CN-116626444-B - Fault identification method and device for direct-current transmission line and computer equipment

CN116626444BCN 116626444 BCN116626444 BCN 116626444BCN-116626444-B

Abstract

The application relates to a fault identification method, device, computer equipment, storage medium and computer program product of a direct current transmission line, and relates to the technical field of intelligent power grids. The method comprises the steps of obtaining fault conditions of an anode line and a cathode line in a direct current transmission line to be identified, respectively collecting voltage data and current data of two ends of the target line under the condition that the target line is faulty, respectively carrying out low-pass filtering processing on the voltage data and the current data, respectively obtaining a differential current average value of the target line according to the filtered current data, obtaining a distributed capacitance current average value of the target line according to the filtered voltage data, and determining a faulty area of the target line according to the ratio between the differential current average value and the distributed capacitance current average value. The method can improve the quick action of fault identification.

Inventors

CHEN LIXIN
SHAO ZHEN
GUO JIANBAO
ZHANG ZHICHAO
WANG QI
YANG YUFENG
PENG GUANGQIANG
WU JIYANG
Huang Zhidi
CHEN HUAN
HE JINGSONG
Gong ze
LI SHIJIE
WANG HAIJUN

Assignees

中国南方电网有限责任公司超高压输电公司电力科研院

Dates

Publication Date: 20260505
Application Date: 20230606

Claims (11)

1. A fault identification method for a direct current transmission line, the method comprising: acquiring fault conditions of an anode line and a cathode line in a direct current transmission line to be identified; for a target line in the positive line and the negative line, respectively acquiring voltage data and current data of two ends of the target line under the condition that the target line fails; the method comprises the steps of obtaining a voltage drop coefficient, a transition resistance and a line capacitance corresponding to a target line, determining a low-pass cutoff frequency of low-pass filtering processing according to the voltage drop coefficient, the transition resistance and the line capacitance, respectively performing low-pass filtering processing on voltage data and current data according to the low-pass cutoff frequency to obtain filtered voltage data and filtered current data, wherein the filtered voltage data comprises a plurality of groups of filtered voltage data, each group of filtered voltage data comprises the filtered voltage data at two ends of the target line at the same moment, and the value range of the low-pass cutoff frequency is determined by the following formula: Wherein, the For the low-pass cut-off frequency, For the coefficient of the voltage drop, In order to provide the transition resistance as described, Line capacitance per unit length, L is the line length of the target line, A line capacitance for the target line; Obtaining a differential current average value of the target line according to the filtered current data, determining a voltage difference between two ends of the target line at a corresponding moment of each group of filtered voltage data according to each group of filtered voltage data, obtaining a line capacitance corresponding to the target line and a time interval between corresponding moments of two adjacent groups of filtered voltage data, obtaining a distributed capacitance current average value of the target line according to the line capacitance, the time interval and the voltage difference between two ends corresponding to each group of filtered voltage data, and calculating the distributed capacitance current at the corresponding moment of each group of filtered voltage data by the following formula: Wherein, the For each said group of filtered ones The group voltage data corresponds to the distributed capacitive current at the instant, For the time interval of the time period in question, And Respectively representing voltage data at two ends of the target line; the method comprises the steps of obtaining a ratio between the differential current average value and the distributed capacitance current average value, obtaining a line protection setting value of a target line, determining that the target line has an intra-area fault when the ratio is larger than the line protection setting value, and determining that the target line has an extra-area fault when the ratio is smaller than or equal to the line protection setting value.
2. The method according to claim 1, wherein the obtaining the fault condition of the positive line and the negative line in the dc transmission line to be identified includes: Aiming at a target line in the positive line and the negative line, acquiring the voltage traveling wave variation of the target line and acquiring the voltage traveling wave variation threshold; And when the voltage traveling wave variable quantity of the target line exceeds the voltage traveling wave variable quantity threshold value, determining that the target line fails.
3. The method of claim 2, wherein the obtaining the voltage traveling wave variance threshold comprises: acquiring rated line voltage and voltage change coefficient corresponding to the target line; And taking the product of the rated line voltage and the voltage change coefficient as the voltage traveling wave change amount threshold.
4. The method of claim 1, wherein the filtered current data comprises a plurality of sets of filtered current data, each set of filtered current data comprising filtered current data across the target line at the same time; and obtaining a differential current average value of the target line according to the filtered current data, wherein the differential current average value comprises the following steps: determining differential current of the target line at the corresponding time of each group of filtered current data according to each group of filtered current data; And determining the differential current average value of the target line according to the differential current corresponding to each group of filtered current data.
5. A fault identification device for a direct current transmission line, the device comprising: The fault acquisition module is used for acquiring fault conditions of an anode line and a cathode line in the direct current transmission line to be identified; the system comprises a data acquisition module, a data processing module and a data processing module, wherein the data acquisition module is used for respectively acquiring voltage data and current data of two ends of a target line aiming at the target line in the positive line and the negative line under the condition that the target line fails; The low-pass filter processing module is used for acquiring voltage drop coefficients, transition resistances and line capacitances corresponding to the target line, determining low-pass cutoff frequencies of low-pass filter processing according to the voltage drop coefficients, the transition resistances and the line capacitances, respectively carrying out low-pass filter processing on the voltage data and the current data according to the low-pass cutoff frequencies to obtain filtered voltage data and filtered current data, wherein the filtered voltage data comprises multiple groups of filtered voltage data, each group of filtered voltage data comprises the filtered voltage data at two ends of the target line at the same moment, and the value range of the low-pass cutoff frequencies is determined by the following formula: Wherein, the For the low-pass cut-off frequency, For the coefficient of the voltage drop, In order to provide the transition resistance as described, Line capacitance per unit length, L is the line length of the target line, A line capacitance for the target line; The data calculation module is used for obtaining a differential current average value of the target line according to the filtered current data, determining a voltage difference between two ends of the target line at a corresponding moment of each group of filtered voltage data according to each group of filtered voltage data, obtaining a line capacitance corresponding to the target line and a time interval between corresponding moments of two adjacent groups of filtered voltage data, obtaining a distributed capacitance current average value of the target line according to the line capacitance, the time interval and the voltage difference between two ends corresponding to each group of filtered voltage data, and calculating the distributed capacitance current at the corresponding moment of each group of filtered voltage data by the following formula: Wherein, the For each said group of filtered ones The group voltage data corresponds to the distributed capacitive current at the instant, For the time interval of the time period in question, And Respectively representing voltage data at two ends of the target line; The area determining module is used for obtaining the ratio between the differential current average value and the distributed capacitance current average value, obtaining the line protection setting value of the target line, determining that the fault occurs in the area of the target line when the ratio is larger than the line protection setting value, and determining that the fault occurs outside the area of the target line when the ratio is smaller than or equal to the line protection setting value.
6. The apparatus of claim 5, wherein the fault acquisition module is further configured to acquire a voltage traveling wave variation of a target line for the target line and the negative line, and acquire the voltage traveling wave variation threshold, and determine that the target line is faulty when the voltage traveling wave variation of the target line exceeds the voltage traveling wave variation threshold.
7. The apparatus of claim 6, wherein the fault acquisition module is further configured to acquire a rated line voltage and a voltage change coefficient corresponding to the target line, and take a product of the rated line voltage and the voltage change coefficient as the voltage traveling wave change amount threshold.
8. The apparatus of claim 5, wherein the data calculation module is further configured to determine a differential current of the target line at a time corresponding to each set of filtered current data based on each set of filtered current data, and determine a differential current average value of the target line based on the differential current corresponding to each set of filtered current data.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 4 when the computer program is executed.
10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 4.
11. A computer program product comprising a computer program, characterized in that the computer program, when executed by a processor, implements the steps of the method of any of claims 1 to 4.

Description

Fault identification method and device for direct-current transmission line and computer equipment Technical Field The present application relates to the technical field of smart power grids, and in particular, to a fault identification method, apparatus, computer device, storage medium and computer program product for a dc power transmission line. Background At present, a direct current transmission system has been widely used for long-distance large-capacity transmission. The traditional high-voltage direct-current transmission system adopts a power grid commutation converter, has high strength requirement on an alternating-current system, and is easy to cause commutation failure. The flexible direct current transmission system adopts a voltage source type converter, has the advantages of flexible control and no commutation failure, and becomes an important direction of the development of the direct current transmission technology. However, most of the direct current transmission lines are overhead lines, and the probability of occurrence of faults is high, and the rising rate of fault current is high, so that direct current line fault identification has been receiving a great deal of attention as a key technology in direct current transmission. At present, although high-resistance faults can be effectively identified based on current differential fault identification, the fault identification by the method further has poor quick action performance for fault protection. Meanwhile, the multi-terminal flexible direct current transmission system is of a net structure, a plurality of converter stations feed fault current to fault points through net lines, the fault current rises fast, the flexible direct current transmission system adopts IGBT (Insulated Gate Bipolar Transistor ) to perform power conversion, but the current passing capability of the IGBT is poor, and the requirement of the multi-terminal flexible direct current transmission system on the line fault identification speed is increased. Disclosure of Invention Based on this, it is necessary to provide a fault identification method, a device, a computer readable storage medium and a computer program product for a direct current transmission line, aiming at the direct current technical problem. In a first aspect, the application provides a fault identification method for a direct current transmission line. The method comprises the following steps: acquiring fault conditions of an anode line and a cathode line in a direct current transmission line to be identified; for a target line in the positive line and the negative line, respectively acquiring voltage data and current data of two ends of the target line under the condition that the target line fails; respectively carrying out low-pass filtering processing on the voltage data and the current data to obtain filtered voltage data and filtered current data; Obtaining a differential current average value of the target line according to the filtered current data, and obtaining a distributed capacitance current average value of the target line according to the filtered voltage data; and acquiring a ratio between the differential current average value and the distributed capacitance current average value, and determining a region where the target line fails according to the ratio. In one embodiment, the obtaining the fault condition of the positive electrode line and the negative electrode line in the direct current transmission line to be identified includes: Aiming at a target line in the positive line and the negative line, acquiring the voltage traveling wave variation of the target line and acquiring the voltage traveling wave variation threshold; And when the voltage traveling wave variable quantity of the target line exceeds the voltage traveling wave variable quantity threshold value, determining that the target line fails. In one embodiment, the acquiring the voltage traveling wave change amount threshold includes: acquiring rated line voltage and voltage change coefficient corresponding to the target line; And taking the product of the rated line voltage and the voltage change coefficient as the voltage traveling wave change amount threshold. In one embodiment, the low-pass filtering the voltage data and the current data respectively includes: acquiring a voltage drop coefficient, a transition resistance and a line capacitance corresponding to the target line; Determining a low-pass cutoff frequency of the low-pass filtering process according to the voltage drop coefficient, the transition resistance and the line capacitance; and respectively carrying out low-pass filtering processing on the voltage data and the current data according to the low-pass cut-off frequency. In one embodiment, the filtered current data includes a plurality of sets of filtered current data, each set of filtered current data including filtered current data at two ends of the target line at a same time; and obtaining