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。     

The world's first use of 500 kV XLPE insulated aluminium sheathedpower cables at the Shimogo and Imaichi power stations

The world's first practical applications of 500 kV XLPE (cross-linked polyethylene) cables took place in 1988 at the Shimogo power station of the Electric Power Development Co. Ltd., and the Imaichi power station of the Tokyo Electric Power Co. Inc.. Research and development work on the cables had been conducted since 1982. Efforts were concentrated on quality control to remove contaminants from the insulation and to extrude the very thick-walled insulation without any defects. Insulation performance tests, including long-term aging, confirmed that the 500 kV XLPE cables and the terminations were highly reliable with superior initial and long-term performance. The installation was completed successfully, and the cables are now in satisfactory operation at both power stations. The cable routes, design of the cable and termination, cable manufacture, results of the insulation performance tests, installation work, and site test are discussed     

我国高压及超高压交联聚乙烯绝缘电力电缆的应用与发展

本文介绍我国 110 k V及 2 2 0 k V交联聚乙烯 (XL PE)绝缘电缆及其附件的发展。高压 XL PE电缆是我国城市电网建设与改造工程采用地下电缆输电系统的首选产品。本文叙述 XL PE电缆的绝缘设计原则、绝缘质量控制要求 ,特别是绝缘中杂质、微孔以及绝缘与半导电屏蔽界面的微孔与凸起、绝缘收缩与交联工艺的关系 ,及电缆附件的选型与预制附件橡胶应力锥的设计方法。介绍了我国特大城市 ,上海、北京与广州高压电缆系统的应用情况。最后对我国 110 k V及 2 2 0 k V XL PE电缆及附件进一步发展以及 5 0 0 k V XL PE电缆系统发展与应用前景作了预测     

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。     

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     

Space charge behavior in full-size 250 kV DC XLPE cables

The space charge in full size 250 kV HVDC power cables was measured using the pulse-electroacoustic method. Measurements of two types of newly developed DC XLPE cables with 20 mm insulation were taken under a DC voltage of 500 kV with the conductor temperature at room temperature and at 85°C. A qualitative analysis of the space-charge distribution and a quantitative analysis of the electric fields in the vicinity of semicon interfaces were conducted. It was shown that the field in the vicinity of the inner semicon tends to increase by 10-40% when the polarity of the applied voltage was reversed, in the case when the conductor was kept at 85°C. However, the distortion of the electric field was significantly less than that expected in conventional XLPE cables. As the result, the subjected DC cables are considered to have stable DC characteristics from the viewpoint of space charge-behavior     

Research and development of ±250 kV DC XLPE cables

This paper describes the development of ±250 kV DC XLPE cables. Through a series of material investigations and the evaluation of model cables using two kinds of XLPE compound containing inorganic filler to suppress the accumulation of space charge within XLPE insulation, ±250 kV DC XLPE cables and factory joints were designed and manufactured. To check the DC electrical performance and reliability of ±250 kV DC submarine cable, electrical tests, mechanical test and long-term aging tests were performed. The test results showed that they had sufficient properties and reliability for practical use     

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     

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     

Study on the dielectric characteristics of DC XLPE cables

The DC characteristics of XLPE (crosslinked polyethylene) power cables were investigated. Cables with an insulation thickness of 2.5 mm, 9 mm, and 13 mm using either XLPE or conductive-inorganic-filled XLPE (XL-A) were manufactured, and four kinds of breakdown tests (DC, polarity reversal, impulse, and superposing opposite polarity impulse on DC prestress) were performed. A 250 kV, XL-A cable (20 mm thickness) was designed and manufactured using the results. The test results show that the XL-A cable possesses much better DC breakdown characteristics than the XLPE cable and is adequate for use in DC cables     

Comparative laboratory evaluation of TR-XLPE and XLPE cables with Super-smooth conductor shields

This paper provides data on four commercial tree retardant crosslinked polyethylene (TR-XLPE) and one cross-linked polyethylene (XLPE) insulated 15 kV cables supplied by three manufacturers. The cables have "super-smooth" conductor shields and "extra-clean" insulation and insulation shields. AC and impulse voltage breakdown and selected other characterization data are presented for cables that were aged immersed in room temperature water (15-30/spl deg/C) up to 24 months of a planned 48 months aging program. The five cables have high ac voltage breakdown strength, three of the TR-XLPE cables, actually increased in breakdown strength during aging. The one TR-XLPE cable that had the lowest ac voltage breakdown had vented trees at the insulation shield and high dissipation factor, which the other cables did not have. The impulse voltage breakdown strength of all cables decreased during aging; the cable with the lowest ac voltage breakdown also has the lowest impulse voltage breakdown. The dissimilar performance of the TR-XLPE cables and the excellent performance of the XLPE cable indicates evaluations at longer times are required to differentiate between modern TR-XLPE and XLPE insulated cables.     

Electrical stress enhancement of contaminants in XLPE insulation used for power cables

The use of XLPE as the insulation for power cables has grown steadily since it first introduction more than 30 years ago. Today XLPE is rapidly becoming the preferred insulation system for even the highest transmission voltages. This preference is due to the high reliability, low dielectric losses, and low environmental impact that can be achieved with XLPE. The positive effects of high quality insulation materials on improved cable performance have been well known since the start of cable making. The purpose of this paper is to investigate the technical background for the cleanliness levels and to quantify the level of performance required from clean materials. The advantages of clean insulation materials are seen at all voltages. However, this work focuses on the technical basis for the benefits for HV and EHV cables, which typically are designed with a water impervious layer to ensure that the cable remains dry throughout its entire lifetime. The presence of metallic contaminants in MV cable is known to enhance the growth of trees by raising the electric stress level locally. The singular impact of cleanliness on the performance of MV cables is somewhat more complicated as it is influenced both by the cleanliness of the insulation and the ability of the insulation material to resist the growth of water trees.     

Long-term characteristics of XLPE cables

To study the long-term characteristics of XLPE cables installed in free air and in water, aging tests were conducted under various testing conditions using XLPE cables with both 3.5 mm and 6 mm insulation. From the Weibull plots of lifetime distribution under the voltage stress E_L as the minimum breakdown strength, the minimum value of time to breakdown t_L under the constant voltage was estimated. The results of accelerated aging tests of XLPE cables installed in free air demonstrated that the V-t characteristics of XLPE cables could not be described by the conventional inverse power law (t ∝ V⁻ⁿ) with a single constant life exponent n. Based on the microscopic observation of a sliced insulation removed from XLPE cables, it was concluded that bow-tie trees with longer tree length observed in cables tested in water were caused by the moisture from outside, whereas the trees in cables tested in free air were caused by the residual moisture originally existing in the insulation. The breakdown strength of the aged cables tested in water increases through cable drying. However, it does not recover to the original values.     

浅谈交联聚乙烯电力电缆的交接、预防性试验

该文阐述了交联聚乙烯 (XL PE)绝缘电力电缆的交接、预防性试验有关问题 ,提出 6～ 10 k V和 35 k V交联聚乙烯电力电缆不同的试验方法和内容     

Space change behavior in full scale ±250 kV dc XLPE cables

Space charge in full size ±250 kV dc cables was measured using a pulse-electroacoustic method. Two newly developed types of dc XLPE cables with 20 mm thick insulation were subjected to measurements at a dc voltage of 500 kV, keeping the conductor temperature either at room temperature or at 85°C. Qualitative analyses of the space charge distribution and the quantitative analysis of the electric fields in the vicinity of semicon interfaces were made. It was shown that the field in the vicinity of the inner semiconductor tends to increase by 10 to 40% when the polarity of the applied voltage was switched, in the case when the conductor was kept at 85°C. However, the distortion of the electric field was significantly smaller than that expected with conventional XLPE cables. As a result, dc cables are considered to have stable dc characteristics from the viewpoint of space charge behavior. © 1998 Scripta Technica, Electr Eng Jpn, 124(2): 16–28, 1998     

Development of 500-kV XLPE cables and accessories for long distanceunderground transmission line. III. Electrical properties of 500-kVcables

500-kV XLPE-insulated cable with an insulation thickness of 27 mm has been developed for long-distance transmission lines. Basic studies on 500-kV XLPE cable have shown that contaminants in the insulation may be the factor determining 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 the electrical characteristics of full-sized cables. Voltage-withstand and long-term tests have confirmed the design values for minimum breakdown stress, for AC and impulse voltage, and for the degradation coefficients     

Electric stresses in three-core cables equipped with optical fibersensors

XLPE cables equipped with optical fiber sensors for on-line fault and problem detection are being manufactured and installed, particularly at the 66 kV level. The insertion of these sensors which generally possess electrical properties different from those of the cable insulation, is expected to influence the electric field distribution in the space surrounding the HV conductors. This situation in turn affects the `electric stress' on the HV insulation. This paper examines those effects not only in terms of subsequent alterations in electric field magnitude but also the changes in the orientation of the field's elliptic polarization which is prelude to the possible initiation of local discharges within the insulation. The boundary element technique is applied to simulate sheathed three-core belted cables with fiber sensors. With an adequate number of strip charges, this method is used to calculate the electric field distribution in a 66 kV power cable containing optical fiber units. The variation of the electric stress at critical spots within the insulation with the location of the sensor and the permittivity of its insulation material is investigated     

电缆绝缘屏蔽在终端浸渍剂中的变性

在解剖一个 110 k V交联电缆的故障终端中 ,发现长时间与终端浸渍剂直接接触的交联电缆的绝缘屏蔽发生了严重变性。验证试验表明交联电缆的绝缘屏蔽材料与常用终端浸渍剂的相溶性能很差 ,长时间接触会导致绝缘屏蔽材料的物理机械性能和电导率发生很大变化。在设计、制造和安装交联电缆终端时 ,应该注意电缆的绝缘屏蔽与终端浸渍剂的隔绝。     

Development of a new type insulation diagnostic method for hot-lineXLPE cables

The authors developed an insulation diagnostic system that makes automatic measurements of the dielectric dissipation factor and DC component in a hot-line XLPE (cross-linked polyethylene) insulated power cable and makes an overall judgement of cable insulation deterioration. This system was tested on XLPE cables in hot-line conditions, the criteria for judgement of insulation deterioration were established based on the results of measurements     

CCV交联工艺生产高压电力电缆的特点及其绝缘偏心的控制

通过对远东控股集团引进德国Troester公司最新的500kV悬链式交联电缆生产线的技术特点、控制绝缘偏心的研究,进一步说明高压交联聚乙烯绝缘电力电缆应用悬链式（CCV）交联工艺是完全可行的,其绝缘偏心控制水平甚至要好于立式（VCV）交联工艺。