The Application Of Dual Tree Complex Wavelet Transform In The Fault Line Selection Of Small Current Grounding

Electricity is widely used in all walks of life,and is closely related to people's lives.The safety and reliability of the distribution network is becoming more and more important.The security and stability of the power system has become a topic of growing concern.The present our country mainly adopts the small current grounding system,of which,the greatest risk of failure is the single-phase grounding fault.When a fault occurs,How to find and solve the faults quickly and effectively is the key to ensure the safe operation of the distribution network.Firstly,this paper introduces the research status of single phase to ground fault line selection in small current grounding system at home and abroad,and summarizes the principle of line selection.Secondly,the basic theory and characteristics of dual tree complex wavelet transform(Dual-Tree Wavelet Transform,DTCWT)and Complex(Energy Relative Entropy,ERE)theory and its application are described in detail.Energy relative entropy and generalized S transform theory and its application.Using the advantages of DTCWT,a new method of fault line selection in distribution network is put forward.DTCWT has the advantages of approximate resolution,approximate translation invariance,anti aliasing,etc.it can extract the characteristic signal well and keep the integrity of the signal,so it can maintains the original signal information more better.The ERE can refines the fault energy distribution characteristics and reflects the subtle differences between the signals.In the characteristic frequency band,when a single-phase earth fault occurs,the fault line can be selected according to the difference of the relative entropy of energy.The generalized S transform has a good time-frequency characteristics,can analyze the signals from the two aspects of time and frequency,small current grounding system fault occurs,the fault line and normal line matrix maximum difference,can select the fault line according to the characteristics of.A 10 kV transmission line is established by MATLAB/Simulink simulation software,and the algorithm is constructed.A large number of simulation examples are given to demonstrate the effectiveness of the proposed method and the practical data of distribution network are analyzed to verify the practicability of this method.The results show that after DTCWT processing,both from the energy entropy judgment or from the S transform judgment,can get accurate line selection results.the method has little influence on the grounding resistance,fault time,fault phase and so on,and it can selects the fault line quickly and accurately under different operating conditions.