A New Method of Single-terminal Protection for Flexible DC Distribution Lines Based on Current-limiting Reactor Voltage
The theoretical research of flexible DC distribution technology has entered a mature stage,and the imperfection of its line protection method has become an important factor restricting the development of this technology,especially the single-terminal protection with the advantage of fast action,which has weak resistance to high resistance and high sampling rate,still needs to be resolved.In order to solve the above problems,a new method of single-terminal protection for flexible DC distribution lines based on the current-limiting reactor voltage is proposed in this paper by analyzing the characteristics of the current-limiting reactor voltage and its negative rate of change in the time limit current reactor voltage when the metal bipolar short circuit fault occurs in the single-pole symmetrical connection system and the transit-resistance fault occurs.The simulation results show that the method can reliably identify faults in the region within 0.5ms,and can withstand the influence of transition resistance(20 Ω)and noise,and requires low sampling rate,which is of practical significance in engineering.
flexible dc distributionmodular multilevel convertercurrent limiting reactorsingle terminal protection
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