CN113659541A - Multi-terminal direct-current power grid reclosing method and system based on waveform similarity matching - Google Patents

Multi-terminal direct-current power grid reclosing method and system based on waveform similarity matching Download PDF

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CN113659541A
CN113659541A CN202110838051.1A CN202110838051A CN113659541A CN 113659541 A CN113659541 A CN 113659541A CN 202110838051 A CN202110838051 A CN 202110838051A CN 113659541 A CN113659541 A CN 113659541A
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fault
line
waveform
sides
traveling wave
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CN113659541B (en
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李正天
郑宇超
林湘宁
魏繁荣
黎钊
童宁
吴通华
李新东
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Huazhong University of Science and Technology
Guangdong University of Technology
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Guangdong University of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
    • 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
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/06—Details with automatic reconnection
    • H02H3/066—Reconnection being a consequence of eliminating the fault which caused disconnection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

The invention relates to a multi-terminal direct-current power grid reclosing method and a multi-terminal direct-current power grid reclosing system based on waveform similarity matching, wherein the method comprises the steps of carrying out derivation calculation on power parameter measured values at the protection positions on two sides of a fault line based on a Bergeron model, and crossing to obtain power parameter theoretical values at the protection positions on two sides of the fault line; obtaining theoretical waveforms and true values of line mode traveling waves at protection positions on two sides of a fault line correspondingly based on Kerenbel transformation; quantitatively calculating the similarity between the real waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line and the theoretical waveform of the line-mode traveling wave based on a Hausdroff distance calculation method; and judging the fault type of the fault in the region according to the similarity between the real waveform of the line mode traveling wave and the theoretical waveform of the line mode traveling wave. The method judges the type of the fault based on the topological structure difference of the line under the permanent fault and the transient fault and the similarity characteristics of the line-mode currents at two sides, and can solve the problem that the fault property of the far-end fault in the area and the high-resistance fault in the area cannot be identified.

Description

Multi-terminal direct-current power grid reclosing method and system based on waveform similarity matching
Technical Field
The invention relates to the field of power grids, in particular to a multi-terminal direct-current power grid reclosing method and system based on waveform similarity matching.
Background
Due to the great variability and unpredictability of clean energy (e.g., wind, solar, tidal, etc.) supply, great difficulties are presented to the concentrated delivery of power. The flexible direct current technology based on the fully-controlled switch device can decouple active power and reactive power during power transmission, has no risk of commutation failure, and can well deal with the problems brought by clean energy grid connection, so that on the premise that the proportion of clean energy is increasing day by day, the new energy grid connection trend gradually develops towards a multi-terminal direct current grid structure, and the use of an overhead line gradually becomes the future development trend of the multi-terminal direct current grid. However, operational experience shows that overhead line faults are the majority of causes of power system faults, and overhead line faults are mostly transient faults and single-phase (single-pole) faults. After the fault isolation, the success probability of reclosing exceeds 60% after a fixed time delay, and the higher the voltage level is, the higher the success probability of reclosing is. Therefore, the adoption of a proper reclosing technology has important significance for improving the operation reliability of the direct-current power grid line.
The reclosing strategy used in the present engineering is: after the circuit breakers on the two sides of the broken direct current point line are disconnected and the fault is dissociated (about 500ms), the direct current circuit breakers on the two sides of the line are superposed after the converter station is unlocked, if the direct current voltage is reestablished, the fault is an instantaneous fault, and if the direct current voltage is not reestablished, the fault is a permanent fault. However, the reclosing method has the following problems: if coincident with a permanent fault, a second fault impact is caused to the system. Therefore, on the premise that fault impact is not generated or is reduced as much as possible, the judgment of the fault property on the flexible direct-current power grid power transmission line is completed, and then reclosing is completed under transient faults.
In order to solve the problems, experts and scholars at home and abroad also develop researches on fault property identification methods of the multi-terminal flexible direct-current power grid, and provide a plurality of self-adaptive reclosing methods for the power transmission line of the multi-terminal flexible direct-current power grid. A typical method is as follows: experts provide a novel hybrid direct-current circuit breaker topology structure which is suitable for the field of rapid reclosing, but the topology structure is too special, so that the topology structure of all circuit breakers in a power grid is difficult to modify and popularize; in addition, experts propose to judge the fault property by adopting a transient control converter station to operate in uncontrolled rectification, the method needs longer restart time, although the method is applicable to a two-end system, the method is not applicable to a multi-end system; further, other experts propose a method for adding additional control to the hybrid DCCB, so that the DCCB injects a pulse signal to detect a fault through the additional control, but the method needs to add additional devices, such as an energy consumption resistor, a thyristor and the like, so that the topology of the circuit breaker is more complex, and the engineering cost is increased. The method needs to change the topological structure of the direct-current circuit breaker and the control mode of the converter station, and even needs to add an auxiliary control device, so that the method has the advantages of increasing the modification cost and reducing the applicability.
An expert proposes a reclosing scheme for actively injecting a characteristic signal by using a full-bridge MMC converter, the scheme can flexibly convert a mode for injecting the characteristic signal, but the scheme is not suitable under a topological structure of a half-bridge MMC converter; in addition, for a direct current line provided with the coupling type direct current circuit breaker, a characteristic signal injection method is provided by a proprietary owner to identify the fault property, but the injection method is only suitable for the line provided with the coupling type direct current circuit breaker and has no universality; in addition, an expert also provides a coincidence scheme for recognizing the fault property by actively injecting traveling waves into a line by using a half-bridge MMC, the scheme designs criteria by the difference of the polarities of the reflected wave heads of the traveling wave heads under transient/permanent faults, the criterion has higher reliability, but is limited by sampling frequency, and dead zones are generated at the tail end of the line.
In summary, the reclosing schemes all rely on single-ended quantities to implement, however, the following problems are common to them: 1) The reclosing scheme is limited by the topological structure of a direct current breaker or a current converter, even an additional control device needs to be additionally arranged, so that the cost for modifying equipment related to the system is high, the process is complex, and the reclosing scheme is not easy to popularize; 2) the reclosing scheme of injecting signals through the MMC converter does not need an additional device, but when a high-resistance fault occurs at the tail end of a line, the fault property is not easy to judge, and the risk of reclosing in a permanent fault exists.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a multi-terminal direct current network reclosing method and system based on waveform similarity matching, so that transient faults and permanent faults can be distinguished without carrying out topological structure improvement and adding auxiliary devices, and therefore, self-adaptive reclosing can be realized.
The technical scheme for solving the technical problems is as follows: the multi-terminal direct-current power grid reclosing method based on waveform similarity matching comprises the following steps,
s1, when an intra-area fault occurs in the multi-terminal direct-current power grid, sequentially performing fault isolation, fault dissociation removal and pre-reclosing on a fault line;
s2, during the pre-reclosing period, extracting the power parameter measurement values of the protection positions on the two sides of the fault line at the same time;
s3, respectively carrying out derivation calculation on power parameter measured values of the protection positions on the two sides of the fault line based on the Bergeron model, and crossing to obtain power parameter theoretical values of the protection positions on the two sides of the fault line;
s4, respectively converting theoretical values of power parameters of the protection positions on the two sides of the fault line based on Kerenbel conversion, and correspondingly obtaining line mode traveling wave theoretical waveforms of the protection positions on the two sides of the fault line; respectively converting the measured values of the power parameters of the protection positions at the two sides of the fault line based on the Kelvin conversion, and correspondingly obtaining the real waveforms of the line-mode traveling waves of the protection positions at the two sides of the fault line;
s5, based on a Hausdroff distance calculation method, carrying out quantitative calculation on the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line to obtain the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave;
s6, based on the pre-constructed differential criterion and setting threshold, judging the fault type of the fault in the area according to the similarity between the real waveform of the line mode traveling wave and the theoretical waveform of the line mode traveling wave; wherein the fault types of the intra-zone fault include a transient fault and a permanent fault;
s7, if the fault type of the fault in the area is transient fault, accelerating the reclosing of the circuit breakers at the protection positions at the two sides of the fault line; and if the fault type of the fault in the area is a permanent fault, stopping reclosing of the circuit breakers at the protection positions on the two sides of the fault line.
Based on the multi-terminal direct-current power grid reclosing method based on the waveform similarity matching, the invention also provides a multi-terminal direct-current power grid reclosing system based on the waveform similarity matching.
The multi-terminal direct-current power grid reclosing system based on waveform similarity matching comprises the following modules,
the fault pre-processing module is used for sequentially carrying out fault isolation, fault dissociation removal and pre-reclosing on a fault line after an intra-area fault occurs in the multi-terminal direct-current power grid;
the electric parameter measuring module is used for simultaneously extracting electric parameter measured values of protection positions on two sides of a fault line during pre-reclosing;
the power parameter theoretical derivation module is used for respectively deriving and calculating power parameter measured values at the protection positions on the two sides of the fault line based on the Bergeron model, and obtaining power parameter theoretical values at the protection positions on the two sides of the fault line in a crossed manner;
the line-mode traveling wave synthesis module is used for respectively converting theoretical values of power parameters at the protection positions on the two sides of the fault line based on Kerenbel conversion to correspondingly obtain theoretical waveforms of the line-mode traveling waves at the protection positions on the two sides of the fault line; respectively converting the power parameter measurement values of the protection positions at the two sides of the fault line based on the Kerenbel conversion, and correspondingly obtaining the real wave forms of the line mode traveling waves of the protection positions at the two sides of the fault line;
the similarity calculation module is used for quantitatively calculating the similarity between the real waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line and the theoretical waveform of the line-mode traveling wave based on a Hausdroff distance calculation method to obtain the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave;
the fault type judging module is used for judging the fault type of the fault in the region according to the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave based on a pre-constructed differential criterion and a setting threshold; wherein the fault types of the intra-zone fault include a transient fault and a permanent fault;
the reclosing control module is used for accelerating the reclosing of the circuit breakers at the protection positions on the two sides of the fault line if the fault type of the fault in the area is an instantaneous fault; and if the fault type of the fault in the area is a permanent fault, stopping reclosing of the circuit breakers at the protection positions on the two sides of the fault line. .
The invention has the beneficial effects that: in the multi-terminal direct-current power grid reclosing method and system based on waveform similarity matching, the type of the fault is judged based on the topological structure difference of the line under the permanent fault and the transient fault and the line mode current similarity characteristics at two sides, the problem that the existing multi-terminal flexible direct-current power grid reclosing technology cannot identify the fault property of a far-end fault in a region and a high-resistance fault in the region can be solved, the error of an individual sampling point cannot influence the similarity trend of the waveform and the judgment result of the criterion, and the multi-terminal direct-current power grid reclosing system has strong anti-noise capability; in addition, the method can be realized based on the existing topological structures of the current converter and the direct-current circuit breaker, and does not need to improve the topological structures and add auxiliary devices.
Drawings
FIG. 1 is a flow chart of a multi-terminal DC power grid reclosing method based on waveform similarity matching according to the present invention;
fig. 2 is a schematic structural diagram of a hybrid dc circuit breaker;
fig. 3 is a schematic diagram of a berelon model of a power transmission line;
FIG. 4 is a schematic illustration of propagation of an on-line mode current wave under transient/permanent fault conditions;
FIG. 5 is a schematic diagram illustrating a four-terminal DC network model and fault location;
FIG. 6 is a waveform diagram of real and theoretical waveforms of down-line mode current traveling waves at a transient fault at a near end of 5km in a region;
FIG. 7 shows the behavior of a criterion for instantaneous reclosing fault at 5km near the end of a zone;
FIG. 8 is a waveform diagram of real and theoretical waveforms of down-line mode current traveling waves at a permanent fault at a near end of 5km in a region;
FIG. 9 shows the behavior of a permanent fault reclosing criterion at 5km from the near end in a zone;
FIG. 10 is a waveform diagram of real and theoretical waveforms of an on-line mode current waveform under a midpoint transient fault in a zone;
fig. 11 shows the action condition of reclosing criterion under the transient fault at the midpoint in the area;
FIG. 12 is a waveform diagram of real and theoretical waveforms of an on-line mode current waveform under a permanent fault at a midpoint within a zone;
fig. 13 shows the action condition of reclosing criterion under a permanent fault at a midpoint in a zone;
FIG. 14 is a waveform diagram of a real waveform and a theoretical waveform of a midpoint transient high-resistance fault line mode current traveling wave in a zone;
fig. 15 shows the reclosing criterion action condition of the instantaneous high-resistance fault at the midpoint in the area;
FIG. 16 is a waveform diagram of a real waveform and a theoretical waveform of a down-mode current traveling wave at a permanent high-resistance fault at a midpoint in a zone;
fig. 17 shows the reclosing criterion action condition under the permanent high-resistance fault at the midpoint in the zone;
fig. 18 is a structural block diagram of the multi-terminal dc power grid reclosing system based on waveform similarity matching according to the present invention.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
In a multi-terminal direct-current power grid, theoretical values of voltage and current of opposite-side protection are obtained through the measurement voltage and current of a local protection part and through the derivation of a Bergeron model, and further through Kernel transformation, the theoretical values and the measurement values of line-mode current traveling waves of the opposite-side protection part can be calculated. When the fault is an instantaneous fault, the Bergeron model is established, and the similarity between the theoretical value of the line mode current and the measured value obtained by deducing the Bergeron model is very high; when the fault is a permanent fault, the Bergeron model is damaged, the difference between the theoretical value of the line mode current and the real-time measured value is large, and the waveform similarity is low.
Based on the theory, the multi-terminal direct-current power grid reclosing method based on waveform similarity matching specifically comprises the following steps:
as shown in fig. 1, the multi-terminal dc power grid reclosing method based on waveform similarity matching includes the following steps,
s1, when an intra-area fault occurs in the multi-terminal direct-current power grid, sequentially performing fault isolation, fault dissociation removal and pre-reclosing on a fault line;
s2, during the pre-reclosing period, extracting the power parameter measurement values of the protection positions on the two sides of the fault line at the same time;
s3, respectively carrying out derivation calculation on power parameter measured values of the protection positions on the two sides of the fault line based on the Bergeron model, and crossing to obtain power parameter theoretical values of the protection positions on the two sides of the fault line;
s4, respectively converting theoretical values of power parameters of the protection positions on the two sides of the fault line based on Kerenbel conversion, and correspondingly obtaining line mode traveling wave theoretical waveforms of the protection positions on the two sides of the fault line; respectively converting the measured values of the power parameters of the protection positions at the two sides of the fault line based on the Kelvin conversion, and correspondingly obtaining the real waveforms of the line-mode traveling waves of the protection positions at the two sides of the fault line;
s5, based on a Hausdroff distance calculation method, carrying out quantitative calculation on the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line to obtain the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave;
s6, based on the pre-constructed differential criterion and setting threshold, judging the fault type of the fault in the area according to the similarity between the real waveform of the line mode traveling wave and the theoretical waveform of the line mode traveling wave; wherein the fault types of the intra-zone fault include a transient fault and a permanent fault;
s7, if the fault type of the fault in the area is transient fault, accelerating the reclosing of the circuit breakers at the protection positions at the two sides of the fault line; and if the fault type of the fault in the area is a permanent fault, stopping reclosing of the circuit breakers at the protection positions on the two sides of the fault line.
The protection at two sides of the fault line is protection at two sides of the fault line, if one side of the protection is defined as local protection, the protection at the other side is opposite side protection opposite to the local protection; the protection on the two sides of the fault line is a local protection and an opposite side protection.
The steps are described in detail below.
In the S1:
in the embodiment, the circuit breakers at the protection positions on the two sides of the fault line are both hybrid direct-current circuit breakers; the structure of the hybrid dc circuit breaker is shown in fig. 2, and includes a main branch, a transfer branch, and an energy dissipation branch. Next, S1 will be described in detail based on the structure of the hybrid dc circuit breaker.
The S1 specifically includes:
when an intra-area fault occurs in a multi-terminal direct-current power grid, firstly, the protection parts at two sides of a fault line control the hybrid direct-current circuit breakers at the corresponding sides to be disconnected, and fault isolation is completed; when the fault isolation is completed, the main branch and the transfer branch of the hybrid direct current circuit breaker in fig. 2 are completely disconnected, and the MOV in the energy dissipation branch can be regarded as an open circuit because there is no breaking voltage;
then waiting for a first preset time to finish the dissociation of the fault; the step of freeing the fault is to wait for a first preset time, wherein the first preset time can be set to be 500 ms;
finally, the protection parts at the two sides of the fault line control the power electronic switches of the transfer branches in the hybrid direct-current circuit breakers at the corresponding sides to be closed, and control the transfer branches in the hybrid direct-current circuit breakers at the corresponding sides to be disconnected after the protection parts at the two sides of the fault line are kept closed for a second preset time, so that the current at the protection parts at the two sides of the fault line is converted from the transfer branches of the hybrid direct-current circuit breakers to the energy dissipation branches of the hybrid direct-current circuit breakers, and the pre-reclosing process is finished; wherein the second preset time is 3 ms; after the fault dissociation is finished after waiting for the first preset time, a closing command is sent to a controllable submodule in the transfer branch, the controllable submodule is composed of a fully controllable I GBT element, and the response speed completely meets the requirement of switching off after 3ms of superposition.
In the S2:
the power parameter measurements comprise electrode voltage measurements and electrode current measurements; the power parameter theoretical value comprises an electrode voltage theoretical value and an electrode current theoretical value; the line mode traveling wave theoretical waveform is a line mode electric prevailing wave theoretical waveform, and the line mode traveling wave real waveform is a line mode current traveling wave real waveform. After dissociation is completed, the direct current circuit breakers at the protection positions on the two sides of the fault line are subjected to pre-reclosing for 3ms, and the protection positions on the two sides of the fault line can measure the pole voltage and the pole current of the corresponding side after pre-reclosing to obtain a pole voltage measurement value and a pole current measurement value. If one side protection of the two side protections of the fault line is defined as local protection, and the other side protection is opposite side protection opposite to the local protection, the pole voltage and pole current of the corresponding side after pre-reclosing measured by the two side protections of the fault line can be defined as a pole voltage measured value of the local protection, a pole current measured value of the local protection, a pole voltage measured value of the opposite side protection and a pole current measured value of the opposite side protection.
In the S3:
the Bergeron model is a good method for describing the power transmission line based on the distributed parameter lossless transmission line model, the method can effectively make up the influence of capacitance current on the power transmission line, and the calculation method is greatly simplified on the premise of ensuring the precision. On the premise that the transmission line parameters are known, the opposite side pole voltage and pole current propagated by the whole line can be calculated based on the Bergeron model, and the Bergeron model of the transmission line is shown in FIG. 3. In FIG. 3, the line is divided equally into two segments of equal length, both l/2. The formula for obtaining the theoretical values of the power parameters at the protection positions at two sides of the fault line based on the Bergeron model is as follows,
Figure BDA0003177948620000091
wherein u iss(t) and is(t) respectively the pole voltage and pole current measurements, u, at one of the two side protections of the fault line (defined as the s-side protection)Jt(t) and iJt(t) respectively obtaining a pole voltage theoretical value and a pole current theoretical value of the other side protection (defined as t side protection) of the two side protection of the fault line through the derivation of a Bergeron model; t is a transmission matrix of the Bergeron model, and the specific expressions of each element in T are as follows,
Figure BDA0003177948620000092
in particular, Me(τ) is the delay factor, Z, transmitted between the protection points on both sides of the faulty linecThe time for the traveling wave to propagate between the two protections on the fault line is the wave impedance between the two protections on the fault line, R is the total resistance between the two protections on the fault line, tau is a time constant, and the value of tau is equal to the time for the traveling wave to propagate between the two protections on the fault line (the time for the traveling wave to propagate between the two protections on the fault line is the time for the traveling wave to propagate from the local protection to the opposite protection, and the time needs to be set according to the line length).
For example, in S3, the pole voltage measurement value at the local protection and the pole current measurement value at the local protection are derived through a berapron model, and the pole voltage theoretical value at the opposite side protection and the pole current theoretical value at the opposite side protection can be derived; the electrode voltage measured value at the opposite side protection and the electrode current measured value at the opposite side protection are derived through a Bergeron model, and an electrode voltage theoretical value at the local protection and an electrode current theoretical value at the local protection can be derived. Therefore, the intersection in S3 is derived from the opposite side, i.e., the opposite side is derived from the local.
In addition, the power parameter measured values of the protection positions at the two sides of the fault line are respectively deduced, calculated and crossed based on the Bergeron model to obtain the power parameter theoretical values of the protection positions at the two sides of the fault line, and the protection can be completed by local side protection without adding other devices.
In the S4:
in order to capture the line mode current traveling wave in the line, the pole voltage and the pole current need to be decoupled, and the line mode traveling wave and the zero mode traveling wave are synthesized. The formula for obtaining the line mode traveling wave theoretical waveform and the line mode traveling wave real waveform at the protection positions at two sides of the fault line based on the Kerenbel transformation is as follows,
Figure BDA0003177948620000101
wherein ipAnd inRespectively a theoretical value of the anode current and a theoretical value of the cathode current, i, of any one of the protection positions at two sides of the fault line1And i0Respectively obtaining a line mode current traveling wave theoretical waveform and a zero mode current traveling wave theoretical waveform of any one of protection positions at two sides of a fault line after Kernel transformation decoupling; or, ipAnd inRespectively a positive electrode current measured value and a negative electrode current measured value i of any one of the protection places at two sides of the fault line1And i0Respectively obtaining a line mode current traveling wave real waveform and a zero mode current traveling wave real waveform of any one of protection positions at two sides of a fault line after Kernel transformation decoupling; s is a Kerenbel moment of transformationAnd (5) arraying.
For example, the local protection synthesizes the deduced theoretical value of the pole voltage and the theoretical value of the pole current at the opposite side protection into the theoretical waveform of the linear mode current traveling wave at the opposite side protection, and intercepts the theoretical waveform of the linear mode current traveling wave at the opposite side protection 3ms after the reclosing as a template and sends the waveform to the opposite side protection; meanwhile, the opposite-side protection similarly synthesizes the deduced theoretical value of the pole voltage and the theoretical value of the pole current at the local protection into the theoretical waveform of the linear mode current traveling wave at the local protection, and intercepts the theoretical waveform of the linear mode current traveling wave at the local protection 3ms after the reclosing as a template to be sent to the local protection. The local protection synthesizes the measured electrode voltage and electrode current values of the local protection position into a real waveform of the linear mode current traveling wave of the local protection position; and the opposite side protection synthesizes the measured electrode voltage measured value and the measured electrode current value of the opposite side protection into a real waveform of the linear mode current traveling wave of the opposite side protection.
In the S5:
the Hausdorff distance is a measurement mode for describing the similarity degree between two groups of point sets, so that the Hausdorff distance is suitable for quantitatively measuring the similarity characteristic between a real value and a measured value waveform.
The set formed by the real wave forms of the line-mode traveling waves at the protection positions at the two sides of the fault line is set M, the set formed by the theoretical wave forms of the line-mode traveling waves at the protection positions at the two sides of the fault line is set N,
Figure BDA0003177948620000111
wherein m isiFor the ith point in the set M, i ∈ [1, a ]]；njAnd nkJ ∈ [1, b ] at j point and k point in set N respectively]，k∈[1,b]And j ≠ k;
then the S5 is specifically the case,
s51, connecting the point M in the set MiRespectively calculating Euclidean distances with all points in the set N, comparing all the Euclidean distances obtained by calculation, and searching the set N for the Euclidean distances meeting the formula | | | mi-nj||≤||mi-nkPoint n of | |j(ii) a Wherein, | | | represents the Euclidean distance between the set M and the selected point in the set N; will satisfy the formula mi-nj||≤||mi-nkPoint N in the set N of | |jAs the point M in the set MiIs called the minimum Euclidean distance point njIs a point miThe minimum euclidean distance point of (c);
s52, calculating all points in the set M according to the method of the S51 method, and meeting the formula | | Mi-nj||≤||mi-nkThe maximum value of all Euclidean distances of | is recorded as the Hausdroff one-way distance h (M, N) from the set M to the set N; and the number of the first and second electrodes,
Figure BDA0003177948620000112
s53, obtaining a Hausdroff one-way distance h (N, M) from the set N to the set M based on the methods of S51 and S52; and the number of the first and second electrodes,
Figure BDA0003177948620000121
s54, obtaining hausdorff distance h between set M and set N according to hausdorff one-way distance h (M, N) from set M to set N and hausdorff one-way distance h (N, M) from set N to set M, where h is max [ h (M, N), h (N, M) ] (hausdorff distance is the maximum value of hausdorff one-way distances from set M to set N and from set N to set M); the Hausdroff distance h between the set M and the set N is the Hausdroff distance Q between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave, and the Hausdroff distance Q between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave is used for quantitatively representing the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave.
For example: the local protection compares the real waveform of the line mode current traveling wave at the local protection position with the theoretical waveform of the line mode current traveling wave at the local protection position sent by the opposite side protection position on the basis of a Hausdroff distance calculation method; meanwhile, the opposite side protection compares the real waveform of the line mode current traveling wave at the opposite side protection with the theoretical waveform of the line mode current traveling wave at the opposite side protection sent by the local protection based on a Hausdroff distance calculation method,
in the S6:
the differences of the line-mode current traveling waves under transient faults and permanent faults are analyzed according to the graph of fig. 4. If the direction of looking at the line is the positive direction, as shown in fig. 4, under the transient fault, the traveling wave direction of the linear mode current at the s-side protection part is the positive direction, and the traveling wave direction of the linear mode current at the t-side protection part is the reverse direction; under the permanent fault, the traveling wave direction of the linear mode current at the protection position at the s side is the positive direction, and the traveling wave direction of the linear mode current at the protection position at the t side is the positive direction. Therefore, even if the counter-lateral mode current traveling wave can be calculated by the Bergeron model under the permanent fault, the calculated counter-lateral mode current traveling wave based on the Bergeron model is opposite to the actual linear mode current traveling wave direction because the Bergeron model is damaged. Therefore, the fault property can be judged based on the obvious difference between the theoretical waveform value of the side-line mode current wave and the real waveform.
The differential criterion is specifically that,
Figure BDA0003177948620000131
wherein Q issetTo set the threshold, i1sAnd-i1tRespectively the true waveform of the line mode current traveling wave and the theoretical waveform of the line mode current traveling wave at the protection positions at two sides of the fault line, Q (i)1s，-i1t) The method is the Hausdroff distance between the real waveform of the line mode current traveling wave at the protection positions on the two sides of the fault line and the theoretical waveform of the line mode current traveling wave.
Hausdroff distance criterion action threshold QsetThe setting needs to be carried out by combining errors of a Bergeron model, transmission error coefficients of a measuring device, influence of temperature on line resistance parameters and errors of individual points in measured data. Therefore, to ensure that the criterion acts correctly, the above-mentioned error conditions are taken into accountLower, Hausdroff distance criterion action threshold QsetThe setting formula of (A) is as follows,
Figure BDA0003177948620000132
wherein, KrelIs a coefficient of reliability, and Krel＝1.2；KerrorFor measuring error coefficients of the device, and Kerro＝0.15；KtransThe error coefficient of the Bergeron model is set after considering the influence of the external temperature change on the resistance of the power transmission line, and is generally 0.1; i isrmsmaxThe maximum value of the effective values of the linear mode currents is the maximum value of the effective values of the linear mode currents at the protection positions on the two sides of the fault line, and the maximum value of the effective values of the linear mode currents at the protection positions (the s side and the t side) on the two sides of the fault line is taken as the value.
The method provided by the invention can be realized based on the existing converter and the topological structure of the direct current breaker, and the topological structure of the direct current breaker is not required to be improved or an auxiliary device is not required to be additionally arranged. The fault property identification method provided by the invention does not depend on a communication channel, does not need to specially improve a converter and a topological structure of a direct current breaker, and has the characteristics of convenience in setting and wide application range. After the pre-reclosing is completed, a theoretical value of the line mode current obtained by deducing the Bergeron model is sent to the opposite side protection.
In order to test the performance of the adaptive reclosing method, a four-end flexible direct current network model shown in fig. 5 is built in the PSCAD/EMTDC, and the model structure and the specific simulation result are as follows:
1) the four-terminal flexible direct current power grid model built in the PSCAD/EMTDC is shown in FIG. 5. Protecting the frequency of a sampling device to be 100kHz, setting the fault time to be 2.0s, tripping off direct-current circuit breakers on two sides of a line when 2.0025s, waiting for the free time to be removed to be 0.5s, starting pre-reclosing after 2.5025s, completing pre-reclosing and disconnecting the mixed direct-current circuit breaker after 3ms of closing, and according to the similarity between the theoretical value and the true value of the lateral mode current traveling waveAnd identifying the nature of the fault. Four-end flexible DC power grid line length and line mode current traveling wave velocity v1Time constant τ, window length TwAnd model error coefficients K at each protection sitetransSetting values, as shown in table 1:
TABLE 1 setting values at each protection position
Figure BDA0003177948620000141
2) Different location fault property identification
The four-terminal flexible direct current power grid model shown in FIG. 5 is provided with the following lines line-1: near end of area failure (F)1) Location, mid-zone failure (F)2) The position is examined to examine the influence of faults at different positions on the action performance of the reclosing criterion provided by the invention, and the action result is shown in a table 2:
TABLE 2 Fault protection action conditions at various locations within zone
Figure BDA0003177948620000142
21) Proximal end in zone (F)1) Transient metal faults and permanent metal faults are set to verify the action performance of the reclosure criterion provided by the invention, and simulation results are shown in fig. 6-9.
The line-to-side mode current traveling wave under the transient metal fault is shown in fig. 6, it can be seen that the similarity between the real waveform and the theoretical waveform of the line-to-side mode current traveling wave is very high, the judgment action condition obtained through the hausdorff distance algorithm is shown in fig. 7, the similarity between the real waveform and the theoretical waveform of the line-to-side mode current traveling wave is very high, and the action value in the reclosing criterion is smaller than the floating threshold value (the setting threshold Q is smaller than the floating threshold Q)set) Therefore, the operating condition is discriminated as a transient fault. The line-to-side line mode current traveling wave under the permanent fault is shown in fig. 8, and the criterion action condition processed by the hausdorff distance algorithm is shown in fig. 9, so that the real waveform and the theoretical waveform of the line-to-side line mode current traveling wave under the permanent fault can be seenThe difference is large, and the action value in the reclosing criterion is larger than the floating threshold value (setting threshold Q)set) The working condition is judged to be a permanent fault and is judged to be correct. Therefore, the reclosing criterion provided by the invention can distinguish the fault property under the near-end fault in the partition.
22) Zone midpoint (F)2) Transient metal faults and permanent metal faults are set to verify the action performance of the reclosure criterion provided by the invention, and simulation results are shown in fig. 10-13.
Under the transient fault, the action conditions of the line mode current traveling wave of the line opposite side protection and the reclosing criterion are shown in fig. 10 and fig. 11; under the permanent fault, the action conditions of the line mode current traveling wave of the line opposite side protection and the reclosing criterion are shown in fig. 12 and fig. 13. According to the simulation result, the similarity between the real waveform of the current traveling wave of the side-line mode and the theoretical waveform is very high due to the establishment of the Bergeron model under the transient fault, and after the current traveling wave is processed by the Hausdroff distance algorithm, the action value is smaller than the threshold value, so that the working condition is accurately judged to be the transient fault; under the condition of permanent fault, the Bergeron model is damaged, the similarity between the real waveform of the current traveling wave of the lateral mode and the theoretical waveform is very low, and the action value is larger than the threshold value (the setting threshold Q) after the real waveform is processed by the Hausdroff distance algorithmset) The operating condition is judged as a permanent fault. Therefore, the fault property of the reclosing criterion area in the middle point fault can be accurately judged.
According to the simulation result, the multi-terminal direct-current network self-adaptive reclosing method based on waveform similarity matching is not affected by the fault position in the direct-current distribution network.
3) Fault property identification under different transition resistances
In order to further investigate the influence of the transition resistance on the reclosing criterion provided by the invention, a 300-ohm high-resistance fault is set at the midpoint of a line-1 in the four-terminal flexible direct-current power grid model shown in fig. 5, and the simulation results are shown in fig. 14-17.
The line mode current traveling wave shape under the transient high-resistance fault and the reclosing criterion action conditions after the processing of the Hausdroff distance algorithm are respectively shown in fig. 14 and fig. 15, even if the transition resistance reaches 300 ohms, the establishment condition of the Bergeron model is not influenced, the similarity between the line mode current traveling wave theoretical wave shape and the true wave shape at the opposite side protection position is still high, and the provided criterion can accurately identify the working condition as the transient fault.
The action conditions of the reclosing criterion after the permanent high-resistance fault offline mode current traveling wave waveform and the Hausdroff distance algorithm are processed are respectively shown in the graph 16 and the graph 17, even if the theoretical waveform of the side protection line mode current traveling wave and the real waveform under the permanent high-resistance fault are still greatly different, the proposed reclosing criterion can accurately identify the working condition as the permanent fault.
The simulation result shows that the reclosing criterion provided by the invention can accurately identify the fault property even under the high transition resistance.
In conclusion, the above embodiments verify the correctness and feasibility of the present invention.
The invention provides a multi-terminal direct current network self-adaptive reclosing method based on waveform similarity by utilizing the difference of similarity characteristics of theoretical waveforms and real waveforms of line mode current traveling waves of opposite side protection on a direct current line, and fault properties can be judged after the traveling wave differences are quantitatively analyzed by a Hausdroff distance algorithm. The invention realizes the fault property judgment through the data communication of the two-side protection, and can be used for judging the cost without additionally arranging an additional device, thereby having higher applicability. Compared with the current reclosing principle based on single-ended measurement, the principle provided by the invention can eliminate the dead zone of the line and cover the full length of the line.
Based on the multi-terminal direct-current power grid reclosing method based on the waveform similarity matching, the invention also provides a multi-terminal direct-current power grid reclosing system based on the waveform similarity matching.
As shown in fig. 18, the multi-terminal dc power grid reclosing system based on waveform similarity matching includes the following modules,
the fault pre-processing module is used for sequentially carrying out fault isolation, fault dissociation removal and pre-reclosing on a fault line after an intra-area fault occurs in the multi-terminal direct-current power grid;
the electric parameter measuring module is used for simultaneously extracting electric parameter measured values of protection positions on two sides of a fault line during pre-reclosing;
the power parameter theoretical derivation module is used for respectively deriving and calculating power parameter measured values at the protection positions on the two sides of the fault line based on the Bergeron model, and obtaining power parameter theoretical values at the protection positions on the two sides of the fault line in a crossed manner;
the line-mode traveling wave synthesis module is used for respectively converting theoretical values of power parameters at the protection positions on the two sides of the fault line based on Kerenbel conversion to correspondingly obtain theoretical waveforms of the line-mode traveling waves at the protection positions on the two sides of the fault line; respectively converting the power parameter measurement values of the protection positions at the two sides of the fault line based on the Kerenbel conversion, and correspondingly obtaining the real wave forms of the line mode traveling waves of the protection positions at the two sides of the fault line;
the similarity calculation module is used for quantitatively calculating the similarity between the real waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line and the theoretical waveform of the line-mode traveling wave based on a Hausdroff distance calculation method to obtain the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave;
the fault type judging module is used for judging the fault type of the fault in the region according to the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave based on a pre-constructed differential criterion and a setting threshold; wherein the fault types of the intra-zone fault include a transient fault and a permanent fault;
the reclosing control module is used for accelerating the reclosing of the circuit breakers at the protection positions on the two sides of the fault line if the fault type of the fault in the area is an instantaneous fault; and if the fault type of the fault in the area is a permanent fault, stopping reclosing of the circuit breakers at the protection positions on the two sides of the fault line.
The invention provides a multi-terminal direct-current power grid reclosing method and system based on waveform similarity characteristic difference of linear mode current traveling waves under the condition of in-region/out-region faults, and the method and system can be applied to the field of multi-terminal flexible direct-current power grid self-adaptive reclosing. When the judgment result is that the area is instantaneously failed, the circuit breakers on the two sides complete rapid reclosing; and when the judgment result is that the permanent fault exists in the area, the circuit breakers on the two sides are forbidden to be reclosed. According to a large amount of simulation, the fault property can be accurately judged through interaction of measurement information of protection devices on two sides of the line, the resistance to transition resistance can reach 300 omega, the method can effectively prevent the line from reclosing in permanent faults, is automatically suitable for various operation modes of the line, and can remarkably improve the safe operation level of the multi-end flexible direct-current power grid.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching is characterized by comprising the following steps of: comprises the following steps of (a) carrying out,
s1, when an intra-area fault occurs in the multi-terminal direct-current power grid, sequentially performing fault isolation, fault dissociation removal and pre-reclosing on a fault line;
s2, during the pre-reclosing period, extracting the power parameter measurement values of the protection positions on the two sides of the fault line at the same time;
s3, respectively carrying out derivation calculation on power parameter measured values of the protection positions on the two sides of the fault line based on the Bergeron model, and crossing to obtain power parameter theoretical values of the protection positions on the two sides of the fault line;
s4, respectively converting theoretical values of power parameters of the protection positions on the two sides of the fault line based on Kerenbel conversion, and correspondingly obtaining line mode traveling wave theoretical waveforms of the protection positions on the two sides of the fault line; respectively converting the power parameter measured values at the protection positions at the two sides of the fault line based on the Kerenbel conversion, and correspondingly obtaining the real wave forms of the line-mode traveling waves at the protection positions at the two sides of the fault line;
s5, based on a Hausdroff distance calculation method, carrying out quantitative calculation on the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line to obtain the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave;
s6, based on the pre-constructed differential criterion and setting threshold, judging the fault type of the fault in the area according to the similarity between the real waveform of the line mode traveling wave and the theoretical waveform of the line mode traveling wave; wherein the fault types of the intra-zone fault include a transient fault and a permanent fault;
s7, if the fault type of the fault in the area is transient fault, accelerating the reclosing of the circuit breakers at the protection positions at the two sides of the fault line; and if the fault type of the fault in the area is a permanent fault, stopping reclosing of the circuit breakers at the protection positions on the two sides of the fault line.
2. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to claim 1, characterized in that: the circuit breakers at the protection positions at the two sides of the fault line are all hybrid direct-current circuit breakers;
specifically, the step S1 is,
when an intra-area fault occurs in a multi-terminal direct-current power grid, firstly disconnecting the hybrid direct-current circuit breakers at the protection positions at two sides of a fault line, then waiting for a first preset time to finish the dissociation of the fault, finally closing the power electronic switches of the transfer branches in the hybrid direct-current circuit breakers at the protection positions at two sides of the fault line, and disconnecting the transfer branches after keeping the switching for a second preset time so that the current is converted from the transfer branches of the hybrid direct-current circuit breakers to the energy dissipation branches of the hybrid direct-current circuit breakers.
3. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to claim 2, characterized in that: the first preset time is 500ms, and the second preset time is 3 ms.
4. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to claim 1, characterized in that: the power parameter measurements comprise electrode voltage measurements and electrode current measurements; the power parameter theoretical value comprises an electrode voltage theoretical value and an electrode current theoretical value; the line mode traveling wave theoretical waveform is a line mode current traveling wave theoretical waveform, and the line mode traveling wave real waveform is a line mode current traveling wave real waveform.
5. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to claim 4, characterized in that: in S3, the formula for obtaining the theoretical values of the power parameters at the protection positions on both sides of the fault line based on the berelong model is as follows,
Figure FDA0003177948610000021
wherein u iss(t) and is(t) respectively the pole voltage and pole current measurements, u, of one of the two side protections of the fault lineJt(t) and iJt(t) respectively obtaining an electrode voltage theoretical value and an electrode current theoretical value of the other side of the protection positions at the two sides of the fault line through the derivation of a Bergeron model; t is a transmission matrix of the Bergeron model, and the specific expressions of each element in T are as follows,
Figure FDA0003177948610000031
in particular, Me(τ) is the delay factor, Z, transmitted between the protection points on both sides of the faulty linecThe wave impedance between the two side protections of the fault line, R is the total resistance between the two side protections of the fault line, tau is a time constant, and the value of tau is equal to the time taken for the traveling wave to propagate between the two side protections of the fault line.
6. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to claim 4, characterized in that: in the S4, the formula of the theoretical waveform of the line-mode traveling wave and the real waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line obtained based on the kelvin transformation is as follows,
Figure FDA0003177948610000032
wherein ipAnd inRespectively a theoretical value of the anode current and a theoretical value of the cathode current, i, of any one of the protection positions at two sides of the fault line1And i0Respectively obtaining a line mode current traveling wave theoretical waveform and a zero mode current traveling wave theoretical waveform of any one of protection positions at two sides of a fault line after Kernel transformation decoupling; or, ipAnd inRespectively a positive pole current measured value and a negative pole current measured value, i, of any one of the two side protections of the fault line1And i0Respectively obtaining a line mode current traveling wave real waveform and a zero mode current traveling wave real waveform of any one of protection positions at two sides of a fault line after Kernel transformation decoupling; and S is a Kerenbel transformation matrix.
7. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to any one of claims 1 to 6, characterized in that: the set formed by the real wave forms of the line-mode traveling waves at the protection positions at the two sides of the fault line is set M, the set formed by the theoretical wave forms of the line-mode traveling waves at the protection positions at the two sides of the fault line is set N,
Figure FDA0003177948610000033
wherein m isiFor the ith point in the set M, i ∈ [1, a ]]；njAnd nkJ ∈ [1, b ] at j point and k point in set N respectively]，k∈[1,b]And j ≠ k;
then the S5 is specifically the case,
s51, connecting the point M in the set MiRespectively calculating Euclidean distances with all points in the set N, comparing all the Euclidean distances obtained by calculation, and searching the set N for the Euclidean distances meeting the formula | | | mi-nj||≤||mi-nkPoint n of | |j(ii) a Wherein, | | | represents the Euclidean distance between the set M and the selected point in the set N; will satisfy the formula mi-nj||≤||mi-nkPoint N in the set N of | |jAs the point M in the set MiIs called the minimum Euclidean distance point njIs a point miThe minimum euclidean distance point of (c);
s52, calculating all points in the set M according to the method of the S51 method, and meeting the formula | | Mi-nj||≤||mi-nkThe maximum value of all Euclidean distances of | is recorded as the Hausdroff one-way distance h (M, N) from the set M to the set N;
s53, obtaining a Hausdroff one-way distance h (N, M) from the set N to the set M based on the methods of S51 and S52;
s54, obtaining hausdorff distance h between set M and set N according to hausdorff unidirectional distance h (M, N) from set M to set N and hausdorff unidirectional distance h (N, M) from set N to set M, where h is max [ h (M, N), h (N, M) ]; the Hausdroff distance h between the set M and the set N is the Hausdroff distance Q between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave, and the Hausdroff distance Q between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave is used for quantitatively representing the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave.
8. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to claim 4, characterized in that: in S6, the differential criterion is specifically,
Figure FDA0003177948610000041
wherein Q issetTo set the threshold, i1sAnd-i1tRespectively the real waveform of the line mode current traveling wave and the theoretical waveform of the line mode current traveling wave at the protection positions at the two sides of the fault line, Q (i)1s，-i1t) For protection at both sides of faulty lineThe Hausdroff distance between the real waveform of the line mode current traveling wave and the theoretical waveform of the line mode current traveling wave.
9. The multi-terminal direct-current power grid reclosing method based on waveform similarity matching according to claim 8, characterized in that: setting threshold QsetThe overall formula of (a) is as follows,
Figure FDA0003177948610000051
wherein, KrelIs a coefficient of reliability, and Krel＝1.2；KerrorFor measuring error coefficients of the device, and Kerro＝0.15；KtransIs a error coefficient of the Bergeron model, and Ktrans＝0.1；IrmsmaxThe maximum value of the effective values of the line mode current is the maximum value of the effective values of the line mode current at the protection positions on two sides of the fault line.
10. Multi-terminal direct current electric wire netting reclosing system based on wave form similarity matches, its characterized in that: comprises the following modules which are used for realizing the functions of the system,
the fault pre-processing module is used for sequentially carrying out fault isolation, fault dissociation removal and pre-reclosing on a fault line after an intra-area fault occurs in the multi-terminal direct-current power grid;
the electric parameter measuring module is used for simultaneously extracting electric parameter measured values at the protection positions on two sides of the fault line during the pre-reclosing period;
the power parameter theoretical derivation module is used for respectively deriving and calculating power parameter measured values at the protection positions on the two sides of the fault line based on the Bergeron model, and obtaining power parameter theoretical values at the protection positions on the two sides of the fault line in a crossed manner;
the line-mode traveling wave synthesis module is used for respectively transforming the theoretical values of the power parameters at the protection positions on the two sides of the fault line based on Kerenbel transformation to correspondingly obtain the theoretical waveforms of the line-mode traveling waves at the protection positions on the two sides of the fault line; respectively converting the power parameter measured values at the protection positions at the two sides of the fault line based on the Kerenbel conversion, and correspondingly obtaining the real wave forms of the line-mode traveling waves at the protection positions at the two sides of the fault line;
the similarity calculation module is used for quantitatively calculating the similarity between the real waveform of the line-mode traveling wave at the protection positions on the two sides of the fault line and the theoretical waveform of the line-mode traveling wave based on a Hausdroff distance calculation method to obtain the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave;
the fault type judging module is used for judging the fault type of the fault in the region according to the similarity between the real waveform of the line-mode traveling wave and the theoretical waveform of the line-mode traveling wave based on a pre-constructed differential criterion and a setting threshold; wherein the fault types of the intra-zone fault include a transient fault and a permanent fault;
the reclosing control module is used for accelerating the reclosing of the circuit breakers at the protection positions on the two sides of the fault line if the fault type of the fault in the area is an instantaneous fault; and if the fault type of the fault in the area is a permanent fault, stopping reclosing of the circuit breakers at the protection positions on the two sides of the fault line.
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CN114649800A (en) * 2022-03-23 2022-06-21 广东工业大学 Pilot protection method and system for power transmission system in channel bidirectional routing inconsistent state
CN114649800B (en) * 2022-03-23 2023-12-05 广东工业大学 Pilot protection method and pilot protection system for power transmission system in channel bidirectional routing inconsistent state

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