电机驱动用长电缆破坏机理分析及防护  

Analysis and Protection of the Failure Mechanism of Long Cable for Motor Driver

作　　者：李晓[1] 王璁[1] 屠幼萍[1] 

机构地区：[1]高电压与电磁兼容北京市重点实验室(华北电力大学)，北京 102206

出　　处：《电气传动》2014年第4期72-76,共5页Electric Drive

摘　　要：采用长线电缆的电动机驱动系统频繁出现电缆绝缘损坏问题,严重影响了系统的可靠运行。在分析变频谐波和电压闪停对长线电缆绝缘影响的基础上,通过PSCAD/EMTDC软件建立了"变频器—长线电缆—异步电机"仿真计算模型,进行了变频谐波和电压闪停情况下长线电缆的过电压、过电流及相应频谱仿真分析。仿真结果表明:变频器输出脉冲波经长电缆传输时会在电缆接头处产生接近两倍的谐波过电压,同时产生谐波过电流导致电缆绝缘降低;电网电压发生闪停后,电机会发生能量倒送,产生短时大电流破坏电缆绝缘。基于仿真结果,设计了一种二阶RLC低通滤波器以抑制变频谐波的危害,并提出了降低电压闪停影响的保护措施,从而有效地保护电缆绝缘。The motor driving systems using long cable frequently appear cable insulation problems,whichseriously influence the reliable operation of the systems. Based on the analysis of the influences of frequency harmonicand voltage transient loss on the long cable insulation,the“converter-long cable-induction motor”simulation modelbased on PSCAD/EMTDC software was built,the over-voltage,over-current and the corresponding spectrum under thesituation of frequency harmonic and voltage transient loss were simulated and analyzed. The results show that theconverter output pulse produce nearly twice harmonic over-voltage in cable tapping through long cable,meawhileproduce a certain harmonic over-current,which results in the decrease of cable insulation;the induction motor delversits energy after happening voltage transient loss,which produce short-term high current that leads to the damage ofcable insulation. Based on the simulation results,a kind of second-order RLC low-pass filter was designed to suppressthe harm of frequency harmonic,and some protection was put forward to decrease the influence of voltage transientloss,which can effectively protect the cable insulation.

关 键 词：PSCAD EMTDC 长线电缆 变频谐波 电压闪停 绝缘 RLC低通滤波器 

分 类 号：TM921[电气工程—电力电子与电力传动]