CN-121978461-A - Fault diagnosis system and method for automatic power distribution network

CN121978461ACN 121978461 ACN121978461 ACN 121978461ACN-121978461-A

Abstract

The invention discloses a fault diagnosis system and a fault diagnosis method for an automatic power distribution network, and relates to the technical field of power distribution network diagnosis, wherein the fault diagnosis system comprises the steps of collecting electrical data and calculating a bus zero sequence voltage difference component and a feeder zero sequence current; generating an event window based on the voltage difference component characteristics, stripping capacitance components in the window by fitting to obtain residual zero sequence current, calculating comprehensive scores based on the ratio of residual energy to original energy to determine a fault feeder line, and further determining a fault section according to the score difference of adjacent measuring points along the fault feeder line. The invention effectively solves the problem of misjudgment caused by the phenomenon of inverting the first peak by stripping the capacitance response component, and improves the accuracy of fault diagnosis.

Inventors

CHANG CHENG
REN LINAN
XUE FANG

Assignees

邯郸学院

Dates

Publication Date: 20260505
Application Date: 20260209

Claims (8)

1. A fault diagnosis system for an automated power distribution network, comprising: The data construction module is used for collecting bus three-phase voltage of the distribution network and three-phase current of each feeder line, and calculating a bus zero-sequence voltage difference component sequence and a zero-sequence current sequence of each feeder line; The window generation module is used for generating an event window set based on the bus zero sequence voltage difference component sequence; The residual calculation module is used for fitting the zero sequence current sequence of each feeder line and the bus zero sequence voltage difference component sequence in each event window in the event window set to obtain a residual zero sequence current sequence of each feeder line in the corresponding event window; the fault line selection module is used for calculating the comprehensive score of each feeder line based on the residual zero sequence current sequence and the zero sequence current sequence of each feeder line in all event windows, and determining the feeder line with the highest comprehensive score as a fault feeder line; the section positioning module is used for acquiring the automatic measuring points on the line of the fault feeder, calculating the comprehensive scores of the automatic measuring points, and determining the fault section according to the comprehensive score difference of the adjacent automatic measuring points.
2. The fault diagnosis system of an automated power distribution network according to claim 1, wherein calculating the zero sequence voltage difference component of the bus and the zero sequence current of each feeder line comprises: carrying out summation and average on the three-phase voltage of the bus at the current moment to obtain a current zero-sequence voltage instantaneous value, and carrying out summation and average on the three-phase voltage of the bus at the previous moment to obtain a previous zero-sequence voltage instantaneous value; Obtaining a bus zero sequence voltage difference component at the current moment according to the difference value between the current zero sequence voltage instantaneous value and the previous zero sequence voltage instantaneous value; forming a bus zero sequence voltage difference component sequence according to the bus zero sequence voltage difference components at each sampling moment; summing three-phase currents of all feeder lines to obtain zero sequence currents of all feeder lines; And forming a zero sequence current of each feeder line according to the zero sequence current of each feeder line at each sampling moment.
3. The fault diagnosis system of an automated power distribution network of claim 1, wherein generating the set of event windows based on the bus zero sequence voltage difference component comprises: Identifying a local extreme point in the bus zero sequence voltage difference component sequence, wherein the local extreme point is a point with an absolute value larger than or equal to the previous moment and larger than the next moment; determining a symbol stable section where each local extreme point is located, wherein the symbol stable section takes two adjacent zero crossing points as boundaries; Each symbol stable segment is defined as a candidate event window, and the overlapping candidate event windows are combined to form an event window set.
4. The fault diagnosis system of an automated power distribution network of claim 1, wherein fitting the sequence of zero sequence current to the sequence of bus zero sequence voltage difference components for each feeder line within each event window in the set of event windows comprises: performing linear fitting on each event window in the event window set, and performing linear fitting on the zero sequence current sequence of each feeder line and the bus zero sequence voltage difference component sequence in the event window to obtain a fitted capacitance current component sequence; And obtaining a residual zero sequence current in the event window according to the difference value between the zero sequence current of the feeder line and the capacitor current component sequence.
5. The fault diagnosis system of an automated power distribution network according to claim 1, wherein calculating a composite score for each feeder comprises: respectively calculating the square sum of residual zero sequence current sequences of all feeder lines in all event windows to be used as residual total energy; Respectively calculating the square sum of zero sequence current sequences of all feeder lines in all event windows to be used as the original total energy; The ratio of the total energy of the residual error to the original total energy is used as the comprehensive score of the corresponding feeder line.
6. The fault diagnosis system of an automated power distribution network according to claim 1, wherein the calculation of the composite score of the automated measurement point is the same as the calculation of the composite score of the feeder line, except that the zero sequence current sequence and the corresponding residual zero sequence current sequence are input as the automated measurement point.
7. The system for fault diagnosis of an automated power distribution network of claim 1, wherein determining a fault section based on a composite score difference between adjacent automated measurement points comprises: according to the electrical connection sequence of the fault feeder lines, calculating the absolute value of the difference value of the comprehensive scores of two adjacent automatic measuring points to be used as the section score of the line section between the adjacent measuring points; Comparing the section scores of all the line sections, and judging the line section with the highest section score as a fault section.
8. A method of fault diagnosis for an automated power distribution network, the method comprising: s1, collecting bus three-phase voltage of a distribution network and three-phase current of each feeder line, and calculating a bus zero-sequence voltage difference component sequence and a zero-sequence current sequence of each feeder line; S2, generating an event window set based on the bus zero sequence voltage difference component sequence; S3, fitting the zero sequence current sequence of each feeder line and the bus zero sequence voltage difference component sequence in each event window in the event window set to obtain residual zero sequence current sequences of each feeder line in the corresponding event window; S4, calculating comprehensive scores of all the feeders based on residual zero sequence current sequences and zero sequence current sequences of all the feeders in all event windows, and determining the feeder with the highest comprehensive score as a fault feeder; S5, acquiring the automatic measuring points on the line of the fault feeder, calculating the comprehensive scores of the automatic measuring points, and determining a fault section according to the comprehensive score difference of the adjacent automatic measuring points.

Description

Fault diagnosis system and method for automatic power distribution network Technical Field The invention relates to the technical field of power distribution network diagnosis, in particular to a fault diagnosis system and method for an automatic power distribution network. Background The urban distribution network widely adopts an underground cable ring network structure and runs in a small-current grounding mode, single-phase grounding faults, particularly intermittent arc grounding faults, are frequent in the system, arcing and arcing processes when faults occur can cause rapid change of bus grounding voltage so as to drive a cable line to generate charge and discharge displacement current to a ground distributed capacitor, and for a distribution system with more outgoing lines and longer cable lines, zero-sequence current peaks with larger amplitude can be generated due to the obvious grounding capacitance effect of non-fault lines at the moment of voltage change, so that a plurality of lines can simultaneously generate obvious first peak components, and even the first peak value of the zero-sequence current of the non-fault lines is larger than that of the fault lines, namely, the first peak inversion phenomenon is caused. The existing fault diagnosis technology of the power distribution network generally depends on amplitude abrupt change or first half-wave polarity of zero sequence current as a judging basis, logic with maximum zero sequence current peak value or maximum abrupt change is generally adopted for line selection and positioning, however, under the condition of inverting the first peak, the judging logic is easily interfered by displacement current caused by line capacitance to ground, a non-fault line generating the maximum zero sequence current peak is erroneously judged as a fault line, and the systematic erroneous judgment not only leads to the reduction of fault line selection accuracy, but also leads to the jumping or positioning error of a fault section positioning result between adjacent sections, so that operation and maintenance staff can not quickly isolate fault areas and recover power supply, and the requirements of a power distribution automation system on high reliability and accurate operation and maintenance can not be met. Disclosure of Invention The invention aims to solve the defect that the traditional fault line selection and positioning logic based on current amplitude or abrupt quantity is easy to misjudge due to the phenomenon of inversion of the first peak of zero sequence current in a small-current grounding system in the prior art, and provides a fault diagnosis system and a fault diagnosis method of an automatic power distribution network. In order to solve the problems existing in the prior art, the invention adopts the following technical scheme: a fault diagnosis system for an automated power distribution network, comprising: The data construction module is used for collecting bus three-phase voltage of the distribution network and three-phase current of each feeder line, and calculating a bus zero-sequence voltage difference component sequence and a zero-sequence current sequence of each feeder line; The window generation module is used for generating an event window set based on the bus zero sequence voltage difference component sequence; The residual calculation module is used for fitting the zero sequence current sequence of each feeder line and the bus zero sequence voltage difference component sequence in each event window in the event window set to obtain a residual zero sequence current sequence of each feeder line in the corresponding event window; the fault line selection module is used for calculating the comprehensive score of each feeder line based on the residual zero sequence current sequence and the zero sequence current sequence of each feeder line in all event windows, and determining the feeder line with the highest comprehensive score as a fault feeder line; the section positioning module is used for acquiring the automatic measuring points on the line of the fault feeder, calculating the comprehensive scores of the automatic measuring points, and determining the fault section according to the comprehensive score difference of the adjacent automatic measuring points. Compared with the prior art, the invention has the beneficial effects that: 1. The invention extracts the capacitance current component driven by the rapid transition of the bus to the ground voltage by collecting the bus zero-sequence voltage difference component and the feeder zero-sequence current and utilizes the fitting relation between the bus zero-sequence voltage difference component and the feeder zero-sequence current to obtain the residual zero-sequence current sequence which cannot be interpreted by capacitance response, constructs a comprehensive scoring mechanism based on the ratio of the residual total energy to the original total energy, effectively inhibits t