Analysis Of Electromagnetic And Thermal Characteristics Of The Saturated Core Fault Current Limiter With Permanent Modules

As the power networks are getting closer,the potential of short-circuit current at the time of the line failure is increasing.Limiting the fault current is a problem that must be considered in the operation of the grid.The saturated core fault current limiter with permanent modules has the characteristics of simple operation and economical operation.Studying the electromagnetic,temperature and other characteristics in the design stage of the body structure was the premise to ensure its security and stable operation.This paper studied the electromagnetic and thermal properties of the saturated core fault current limiter with permanent modules,the main works as follows:(1)A segmented magnetic circuit model was established for the new fault current limiter developed by our research group.Based on this,the instantaneous current waveform of the circuit with fault current limiter was calculated.The theoretical calculation and test results verified that this fault current limiter had the ability to limit the short-circuit current of the line.(2)Calculated respectively the power loss density of core,permanent magnet,DC winding and AC windings.And then calculated the two steady-state of the saturated core fault current limiter with permanent modules under normal working condition and line fault condition.The temperature field distribution showed that the permanent magnets had good magnetic field thermal stability under both working conditions in normal temperature environment.(3)Calculated the transient electromagnetic force of the DC winding and the AC windings under the fault current,and obtained that the maximum electromagnetic force appeared at the ends of the windings.The strength check formula of the windings radial direction is derived,and the ability of the winding radial and axial directions to withstand short-circuit current is checked.The results showed that the DC winding and the AC windings of the saturated core fault current limiter with permanent modules could maintain good dynamic stability under the fault current.