Prevention of reignition overvoltages by phase-angle-controlled switching of a gas circuit breaker at shunt reactor current interruption

Shunt reactors installed at gas-insulated switchgear substations (GIS-substations) are switched relatively frequently by large-capacity gas circuit breakers (GCBs). Surge voltages appear at such switching operations through various mechanisms. Among them, high-frequency current interruption and subsequent multiple reignition might cause the highest overvoltage and may be harmful to the insulation of the components of the substation. In this paper, shunt reactor current-interrupting tests are conducted in high-power laboratory. The existence of critical arcing time above which reignitions never occur is shown through these tests. From this fact, a phase-angle-controlled-interruption system is proposed. With this system, arcing time is set artificially so that reignitions should be prevented. The reliability of this system is confirmed through the reactor current-interrupting test in the laboratory as well. Afterward the phase-angle-controlled-interruption system is applied to the shunt reactor switching at an actual 275-kV substation. The switching performance of this system is measured over three months. Reignition-free interruption is shown to be attained with this system.     

应用串联电抗器限制500 kV短路电流分析

介绍了串联电抗器限制短路电流的工作原理和特点;超高压输电网中限流串联电抗器的典型应用实例和制造水平以及串联电抗器的美国国家标准和美国PJM电网的应用指导意见。根据华东电网短路电流水平的分析结论,对串联电抗器参数设计和安装地点进行了初步分析。     

Development of 500-kV XLPE cables

A 500-kV XLPE insulated cable with an insulation thickness of 27 mm has been developed for long-distance transmission lines. Basic studies on the 500-kV XLPE cable have shown that contaminants in the insulation may determine electrical performance. This hypothesis is justified by the good correlation obtained between statistical estimations of the size of the largest contaminant in the insulation and electrical characteristics of full-size cables. Voltage-withstand and long-term tests have confirmed design values for minimum breakdown stress, ac and impulse voltage, and degradation coefficients. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (1): 28–40, 1997     

500 kV电抗器保护装置管理软件的开发

按照超高压设备双重化保护配置的要求,500kV电抗器保护装置底层保护系统由两套并行的保护子系统构成.上层管理系统作为装置中的重要一环,一方面承担着人机接口管理和监控整个保护装置的任务;另一方面是实现对内对外通讯联系的桥梁.在简要介绍整个保护装置的基础上,系统地说明了管理系统软件的整体功能和程序框架结构设计.根据保护装置内部通讯的特点和应用要求,在我国电力行业标准IEC60870-5-103基础上,提出了一种适用于微机保护装置的内部通讯协议.该协议能够方便、快捷地实现保护装置内部通讯的报文格式转换.管理软件采用模块化的程序设计方法,界面友好且操作简单,具有程序层次清晰、扩展性强、运行稳定等特点.     

相控断路器在抑制35kV并联电抗器操作过电压中的应用

近年来我国频繁发生220 kV变电站35 kV并联电抗器切除时操作过电压导致的设备故障,危及电网安全稳定运行。对切除并联电抗器过电压产生的机理、危害和抑制进行系统分析,提出了并联电抗器的选相投切策略,并开展了现场过电压实测和PSCAD仿真分析,为35 kV并联电抗器操作过电压的抑制提供了解决思路和工程经验。     

快速响应磁控电抗器抑制特高压操作过电压研究

针对高电压等级电网的过电压限制与无功补偿存在矛盾的问题,提出了一种大容量并具有快速响应能力的磁控电抗器的设计方案.磁控电抗器的本体采用单相双绕组结构,保证了运行可靠性;接入电网的三相电抗器组的工作绕组以星形联结,中性点接小电抗,控制绕组为三角形联结以减小输出谐波;通过对低压控制回路直流电压的调节实现对电抗器输出容量的控制.提出2种励磁方式实现了磁控电抗器响应速度的大幅提高;也可采用控制绕组短接的方法实现电抗器容量的突增,以限制线路的操作过电压水平.应用一条1000 kV特高压线路模型,对采用常规并联高压电抗器和磁控高压电抗器时对三相对称合闸过电压的限制效果进行了计算分析,结果表明应用快速响应磁控电抗器可以对特高压线路操作过电压进行有效限制.     

Re‐ignition surge and high‐frequency arc extinction phenomena at 550‐kV shunt reactor current interruption

At substations connected with transmission lines and cables, shunt reactors are sometimes installed to compensate the capacitive current of these lines and cables. It is known that re‐ignitions occur and high‐frequency currents flow during interruption of the shunt reactor currents by switches. When the high‐frequency currents are interrupted immediately after the re‐ignitions (which is called high‐frequency arc extinction), the result is often repetitive re‐ignitions or voltage escalations that produce dangerous overvoltages. The authors investigated the occurrence of high‐frequency arc extinctions in a 550‐kV one‐break SF₆ gas circuit breaker during interruption of a 550‐kV shunt reactor current. Computations for a real 550‐kV substation gave a minimum frequency of 290 kHz for the high‐frequency current. However, 550‐kV reactor current interruption tests showed that high‐frequency arc extinctions did not occur even when this frequency was lowered to 26 kHz. Since high‐frequency arc extinction is generally likely to occur at lower frequencies, it was concluded that high‐frequency arc extinction will not occur in a 550‐kV one‐break SF₆ gas circuit breaker during interruption of shunt reactor current in real substations. © 2001 Scripta Technica, Electr Eng Jpn, 136(2): 18–25, 2001     

500-kV compact type over-head line to be constructed in Yunnan

Boshang-Mojiang Line is the first 500-kV compact type transmission line to be built in high altitude areas of Yunnan Province with a total length of 315 km. The project has now completed its most field routing survey and entered into the stage of designing working drawing. This line and its associated 500-kV Dehong Substation are planned to be finished in 2008.     

Development of 500-kV XLPE cables and accessories for long-distanceunderground transmission lines. V. Long-term performance for 500-kV XLPEcables and joints

500-kV XLPE-insulated cable with an insulation thickness of 27 mm and its joint have been developed for long distance transmission lines. First, in the basic research made from 1989 to 1992, elicited were the performance-determining factors of XLPE cables and joints. Their respective insulation designs were made in terms of these factors. On the basis of these designs, full-sized cables and joints were manufactured in the course of the development research performed from 1992 to 1993. The next step was to evaluate the initial electrical performance to estimate the suitability of our designs. As the final step of our series of researches so far carried out, a long-term loading cycle test was carried out by means of a model line with joints as installed and using the same techniques as employed in the actual commercial lines for full eight months. We could thus verify the long-term reliability for commercial use. The authors discuss EMI, performance dominating effects and quality control, and initial and long term electrical performance testing     

末端制动的新型数字式高压并联电抗器纵差保护

高压并联电抗器内部线圈接地故障或引出线的接地及相间短路故障是电抗器常见的故障形式,电抗器纵差保护是这些故障形式的主保护,但是在空投电抗器以及区外扰动的暂态过程中,由于直流分量大而且衰减慢可能引起CT直流饱和而导致纵差保护误动.针对上述问题,提出了一种取电抗器末端电流作为制动电流、采用三段式比率制动特性的数字式纵差保护的方法.本保护具有电抗器空投检测功能、间隙性电流互感器断线检测判据以及电流互感器直流饱和检测判据.经动模试验及现场运行结果证明该保护灵敏反应内部故障,并在空投和区外扰动情况下可靠闭锁保护.     

基于高耦合电抗器的500 kV限流器限流特性等效试验

基于高耦合电抗器的500 kV限流器在限流状态下的阻抗较大,而由于试验室电源电压有限,限流状态下的试验电流远小于额定短路电流,因此500 kV限流器在额定短路工况下的限流特性试验和动稳定性考核试验无法直接进行。针对上述问题,提出了一种间接验证限流器限流特性的等效试验方法。通过设计降低阻抗参数的比例缩小样机,在试验室条件下进行全电流的比例缩小样机间接试验,同时结合试验室内500 kV限流器比例缩小样机的低电压试验和500 kV限流器接入实际系统的高电压人工短路试验,综合验证500 kV限流器的限流能力。研究结果表明,500 kV限流器在额定短路工况下的限流幅度满足设计要求,所设计试验方法具有良好的等价性。     

并联电抗器套管CT点极性方法的分析与改进

分析了电抗器套管CT点极性存在的问题,结合现场工作状况,分析了点极性过程中刀闸断口处过电压与电弧的产生原因,提出了一种新的点极性方案,解决了刀闸断口处过电压与拉弧的问题,并设计了一种新的极性测试电路,解决了点极性时CT二次串接电流表指针偏转不明显的问题.     

基于并联电抗器电流判别的超高压输电线路单相自适应重合闸

针对带并联补偿的超高压输电线路,提出了根据恢复电压阶段并联电抗器中故障相电流的低频分量判别故障性质的方法,并定义了一个能量函数,用于检测低频分量的含量,能在2～4个基波周期内快速识别故障性质.详细分析了并联电抗器中故障相的电流特性,并基于该特性区分永久性和瞬时性故障:永久性故障时,并联电抗器故障相电流只舍有基频分量和衰减较慢的直流分量;瞬时性故障时,故障相电流中除基频外还含有低频分量,其幅值接近基频分量.理论分析和EMTP仿真结果表明,该识别方法可以准确区分线路的故障性质,大幅度提高重合闸成功率.     

Electromagnetic Environmental Impact of 500-kV Double -Circuit Transmission Lines

The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere’s Law, and the environmental impact factors of the fields were evaluated. By optimizing the phase sequence, the frequency electric intensity and magnetic field strength can be reduced. Within a distance of 25 m from the center of the transmission line, the power frequency electric intensity and magnetic field strength fall off sharply with the distance increase. Finally, the best phase sequence and the minimum ground clearance of the transmission lines were obtained to meet the requirements of the least impact on envionment.     

并联电抗器在750kV超高压输电线路中的应用

通过分析并联电抗器的结构与原理、750kV超高压输电线路空载容升效应及单相重合闸潜供电流的特点,阐明了并联电抗器在750kV超高压输电线路中的作用.     

Application of 800-kV SF6 dead tank circuit breaker with transmission line surge arrester to control switching transient overvoltages

An 800-kV metal oxide transmission line surge arrester (TLA) has been developed, installed and tested on the AEP 765-kV Marysville-Kammer transmission line. The purpose of this TLA is to pave the way for the development, construction and application of an 800-kV SF/sub 6/ dead tank circuit breaker without closing resistors and free standing current transformers at American Electric Power's (AEP) 800-kV Orange station. Eight hundred kilovolts is the maximum design operating voltage, and 765 kV is the nominal operating voltage. Successful field test results of the TLAs ability to limit switching overvoltages emanating from circuit breaker operation to below the transmission line switching withstand are given. In addition, successful test results of the 800-kV dead tank circuit breaker design dielectric test are given in this paper.     

Transients during 138-kV SF6 breaker switching of low inductivecurrents

The authors discusses the effects of switching low inductive currents with 138 kV SF₆ breakers in a petrochemical plant. Switching transients are believed to have contributed to the failure of a 13.8 kV PT and a 13.8 kV air magnetic circuit breaker. The high-frequency transient surge can transfer across a transformer due to transformer capacitances between the high- and low-voltage windings. The electromagnetic transient program system (ETPS) model and different case studies are discussed with the effect of different transformer winding capacitances. The interruption mechanism of low inductive currents is also described. This analysis demonstrates the need to conduct switching transient studies and the need for surge arresters on transformer secondary terminals under certain system conditions     

华东电网500 kV故障电流限制器应用研究

就华东500 kV电网故障电流限制器应用的选点原则、限制器安装后对系统暂态稳定性的影响、电磁暂态仿真及RTDS实时仿真等关键问题,进行了全面深入的研究,为华东500 kV电网的故障电流限制器示范性工程提供了有力的技术支持.     

故障电流限制器在500kV变电站的应用

介绍了故障电流限制器(FCL)的结构图和各个电气元件的作用、串联谐振型FCL的基本原理及其显著特点,详细说明了FCL控制保护系统中的动作依据、动作过程、电容器组的重投机制等,分析了如何利用故障电流瞬时值和故障电流斜率等判据来实现FCL的可靠动作,阐述了FCL对电流差动保护、距离保护、方向零流、线路联动保护等继电保护的影...