借鉴以往复合横担杆塔的设计经验,从绝缘配置、电磁环境、空气间隙、电位分布计算和纵向不平衡张力等方面对特高压直流线路杆塔的复合横担布置方式进行研究,通过对杆塔钢材、基础指标、绝缘子串费用以及线路走廊费用进行综合经济比较,选择出合理的复合横担布置方案,为特高压直流线路复合横担塔设计提供借鉴和参考.

1 前言 随着国家“西部开发”、“西电东送”战略的实施,河西走廊通道内密集分布着电力线路、铁路、高速公路、油气管线等各种设施,廊道拥挤,已建的哈密-郑州±800kV直流线路、正在建设的准东-华东送出±1100kV、规划建设准东-成都±1 100kV直流输电线路工程及多条750kV、330kV也将从此通过,因此有利用已有的330kV通道,采用1100kV与330kV同塔多回输电技术是解决河西走廊电力通道问题的有效手段.

同塔四回输电技术是电网建设中解决输电走廊紧张、提高输电容量、实现“资源节约型”电网的有效手段.依托特高压交流输电技术研究成果,通过理论分析和数值计算对1 000kV与500 kV同塔四回交流输电线路杆塔型式进行研究.借鉴超高压输电线路同塔四回输电技术的经验,基于2种典型杆塔结构,从电磁环境、防雷性能、覆冰校验和经济性等方面进行了比较和分析,选择出合理的杆塔型式,并推荐了塔头布置方案,为1 000 kV与500 kV同塔四回输电线路塔型设计提供借鉴和参考.

Frost-heaving is the key factor that impacts the stability of foundation in the frozen-soil region.In this paper,the conventional anti-frost heaving measures are improved by six treatment measures,such as cone cylindrical foundation,the replacement of heaving material,lubricant smearing and the application of glass steel formwork.These measures have been proved reasonable and effective through engineering practices.

The application situations of diameter-extended conductor for UHVAC transmission line projects were presented. Based on 1 000 kV Ximeng-Nanjing UHVAC transmission line project, the electrical characteristics, mechanical performances and the economic features of diameter-extended conductor and conventional conductors were compared. The results show that the diameter-extended conductor not only meets the electromagnetic environment requirements, but also can effectively reduce the project investment for UHVAC transmission line projects, under the precondition of satisfying the transmission capacity, which has great practical significance for the construction of environmentally friendly and resource-saving UHVAC transmission lines.

Considering the features of sequentiality and self-correlation of wind speed, an auto-regressive and moving average (ARMA) model for wind speed is built. Combining with the state models of conventional generating units, transmission lines and transformers, a Monte Carlo simulation based wind farm reliability model is established to perform reliability assessment of power generation and transmission system containing wind farm, meanwhile, a multi-state service provider (MSP) model of power generation and transmission system is built; combining the MSP model with distribution system, the reliability indices of distribution network such as average interruption frequency and interruption caused electricity loss are calculated. By means of comparing and analyzing the reliability indices, the impact of wind farm on distribution system is researched and the results show that interconnection of wind farm with power grid can play a certain role in the improvement of power system reliability.

Modern HVDC transmission systems generally use 12-pulse valve groups or 2x12-pulse valve groups per pole as a main circuit designing structure. In this paper, the two configurations are compared with each other by the main circuits, operating capacity states and equivalent models, and then their reliability indices are calculated using the theory of Markov process and FD method based on the same reliability parameter for each equipment. The results of calculation indicate that the HVDC system used 2x12-pulse valve group has dramatic improvement on the operation efficiency of system and level of reliability compared with the one used 12-pulse valve group. Moreover, the sensitivity indices of reliability with respect to equipment parameters are also analyzed in this paper. The sensitivity indices open out the main factors that affect the reliability of system. The analysis and conclusions in the paper can be used as a reference to find the weak reliability links of the HVDC system and improve operation and management of HVDC system.

The status quo of research about reliability evaluation of HVDC is presented in this paper.The typical configuration and reliability index of HVDC is giren.The common methods of reliability evaluation of HVDC which contain Frequency and Duration Method,Fault Tree Analysis,Analysis Method of series and parallel network,Monte Carlo-FD hybrid method and FAT and FD hybrid method is analysed.The further theoretical research and the application of distribution system reliability is pointed out.

The statistical data about the operation reliability indices of the national HVDC transmission projects during the years of 2001 to 2005 and the historical data abroad from 1998 to 2002 are summarized.Through analyzing and comparing among reliability indices of these HVDC projects,the main factors influencing reliabilities of systems and the tendencies of these factors are clarified.Using the resulting information including HVDC projects abroad,the paper then makes a comparison among reliability indices of HVDC projects with two converters per pole and single converter per pole,respectively.The statistical analysis and conclusions are capable of being used as reference to decision making for the operating,planning and management of HVDC projects.