Research On Line Selection And Location Of Single-phase Grounding Faults In Distribution Networks

With the vigorous development of new energy technology,the penetration rate of Distribution Generation(DG)in the distribution network has continued to increase,which has transformed the traditional distribution network into an Active Distribution Network(AND).The current flow in the power grid,the fault characteristics after a single-phase ground fault,and other issues have become more complex and diverse.The fault line and fault location methods of the traditional distribution network cannot correctly select the fault line and fault section.The fault line selection and fault location technology,as an important function of distribution automation,is the key to ensuring the safe and reliable operation of the distribution network.Therefore,it is necessary to study the single-phase grounding fault line selection and fault location technology of active distribution network.This paper takes the active distribution network as the main research object,and uses the feeder terminal unit(FTU)of the distribution network to sample and detect fault data for fault line selection and fault location technology research.The main research contents of this paper are as follows:The steady-state and transient fault characteristics of the active distribution network and the traditional distribution network after a single-phase grounding fault are compared and analyzed,and the fault characteristics under the PQ control strategy of the inverter-type DG and the effect of the single-phase grounding fault are analyzed in detail.Influence,and use the PI control process under the power outer loop and the current inner loop to simulate the PQ control strategy.According to the fault characteristics after a single-phase grounding fault occurs in the active distribution network system,a wavelet packet method is proposed to extract the fault transient characteristics for fault line selection.During the research process,it is found that when the signal sampling frequency is relatively low,the collected temporary The signal will be attenuated,sometimes even severely attenuated,resulting in wrong line selection results.Aiming at the problem that the wavelet packet line selection method may have errors in single-phase ground fault line selection,the skewness characteristics of the collected signal are introduced and proposed A fault line selection method based on wavelet packet and skewness featuresIn order to realize the fast and accurate segment location after a single-phase grounding fault occurs in the active distribution network,the dynamic time warping(DTW)distance algorithm is used to reduce the distance between similar signals and the principle that the distance between similar signals is larger.An improved DTW distance algorithm is proposed to locate the fault section of the active distribution network.The fault zone is determined by calculating the distance between the detected fault data collected by each FTU.The simulation verification results show that the improved DTW distance algorithm can quickly and accurately locate the fault zone.