换流变套管末屏电压采集器铁磁谐振机理分析及抑制

特高压换流变压器的阀侧套管安装有电容型末屏分压装置,用于传变阀侧交流电压。实际运行过程中发现,在线投入阀组时,由于在运直流系统的激励,投入阀组换流变阀侧套管末屏电压采集器会发生铁磁谐振现象,可能引发充电状态下的换流变压器保护误动作。文中基于实际运行故障录波进行了谐波分析,得出谐振发生的特征频率;通过分析末屏分压器及电压变送器电气原理搭建了暂态仿真模型,利用PSCAD/EMTDC建模重现了铁磁谐振发生的工况;在理论分析的基础上提出了改进分压器避免谐振发生的具体措施。

Ferromagnetic Resonance Mechanism of Voltage Divider of the Converter Transformer Bushing and its Suppression

In the valve-side busing of the UHV converter transformer,a capacitor-type bushing tap voltage divider is installed.In order to transmit the valve-side voltage to the control and protection equipment,after the converter is charged,a voltage transformer is connected to the bushing tap.During the actual operation,it was found that the ferro-magnetic resonance phenomenon occurred between the bushing tap capacitor and the voltage transformer of the converter valve side bushing,which may lead to the malfunction of the converter transformer in charging state.The article carries on the harmonic analysis based on the actual transiet fault recording,and obtains the characteristic frequency of the resonance.By analyzing the electrical principle of the voltage divider and voltage transmitter of the bushing tap,a transient simulation model is built,and the working condition of the ferroresonance is reproduced by using PSCAD/EMTDC simulation.Based on the theoretical analysis,the concrete measures of improving the voltage divider to avoid the resonance are put forward.