Research On Grounding Fault Detection Method Of United Adjustment Power Source System Based On VMD And Comprehensive Energy Relative Entropy

The stable operation of the power system is related to all aspects of production and living,but the problem of grounding fault has not been effectively solved.It affects the stable and safe operation of the distribution network.The proportion of single phase to ground faults in various grounding faults is more than 80%.With the use of isolated network system,it is more difficult to detect single-phase grounding faults.Therefore,it is necessary to study the method of selecting line with the single-phase grounding fault that can adapt to various working conditions.The power source system of power plant has the characteristics of small feed lines,short lines and the change of the system running frequency with the load.The decrease of frequency leads to the smaller amplitude of the zero sequence current,the fault feature is not obvious,the feature extraction is more difficult,and the fault line selection is inaccurate.In this paper,the model of power source system is set up in Matlab,and the simulation research is carried out on the four operating modes.The different fault angles,fault distance,zero sequence current and zero sequence voltage in the transition resistance are simulated,the fault rules of different operation modes are summarized,and the fault data are obtained.Then a method of line selection based on the relative entropy of VMD and integrated energy is proposed.The method is used to decompose the interval data of the transient fault of the zero sequence current by VMD.The decomposition results are transformed by Hilbert transformation.The relative entropy and phase of the integrated energy are calculated by the transformation results,and the relative entropy of the integrated energy of the fault line and the non-fault line is calculated.The difference of the phase is used to select the fault line.To verify the fault data obtained from the simulation,the simulation experimental circuit simulation power source system is built in the laboratory to verify the collected data.In the simulation,the more real power grid environment is added to the simulation of harmonic and white noise.In addition to the neutral point ungrounded system and the neutral point via arc suppression coil grounding system,the line selection algorithm is verified.The results show that the proposed line selection algorithm in this paper is of high accuracy and adaptability,and has great engineering guiding significance.Finally,The unified power source on-line monitoring system was designed based on STM32F767 and TPC7062KX.The real-time data,historical data and fault data of the zero-sequence voltage and zero-sequence current with the small current grounding system can be viewed in digital and curve manner.It can provide great convenience for Engineers.