The invention discloses a distribution network fault line selection method based on a zero sequence current variable quantity waveform correlation coefficient matrix. According to the distribution network fault line selection method disclosed by the invention, a row off-diagonal element of each feeder zero sequence current variable quantity waveform correlation coefficient matrix and feeders in minimum corresponding before and after switching of a parallel resistance are utilized to carry out line selection for a fault line principle; and zero sequence voltage of a distribution network bus is larger than 15% phase voltage, the parallel resistance is switched by keeping arc suppression coil parameters invariable, a zero sequence current sampling value of each feeder flowing before and after switching of the parallel resistance is measured, the zero sequence current variable quantity waveform correlation coefficient matrix is further calculated, and the row off-diagonal element of each feeder zero sequence current variable quantity waveform correlation coefficient matrix and the feeders in minimum corresponding are selected as fault lines. With the adoption of the method, a line selection result is not influenced by factors such as transition resistance, line parameters, line length, distribution network running mode and fault position, the line selection principle is simple, and the line selection result is high in reliability and strong in practicability.

Distribution network fault line selection method based on zero sequence current variable quantity waveform correlation coefficient matrix

Embodiments of the present invention provide a method and an apparatus for monitoring and positioning faults in a power distribution network. The method mainly comprises steps that a power distribution line online monitoring unit distributed on a branch of a power distribution line determines a short circuit fault of the power distribution line according to the detected load current changes of the power distribution line, transmits the short circuit fault information of the power distribution line to a power distribution single-phase grounding comprehensive protection apparatus and a fault information processing apparatus; and the fault information processing apparatus, based on preset determination information, performs fusion processing on the short circuit fault information sent by the power distribution line online monitoring unit, and acquiring fault position information of the short circuit fault information. According to the embodiments of the invention, multiple power distribution faults such as short circuits, open circuits, single-phase grounding can be accurately detected; faults in the power distribution network are comprehensively solved; accidents are not enlarged; the equipment is protected; risks that people get electric shocks are reduced; and the selection of a fault line and the positioning of a fault point can be realized rapidly and accurately.

Method and apparatus for monitoring and positioning fault in power distribution network

The invention discloses a single-phase grounding line selection method for a small-current grounding system, and the method comprises the following steps: 1, collecting the zero sequence voltage of a bus or an outgoing line and the zero sequence current of the outgoing line, and calculating the amplitude of the zero sequence voltage in real time; 2, determining that the bus or the outgoing line has a single-phase grounding fault when the amplitude of the zero sequence voltage is greater than the amplitude of a line selection start voltage, and switching to step 3; 3, extracting the data of zero sequence current and voltage of a cycle before a moment when a fault happens and a cycle after the moment of the fault happens, and carrying out the wavelet packet transformation of the data of transient zero sequence voltage and current; 4, comparing the phases of the transient zero sequence current and voltage after the wavelet packet transformation: determining that a line is not a fault line if the phases are the same, and determining that the line is a fault line if the phases are opposite, thereby completing the grounding line section The method solves a problem of a higher line selection misjudgment rate caused by that the phases and amplitudes of the zero sequence currents of the fault line and the non-fault line when a conventional arc suppression coil grounding system has a single-phase grounding fault

Single-phase grounding line selection method for small-current grounding system

The present invention discloses a small current grounding fault line selection method based on a transient traveling wave. The method comprises a step of using a working frequency zero-sequence voltage signal to determine the grounding fault of a system, a step of selecting a fault phase for any outlet in a same bus, a step of calculating the polarity relationship between a transient traveling wave current signal and a transient traveling wave voltage signal for any outlet in the same bus, and a step of determining the outlets in the same bus is a failed line or not according to the polarity relationship. According to the method, through comparing the dyadic wavelet transform maximum value of each outlet three-phase transient traveling wave current, the largest phase of each outlet transient traveling wave current is selected, then a fault line is selected according to the polarity relationship between the transient traveling wave current and transient traveling wave voltage, the principle is simple, the range of application is wide, the method is not influenced by the factors of the magnitude of transition resistance, a neutral point grounding mode, and the existence of a branch line and has a high engineering practical value.

Small current grounding fault line selection method based on transient traveling wave

The invention discloses a small current grounded line gating and tuning method based on an arc suppression coil access control short time heteromorphic signal. The method comprises the following steps: (1) carrying out extraction and grounded line gating on the arc suppression coil access control short time heteromorphic signal; (2) preferentially tuning the faulted gated grounded line along with the arc suppression coil; and (3) putting the arc suppression coil into operation, compensating for capacitance current of a fault point, and extinguishing an electric arc. The method disclosed by the invention has the advantages that in the step (1), the arc suppression coil is not accessed into a power system, and the grounded line is gated and a tuning device is used for rapidly acquiring and analyzing voltage and current signals of the power system when the power system has a single phase grounded fault, so that the grounded faulted line is accurately selected; and in the step (2), the rated zero sequence capacitance current ICn0N of each line of the system is calculated in advance and stored in a designated database, the total rated zero sequence capacitance current ICsigma0N of the line is calculated by utilizing the data obtained by acquiring and analyzing after a fault and combining the line gating result and the data in the database, so as to take ICsigma0N and a reasonable tuning coefficient as a basis for calculating a tuning work point of the arc suppression coil, and then the arc suppression coil is correctly tuned.

Small current grounded line gating and tuning method based on arc suppression coil access control short time heteromorphic signal

A residual-variable-based line selection method for small current grounding, including the steps of: (1) using the displacement voltage U0 of the neutral point in a power distribution network as a characteristic, correctly identifying whether or not a single phase grounding fault has occurred in the power distribution network; (2) after a grounding fault occurs, an arc suppression coil compensating the grounding current of the fault point to reach the effects of decreasing the grounding current and extinguishing the grounding arc; (3) regulating the gear position of a gear arc suppression coil while ensuring that the grounding residual meets the standard requirements; (4) given that before and after regulating the gear position of the arc suppression coil the displacement voltage of the neutral point varies, using a voltage conversion method to convert the zero-sequence current of each outlet after gear regulation to the voltage level before gear regulation, so as to avoid the displacement voltage of the neutral point affecting the characteristic of the selected line; and (5) selecting the line where a single phase grounding fault has occurred according to the variation value of the zero-sequence current of each outlet before and after gear regulation after voltage conversion.The method can improve the accuracy of line selection.

Residual-variable-based line selection method for small current grounding

Low current grounding wire selection method based on residual current variable

Low-current grounding wire-selecting method

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Residual-variable-based line selection method for small current grounding

Low current grounding wire selection method based on residual current variable

Low-current grounding wire-selecting method