CN-120993119-B - Low-voltage distribution network fault detection method and device

CN120993119BCN 120993119 BCN120993119 BCN 120993119BCN-120993119-B

Abstract

The application relates to the technical field of fault detection of a power distribution network, in particular to a fault detection method and device of a low-voltage power distribution network, wherein the method comprises the steps of adopting a pulse signal injection method, receiving reflected signals after pulse signals are injected into the low-voltage power distribution network each time with different pulse widths, and recording the reflected signals as response signals after pulse injection each time; the method comprises the steps of carrying out modal decomposition on a response signal, obtaining a plurality of modal components, calculating the relative difference of the modal components after each pulse injection, obtaining the modal components corresponding to fault points, calculating a first interference value and a second interference value after each pulse injection, determining the pulse width adjustment quantity and the pulse width when the next pulse is injected, and selecting an optimal response signal to locate single-phase grounding faults in a low-voltage distribution network through continuous pulse injection. The application improves the dynamic adaptability to the nonlinear characteristics of the electric arc and the network topology in the power distribution network by adjusting the pulse width in real time, and improves the accuracy of the pulse signal injection method to fault detection.

Inventors

LIU HUI
GU YANG
WANG WEIBIN
ZHANG JINXI
ZHAO WEI
ZHANG HAICHAO
ZHANG DONG
LI CONG
YANG SEN
REN JIFEI

Assignees

国网河南省电力公司卫辉市供电公司

Dates

Publication Date: 20260512
Application Date: 20251013

Claims (8)

1. The fault detection method for the low-voltage power distribution network is characterized by comprising the following steps of: Adopting a pulse signal injection method, after pulse signals are injected into a low-voltage distribution network each time with different pulse widths, receiving reflected signals, and recording the reflected signals as response signals after each pulse injection; Analyzing the difference condition of energy distribution of each modal component after each pulse injection and the modal component of the corresponding serial number after the previous pulse injection on the frequency domain, and calculating the relative difference quantity of each modal component after each pulse injection; acquiring the modal components corresponding to the fault points after each pulse injection based on the relative difference of all the modal components after each pulse injection; Analyzing the change condition of all signal amplitudes around the maximum signal amplitude in the modal component corresponding to the fault point after each pulse injection, and calculating a first interference value after each pulse injection by combining the relative difference quantity of the modal components corresponding to the fault point; Determining the pulse width adjustment amount in the next pulse injection based on the second interference value after each pulse injection, combining the pulse width in each pulse injection to obtain the pulse width in the next pulse injection, and selecting an optimal response signal to locate a single-phase grounding fault in the low-voltage distribution network by continuously injecting pulses; the calculating the first interference value after each pulse injection comprises: After each pulse injection, extending from the maximum value of all signal amplitudes in the modal components corresponding to the fault point to two sides until the signal amplitudes at the two sides are reduced to all signal amplitudes between positions corresponding to preset multiples of the maximum value, and forming a signal sequence; calculating the energy of the signal sequence, marking the energy as local energy, and carrying out negative mapping on the local energy; The first interference value is the product of the relative difference quantity of the modal components corresponding to the fault point and the result of the negative mapping; the determining the second interference value after each pulse injection includes: Calculating the sum of all energy in the marginal spectrum of each modal component when each pulse is injected, and recording the sum as total energy; The ratio between the total energy corresponding to the modal component corresponding to the fault point and the accumulated sum of the total energy of all the modal components during each pulse injection is recorded as the energy duty ratio; The second interference value is a product of the energy duty cycle and the first interference value.
2. A low voltage power distribution network fault detection method as claimed in claim 1 wherein said numbering of the modal components comprises numbering all modal components after each pulse injection in order from high frequency to low frequency.
3. A method for fault detection in a low voltage power distribution network as claimed in claim 1, wherein said calculating the relative difference between the modal components after each pulse injection comprises: carrying out frequency domain analysis on each modal component to obtain a marginal spectrum of each modal component, and carrying out normalization processing on all energy in the marginal spectrum to form an energy sequence; The relative difference is the distance of the energy sequence between each modal component after each pulse injection and the modal component corresponding to the same serial number after the previous pulse injection.
4. The method for detecting faults of the low-voltage distribution network according to claim 1, wherein the further obtaining process of the modal component corresponding to the fault point is that the modal component corresponding to the maximum value of all the relative difference amounts after each pulse injection is recorded as the modal component corresponding to the fault point.
5. A method for fault detection in a low voltage power distribution network as claimed in claim 1, wherein the first step is Pulse width adjustment amount at the time of secondary pulse injection The calculation formula of (2) is as follows: , wherein, Is the first The pulse width adjustment amount at the time of the secondary pulse injection, Is the first A second disturbance value after the sub-pulse injection, Is the first A second disturbance value after the sub-pulse injection, Is a normalization function.
6. A method of fault detection for a low voltage distribution network as claimed in claim 1, wherein the pulse width at the time of the next pulse injection is the sum of the pulse width at each pulse injection and the pulse width adjustment amount.
7. The method for detecting faults of a low voltage distribution network according to claim 1, wherein the method for acquiring the optimal response signal is that if the pulse width in the next pulse injection exceeds a preset adjustment range, the response signal after the pulse injection is recorded as the optimal response signal.
8. A low voltage distribution network fault detection device comprising a memory, a processor and a computer program stored in the memory and running on the processor, characterized in that the processor, when executing the computer program, carries out the steps of a low voltage distribution network fault detection method according to any one of claims 1-7.

Description

Low-voltage distribution network fault detection method and device Technical Field The application relates to the technical field of fault detection of power distribution networks, in particular to a fault detection method and device for a low-voltage power distribution network. Background The fault detection difficulty of the low-voltage distribution network is high due to the complex topological structure and the access of various power equipment. In particular, single-phase ground faults frequently occur in low-current grounding systems, and detection is difficult, with important effects on line repair and power supply reliability. However, single-phase ground faults are often accompanied by intermittent arcing, the impedance characteristics of which exhibit significant nonlinearities and time-variations, which cause severe distortions in the reflected signal waveform. Meanwhile, the ground fault characteristics are more complex and difficult to accurately extract due to interference influences such as reflected signals of grid nodes and nonlinear impedance characteristics of intermittent arcs, pulse signals with fixed pulse widths are difficult to adapt to complex signals with different interference degrees, dynamic adaptation mechanisms for the influences of the nonlinear characteristics of the arcs and network topology are lacking, detection interference of the pulse signals at different positions of a power distribution network is different, and therefore adaptability and accuracy of a pulse signal injection method in fault detection are reduced. Disclosure of Invention In order to solve the technical problems, a fault detection method and device for a low-voltage power distribution network are provided, so that the existing problems are solved. The application provides a fault detection method and device for a low-voltage power distribution network, which solve the technical problem and comprise the following steps: In a first aspect, an embodiment of the present application provides a method for detecting a fault in a low-voltage power distribution network, where the method includes the following steps: Adopting a pulse signal injection method, after pulse signals are injected into a low-voltage distribution network each time with different pulse widths, receiving reflected signals, and recording the reflected signals as response signals after each pulse injection; Analyzing the difference condition of energy distribution of each modal component after each pulse injection and the modal component of the corresponding serial number after the previous pulse injection on the frequency domain, and calculating the relative difference quantity of each modal component after each pulse injection; acquiring the modal components corresponding to the fault points after each pulse injection based on the relative difference of all the modal components after each pulse injection; Analyzing the change condition of all signal amplitudes around the maximum signal amplitude in the modal component corresponding to the fault point after each pulse injection, and calculating a first interference value after each pulse injection by combining the relative difference quantity of the modal components corresponding to the fault point; And determining the pulse width adjustment amount of the next pulse injection based on the second interference value after each pulse injection, combining the pulse width of each pulse injection to obtain the pulse width of the next pulse injection, and selecting an optimal response signal to locate the single-phase grounding fault in the low-voltage distribution network by continuously injecting the pulse. Preferably, the numbering of the modal components includes numbering all modal components after each pulse injection in order from high frequency to low frequency. Preferably, the calculating the relative difference amount of the modal components after each pulse injection includes: carrying out frequency domain analysis on each modal component to obtain a marginal spectrum of each modal component, and carrying out normalization processing on all energy in the marginal spectrum to form an energy sequence; The relative difference is the distance of the energy sequence between each modal component after each pulse injection and the modal component corresponding to the same serial number after the previous pulse injection. Preferably, the further obtaining process of the modal component corresponding to the fault point includes recording the modal component corresponding to the maximum value of all the relative difference amounts after each pulse injection as the modal component corresponding to the fault point. Preferably, the calculating the first interference value after each pulse injection includes: After each pulse injection, extending from the maximum value of all signal amplitudes in the modal components corresponding to the fault point to two sides until the signal amplitudes at the tw