Study On Restraining Measures And Characteristics Of Secondary ARC In UHV Transmission Line With Series Capacitors

UHV transmission power technology effectively not only reduces transmission losses, but si an excellent way to save land resource and enhance the power transmission capability,it has obvious advantages of saving the project investment.With the improving of power system, eries capacitor compensator is widely used to improve the system stability and increase transmission capacity of power lines, transmission line adopt the single-pole auto-reclosure to enhance the power system stabilization, when transmission line single-phase ground fault occurs,self extinction smoothly of the secondary arc at fault points is a necessary condition for single-pole auto-reclosure successful. because of the existence of series compensation device, the extinction of secondary arc are more complex than conventional series compensation system, if we don’t take any measures to restrict the secondary arc occurrence, the secondary arc will be difficult to extinguish, which directly affects the system stability and circuit reliability, so it is necessary to deeply study on the characteristics of secondary arc and the frequency characteristics of secondary arc current and recovery voltage.Firstly, the research status for UHV transmission Power technology is summarized in this paper, then introduce the series compensation technology will be adopted in transmission lines, analyze secondary arc current and recovery voltage concening of line Parameters. The capacitance and inductance of secondary arc is calculated. Generating mechanism of secondary Arc and various influence factors of secondary arc current and recovery voltage is revealed.Secondly,the single-phase ground fault of UHV series compensated transmission lines is established by using electromagnetic transient simulation software ATP and PSCAD, and studied the influence factors on characteristics of secondary arc referring to the UHV single-circuit,double-circuit transmission line, found that if the fault point approach series compensation device will enlarges the amplitude value of the secondary arc current. The results show that value of the secondary current and recovery voltage can be effectively limited by using the parallel compensation reactors with small reactor and High Speed Grounding Switehes(HSGS). The paper mainly studies the effect of the small reactors value and ground resistance of the HSGS on the secondary arc restriction.Finally, by using of Laplace transform, the series compensation transmission lines are transformed,so as to analyz that when the single-phase-to-ground-faults orcurs in series-parallel compensation system, the wave form of the secondary current and recovery voltage on the fault point in theory.we can found that secondary current and recovery voltage will generate low-frequency components, as well as recovery voltage will generate phenomenon of "beat frequency".this paper utilizes MATLAB to analyze the analytical expression,so we can obtain the reference frequency of freedom-oscillation components and low-frequency-oscillation components,and further validate the correctness of theoretical analysis. On the basia of the frequency characteristics of secondary arc current and recovery voltage with new change in series compensation transmission lines.This paper presents measures to reduce the secondary arc current and optimizes the configuration parameters of the related devices.