Simulation Of The Stability Of The New Magnetically Shielded Superconducting Fault Current Limiter Of The Power System

Development of electrical power systems is accompanied by a constant increase in fault currents and short circuit breaking capacity, these impose thermal stability requirements and enhanced electrodynamical to be met by electrical device. It in turn leads to a significant increase in cost, weight and size of electrical power equipment.Exorbitant short current would pose threat to the power equipments and the operators.During the last few years, a number of programs have been sponsored to investigate various techniques and devices applicable to limit fault currents in power systems in order to cut the fault current to the lower level when the control equipment of power system can break. The most ideal one of such devices is the superconducting fault current limiting devices.An improved magnetic shielding type HTSFCL with a control ring and an air gap is developed in the paper, it is mainly consists of a primary high-Tc superconducting winding, an iron core and a sub-cooled nitrogen cryostat with a cryocooler, a high-Tc superconducting cylinder ring as the secondary winding, an iron core and a sub-cooled nitrogen cryostat with a cryocooler, the principle of the device’s operation is based on a rapid rise of the device’s impedance at the transition of the winding and the ring from the superconducting to the normal state. It can effectively avoid the reduction of a limiting impedance in the HTSFCL by using an effective air gap under the higher current, and reduced the fault current and shorten recovery time with a copper ring.Due to improved superconducting current limiter reactance value much greater than its own resistance, ignoring the impact resistance of the new magnetic shield superconducting current limiter into machine infinite system.The new magnetic shield superconducting current limiter into machine infinite system, in the three-phase short-circuit and asymmetrical short circuit(including the two-phase ground short circuit, two-phase and single-phase ground short circuit shorted) transmission line system occur respectively, the use of matlab platform simulation, through changes in the engine rotor rocking curve, determine the impact of new magnetic shield current limiter for transient stability of power systems.The results of simulation demonstrate that the improved magnetic shielding type HTSFCL can reduce both the steady-state and the transient fault current significantly, the devices are enhancing the electrical energy quality of power systemand of great benefit in improving transient stability.