随着投入运行的直流输电工程日益增多，直流偏磁现象在输电线路周边变电站时有发生，危害电网的安全运行。使用PSCAD电力系统仿真软件对地上直流电网进行了建模，以500 kV含山变电站为例，对主变压器中性点采用小电阻或电容装置隔直时的电网直流潮流进行了计算，并采取了相应的抑制措施，提高了变电站稳定运行的能力。

With the operation of DC transmission projects increases, the DC magnetic biasing phenomena occurs sometimes in surrounding substations, which will harm the safe operation of power grid. This paper used PSCAD software for power system to build the model of DC power grid. Taking 500 kV Hanshan substation as an example, the DC power flow was calculated, when the neutral point of main transformer used low resistance or blocking capacitor. Finally, the suppression measures were adopted to improve the ability of stable operation for transformer substations.