Research On Single-phase Grounding Short-circuit Fault Location Method For Wind Farm Collector Line

Clean energy replaces fossil energy is the current direction to solve energy shortages,and wind power as a clean energy power generation has attracted much attention.At present,the phenomenon of abandoning wind nest electricity caused by faults of transmission lines in wind farms occurs from time to time.In order to solve the problem of quickly finding and repairing the fault points after the fault,and to ensure the safe and reliable delivery of wind power,the methods of realizing single-phase ground fault location in wind farms are studied from different perspectives.This paper summarizes and analyzes the existing transmission line fault location methods,and presents the problems of these methods in the single-phase ground fault location of wind farm collector lines.The structural characteristics of the wind farm are analyzed.Based on the topology and characteristics of the wind farm’s current collection line,an electrical model for fault location of the wind farm’s current collection line is established.Aiming at the problem of low positioning accuracy of the current impedance method,this paper proposes a single-phase ground fault location method for wind farm collector lines based on step-by-step recursion.In order to improve the positioning accuracy of the existing impedance method in the wind farm current collection line,two core error sources are analyzed and improved-namely the ground resistance and the injected current.After deriving,the expression of the fault grounding branch including the transition resistance is obtained,and the equivalent injection current model of the fan branch is established.Based on the above-mentioned fault grounding branch model and fan equivalent injection current model,a fault location method based on stepwise recursion is proposed.First,use the magnitude of the zero-sequence current to determine the branch where the fault is,and then calculate from the overhead end of the overhead line.Recursively search for the location of the fault point segment by segment.Determine whether the final result is obtained or whether to continue by judging whether the calculation result is in the current interval Recursive calculations to subsequent intervals.This method requires few measurement points,small calculation amount,and good economy.PSCAD / EMTDC simulation was used to verify the correctness of the proposed method.Combined with the currently widely used intelligent processing algorithms,the paper proposes a single-phase ground fault location method for wind farm collector lines based on RF-XGBoost.In this method,the random forest algorithm and XGBoost algorithm cooperate to realize fault location.First,the historical fault data is used as the original data set,and the random forest algorithm is used to reduce the dimension of the original data set to remove the poorly correlated data;the retained strong correlation feature values and label values are input into the XGBoost algorithm for learning and training,and finally fitted The relationship between the tag value and each characteristic value is used for fault location.This method has high positioning accuracy and good ductility.It is not only suitable for wind farm collector lines,but also suitable for other complex radial topologies.The correctness of the proposed method was verified by using PSCAD / EMTDC and Python simulation.