抗雷击架空配电线路的可靠性毕业论文外文翻译.doc

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1、外文资料翻译Reliability of Lightning Resistant Overhead Distribution Lines Lighting continues to be the major cause of outages on overhead power distribution lines. Through laboratory testing and field observations and measurements, the properties of a lightning stroke and its effects on electrical distri

2、bution system components are well-understood phenomena. This paper presents a compilation of 32 years of historical records for outage causes, duration, and locations for eight distribution feeders at the Oak Ridge National Laboratory (ORNL) .Distribution type lightning arresters are placed at dead-

3、end and angle structures at pole mounted wormer locations and at high points on the overhead line. Station class lightning arresters are used to protect underground cable runs, pad mounted switchgear and unit substation transformers. Resistance to earth of each pole ground is typically 15 ohms or le

4、ss. At higher elevations in the system, resistance to earth is substantially greater than 15 ohms, especially during the dry summer months. At these high points, ground rods were riven and bonded to the pole grounding systems in the 1960s in an attempt to decrease lightning outages. These attempts w

5、ere only partially successful in lowering the outage rate. From a surge protection standpoint the variety of pole structures used (in-line, corner, angle, dead end, etc.) and the variety of insulators and hardware used does not allow each 13.8 kV overhead line to be categorized with a uniform impuls

6、e flashover rating (170 kV, etc.) or a numerical BIL voltage class (95 kV BIL; etc.). For simplicity purposes in the analysis, each overhead line was categorized with a nominal voltage construction class (15 kV, 34 kV, or 69 KV). Six of the eight overhead lines (feeders 1 through 6) were built with

7、typical REA Standard horizontal wood cross arm construction utilizing single ANSI Class 55-5 porcelain pin insulators (nominal 15 kV insulation). The shield angle of the overhead ground wire to the phase conductors is typically 45 degrees. One overhead line (feeder 7) was built with transmission typ

8、e wood pole construction because the line extended to a research facility which was to have generated electrical power to feed back into the grid. Pole structure of this line are of durable wood cross a construction which utilize double ANSI 52-3 porcelain suspension insulators to support the conduc

9、tors (nominal 34 kV insulation). The shield angle of the overhead ground wire to the phase conductors for feeder 7 is typically 30 degrees. In 1969, an overhead line (feeder 8) was intentionally built with lightning resistant construction in an attempt to reduce lightning caused outages. Pole struct

10、ures of the line have phase over phase 24-inch long fiberglass suspension brackets with double ANSI 52-3 porcelain suspension insulators to support the conductors (nominal 69 kV insulation). The shield angle of the overhead ground wire to the phase conductors for feeder 8 is typically 30 degrees. Th

11、e failure data was compiled for each of the eight 13.8 kV feeders and is presented in Table, along with pertinent information regarding feeder construction, elevation, length, and age.A key finding of the failure analysis is that weather-related events account for over half (56%) of the feeder outag

12、es recorded. Fifty-seven of the 76 weather-related outages were attributed to lightning. Insulation breakdown damage due to lightning is also suspected in at least a dozen of the equipment failures observed. The data indicates overhead lines which pass over high terrain are less reliable because of

13、the greater exposure to lightning. For example, feeder 3 had the most recorded outages (48), of which two-thirds were due to weather-related events; this feeder is also the highest line on the plant site, rising to an elevation of 450 above the reference valley elevation. Overhead lines that are lon

14、ger and to which more substations and equipment are attached were also observed to be less reliable (more exposure to lightning and more equipment to fail). The age of the line does not appear to significantly lessen its reliability as long as adequate maintenance is performed; none of the lines hav

15、e had a notable increase in the frequency of outages as the lines have aged. As would be expected, the empirical data presented in Table I confirms the two overhead lines which have been insulated to a higher level (34 or 69 KV) have significantly better reliability records than those utilizing 15 k

16、V class construction. Feeder 7 (insulated to 34 KV) and feeder 8 (insulated to 69 kV) have bad only 3 outages each over their 32 and 23 year life spans, respectively. These lines follow similar terrain and are comparable in length and age to the 15 kV class lines, yet they have a combined failure ra

17、te of 0.22 failures per year versus 4.32 failures per year for the remaining feeders.On typical 15 kV insulated line construction, lightning flashovers often cause 60 cycle power follow and feeder trip. With the higher insulation construction, outage rates are reduced by limiting the number of flash

18、overs and the resultant power follow which causes an over current device to trip. This allows lightning arresters to perform their duty of dissipating lightning energy to earth. The number of re closer actions and their resultant momentary outages are also reduced. This is beneficial for critical fa

19、cilities and processes which cannot tolerate even momentary outages. An additional benefit is that outages due to animal contact are also reduced because of the greater distance from phase conductor to ground on pole structures. Distribution line equipment to increase line insulation values are off

20、the shelf items and proven technology. New lightning resistant construction typical by utilizes horizontal line posts, fiberglass standoff brackets or any other method which world increase the insulation value. The replacement of standard pin insulators with line post insulators of greater flashover

21、 value is an effective means to retrofit existing wood cross arm construction. The doubling and tripling of dead end and suspension insulators is also a means of increasing flashover values on existing angle and dead-end structures. Current fiberglass, polymer, and epoxy technologies provide an affo

22、rdable means to increase line insulation.While the use of increased insulation levels to reduce lightning flashovers and the resultant outages on overhead distribution lines has been thoroughly tested and demonstrated in laboratory and experimental tests 5, long term history field data has positivel

23、y demonstrated that the use of lightning resistant construction can greatly reduce outages. Field use at ORNL has shown that in areas which are vulnerable to lightning, the use of increased insulation and a smaller shielding angle is an impressive and cost effective means to appreciably increase the

24、 reliability of overhead distribution lines. This reliability study clearly illustrates that the insulation requirements for high-reliability distribution feeders should be determined not by the 60 Hz operating voltage but rather by withstand requirements for the lightning transients or other high v

25、oltage transients that are impressed upon the line. Electrical equipment (switchgear, insulators, transformers, cables, etc.) have a reserve (BE level or flashover value) to handle momentary over voltages, and by increasing that reserve, the service reliability is appreciably increased. As the elect

26、rical industry gradually moves away from standard wood cross arm construction and moves toward more fiberglass, polymer and epoxy construction, increased insulation methods can be applied as part of new construction or as part of an upgrade or replacement effort. In considering new or upgraded overh

27、ead line construction, the incremental increased cost of the higher insulation equipment is d in proportion to the total costs of construction (labor, capital equipment, cables, electric poles, right-of-way acquisition), Its cost effectiveness varies with the application and the conditions to which

28、it is be applied. Economic benefits include increased electrical service reliability and its inherent ability to keep manufacturing processes and critical loads in service. Other more direct benefits include less repair of overhead distribution lines, which can have a significant reduction in mainte

29、nance cost due to less replacement materials and a large reduction in overtime hours for maintenance crews.抗雷击架空配电线路的可靠性闪电仍然是架空配电线路上的中断1的主要原因。通过实验室测试和现场观察和测量，雷击和其对配电系统组件的属性是很好理解的现象。本文提出了一个32年的历史记录，停运的原因，时间，地点，在橡树岭国家实验室的八个配电馈线汇编。配电型避雷器在死胡同和角度的结构被放置在极安装W奥莫尔的位置，并在高点上的架空线。站级避雷器是用来保护地下电缆运行，垫置式开关柜，单位变电站变压

30、器。每个极接地的接地电阻通常是15欧姆或更小。在高海拔系统中，基本上是对地电阻大于15欧姆，尤其是在干燥的夏季。在这些高点，研磨棒极接地系统，在1960年，企图以减少雷击停电驱动和保税。这些尝试只是部分成功地降低停电率。从浪涌保护的角度来看，使用各种不同的杆件结构（列直插式，角，角，死路，等），和绝缘体及使用的硬件的各种不允许每13.8千伏架空线具有均匀的冲击闪络分类评价（170千伏，等）或一个数值的的BIL电压类（95千伏BIL，等等）。在分析中为了简单起见，每个分类的额定电压建筑类（15千伏，34千伏，69千伏）架空线。六七八个架空线（馈线1至6）建立典型的REA标准水平木横担，利用单级的

31、ANSI 55-5瓷针式绝缘子（标称15千伏绝缘）。架空地线相导线的屏蔽角通常是45度。一架空线（馈线7）建延长线传输型木杆建设，因为这是已产生的电能反馈到电网的研究设施。这条线极结构耐久的建设的其中利用双ANSI 52-3瓷悬式绝缘子支持（标称34千伏绝缘）。馈线7的架空地线的相导体的屏蔽角通常是30度。在1969年，架空线（馈线8）有意建立“抗雷击”试图减少雷电造成的停电。该行的极结构阶段阶段超过24英寸长的玻璃纤维悬挂支架与双ANSI 52-3瓷悬式绝缘子，支持标称69千伏绝缘的导体。馈线8架空地线的相导体的屏蔽角通常是30度。编制各八个13.8千伏馈线故障数据列于表I中，沿馈线结构，海

32、拔高度，长度，和年龄的相关信息。故障分析的一个重要发现是，与天气有关的事件占了一半以上（56）的馈线停电记录。五十七名76天气有关的中断是由于雷击。绝缘击穿损坏，由于雷击还涉嫌至少有十几观察到的设备故障。数据表明架空线路经过地势高，是不可靠的，因为雷击风险更大。例如，馈线3最录制中断（48），其中三分之二是由于与天气有关的事件，这也是最高的馈线线厂区，上升到海拔450英尺以上的参考山谷高度。也观察到架空线更长，更多的变电站和设备连接不可靠（多接触雷击和更多的设备失败）。行的年龄似乎并不显着减轻其只要足够的维护;线中断的频率有一个显着的增加作为线路岁。正如所预料的，实证的数据列于表我确认两架空线

33、路绝缘已到一个更高的水平（34或69千伏），有显着更好的可靠性记录比那些利用15千伏级建设。馈线7（绝缘的34千伏）和馈线8（绝缘的69千伏）每过32年和23年的寿命只有3停电有坏。下面的几行类似的地形，在15千伏级线路长度和年龄相媲美，但他们有一个合并的失败率每年0.22次失败与4.32每年剩余的馈线故障。在典型的15千伏绝缘线建设，雷电闪络往往造成60循环发电后续和馈线跳闸。具有较高的绝缘结构，减少停机率次数限制的闪络，这会导致过电流跳闸的移动设备以所得的功率后续。这使避雷器雷电能量耗散地球履行抚养义务。重新接近的行动和其产生的瞬间中断的数量也减少了。这有利于对关键设备和工艺无法容忍甚至瞬

34、间停电。另外一个好处是，由于动物接触的停电也减少了，因为更大的距离从相导线接地极结构。配电线路设备，以提高线路的绝缘值是“现成的”项目和成熟的技术。新抗雷击建设典型的利用水平线职位，玻纤对峙括号或任何其他方法，增加保温值世界。更换标准针式绝缘子线路柱式绝缘子闪络值更是一种有效的手段来改造现有的木材横担建设。增加一倍和两倍死路一条悬式绝缘子闪络值增加现有的角度和死胡同结构的一种手段。电流的玻璃纤维，聚合物，和环氧技术提供价格合理的手段，以提高线路的绝缘。雷击闪络，以及由此产生的架空配电线路停电，虽然使用的绝缘水平增加已彻底测试，在实验室和实验测试证明，长期历史的现场数据，积极表明，使用“抗雷击”

35、可大大减轻施工中断。在橡树岭国家实验室的现场使用表现出易受雷电领域，使用增加的绝缘和一个较小的遮光角是一个令人印象深刻的和成本有效的手段架空配电线路的可靠性明显增加。这种可靠性研究清楚地表明，绝缘要求高可靠性的配电馈线应确定，而不是由60赫兹工作电压，而是承受雷电瞬变要求或其他高电压瞬变行后留下了深刻的印象。电气设备（开关，绝缘子，变压器，电缆等）储备（水平或闪络值）来处理瞬时过电压，并通过增加储备，服务的可靠性明显提高。由于电器行业逐渐移开木横担从标准建设和走向更多的玻璃纤维，聚合物和环氧树脂建设，增加保温方法可用于新建筑的一部分，或作为升级或更换努力的一部分。在考虑新的或升级的架空线路施工，更高的绝缘设备的增量成本增加比例为的总建设成本（电缆，电线杆，偏右的方式收购），它的成本效益变化与该应用程序和条件是它是被应用。经济效益包括增加电力服务的可靠性和其固有的能力，以保持制造工艺和关键负载的服务。其他更直接的好处包括架空配电线路较少的维修，它可以有一个显着减少维护成本较少的替代材料，并大量减少维修人员的加班时间。