苏州电网主变直流偏磁分析及抑制措施研究

发布时间：2018-04-21 07:01

本文选题：直流输电 + 单极运行　；参考：《华北电力大学》2014年硕士论文

【摘要】：特高压直流输电具有“大容量、远距离”输电的优点,依托特高压直流输电,构建西部大型能源基地外送通道,能有效缓解我国能源资源与负荷中心逆向分布的矛盾,促进国家雾霾治理、节能减排可持续发展战略的实现。然而,特高压直流输电单极运行时产生的地电流会引发变压器直流偏磁,此时变压器铁芯高度磁饱和,漏磁增加,变压器会出现振动加剧、噪音增大、局部过热、谐波激增等现象,影响变压器的安全稳定运行。因此,特高压直流输电引起变压器直流偏磁及其抑制措施方面的研究,具有重要的理论意义和重大的工程实用价值。本文以锦屏～苏南±800kV特高压直流输电工程为背景,围绕直流偏磁电流的产生、变压器直流偏磁的机理及影响和变压器中性点串接小电阻抑制直流偏磁展开研究。本文根据苏州电网结构参数建立了电网拓扑模型,根据苏州地区的地质情况建立了土壤分层模型,采用电力系统接地分析软件CDEGS对苏州换流站单极大地回线运行方式下附近变电站地电位和直流分布情况进行了计算分析。本文从变压器的理论模型出发,研究分析了变压器直流偏磁情况下励磁电流和谐波分量的变化情况。结合锦屏～苏南±800kV特高压直流输电工程单极运行调试,分析了直流偏磁对苏州电网部分变电站变压器的影响。本文分析了几种常见的直流偏磁抑制方法,并针对苏州电网直流偏磁情况提出了变压器中性点串接小电阻抑制直流偏磁的方案,对500kV木渎变主变中性点串接小电阻抑制直流偏磁的的方案进行了可行性研究,对应用效果进行了评估。
[Abstract]:UHV DC transmission has the advantages of "large capacity, long distance" transmission. Relying on UHVDC transmission, the construction of the western large energy base external transmission channel can effectively alleviate the contradiction between the reverse distribution of energy resources and load center in China. Promote national haze governance, energy conservation and emission reduction sustainable development strategy to achieve. However, the earth current generated by the unipolar operation of UHVDC transmission will lead to DC bias of transformer. At this time, the transformer core is highly magnetically saturated, the leakage of magnetic flux increases, the vibration of the transformer increases, the noise increases, and the local overheating occurs. Harmonic surge and other phenomena affect the safe and stable operation of transformers. Therefore, the research on DC bias of transformer caused by UHVDC transmission and its suppression measures has important theoretical significance and great engineering practical value. With the background of Jinping ~ Sunan 卤800kV UHV HVDC transmission project, this paper studies the generation of DC bias current, the mechanism and influence of transformer DC bias, and the suppression of DC bias by series small resistance of transformer neutral point. According to the structural parameters of Suzhou power network, the topology model of power network is established in this paper, and the soil stratification model is established according to the geological conditions in Suzhou area. The ground potential and DC distribution of substations in Suzhou converter station under the operation mode of unipolar earth loop are calculated and analyzed by using the power system grounding analysis software CDEGS. Based on the theoretical model of transformer, the variation of excitation current and harmonic component under DC bias of transformer is studied and analyzed in this paper. Combined with unipolar operation debugging of Jinping ~ Sunan 卤800kV UHVDC transmission project, the influence of DC bias on transformer in some substations of Suzhou power network is analyzed. In this paper, several common methods of DC bias suppression are analyzed, and a scheme of transformer neutral-point series connection with small resistance to suppress DC bias is put forward in view of the DC bias of Suzhou power network. In this paper, the feasibility of the scheme of 500kV Mudu main transformer series connected with small resistance to restrain DC bias magnetic field is studied, and the application effect is evaluated.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM712

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