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     

The world's first long-distance 500 kV-XLPE cable line. 2. Jointsand after-installation test

For pt. 1 see ibid., vol. 18, no. 2, p. 65-67 (2002). In this second part of a three part series introducing the Shin-Keiyo/Toyosu underground transmission line using a 500-kV XLPE cable, the authors describe the specially developed extrusion-molded joints and after-installation test procedures. Based on the results of basic research extensively done to design the 500-kV extrusion-molded joints, the insulation thickness was determined to be 36 mm through careful considerations of various design parameters obtained. As in the case of the cable, the main factors that determine the performance of the joints are contaminants and voids, and their permissible levels are determined. Unlike cables, it is impossible to conduct sampling inspections for the extrusion-molded joints after they were assembled. Therefore, particular emphasis has to be placed on supervision and inspection of conditions during the assembly process     

Development of 500-kV XLPE cables and accessories for long-distanceunderground transmission lines. IV. Electrical properties of 500-kVextrusion molded joints

Joints for 500-kV XLPE cable are now under development in Japan to enable the long-distance transmission of high-capacity power to urban areas. Basic research was carried out from 1989 to 1992 that determined joint type and design values. This paper reports on the electric performance of the fabricated joints. Various tests were conducted to evaluate the performance and the design values. As a result of this evaluation it was found that it was possible to realize joints for 500-kV XLPE cable. Field tests are conducted as the final stage to confirm the long-term performance of the system     

500-kV long-distance cable completed in Japan

The first 500-kV long-distance cable line is described. This oil filled self-contained cable has been installed along the Seto-Ohashi bridge connecting Shikoku, the fourth largest of the four major islands that constitute Japan with Honshu, the main island. The power flow will generally be from Shikoku where there is a surplus of power to Honshu, the main island. The technical features of the cable and its installation are described. Polypropylene laminated paper (PPLP), a low-loss insulation paper with high dielectric performance, was adopted, allowing the cable to carry the required transmission capacity of 1200 MW per circuit without forced cooling. The number of splices is also reduced by approximately 40%, resulting in further economy     

Development of prefabricated joint for 275-kV XLPE cable

Application of XLPE cables to extra-high-voltage (EHV) transmission lines is expanding due to their excellent electrical properties and ease of maintenance, and 275-kV long-distance underground transmission lines are reaching the stage of practical utility. Extrusion molded joints (EMJs) are widely used as the XLPE cable joint for EHV transmission lines. However, EMJs have presented problems because of their insulation. They are formed on site through extruding and molding of crosslinkable PE like the cable, and need a long time for installation on site and higher jointing technique. The prefabricated joints (PJs), which are already applied to 154-kV transmission line, are installed on site by using the parts manufactured and tested in the factory, they require a shorter installation environment. This report introduces the results obtained regarding the improvement of the electrical property, workability and the performance of PJs, designed for 275-kV XLPE cable. These joints are planned to be used for 275-kV transmission lines from 1995     

A study of treeing phenomena in the development of insulation for500 kV XLPE cables

This review summarizes research on treeing phenomena, i.e. the formation of electrical trees and water trees, that has been undertaken in Japan for the development of 500 kV XLPE cable. Section 1 presents the results of factors affecting XLPE cable insulation breakdown under commercial ac and lightning impulse voltages. Section 2 verifies the phenomena of electrical tree formation in XLPE cable insulation using block samples and model cables, and gives the results of studies to determine the level electrical field stress initiation for such trees. Section 3 summarizes the results of studies on long-term aging characteristics, which is a particular problem under commercial ac voltages, while Section 4 explains how this research influenced the design of 500 kV XLPE cable insulation. All authors were members of `The investigation committee of fundamental process of treeing degradation' under IEEJ     

Development of 500 kV DC PPLP-insulated oil-filled submarine cable

This paper outlines the development of a 500 kV DC oil-filled submarine cable capable of transmitting 2800 MW with ±500 kV 2800 A bipole system. Polypropylene laminated paper (PPLP) was employed as the insulation material, which is the world's first application to DC cables. The conductor size is 3000 mm², which is the largest size for submarine cables ever put into practical use. Through various fundamental and prototype tests, the cable proved to have excellent electrical characteristics for DC voltage as well as transient overvoltage. The cable and accessories are undergoing a long-term accelerated aging test as the final confirmation of their reliability and stability     

Technological progress in high-voltage XLPE power cables in Japan.II

For pt.I see ibid., vol.4, no.5, p.9-16 (1988). Cables designed for particular applications and improved performance are described. The products discussed are: (1) water-impervious cable; (2) composite XLPE/optical fiber cable; (3) 66-kV submarine cable; (4) commercial long-distance 275-kV line; and (5) 500-kV short-distance line. The discussion is confined to the Japanese cable industry     

500kV XLPE电缆绝缘中树枝化现象的述评

介绍日本开发 5 0 0 k V XL PE电力电缆时研究树枝化现象的形成 ,评述 XL PE电缆形成电树和水树与场强的相关性、树枝引发场强和长期寿命特性的研究结果 ,说明由此确定 5 0 0 k V XL PE电力电缆的绝缘设计。     

Voltage distribution analysis of 500-kV DC transmission-line voltage divider under impulse voltages: stray parameter extraction

It is essential to extract the stray parameters accurately and efficiently in analyzing impulse responses of a power apparatus. In this paper the stray capacitances and stray inductances of a 500-kV dc transmission-line voltage divider are extracted by the hybrid finite element-analytical approach, and the corresponding equivalent circuit for analyzing the impulse voltage response of the voltage divider is established. According to the discussion of the results of the extracted stray parameters of the voltage divider, reasonable simplification of the equivalent circuit of the voltage divider is made. In addition, the influence of the insulating housing and the electrical insulation oil on the stray capacitances of the voltage divider is discussed.     

500kV交联聚乙烯绝缘电缆绝缘结构研究

本文叙述交联聚乙烯 (XL PE)绝缘电缆绝缘统计设计方法。论述我国研制开发 5 0 0 k V XL PE电缆的绝缘结构采用绝缘统计设计方法的合理性。叙述我国 5 0 0 k V XL PE电缆的绝缘水平要求。论述对照日本已经运行的 5 0 0 k V XL PE电缆的绝缘结构参数和绝缘质量控制要求 ,采用绝缘统计设计方法 ,按相同可靠性原则作为我国 5 0 0 k V XL PE电缆确定电缆绝缘厚度和绝缘质量控制要求的基础是合理的。本文提出不同导体截面 5 0 0 k V XL PE电缆的推荐绝缘厚度。     

Development of XLPE insulated DC cable

This paper describes the development of dc XLPE cable. Through a series of material investigations, an XLPE compound containing highly purified special filler was developed. To check the dc insulation performance of the cable insulated with this new material, a prototype cable with 9 mm insulation thickness was manufactured. It was confirmed that the performance of the prototype cable was excellent. Based on the study of the prototype cable, a 250-kV dc cable with 20 mm insulation thickness was designed and manufactured. Through a series of voltage tests, excellent dc insulation performance of the developed cable was verified.     

Performance characteristics of XLPE versus EPR as insulation forhigh voltage cables

The physical and electrical properties of crosslinked polyethylene (XLPE) and ethylene propylene rubber (EPR) are compared in the context of their use in transmission class cables. Results indicate that the 138-kV XLPE cable has AC withstand/breakdown strength at least 25% higher than the 150-kV EPR cable. The XLPE cable exhibits about 70% higher impulse strength than the EPR cable. The loss factor of the XLPE cable is at least 20 times lower than that of EPR cable. Thus with XLPE cables, the yearly energy savings can be on the order of 15 MWh/cct. km for a 69-kV system, 52 MWh/cct. km for a 138-kV system and 127 MHh/cct. km for a 230-kV system     

Application of controlled switching to 500-kV shunt reactor current interruption

To suppress reignition overvoltages caused when a 500-kV shunt reactor current is interrupted by a 550-kV one-break circuit breaker (CB), a study was carried out on controlled switching. Using a full-scale test circuit, reactor current interruption tests were carried out to obtain the relation between opening phase angle and generation of reignition. The results showed that even with the dispersion of CB operations taken into account, there were contact separation points free from high reignition overvoltages. It was also proved that no voltage escalations were caused by reignition and high-frequency arc extinction, and that overvoltages due to current chopping were at a safe level in terms of equipment insulation.     

一起500 kV电缆外护套放电故障分析及防治措施研究

交联聚乙烯由于其电气性能、结构轻便等优势被广泛应用于高压交直流电缆绝缘领域,但是近年来因电缆故障导致的停电事件呈现出逐年增多的趋势。文中针对某水电厂主变压器空载充电过程中存在的500 kV交联聚乙烯电缆外护套对夹件间隙放电的问题。首先,利用ATP-EMTP仿真软件建立了全厂一次设备电磁暂态仿真分析模型,对导致电缆铝护套放电现象的故障原因进行了分析;然后,对不同种类的故障治理措施进行比较;最后,提出了针对性解决方案。     

日本东京500 kV地下变电站及电缆的设计和建设

介绍日本东京市中心新丰洲线500kV地下变电站和新丰洲线电缆设计和建设的相关情况，新丰洲变电站是世界上目前唯一建成的500kV地下变电站，新丰洲线是世界上最长的500kV交联聚乙烯电缆线路。文章描述东京电网的地理接线情况以及500kV电缆规划，介绍新丰洲变电站的主要设备、电缆绝缘设计、电缆接头以及电缆的局放试验。     

广东—海南500 kV海底电缆输电系统电磁暂态研究

海南联网工程是中国第一个500kV超高压、长距离、较大容量的跨海联网工程,也是继加拿大本土与温哥华岛交流跨海联网工程之后、世界上第二个同类工程。文章研究了广东—海南500 kV海底电缆输电系统的电磁暂态问题,主要包括电缆参数、工频过电压、单相重合闸过程中的潜供电流和恢复电压、工频谐振过电压、操作过电压等,并在此基础上分析了500 kV海底电缆可选择的绝缘水平,为国内500 kV海底电缆输电工程的建设提供了依据。     

大长度500kV XLPE超高压海底电缆关键技术研究

大长度超高压500 kV XLPE绝缘交流海底电缆的生产工艺控制与220 kV及以下电压等级交流海缆有较大区别,着重介绍了500 kV超高压海底电缆的连续大长度绝缘挤出工艺、厚绝缘除气技术、铜丝铠装和试验验证等关键技术的研究。     

Development of 500-kV XLPE cables and accessories for long distanceunderground transmission lines-Part II: jointing techniques

This paper reports on the results of a basic inquiry for the purpose of developing extrusion-molded joints (EMJ) for use with 500 kV XLPE power cable. The authors have made it clear that the factors that govern EMJ performance, like cable performance, are contaminants in the insulation and protrusions in the semiconductor layer. Through modeling experiments, the authors determine the minimum breakdown strength of EMJ and use this to determine design values for 500 kV EMJ. Finally, they carry out breakdown tests on actual equipment, resulting in the prospect of the actual realization of 500 kV EMJ