测。文章在研究氧化锌避雷器常用的在线监测方法的基础上,提出了一种基于谐波分析法的新的氧化锌避雷器阻性电流提取方法。该方法采用准同步DFT谐波分析线性修正算法来实现氧化锌避雷器的阻性电流的测量。仿真实验和现场实验表明,该方法可行、有效,有极高的应用价值。     

Improved zinc oxide surge arresters using high voltage gradient 300V/mm, 400 V/mm ZnO elements

Zinc oxide surge arresters using zinc oxide (ZnO) elements have been widely used for insulation coordination in the world's power systems. These ZnO elements have basically reference voltage of about 200 V/mm. Recently, new ZnO elements having about 1.5, 2 times high voltage gradient zinc oxide element have been developed. This paper describes applications of high voltage gradient 300 V/mm ZnO elements to high performance porcelain type surge arresters and oil immersed surge arresters, and 300 V/mm or 400 V/mm ZnO elements to gas insulated tank type surge arresters for power systems. Adequate selection of voltage gradient of ZnO elements makes more compact design of the surge arresters     

Light rail transit DC traction power system surge overvoltageprotection

At present, there are no industry standards or recommended guidelines for the application of DC surge arresters. It appears that such devices are applied based upon a rule of thumb without the benefit of analyzing characteristics, wave shape, and energy content of the expected overvoltage surges against the capabilities of the surge arrester. AC surge arresters are rerated for DC application. A difficulty arises due to a lack of clear published application literature on DC surge arresters, as well as lack of measured data on DC power system transient surges. This leads to the application of surge protective devices, which may be inappropriate. This paper describes the application of DC surge arresters to a typical light rail transit traction power system, and it makes a recommendation for the need of a standard on DC surge arresters test requirements and application guidelines     

Suppressing the effect of lightning-induced overvoltages by the combined use of surge arresters and overhead ground wires

Lightning voltage induced by nearby strokes is one of the causes of major overvoltages which threaten the insulation of power distribution lines. Surge arresters as well as an overhead ground wire usually are employed for the protection of equipment and line insulation on overhead power distribution lines. The fundamental mechanism of suppressing effects of overvoltages induced by nearby strokes has been demonstrated independently by one of the present authors for surge arresters and for an overhead ground wire. In this paper, the protective effect of the combination of surge arresters and overhead ground wire is analyzed. As a result, it is found that the effect of surge arresters used together with an overhead ground wire is almost the same as that of surge arresters alone.     

Coordination of surge arresters with medium-voltagecurrent-limiting fuses

Current-limiting fuses (CLFs) are commonly used for unit substation primary protection. Simultaneously, surge arresters are also provided on the primary side of the transformers, more so for the dry-type transformers. The arc voltages generated by CLFs will store energy in the inductive elements of a distribution system. This stored energy divides between the CLF and surge arrester, and the surge arrester may operate. This paper outlines a procedure to calculate the energy diverted to the surge arresters and shows that, in some cases, surge arresters may fail on operation of the CLFs. Guidelines are developed for selection and application of the surge arresters at 13.8-, 4.16-, and 2.4-kV voltage levels     

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     

Transmission line arrester energy, cost, and risk of failureanalysis for partially shielded transmission lines

Application of metal oxide surge arresters in power systems has been traditionally linked to electrical equipment protection. The industry has noted a very significant increase in the application of metal oxide arresters on transmission lines in an effort to reduce lightning initiated flashovers. This paper describes a cost-effective installation of surge arresters on a partially shielded transmission line. It compares several options with respect to cost and gains in terms of lightning performance improvement. This paper also presents a new approach to calculate risk of failure of transmission line surge arresters (TLSAs) due to lightning strokes to towers, shield/phase conductors, and illustrates the method with an example for a partially shielded line. Results show that the risk of failure is very small. The installation of TLSAs completed in 1997 demonstrated that it is possible to afford adequate lightning protection levels by selectively applying surge arresters only to the towers most sensitive to backflashover and shielding failures     

Detection of Damaged Distribution Surge Arresters Using an Impulse Generator

Distribution surge arresters with an internal series gap have been installed on Japanese distribution lines at high density to reduce lightning‐related overvoltages. In contrast, surge arresters are sometimes damaged by direct lightning strokes, particularly in winter. Measurement of the insulation resistance between the terminals of the surge arrester and measurement of the dc discharge voltage of the surge arrester are generally adopted to detect damaged arresters. However, if metal‐oxide (MO) varistors are damaged and the internal series gap is not damaged, it is difficult to detect damaged arresters by the two conventional methods. Therefore, this paper presents a proposed detection method that can accurately detect damaged arresters. In the proposed method, first, the voltage between the terminals of the surge arrester is measured when the output of an impulse generator is applied to the surge arrester. Second, the damaged arrester is detected by comparison between its voltage waveform and the voltage waveform of the nondamaged arrester. The detection rate of damaged arresters by the proposed method is markedly higher than the rates of detection by the two conventional methods.     

Evaluation and application of oil-immersed zinc oxide elements enclosed in pole-mounted distribution transformers

Voltage due to lightning surge is now a major problem to be overcome to ensure full reliability of any power supply. Hence, gapless oil-immersed surge arresters using zinc oxide elements have been applied to pole transformers. These surge arresters are used as a means of insulation coordination for pole transformers. These arresters contribute to the reduction of the number of failure of pole transformers. This paper describes applications and effects of specially developed oil-immersed surge arresters in pole transformers on 6.6-kV distribution lines. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 121(2): 37–46, 1997     

Temporary overvoltage capability of surge arresters for 1000 kV power systems

Insulation level (LIWV 2250 kV) of 1000 kV gas insulated switchgear will be adopted by installing high performance 1000 kV surge arresters. But when temporary overvoltage (TOV) is generated in power systems at line faults and load rejection including Ferranti effects, high performance surge arresters flow discharge current according to the value of TOV. Therefore, it is important to check TOV discharge capability of surge arresters. This paper describes the screening of zinc oxide elements using thermography (thermal uniformity factor) obtained by an infrared radiation camera, with discharge capability of surge arresters for 1000 kV power system.