直流单极-大地方式谐波特性及其对交流保护影响的分析

Harmonic characteristics of power transformer for DC bias and its impact on power system protection

直流输电系统单极-大地运行方式对交流电网继电保护产生影响的根源在于直流偏磁导致电力变压器谐波以及电流互感器传变特性的变化,基于PSCAD/EMTDC电磁暂态仿真程序对直流偏磁下的变压器谐波特性以及保护用电流互感器传变特性进行了全面的仿真分析,得出相应的变化规律与特点,并以此为基础分析和评估了直流输电系统单极-大地运行方式对交流电网保护的影响。

The monipolar ground circuit operation mode of HVDC system results in the DC bias of power transformers and current transformers in AC power system. It causes the harmonics generated from power transformer and changes the transforming characteristics of CT. Harmonic characteristics of power transformer and transforming characteristics of CT for DC bias are fully studied in the paper by simulation using PSCAD/EMTDC software. The results are used to evaluate the impact on power system protection.