The Research And Development Of High-voltage Transmission Line Adaptive Reclosure

At present, the automatic reclosing device is commenly used in the high-voltage transmission lines, which can improve the supply reliability to some extent. However,when the device has reclosed the permanent fault or the transient fault that the secondary arc is not extinguished, it will lead to reclose failure, and thus bring the secondary impact to the electric power system. Therefore, the reclosing method,namely adaptive reclosure,is especially important, which can avoid reclosing the permanent fault or the transient fault when the secondary arc is not extinguished.This paper studies the adaptive reclosure from four aspects: the characteristics of fault terminal voltage when the transmission line has been single-phase grounded,the identification of fault nature, the determination of extinction time of secondary arc for the transient fault, the implement plan of adaptive reclosure.Firstly, this paper analyses the characteristics of fault arc in the high-voltage transmission lines, provides the first and secondary arc mathematical model, builds the simulation model by using of TACS and MODELS language in ATP-EMTP, and studies the characteristics of fault phase terminal voltage of the transient and permanent fault.Secondly, the fault phase terminal voltage is adaptively decomposed into numbers of pure frequency modulation components with physical meaning using local mean decomposition, the fault voltage of specific frequency band is taken out to and avoid the interference of high-frequency signal and noise to the fault analysis;The fault nature is determined by the difference among the local extremum numbers of the terminal voltage of high-voltage transmission line after the circuit breaker tripping. Theoretical analysis and simulation result show that the method can accurately identify the nature of the fault.Thirdly, having judged the nature of the fault can’t make sure of the success of reclosing, and now the time delay of automatic reclosing is fixed, which can’t restore the power supply quickly for the transient fault of the secondary arc extinct. In order to further improve the success rate of reclosing and reduce the outage time, this paper analyses the frequency characteristics of transient fault’s secondary arc in high-voltage transmission lines and the fault terminal voltage in recovering period.By using wavelet to extract specific band voltage signal, the arc extinction time is determined by the difference of energy function ratio in two voltage periods. It provides the reclosing scheme based on the adaptive arc extinction time and reduces the outage time to some extent.Lastly, this paper presents the hardware device and software design of the adaptive reclosure for the high-voltage transmission line based on DSP. The hardware device consists of four parts : the acquisition, processing and storage of data and the control of system. This software part provides the flow chart of main modules, such as the acquision, processing of data, serial communication, display,and buttons.