提高直流谐波稳定性的技术研究

Study on the Measures to Improve the Stability of Niu-cong HVDC Harmonic Wave

为减小牛从直流牛寨站交流系统发生故障时直流线路中的谐波含量,避免从西站谐波保护误动,借助牛从直流PSCAD/EMTDC仿真模型,对牛寨站交流系统发生故障时从西站谐波保护动作机理进行研究,提出两种降低直流线路中谐波含量的措施,并对两种措施的滤波效果进行仿真分析。研究发现在牛寨站高压直流出线处装设单调谐及双调谐滤波器时,对滤除直流电流中的总谐波含量及100 Hz谐波分量效果明显,但双调谐滤波器容易失谐,可能导致从西站50 Hz保护误动,单调谐滤波器滤除50 Hz谐波分量效果比较理想。在牛寨站高压直流出线处装设一组单调谐滤波器能达到较好的滤波效果,该设计思路可为其余高压直流输电工程设计提供理论参考。

In order to reduce the harmonic content in the HVDC line when the AC system of Niu-cong HVDC Niuzhai station fault,and avoid malfunction of harmonic protection from Congxi station.Based on the PSCAD/EMTDC simulation model of Niu-cong HVDC,the action mechanism of the harmonic protection in the Congxi station when the AC system of Niuzhai station failure is studied.Two measures to reduce the harmonic content in HVDC line are proposed,and the filtering effect of the two measures is simulated and analyzed.It is found that when a single tuning filter and a double tuning filter are installed at the HVDC outgoing line of Niuzhai station,the total harmonic content and 100 Hz harmonic component in the HVDC current are obviously eliminated,but the double tuning filter is easy to be detuned,which may lead to the misoperation of 50 Hz protection from the Congxi station.The effect of filtering 50 Hz harmonic component by a single tuning filter is ideal.A group of single tuned filters installed at the HVDC outgoing line of Niuzhai station can achieve better filtering effect,which can provide theoretical reference for the design of other HVDC transmission projects.