Design And Experimental Study Of Current Limiting System Based On Magnetic-Saturated Switcher Type Fault Current Limiter

In recent years,the scale and structure of the power system have been developing steadily and rapidly;at the same time,the short-circuit current level of the power grid has also increased continuously,which seriously threatens the stability and reliability of the system operation process.As a device that can effectively limit the short-circuit current of the power grid,the fault current limiter has the advantages of fast response speed,and easy cooperation with reclosing,and has become a hot research direction in the current power system.In this paper,based on the existing research of magnetic-saturated switcher type fault current limiter,this paper had further studied the key technologies.The main contents are as follows:In this paper,the principle of the magnetic-saturated switcher type fault current limiter was described in detail.Based on this,a topology model of the magnetic-saturated switcher type fault current limiter was proposed,and a corresponding electromagnetic simulation model was established in the JMAG.The electromagnetic transient simulation was performed on the designed current limiter.The result achieved the set target of the short-circuit current limit,which provided a theoretical basis for the development of the current limiter prototype.The control system of the magnetic-saturated switcher type fault current limiter depends on the monitoring system's judgment of the short circuit current.Therefore,the use of a fast and reliable short circuit fault detection algorithm is the key to improving current limiter current limiting performance.In this paper,the traditional power-frequency-based fault detection algorithm and traveling wave-based wavelet transform detection algorithm are introduced in detail,and the principle,advantages and disadvantages of these algorithms are analyzed.Based on this,a complex fault detection algorithm based on cube criterion was proposed.The simulation experiment was performed on Matlab and the expected results are achieved.Based on the simulation,DSP28335 was took as the hardware experiment platform to carry out the hardware experiment.The experimental results verified the reliability and real-time performance of the algorithm further.At last,based on the theoretical research,a 10kV/200 kVA prototype was developed.The NI PXIe-5170 R high-performance data acquisition board was used as the hardware platform to design a fault detection system,and a 10 kV short circuit simulation test was performed on the prototype.The experiment simulates the current limiting process of the current limiter under various short circuit fault conditions in the power system.The experimental results had achieved the expected results in response time and current limiting capability.on the one hand,the designed magnetic-saturated switcher type fault current limiter model was verified to have a good current limiting capability.On the other hand,it also validated that the composite fault detection algorithm can effectively identify faults and provide reliable protection start signals.