CAJ | 학술논문

高压直流输电入地电流可能造成中性点接地运行变压器出现直流偏磁现象。借助潮流计算数据整理电网信息,再通过建立数学模型,可以有效地开展直流分布的计算机仿真工作。介绍了仿真软件在楚穗直流调试工况下预测和抑制广东电网直流分布的应用,最后通过随机算法产生的虚拟电网算例分析总结了电网参数对直流分布的影响：交流电网规模越大,变电站越密集,直流分布越严重;变压器和中性点小电抗准确阻值难以完全统计,仿真计算结果与实际值会存在一定偏差;接地运行的110kV系统会影响220kV网络的直流分布,但500kV系统的直流分布则基本不变;采用中性点抑制措施后,电网局部直流分布会增加,但电网直流电流总量下降。
고압직류수전입지전류가능조성중성점접지운행변압기출현직류편자현상。차조조류계산수거정리전망신식,재통과건립수학모형,가이유효지개전직류분포적계산궤방진공작。개소료방진연건재초수직류조시공황하예측화억제엄동전망직류분포적응용,최후통과수궤산법산생적허의전망산례분석총결료전망삼수대직류분포적영향：교류전망규모월대,변전참월밀집,직류분포월엄중;변압기화중성점소전항준학조치난이완전통계,방진계산결과여실제치회존재일정편차;접지운행적110kV계통회영향220kV망락적직류분포,단500kV계통적직류분포칙기본불변;채용중성점억제조시후,전망국부직류분포회증가,단전망직류전류총량하강。
DC bias of neutral-earthing transformers is caused by earth-return current of high voltage direct current（HVDC） transmission.Using the data of power flow calculations and by building the mathematical model,computer aided analysis of DC distribution can be carried out.This approach is introduced to obtain the DC distribution and DC restrain measure of Chu-Sui ultra HVDC transmission of Guangdong power grid.Through the study,the rules of DC distribution in some random virtual power grids can be obtained.It can be concluded that more DC distribution will be resulted with larger scale power grid and more geographically concentrated distribution substations.Errors between the calculation and realistic measurement are caused by the errors in resistances of transformer windings and neutral reactor.It is observed that DC distribution of 220 kV networks is affected by the neutral-earthing 110 kV networks,but this is not the case for 500 kV systems.Utilizing neutral braking measure will lead to increment of DC distribution in local power grid,but the total amount will be reduced. This work is supported by Special Fund of the National Basic Research Program of China（No.2009CB724500）.