Research On Single-Phase Grounding Short-Circuit Fault Location Method For Wind Farm Collector Line Based On Zero Sequence Network

With the "carbon peak" goal proposed,our country’s construction of new energy power generation continues to expand.Wind power is one of the most promising clean energy power generation,and its total installed capacity continues to grow.However,the efficiency of the system’s utilization of wind power needs to be improved.Every year,there is a phenomenon of abandonment of wind power due to short-circuit failures of the collection lines in the wind farm.Therefore,how to quickly find the short-circuit fault location of the collecting line and restore the wind power transmission in time will have important research significance.Based on the structural characteristics of wind farms,this paper studies the distance measurement methods that can be applied to wind farm collection lines.The wind farm collection system and its zero-sequence network model are established.According to the primary wiring diagram of the current large-scale wind farm,the analysis is carried out from the four aspects of the wind farm collecting line structure,line connection method,neutral grounding method,and wind turbine type and characteristics.The respective characteristics are explained in detail on this basis.The model of the wind farm collection line system and its zero-sequence network model are constructed above,and the advantages of using the zero-sequence network to conduct fault location research on the collection are summarized.Taking into account the short distance between the fans on the collector line of the actual wind farm,this paper takes the distance between the two fans as the section,and designs a fault section location method based on the distributed current phasor.By analyzing the current components of each section,the vector difference is used to offset the current components of the same component,and the faulty section is identified according to the modulus characteristics of the current vector difference of each section.In order to reduce the number of synchronous measuring points and the influence of the fault current provided by the fan,the method is optimized by using the established zero-sequence network model.Finally,in order to identify the fault section quickly and effectively,a section current difference objective function model is established,and the fault section is determined according to the objective function value.The proposed method has the advantages of convenient fault information extraction and obvious characteristics.By setting up simulation experiments with different fault sections and different transition resistances,it is verified that the proposed method can accurately realize the fault segmentation and is less affected by the transition resistance.Aiming at the problems of current fault analysis methods in multi-branch hybrid lines,this paper designs a fault location method based on impedance measurement and zero sequence network.This method establishes the measurement impedance equation under the zero-sequence network to perform error analysis on the applicability of the collection cable.Combining the two main sources of error-mixed line parameter inconsistency and transition resistance,the constructed ranging equation is improved from two aspects: 1)To solve the problem of parameter inconsistency,a piecewise function method is used to classify and establish the ranging equation;2)Based on the new equation constructed,the ranging equation without transition resistance is derived,which theoretically eliminates the influence of transition resistance on positioning.Through PSCAD/EMTDC simulation experiments,it is illustrated from the horizontal and vertical angles that the improved ranging equation is less affected by the fault location,fault section type and transition resistance,which verifies the correctness of the improved algorithm and improves Ranging accuracy.