The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were pr...The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems.At first,novel generating mechanisms of zero-sequence voltage and residual current were proposed.Then the compositions of residue parameters,including residual current and residual admittances,were decomposed in detail.After that,an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed,and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection.Furthermore,the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder,which cannot be affected by the asymmetry of the network.Theoretical analysis and the MATALB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms.展开更多
When a fault occurs in a DC system,the fault current rises rapidly with no zero-crossing point which makes fault-line selection and fault-type identification difficult.In this paper,an online detection and protection ...When a fault occurs in a DC system,the fault current rises rapidly with no zero-crossing point which makes fault-line selection and fault-type identification difficult.In this paper,an online detection and protection method based on graph theory,namely the“double D method”,is proposed for fault-line selection and fault-type identification in DC systems.In the proposed method,the entire distribution network is visualized as a“map”with vertices representing the line convergence points and edges representing the connection lines.A network topology matrix“D”is formed by detecting the current directions as the current directions are altered following a fault,whereas the current directions at the ends of non-fault lines remain the same.In order to prevent misjudgment problems arising from power flow reversal,the rates of change of the fault currents are used to further determine whether a fault has occurred and the“double D method”is introduced to identify the fault type.Simulations results with different fault types verify the effectiveness and reliability of the proposed method.展开更多
基金This work was supported in part by the National Natural Science Foundation of China(No.51177039)in part by the Fundamental Research Funds for the Central Universities(2018B06314)the 111 Intelligence project(B14022).
文摘The fast and accurate detection of the single-phaseto-ground fault is of great significance for the reliability and safety of the power supply.In this paper,novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems.At first,novel generating mechanisms of zero-sequence voltage and residual current were proposed.Then the compositions of residue parameters,including residual current and residual admittances,were decomposed in detail.After that,an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed,and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection.Furthermore,the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder,which cannot be affected by the asymmetry of the network.Theoretical analysis and the MATALB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms.
基金Thanks for the financial support from the following fund projects:Project Supported by National Natural Science Foundation of China(51607070)。
文摘When a fault occurs in a DC system,the fault current rises rapidly with no zero-crossing point which makes fault-line selection and fault-type identification difficult.In this paper,an online detection and protection method based on graph theory,namely the“double D method”,is proposed for fault-line selection and fault-type identification in DC systems.In the proposed method,the entire distribution network is visualized as a“map”with vertices representing the line convergence points and edges representing the connection lines.A network topology matrix“D”is formed by detecting the current directions as the current directions are altered following a fault,whereas the current directions at the ends of non-fault lines remain the same.In order to prevent misjudgment problems arising from power flow reversal,the rates of change of the fault currents are used to further determine whether a fault has occurred and the“double D method”is introduced to identify the fault type.Simulations results with different fault types verify the effectiveness and reliability of the proposed method.
