高压直流输电系统不平衡运行时直流电流分布规律及直流偏磁现象分析

发布时间：2018-01-16 02:03

本文关键词：高压直流输电系统不平衡运行时直流电流分布规律及直流偏磁现象分析　出处：《三峡大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着我国高压直流输电的发展，在直流系统单极-大地运行时对变压器直流偏磁影响日益明显。变压器中性点电流作为变压器直流偏磁情况的直接影响因素，反映了变压器直流偏磁状况，因此如何在电力系统角度全面计算交流电网中各变压器中性点电流分布情况，深度解析变压器直流电流分布机理是电网发展需求。本文在此背景下，研究针对湖北省直流密集型地区宜昌电网进行直流偏磁仿真建模，在收集了宜昌电网交直流输电系统工程的实际参数基础上，采用交流系统网络化建模的方法，基于PSCAD/EMTDC电磁暂态仿真软件平台建立了包含宜昌电网两条500kV直流输电线路以及直流接地极周围220kV及以上交流变压器中性点电流分布仿真模型。实现了基于电网实际参数建立反映全网变压器中性点电流分布以及变压器直流偏磁的交直流混联仿真模型。模型经过电网运行的实测数据验证有效。在建立的电网仿真模型基础上，，仿真计算了葛洲坝上海直流输电工程和宜都华新直流输电工程在不同工况下交流电网各变压器中性点电流分布情况，得出了各直流接地极与变压器中性点电流间定量关系。同时对交流系统运行方式改变后变压器中性点电流分布以及直流偏磁情况进行仿真分析。在解析各变压器中性点电流分布规律基础上得出了系统不同运行方式对变压器直流偏磁影响机理。为后续研究如何从系统角度抑制、减轻交流电网各变压器直流偏磁提供一定的理论基础。
[Abstract]:With the development of HVDC transmission in China, the influence of DC bias on DC bias of transformer is becoming more and more obvious when unipole-earth operation of DC system. The neutral current of transformer is the direct influence factor of DC bias of transformer. It reflects the DC bias of the transformer, so how to calculate the neutral current distribution of the transformer in the AC network from the angle of the power system. The depth analysis of DC current distribution mechanism of transformer is the demand of power grid development. Under this background, this paper studies the simulation modeling of DC bias for Yichang power grid in the concentrated area of Hubei province, and collects the actual parameters of Yichang power grid AC / DC transmission system project. The network modeling method of AC system is adopted. Based on PSCAD/EMTDC electromagnetic transient simulation software platform, the neutral point of AC transformer including two 500kV HVDC transmission lines and 220 kV and above AC transformers around DC earths is established. Based on the actual parameters of the power network, an AC / DC hybrid simulation model reflecting the neutral point current distribution and DC bias of the transformer is established. The model is verified by the measured data of the operation of the power network. Based on the established power network simulation model. The distribution of neutral point current of transformer in Gezhouba Shanghai HVDC Project and Yidu Huaxin HVDC Project under different working conditions is simulated and calculated. The quantitative relationship between the DC earth electrode and the neutral current of the transformer is obtained. At the same time, the distribution of the neutral current and the DC bias of the transformer after the change of the operation mode of the AC system are simulated and analyzed. Based on the current distribution of neutral point, the influence mechanism of different operation modes on DC bias magnetic field of transformer is obtained. Reducing DC bias of AC power transformers provides a theoretical basis.
【学位授予单位】：三峡大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1

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