CN112731060A - Self-adaptive reclosing method for high-voltage overhead-cable hybrid line - Google Patents

Self-adaptive reclosing method for high-voltage overhead-cable hybrid line Download PDF

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CN112731060A
CN112731060A CN202011550650.5A CN202011550650A CN112731060A CN 112731060 A CN112731060 A CN 112731060A CN 202011550650 A CN202011550650 A CN 202011550650A CN 112731060 A CN112731060 A CN 112731060A
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line
voltage
cable
overhead
fault
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梁振锋
李天婷
王晓卫
张惠智
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Xian University of Technology
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Xian University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/083—Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing

Abstract

The invention discloses a high-voltage overhead-cable mixed line self-adaptive reclosing method, which is characterized in that a wave trap is arranged at the joint of an overhead line and a cable line, when the mixed line breaks down, three-phase voltage sampling values at the end of the overhead line are collected, after protection action, phase-mode conversion is carried out on the collected three-phase voltage sampling values to obtain the modulus of the voltage line, wavelet conversion is carried out on the modulus of the voltage line to obtain a voltage spectrogram, a high-frequency band and a low-frequency band are selected according to the voltage spectrogram, the sum of the voltage amplitudes of the high-frequency band and the sum of the voltage amplitudes of the low-frequency band are calculated, the fault section is judged at the end of the overhead line by utilizing the ratio of the two, the judgment result is sent to the cable end through a communication channel. The method avoids the larger damage caused by reclosing when the fault is in the cable section, and simultaneously, the reclosing opportunity cannot be lost when the fault is in the overhead line section.

Description

Self-adaptive reclosing method for high-voltage overhead-cable hybrid line
Technical Field
The invention belongs to the technical field of power system relays, and particularly relates to a self-adaptive reclosing method for a high-voltage overhead-cable hybrid line.
Background
The high-voltage overhead-cable hybrid line is widely applied to space saving, city beautification, crossing of straits and large waterways and offshore wind power networking.
The faults of the overhead line are mostly instantaneous faults, the circuit breakers are reclosed after certain time delay (reclosing time) after the circuit breakers on the two sides of the line are tripped by protection actions, normal operation of the line can be recovered, and good social and economic benefits are achieved. And cable run's short-circuit fault is mostly unrecoverable permanent trouble, if coincidence circuit breaker after the protection action, the fault point will be can the electric arc of having a fire again, causes the impact once more to system and electrical equipment, can enlarge cable fault simultaneously, causes the explosion accident even, therefore cable run trouble, protection action no longer coincide after jumping off both sides circuit breaker. For a high-voltage overhead-cable mixed line, if a short-circuit fault is in a cable part, opening reclosure can cause more serious accidents; if the closing is locked and reclosed, the reclosing opportunity is lost when the overhead line fails, and the stable and safe operation of the system can be endangered. Therefore, it is difficult to open or close the reclosing valve of the high-voltage overhead-cable line.
Disclosure of Invention
The invention aims to provide a self-adaptive reclosing method for a high-voltage overhead-cable hybrid line, which solves the problem that the high-voltage overhead-cable hybrid line cannot identify a fault section easily and cannot determine opening or closing reclosing.
The technical scheme adopted by the invention is that the self-adaptive reclosing method for the high-voltage overhead-cable hybrid line is implemented according to the following steps:
step 1, installing a wave trap at the joint of a high-voltage overhead line and a cable;
step 2, when the overhead-cable mixed line has a fault, collecting a three-phase voltage sampling value of an overhead line end of the overhead-cable mixed line;
step 3, after the protection action, carrying out phase-mode conversion on the three-phase voltage sampling value collected in the step 2 to obtain a modulus of the voltage line, and carrying out wavelet conversion on the modulus of the voltage line to obtain a voltage spectrogram;
step 4, selecting a high frequency band and a low frequency band according to the voltage spectrogram obtained in the step 3, and calculating the sum U of the voltage amplitudes of the high frequency bandHAnd the sum U of the voltage amplitudes of the low frequency bandL；
Step 5, utilizingU obtained in step 4HAnd ULThe ratio of the first and second signals is used as a criterion to judge a fault section at the overhead line end, a head end judging result is sent to the cable end through a communication channel, and the two ends of the hybrid line select to open or close a reclosing according to the judging result.
The present invention is also characterized in that,
and 3, adopting Clark transformation as a phase-mode transformation method.
And 3, discrete wavelet transform is adopted in wavelet transform.
The distinguishing method in the step 5 is as follows:
Figure BDA0002857108230000021
wherein, KsetDetermining the setting value according to the line parameter and the wave trap parameter;
if the formula (1) is established, the fault occurs in the overhead line section, and the reclosing is opened;
if the formula (1) is not established, the fault occurs in the cable section, and the reclosing is locked.
The invention has the beneficial effects that: according to the invention, the wave trap is arranged at the joint of the high-voltage overhead line and the cable line, and the ratio of the sum of the voltage amplitudes of the high-frequency band and the sum of the voltage amplitudes of the low-frequency band of the voltage modulus component when the overhead line and the cable line have faults is utilized to judge the fault section, so that whether reclosing is opened or not is determined, the fault superposed on the cable section is avoided, and meanwhile, the superposition opportunity cannot be lost when the fault is in the overhead line section.
Drawings
FIG. 1 is a flow chart of the adaptive reclosing method of the present invention;
FIG. 2 is a schematic diagram of a high voltage overhead-cable hybrid line of the adaptive reclosing method of the present invention;
FIG. 3 is a voltage waveform diagram of the M end of a hybrid line during a single-phase ground fault of an overhead line section according to the adaptive reclosing method of the present invention;
FIG. 4 is a voltage spectrum analysis diagram of the M end of a hybrid line during a single-phase ground fault of an overhead line section according to the adaptive reclosing method of the present invention;
FIG. 5 is a voltage waveform diagram of the M end of the hybrid line when a single-phase earth fault occurs in a cable segment according to the adaptive reclosing method of the invention;
FIG. 6 is a voltage spectrum analysis diagram of the M end of the hybrid line when the cable segment has a single-phase earth fault according to the self-adaptive reclosing method of the invention;
FIG. 7 is a graph of the voltage waveform at the M end of the hybrid line during a two-phase ground fault in the overhead line section according to the adaptive reclosing method of the present invention;
FIG. 8 is a graph of a voltage spectrum analysis of the M end of a hybrid line during a two-phase ground fault in an overhead line section according to the adaptive reclosing method of the present invention;
FIG. 9 is a voltage waveform diagram of the M end of the hybrid line during a two-phase ground fault in a cable segment according to the adaptive reclosing method of the present invention;
FIG. 10 is a graph of a voltage spectrum analysis of the M end of a hybrid line during a two-phase ground fault of a cable segment according to the adaptive reclosing method of the present invention;
FIG. 11 is a voltage waveform diagram of the M end of the hybrid line during a two-phase short circuit fault in the overhead line section according to the adaptive reclosing method of the present invention;
FIG. 12 is a graph of a voltage spectrum analysis of the M end of a hybrid line during a two-phase short circuit fault in an overhead line section according to the adaptive reclosing method of the present invention;
FIG. 13 is a voltage waveform diagram of the M end of the hybrid line during a two-phase short circuit fault in a cable section according to the adaptive reclosing method of the present invention;
FIG. 14 is a voltage spectrum analysis diagram of the M end of the hybrid line when a two-phase short circuit fault occurs in a cable segment according to the adaptive reclosing method of the invention;
FIG. 15 is a graph of the voltage waveform at the M end of the hybrid line during a three-phase short circuit fault in the overhead line section of the adaptive reclosing method of the present invention;
FIG. 16 is a diagram of a voltage spectrum analysis of the M end of a hybrid line during a three-phase short circuit fault in an overhead line section according to the adaptive reclosing method of the present invention;
FIG. 17 is a voltage waveform diagram of the M end of the hybrid line during a three-phase short circuit fault in a cable section according to the adaptive reclosing method of the present invention;
FIG. 18 is a voltage spectrum analysis diagram of the M end of the hybrid line when a three-phase short circuit fault occurs in a cable segment according to the adaptive reclosing method of the present invention;
in the figure, 1 is an overhead line, 2 is a cable line, and 3 is a wave trap.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention provides a self-adaptive reclosing method for a high-voltage overhead-cable mixed line, which is implemented according to the following steps as shown in figure 1:
step 1, as shown in fig. 2, installing a wave trap 3 at the connection position of a high-voltage overhead line 1 and a cable line 2;
step 2, when the overhead-cable mixed line has a fault, collecting a three-phase voltage sampling value of the M side of the overhead-cable mixed line;
step 3, after the protection action, carrying out phase-mode conversion on the three-phase voltage sampling value collected in the step 2 to obtain a modulus of the voltage line, and carrying out wavelet conversion on the modulus of the voltage line to obtain a voltage spectrogram;
wherein, Clarke (Clarke) transformation is adopted in the phase-mode transformation method; the wavelet transform adopts discrete wavelet transform, and db5 wavelets are selected;
step 4, selecting a high frequency band and a low frequency band according to the voltage spectrogram obtained in the step 3, wherein the high frequency band is 230-280kHz, and the low frequency band is 5-10kHz, and calculating the sum U of the voltage amplitudes of the high frequency bandHAnd the sum U of the voltage amplitudes of the low frequency bandL；
Step 5, utilizing the U obtained in the step 4HAnd ULThe ratio of (A) is used as a criterion to judge the fault section at the overhead line end, namely
Figure BDA0002857108230000051
Wherein, KsetTaking 450 out in the embodiment as a setting value; and sending a head end judgment result to the cable end through a communication channel, and selecting to open or close the reclosing at the two ends of the hybrid line according to the judgment result. (ii) a
If the formula (1) is established, the fault occurs in the overhead line section, and the reclosing is opened;
if the formula (1) is not established, the fault occurs in the cable section, and the reclosing is locked.
A model a 500kV overhead-cable hybrid line model was built using simulation software PSCAD/EMTDC, as shown in fig. 2. Wherein, the overhead line parameter is: r1＝0.02083Ω/km，L1＝0.8684mH/km，C1＝0.0129uF/km，R0＝0.1148Ω/km，L0＝2.2886mH/km，C00.0052uF/km, and an overhead line section of 100 km; the cable line parameters are: r1＝0.0242Ω/km，L1＝0.08894mH/km，C1＝0.2811uF/km，R0＝0.4121Ω/km，L0＝1.5347mH/km，C00.1529uF/km, and the cable line section is 20 km; the parameters of the wave trapper are as follows: l is1＝1mH，L2＝0.43mH，C1＝380pF，C2＝1100pF，R＝910Ω。
In order to verify the effectiveness of the self-adaptive reclosing method, a large amount of fault simulation and analysis are carried out, and the method specifically comprises the following steps: the simulation and section discrimination of the single-phase earth fault, the two-phase short-circuit fault and the three-phase short-circuit fault of the overhead line section and the cable section are respectively carried out, the simulation results are shown in figures 3-18, and as can be seen from the figures, when the overhead line section has faults, the voltage waveform has serious distortion and contains a large amount of high-frequency components; when a cable section fails, the voltage waveform is slightly distorted and the high frequency components are rapidly attenuated.
Since the high-frequency component also has attenuation phenomenon in the high-voltage long-distance transmission line, in this embodiment, firstly, fault simulation and calculation are performed at positions 1km away from the cable connection position on the overhead line section and the cable line section, respectively, and the simulation results are shown in tables 1 and 2.
TABLE 1U when different types of faults occur near the junction of an overhead line and a cable lineL/UHValue of
Figure BDA0002857108230000062
TABLE 2U near the junction of overhead line and cable line at fault through different transition resistancesL/UHValue of
Figure BDA0002857108230000061
As can be seen from tables 1 and 2, when there is a fault in the overhead line section and a fault in the cable section, U is setL/UHThe ratio of (A) is very different, taking into account a certain margin, so this example criterion KsetThe whole is 450.
In this embodiment, simulation and calculation of single-phase ground faults, two-phase short-circuit faults and three-phase short-circuit faults occurring at different fault positions of the overhead-cable hybrid line are performed, where a is a percentage of a length from the fault position of the overhead line to an end M of the hybrid line to the entire length of the overhead line, b is a percentage of a length from the fault position of the cable line to a cable connection point (point P) to the entire length of the cable line, and simulation results are shown in table 3.
TABLE 3U at different fault locations with different types of faultsL/UHValue of
Figure BDA0002857108230000071
As can be seen from Table 3, when different types of faults occur in different positions on the overhead line section of the hybrid line, UL/UHThe ratio of the U is smaller than the set value of the criterion, and when different types of faults occur at different positions of the cable section, the U is used for judging whether the fault occursL/UHThe ratio of the two is obviously larger than the set value K of the criterionset450, namely different fault positions and different fault types, the method can accurately judge the fault occurrence section.
In order to verify the influence of the transition resistance on the method of the present invention, simulation of the hybrid line at different positions and through different transition resistance faults is also performed in this embodiment, and tables 4 and 5 respectively show simulation results of a single-phase ground fault through the transition resistance and a two-phase interphase short circuit.
TABLE 4U at single-phase earth fault via different transition resistancesL/UHValue of
Figure BDA0002857108230000081
TABLE 5U at interphase short-circuit fault through different transition resistancesL/UHValue of
Figure BDA0002857108230000082
As can be seen from tables 4 and 5, the transition resistance does not affect the effectiveness of the adaptive reclosing method of the present invention.
According to the mode, the invention provides a high-voltage overhead-cable mixed line self-adaptive reclosing method, a wave trap is installed at the joint of an overhead line and a cable of a mixed line, when the mixed line fails, the difference of high-frequency voltage components when the overhead line section fails and the cable section fails is utilized to form a criterion, the fault section is judged, and whether reclosing is opened or not is further determined; reclosing when the fault is in the cable section is avoided, and the opportunity of reclosing is not lost when the fault is in the overhead line section.

Claims (4)

1. The self-adaptive reclosing method for the high-voltage overhead-cable hybrid line is characterized by comprising the following steps:
step 1, installing a wave trap at the joint of a high-voltage overhead line and a cable;
step 2, when the overhead-cable mixed line has a fault, collecting a three-phase voltage sampling value of an overhead line end of the overhead-cable mixed line;
step 3, after the protection action, carrying out phase-mode conversion on the three-phase voltage sampling value collected in the step 2 to obtain a modulus of the voltage line, and carrying out wavelet conversion on the modulus of the voltage line to obtain a voltage spectrogram;
step 4, selecting a high frequency band and a low frequency band according to the voltage spectrogram obtained in the step 3, and calculating the sum U of the voltage amplitudes of the high frequency bandHAnd the sum U of the voltage amplitudes of the low frequency bandL；
Step 5, utilizing the U obtained in the step 4HAnd ULRatio of (A to (B)And the value is used as a criterion to judge a fault section at the overhead line end, a head end judging result is sent to the cable end through a communication channel, and the two ends of the hybrid line select to open or close a reclosing according to the judging result.
2. The adaptive reclosing method for the high-voltage overhead-cable hybrid line according to claim 1, wherein the phase-mode transformation method in step 3 adopts Clark transformation.
3. The adaptive reclosing method for the high-voltage overhead-cable hybrid line according to claim 1, wherein discrete wavelet transform is adopted in wavelet transform in step 3.
4. The adaptive reclosing method for the high-voltage overhead-cable hybrid line according to claim 1, wherein the determination method in the step 5 is as follows:
Figure FDA0002857108220000011
wherein, KsetDetermining the setting value according to the line parameter and the wave trap parameter;
if the formula (1) is established, the fault occurs in the overhead line section, and the reclosing is opened;
if the formula (1) is not established, the fault occurs in the cable section, and the reclosing is locked.
CN202011550650.5A 2020-12-24 2020-12-24 Self-adaptive reclosing method for high-voltage overhead-cable hybrid line Pending CN112731060A (en)

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CN110829388A (en) * 2019-11-14 2020-02-21 国网湖南省电力有限公司 Single-phase earth fault judgment method and reclosing method of double-fed wind power plant
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Publication number Priority date Publication date Assignee Title
CN101964515A (en) * 2010-08-27 2011-02-02 昆明理工大学 Method for converting boundary element by extra-high voltage direct current transmission line mode voltage S
CN102005739A (en) * 2010-08-27 2011-04-06 昆明理工大学 Method for identifying extra-high voltage direct current transmission line area inside and outside fault wavelet energy
CN102122814A (en) * 2010-12-30 2011-07-13 山东理工大学 Adaptive reclosing method based on travelling wave segmentation principle for mixed line
CN103323741A (en) * 2013-05-30 2013-09-25 昆明理工大学 Method for judging D-shaped cable hybrid circuit fault section directing at strong fault and based on fault voltage initial row amplitude value comparison
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