Research On Transmission Line Adaptive Reclosing Method

Nowadays,traditional automatic reclosing,which adopts fixed interval time reclosing scheme,is widely used in high-voltage transmission lines.The nature of the fault is not judged before closing.Once it coincides with a permanent fault or a transient fault with unextinguished arc,it will inevitably cause serious secondary impact on the power system and electrical equipment,which is not conducive to the safe and stable operation of the power system.The adaptive reclosing technology can not only improve the parallel operation stability and continuous power supply reliability of the power system,but also have the ability to discriminate the nature of the fault and capture the moment of secondary arc extinction under transient fault conditions,thereby avoid the failure of the closing action caused by the blind reclosure,and simultaneously shorten the non-full phase running time under single-phase reclosure.The key point of the research on the adaptive reclosing scheme is how to identify the nature of the fault after the fault phase circuit breaker is opened,and capture the stable arc extinction moment of the transient fault,so as to judge whether to reclose the circuit breaker.This paper analyzes in detail the time and frequency domain characteristics of the voltage at the fault terminal after the circuit breaker trips in the case of single-phase ground short circuit,two-phase ground short circuit and inter-phase short circuit faults,focusing on the research and explore of.single-phase adaptation adaptive reclosing methods and three-phase adaptive reclosing methods.First of all,the research background and current status of single-phase adaptive reclosure and three-phase adaptive reclosure are introduced.Starting from the dynamic characteristics of primary arc and secondary arc of faulted lines,a fault arc model and 500 k V are built using the ATP/EMTP simulation platform The single-phase ground fault simulation model of the transmission line obtains the voltage waveform of the fault phase terminal under different fault properties.Secondly,a single-phase adaptive reclosing method based on the Phase-locked loop technology and the average distortion rate of the fault feature quantity is proposed.The voltage characteristics of single-phase ground faults in the high-voltage transmission line with parallel reactors in the secondary arc stage and the recovery voltage stage are analyzed.The construction method of the fault characteristic quantity TDA,the extraction method of the fault signal and the use of the judgment are introduced.According to the principle of realizing instantaneousfault arc extinction moment capture.ATP/EMTP and MATLAB simulations verify that the method can accurately capture the secondary arc extinguishing moment under different shunt reactor compensation degrees,different power supply angles,different fault locations and different grounding resistance conditions,and can quickly reclose smoothly.be ready.Finally,a three-phase adaptive reclosing method based on the change of even harmonic content and the rate of change of the fault phase voltage is proposed.The two-phase ground short-circuit and inter-phase short-circuit faults are analyzed,and the three-phase circuit breaker trips when the fault phase voltage changes.Using the sudden change of the fault phase voltage change rate and even harmonic content before and after the secondary arc extinguishment of the transient fault,the arc extinguishing moment is captured and the fault nature is judged.This method is easy to implement,and a large number of ATP/EMTP and MATLAB simulations verify the effectiveness of the criterion for capturing the arc-extinguishing moment under different working conditions.