Study Of Single Phase Adaptive Reclosure Technology On High Voltage Transmission Line

Automatic reclosing technology has the defect of closing blindly, once it is closed by a permanent fault, it will impair the system again and lead to a deterioration of electrical equipment operating conditions. Adaptive reclosure technology has the functions of identifying the properties of fault in advance and capturing the moment when the arc extinguished so that the system can avoid being closed because of the permanent fault and non- extinction arc instantaneous fault. This paper analyzes the fault voltage characteristic of instantaneous fault during the recovery voltage period and the secondary arc stage, studies the identification of the single phase adaptive reclosure technology on high voltage transmission line as well as the methods of capturing the moments when the arc extinguished because of instantaneous fault.Firstly, the thesis studies the dynamic characteristics of the primary arc when different types of faults occur on transmission line, it analyzes reignition characteristics of the secondary arc in instantaneous fault as well as the characteristics of voltage waveform in fault phase terminal, by using ATP / EMTP to build high-voltage transmission line fault simulation models, the primary and the secondary arc model so that waveform of fault phase terminal voltage on High-voltage transmission line could be obtained by simulation.Secondly, by using instantaneous fault on the transmission line with shunt reactor to recover voltage beat phenomenon, the reclosing cheme(scheme 1) based on the identification of fault in recovery of voltage envelope slope is put forward. The scheme aims to find the waveform envelope of fault phase terminal voltage during the stage of voltage recovery, so as to get the average slope envelope between two adjacent extreme points. When the average slope envelope is greater than the setting value, it will be recognized as instantaneous fault, the reclosing command would be executed. Otherwise, it will shut down for a permanent fault.Thirdly, according to the characteristics of voltage signal of instantaneous fault in the secondary arc fault phase, this paper presents two schemes of single phase adaptive reclosure technology that is scheme 2 and scheme 3. Scheme 2 is based on different terminal voltage waveform distortion rate of the secondary arc, high frequency energy, and voltage amplitude under different properties of fault, by using Fourier transform to get the terminal voltage waveform distortion rate, high frequency energy, voltage amplitude, and then use the waveform distortion rate and high frequency energy, waveform distortion rate and voltage amplitude as two dimensional characteristic vector respectively. Using two support vector machine(SVM) to classify the above mentioned two-dimensional characteristic vector so as to identify the properties of fault and capture the moment when the secondary arc is extinguishing. Scheme 3 is based on the different complexity of the fault phase voltage waveform between instantaneous fault and permanent fault. PF component are obtained by decomposition of fault signal through LMD. Using Approximate Entropy(Ap En) to calculate the complexity of the PF component as eigenvectors, which are then given to SVM as feature vectors to identify the properties of fault on transmission line as well as capture the secondary arc extinguishing time.Finally, the above mentioned three schemes are verified through simulation under different properties of fault, at different positions of short circuit as well as under the condition of different transition resistance. The results show that scheme 1 can quickly identify the transient faults and permanent faults; scheme 2 and scheme 3 can not only quickly identify the nature of the fault but also could capture the arc extinguishing time accurately, besides, it has good anti-noise capability.