Abstract: The series resonant type fault current limiter is an effective mean to solve the excessive level of fault current of EHV grid, and the performance of capacitor bank by-pass device and the limiting depth are the key technologies that need to be studied for series resonant type fault current limiter. In this paper, combined with previous work, a study is made on the two technologies, and a new type of series capacitor bank bypass device and a variable impedance limiting reactor are proposed, which can effectively improve the limiting effects of series resonant type fault current limiter for EHV grid. Besides, the research status of fault current limiter for EHV grid is also reviewed, and the two technologies of series capacitor bank by-pass device and limiting depth are analyzed. An analysis of the principle, structure and performance of the new-type series capacitor bank bypass device shows that the new-type series bypass device has high performance in reliability, action speed, ampacity and economy. Finally, based on the principle and structure of variable impedance limiting reactor, a verification experiment is conducted, which shows that the impedance can increase by more than 100 times.

Key words: series resonant type fault current limiter, by-pass device, multi-stage spark gap, variable impedance limiting reactor