水电站内部铁磁谐振及抑制措施仿真研究

Simulation Study on Ferroresonance and Its Suppression Measures in Hydropower Station

电力系统中铁磁谐振时有发生,严重影响着电网的安全运行。由于导致铁磁谐振的主要原因为铁心设备的非线性磁饱和,仿真分析难度较大。文中利用非线性电抗器加理想变压器的模型等效电磁式电压互感器,准确模拟了某水电站铁磁谐振现象及发生的条件,并在此基础上提出了基于CVT的铁磁谐振抑制措施。仿真结果表明,采用CVT可以有效抑制一次系统中铁磁谐振的发生,但是在CVT二次侧短路且在短时间内消除的极端情况下,CVT内部会发生铁磁谐振。在分析此铁磁谐振产生原因的基础上,提出了在CVT二次侧保护段投入消谐电阻的抑制措施,并进行了仿真验证。

Ferroresonance often occurs in power systems,and threats the safety of the whole grid. Since the main rea-son of ferroresonance is nonlinear magnetic saturation of equipment with iron core,it is difficult to built accurate sim-ulation model. In this paper,PT is modeled with nonlinear reactor and ideal transformer,and the ferroresonance phe-nomena and its appearing conditions are accurately simulated. Based on the simulation,the suppression measure offerroresonance is proposed by using CVT. The simulation results show that utilizing CVT can effectively suppress theferroresonance in primary system. However,when short circuit happens at the secondary side of CVT and is eliminat-ed quickly,ferroresonance happens inside CVT. The reason of the internal ferroresonance is further analyzed,based on which the suppression measure of adding harmonic elimination resistance is proposed and verified.