Fault Nature Identification Method for Transmission Line of Doubly-fed New Energy Cluster Station Based on TT Transform Harmonic Saliency
Fault property identification is an important basis for adaptive reclosing.However,the grid connection of new energy clusters changes system harmonic characteristics during the open-phase operation and exacerbates the risk of misjudgement or failure of existing fault property identification schemes.Thus,this paper proposes a fault nature identification method for the transmission line of doubly-fed new energy cluster station based on TT transform harmonic saliency.Firstly,it introduces the harmonic feed-out characteristics of arc and doubly-fed induction generators(DFIG)during open-phase operation,and analyzes the principle of harmonic characteristic change during reclosing.To cope with different harmonic scenarios,it uses the time-time(TT)transform to effectively amplify the odd harmonic effective value characteristics and enhance the fault visibility.By threshold rectification,it constructs a fault nature and arc extinction moment identification method adapted to DFIG cluster access.PSCAD simulation verification shows that the proposed method is flexible and simple in threshold adjustment,which can accurately recognize the fault nature and arc extinction time in different fault locations,different fault angles and noise interference scenarios.This method has good adaptability when dealing with DFIG cluster access,and makes up for the shortcomings of the traditional fault nature identification scheme.The proposed method can also effectively improve the fault nature identification accuracy of new energy centralized transmission lines,which is conducive to improving the reclosing success rate.
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