Impact of saturation depth ratio of iron-core on the PMFCL

Fault current limiter based on permanent magnet biased saturation (PMFCL) is believed to foresee preferable application potentials in power systems due to its obvious advantages in both the technical and economical aspects. However, it is necessary to improve and optimize the operational characteristics of a PMFCL as a result of the deep saturation magnetization effect of the iron-core. A new concept ldquosaturation depth ratiordquo is then proposed in the paper to describe and quantify the saturation extent of the iron-core. Equivalent magnetic circuit method is employed to analyze the influence of saturation depth ratio on the current limiting inductance and fault current considering the working point variation of permanent magnet according to the relationship between saturation depth ratio and the parameters of the PMFCL. Finite Element Method (FEM) simulation is also performed to prove the above conclusions. The results of the analysis and simulation indicate that saturation depth ratio as a key parameter is quite useful for the comprehensive optimization of the PMFCL.