永磁饱和型故障限流器的永磁体稳定性实验研究

为获得用于永磁饱和型故障限流器(permanent-magnet-biased saturation based fault current limiter,PM-FCL)的钕铁硼(Nd-Fe-B)N35永磁体的运行稳定性能,从时间、温度和外磁场影响3方面展开了实验研究。以永磁体随时间的退磁率来表征时间稳定性,以可逆损失率和可逆温度系数来表征温度稳定性,并分析了永磁部件的面积厚度比S/L对温度稳定性的影响。进一步,用通电螺线管模拟220kV变电站的工程磁场环境,通过实验考查了PMFCL永磁体的外磁场稳定性。实验表明,钕铁硼永磁体具有较好的时间稳定性和外磁场稳定性,在温度较高时的退磁效应并不明显,并可通过设计面积厚度比S/L较低的限流拓扑予以抵消。所得研究结果为研制面向工程应用的高压大容量PMFCL提供了基础依据。

Experimental Research on Permanent Magnet Stability of the Permanent-magnet-biased Saturation Based Fault Current Limiter

To obtain the operational stability characteristics of the permanent magnet(PM)Nd-Fe-B N35which is widely used in permanent-magnet-biased saturation based fault current limiter(PMFCL),experimental research was carried out in three aspects,namely,time,temperature,and environmental field dependency.The demagnetization rate was adopted to denote the PMs’time stability,while both the reversible loss rate and the reversible temperature coefficients were introduced to express the PMs’temperature stability,and the impact of the S/L ratio between the cross section area and the thickness on temperature stability was also elucidated.Furthermore,under an engineering magnetic field physically simulated through an activated solenoid coil,the PMs’external magnetic field stability was experimentally verified.The experimental results demonstrate that,the PM Nd-Fe-B N35possesses preferable time and external magnetic field stability,though indistinctive demagnetization effect under high temperature may be produced,which can be counteracted through optimal PMFCL topology design for a reduced ratio S/L.The above research presents elemental basis for development of the high voltage large-capacity PMFCLs being oriented for practical applications.