CN112363023A - Multi-terminal flexible direct-current power grid fault section identification method and system - Google Patents
Multi-terminal flexible direct-current power grid fault section identification method and system Download PDFInfo
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- 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
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- G—PHYSICS
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- 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 relates to a method and a system for identifying fault sections of a multi-terminal flexible direct-current power grid, which are used for respectively detecting direct-current voltage and direct current at protective installation positions at two ends of each direct-current line in the multi-terminal flexible direct-current power grid, judging that the direct-current line has no fault if the direct-current voltage is not less than a direct-current voltage threshold, determining a Hausdorff distance value according to the direct current if the direct-current voltage is less than the direct-current voltage threshold, and judging that the direct-current line has no fault if the Hausdorff distance value is not more than the distance threshold, wherein the fault is an out-of-area fault; if the current waveform is greater than the distance threshold, obtaining the integral distance offset amplitude of the current waveform according to the Hausdorff distance value, and if the current waveform is not greater than the amplitude threshold, judging that the current waveform is in an out-of-area fault; if the amplitude is larger than the amplitude threshold value, the fault in the area is judged. According to the invention, the Hausdorff distance value and the integral current waveform distance offset amplitude at the protection installation positions at two ends of the direct-current line are utilized, and the fault section can be rapidly and accurately identified after the direct-current line fault occurs.
Description
Technical Field
The invention relates to the field of power system protection, in particular to a method and a system for identifying a fault section of a multi-terminal flexible direct-current power grid.
Background
With gradual depletion of traditional energy and increasing of environmental problems, large-scale new energy grid-connected power generation is rapidly developed, and great challenges are brought to safe and stable operation of a power system. To solve the problem, a flexible direct current transmission technology based on a Modular Multilevel Converter (MMC) has received wide attention from experts and scholars at home and abroad. The multi-terminal flexible direct-current power grid can realize multi-power supply and multi-drop point power receiving, and the flexibility and reliability of the system are improved. However, the direct current power grid is a 'low damping' system, the distance of an overhead line is long, the environment is complex, the fault occurrence probability is high, when a short-circuit fault occurs on the direct current side line, the converter station immediately feeds a fault current to a fault point, so that the fault current rapidly rises to a peak value within a short time, a great influence is generated on the operation of the whole system, the requirement on protection is higher, the fault is accurately identified and positioned within a few milliseconds, and the protection is ensured not to be mistakenly operated and not to be refused. Therefore, how to rapidly and accurately detect the direct current line fault and formulate a proper protection scheme has extremely important significance and practical value.
Disclosure of Invention
The invention aims to provide a method and a system for identifying a fault section of a multi-terminal flexible direct-current power grid, so that the fault section can be quickly and accurately identified after a direct-current line fault occurs.
In order to achieve the purpose, the invention provides the following scheme:
a multi-terminal flexible direct current power grid fault section identification method comprises the following steps:
respectively detecting the voltage and the current of the protection installation positions at the two ends of each direct current line in the multi-end flexible direct current power grid to obtain the direct current voltage and the direct current of the protection installation positions at the two ends at each sampling time point;
judging whether the direct current voltage is smaller than a direct current voltage threshold value or not, and obtaining a first judgment result;
if the first judgment result shows no, judging that the direct current line has no fault;
if the first judgment result shows that the current values are positive, determining the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct current line based on the Hausdorff distance principle according to the direct current at the protection installation positions at the two ends at each sampling time point;
judging whether the Hausdorff distance value is larger than a distance threshold value or not, and obtaining a second judgment result;
if the second judgment result shows no, judging that the direct current line has no fault, and judging that the current fault is an out-of-area fault; the area outside the direct current circuit is an area outside the direct current circuit;
if the second judgment result shows that the current waveform is the integral current waveform, obtaining the integral distance offset amplitude of the current waveform according to the Hausdorff distance value;
judging whether the integral distance offset amplitude of the current waveform is larger than an amplitude threshold value or not, and obtaining a third judgment result;
if the third judgment result shows no, judging that the direct current line has no fault, wherein the current fault is an out-of-area fault;
and if the third judgment result shows that the direct current line is faulty, judging that the direct current line is faulty.
Optionally, the determining, according to the dc current at the two-end protection installation at each sampling time point, a Hausdorff distance value of the dc current at the two-end protection installation of each dc line based on the Hausdorff distance principle specifically includes:
calculating the Euclidean distance between the direct current of the first end protection installation position at each sampling time point and the direct current of the second end protection installation position at all the sampling time points;
taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current of the first end protection installation position at each sampling time point;
selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position as a first one-way Hausdorff distance from the first end protection installation position to the second end protection installation position;
calculating the Euclidean distance between the direct current of the second end protection installation position at each sampling time point and the direct current of the first end protection installation position at all the sampling time points;
taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current of the second end protection installation position at each sampling time point;
selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position as a second one-way Hausdorff distance from the second end protection installation position to the first end protection installation position;
and determining the maximum value of the first one-way Hausdorff distance and the second one-way Hausdorff distance as the Hausdorff distance value of the direct current at the protection installation position at the two ends of each direct current line.
Optionally, the obtaining of the overall distance offset amplitude of the current waveform according to the Hausdorff distance value specifically includes:
if the Hausdorff distance value is the first one-way Hausdorff distance, acquiring the minimum Euclidean distance of the direct current of the first end protection installation position at each sampling time point;
counting the number of the direct current with the minimum Euclidean distance larger than the distance threshold value at all sampling time points of the first end protection installation position, and taking the number as the integral distance offset amplitude of the current waveform;
if the Hausdorff distance value is the second one-way Hausdorff distance, acquiring the minimum Euclidean distance of the direct current of the second end protection installation position at each sampling time point;
and counting the number of the direct current with the minimum Euclidean distance larger than the distance threshold value at all sampling time points of the second end protection installation position, and taking the number as the integral distance offset amplitude of the current waveform.
Optionally, the dc voltage includes a positive voltage and a negative voltage.
A multi-terminal flexible dc grid fault section identification system, the system comprising:
the direct current voltage and direct current acquisition module is used for respectively detecting the voltage and current of the protection installation positions at the two ends of each direct current line in the multi-end flexible direct current power grid and acquiring the direct current voltage and the direct current of the protection installation positions at the two ends at each sampling time point;
the first judgment result obtaining module is used for judging whether the direct current voltage is smaller than a direct current voltage threshold value or not and obtaining a first judgment result;
the direct-current line fault-free judging module is used for judging that the direct-current line has no fault if the first judging result shows that the direct-current line has no fault;
the Hausdorff distance value determining module is used for determining the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct current line based on the Hausdorff distance principle according to the direct current at the protection installation positions at the two ends at each sampling time point if the first judgment result indicates that the two protection installation positions are positive;
the second judgment result obtaining module is used for judging whether the Hausdorff distance value is greater than a distance threshold value or not and obtaining a second judgment result;
the direct-current line fault-free judging module is used for judging that the direct-current line has no fault if the second judging result shows that the direct-current line has no fault, and the current fault is an out-of-area fault; the area outside the direct current circuit is an area outside the direct current circuit;
a current waveform overall distance offset amplitude obtaining module, configured to obtain a current waveform overall distance offset amplitude according to the Hausdorff distance value if the second determination result indicates yes;
a third judgment result obtaining module, configured to judge whether the overall distance offset amplitude of the current waveform is greater than an amplitude threshold value, and obtain a third judgment result;
the external fault determination module is used for determining that the direct-current line has no fault if the third determination result shows that the direct-current line has no fault, and the current fault is an external fault;
and the in-area fault determination module is used for determining that the direct-current line has a fault if the third determination result shows that the direct-current line has the fault.
Optionally, the Hausdorff distance value determining module specifically includes:
the first end Euclidean distance calculation submodule is used for calculating the Euclidean distance between the direct current of the first end protection installation position at each sampling time point and the direct current of the second end protection installation position at all the sampling time points;
the first end minimum Euclidean distance obtaining submodule is used for taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current at each sampling time point of the first end protection installation position;
the first one-way Hausdorff distance obtaining submodule is used for selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position as the first one-way Hausdorff distance from the first end protection installation position to the second end protection installation position;
the second end Euclidean distance submodule is used for calculating the Euclidean distance between the direct current of the second end protection installation position at each sampling time point and the direct current of the first end protection installation position at all the sampling time points;
the second-end minimum Euclidean distance submodule is used for taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current at each sampling time point of the second-end protection installation position;
the second unidirectional Hausdorff distance obtaining submodule is used for selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position as the second unidirectional Hausdorff distance from the second end protection installation position to the first end protection installation position;
and the Hausdorff distance value determining submodule is used for determining the maximum value of the first one-way Hausdorff distance and the second one-way Hausdorff distance as the Hausdorff distance value of the direct current at the protection installation positions at two ends of each direct current line.
Optionally, the current waveform overall distance offset amplitude obtaining module specifically includes:
the first end protection installation position minimum Euclidean distance acquisition submodule is used for acquiring the minimum Euclidean distance of the direct current at each sampling time point at the first end protection installation position if the Hausdorff distance value is the first one-way Hausdorff distance;
the first terminal number counting submodule is used for counting the number of the first terminal protection installation positions, at which the minimum Euclidean distance of the direct current is larger than the distance threshold value at all sampling time points, and taking the number as the integral distance offset amplitude of the current waveform;
the second end protection installation position minimum Euclidean distance obtaining submodule is used for obtaining the minimum Euclidean distance of the direct current at each sampling time point of the second end protection installation position if the Hausdorff distance value is the second one-way Hausdorff distance;
and the second end number counting submodule is used for counting the number of the second end protection installation positions, at all sampling time points, of the minimum Euclidean distance of the direct current larger than the distance threshold value, and taking the number as the integral distance offset amplitude of the current waveform.
Optionally, the dc voltage includes a positive voltage and a negative voltage.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a method for identifying fault sections of a multi-terminal flexible direct-current power grid, which comprises the steps of respectively detecting the voltage and the current of protection installation positions at two ends of each direct-current line in the multi-terminal flexible direct-current power grid, obtaining the direct-current voltage and the direct current of the protection installation positions at the two ends at each sampling time point, judging that the direct-current lines have no fault if the direct-current voltage is not less than a direct-current voltage threshold, determining the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct-current line according to the direct current if the direct-current voltage is less than the direct-current voltage threshold, and judging that the direct-current lines have no fault if the Hausdorff distance value is not more than the distance threshold, wherein the Hausdor; if the Hausdorff distance value is larger than the distance threshold, obtaining the integral distance offset amplitude of the current waveform according to the Hausdorff distance value, judging whether the integral distance offset amplitude of the current waveform is larger than the amplitude threshold, and if the integral distance offset amplitude of the current waveform is not larger than the amplitude threshold, judging that the fault is outside the area; if the amplitude is larger than the amplitude threshold value, the fault in the area is judged. According to the invention, the Hausdorff distance value and the integral current waveform distance offset amplitude at the protection installation positions at two ends of the direct-current line are utilized, and the fault section can be rapidly and accurately identified after the direct-current line fault occurs.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a flowchart of a method for identifying a fault section of a multi-terminal flexible direct-current power grid according to the present invention;
FIG. 2 is a schematic diagram of a method for identifying a fault section of a multi-terminal flexible DC power grid according to the present invention;
fig. 3 is a schematic diagram of a four-terminal bipolar flexible dc power grid according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a method and a system for identifying a fault section of a multi-terminal flexible direct-current power grid, so that the fault section can be quickly and accurately identified after a direct-current line fault occurs.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Compared with an alternating current system, a conventional direct current system and a two-end flexible direct current transmission system, fault protection of a multi-terminal flexible direct current (MTDC) power grid is more complex and has higher requirements. The MTDC power grid has small damping, and fault current can rapidly rise to a peak value within a few milliseconds after a direct-current line fails, so that the safe operation of the whole system is seriously threatened. In order to quickly and accurately identify a fault section after a fault of a direct-current line occurs, the invention discloses a method for identifying a fault section of a multi-terminal flexible direct-current power grid, which comprises the following steps of:
s101, respectively detecting the voltage and the current of the protection installation positions at the two ends of each direct current line in the multi-end flexible direct current power grid, and obtaining the direct current voltage and the direct current of the protection installation positions at the two ends at each sampling time point.
S102, judging whether the direct current voltage is smaller than a direct current voltage threshold value or not, and obtaining a first judgment result;
and S103, if the first judgment result shows no, judging that the direct current line has no fault.
And S104, if the first judgment result shows that the current values are positive, determining the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct current line based on the Hausdorff distance principle according to the direct current at the protection installation positions at the two ends at each sampling time point.
S105, judging whether the Hausdorff distance value is larger than the distance threshold value or not, and obtaining a second judgment result.
S106, if the second judgment result shows no, judging that the direct current line has no fault, and judging that the current fault is an out-of-area fault; the outside is the area outside the direct current circuit.
And S107, if the second judgment result shows yes, obtaining the integral distance offset amplitude of the current waveform according to the Hausdorff distance value.
And S108, judging whether the overall distance offset amplitude of the current waveform is larger than an amplitude threshold value or not, and obtaining a third judgment result.
And S109, if the third judgment result shows no, judging that the direct current line has no fault, and judging that the current fault is an out-of-area fault.
And S110, if the third judgment result shows yes, judging that the direct current line has a fault.
The specific process is as follows:
and S101, the multi-terminal flexible direct-current power grid comprises a plurality of direct-current lines, protective installation positions are respectively arranged at two ends of each direct-current line, and voltage and current detection is carried out on each protective installation position.
Step S102, this step is to determine whether the protection operation condition is satisfied. The direct-current voltage comprises a sampling voltage of a positive line and a sampling voltage of a negative line, and whether the sampling voltage of the positive line or the negative line at each protection installation position is lower than a direct-current voltage threshold value is judged, wherein the direct-current voltage threshold value is 80% of a rated direct-current voltage. If the sampling circuit of one line at one protection installation position is lower than 80% of the rated direct current voltage, continuing to execute the step S104; if the sampling circuits of the positive line and the negative line at the protection installation position are not lower than 80% of the rated direct current voltage, step S103 is executed, the direct current line is judged to be free of faults, and protection is recovered. As shown in FIG. 2, | Ux(k) I represents the sampling voltage of the positive line or the sampling voltage of the negative line, 0.8UdcRepresenting 80% of the rated dc voltage.
Step S104, the Hausdorff distance principle is as follows: let A, B two sets of points exist in space:
A＝{a1,...,aq}
B＝{b1,...,bq}
then the specific calculation formula of the Hausdorff distance of the point sets a and B is as follows:
H(A,B)＝max[h(A,B),h(B,A)]
in the formula (I), the compound is shown in the specification,
l | · | is a distance norm between two points, and an euclidean distance is commonly used; a is1And aqRespectively the 1 st and the q th elements in the point set A, b1And bqThe 1 st and the q th elements in the point set B are respectively, H (A, B) is the Hausdorff distance of the point sets A and B, H (A, B) is the unidirectional Hausdorff distance from the point set A to the point set B and the unidirectional Hausdorff distance from the point set B to the point set A, and a and B respectively represent all the elements of the point set A and the point set B. For a certain point a in the point set AiComparing it with all points in point set B to find out the AiClosest point bjB is caused to bejThe following formula is satisfied:
for all elements in the point set a, there are q minimum distance values, where the largest minimum distance value is h (a, B), that is, the following formula is satisfied:
h (B, A) is calculated in the same way, so that H (A, B) is obtained.
According to the current data obtained by sampling, based on the Hausdorff distance principle, the Hausdorff distance value of the current on two sides of the direct current line is calculated, and the method specifically comprises the following steps:
calculating the Euclidean distance between the direct current of the first end protection installation position at each sampling time point and the direct current of the second end protection installation position at all the sampling time points;
taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current of the first end protection installation position at each sampling time point;
selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position as a first one-way Hausdorff distance from the first end protection installation position to the second end protection installation position;
calculating the Euclidean distance between the direct current of the second end protection installation position at each sampling time point and the direct current of the first end protection installation position at all the sampling time points;
taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current of the second end protection installation position at each sampling time point;
selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position as a second one-way Hausdorff distance from the second end protection installation position to the first end protection installation position;
and determining the maximum value of the first one-way Hausdorff distance and the second one-way Hausdorff distance as the Hausdorff distance value of the direct current at the protection installation position at the two ends of each direct current line.
Step S105, calculating the Hausdorff distance value and the distance threshold value HsetA comparison is made.
Step S106, if the Hausdorff distance value is less than or equal to the distance threshold value HsetThen it is determined as an out-of-area fault. The division of the inside and outside of the zone is divided according to the protection range of protection, the fault in the protection range is the inside fault, otherwise, the fault outside the protection range is the outside fault. The protection range of the invention is that the direct current line between the two ends of the protection installation is protected, so the fault on the direct current line is an intra-area fault, and the fault outside the direct current line is an extra-area fault.
Step S107, if the Hausdorff distance value is larger than the distance threshold value HsetAnd if H (A, B) is larger, the minimum distance value corresponding to each current sampling point in the data window of the point set A is judged to be larger than a set distance threshold value HsetThe number of points of (a); if H (B, A) is larger, the minimum distance value corresponding to each current sampling point in the data window of the point set B is judged to be larger than a set distance threshold value HsetThat is, the distance value of the minimum distance sequence point is greater than the distance threshold value HsetN is the overall distance offset amplitude of the current waveform. The method specifically comprises the following steps:
if the Hausdorff distance value is the first one-way Hausdorff distance, acquiring the minimum Euclidean distance of the direct current of the first end protection installation position at each sampling time point;
counting the number of the direct current with the minimum Euclidean distance larger than the distance threshold value at all sampling time points of the first end protection installation position, and taking the number as the integral distance offset amplitude of the current waveform;
if the Hausdorff distance value is the second one-way Hausdorff distance, acquiring the minimum Euclidean distance of the direct current of the second end protection installation position at each sampling time point;
and counting the number of the direct current with the minimum Euclidean distance larger than the distance threshold value at all sampling time points of the second end protection installation position, and taking the number as the integral distance offset amplitude of the current waveform.
Step S108, judging the integral distance deviation amplitude of two current waveforms, and comparing n with a given amplitude threshold value nsetA comparison is made. If n is less than or equal to nsetIf the overall waveform offset amplitude is low, it is determined that the dc line has no fault, and it is an out-of-range fault, that is, step S109; if n is greater than nsetIf the overall waveform offset amplitude is high, it is determined that the dc link has a fault, and the dc link is an in-zone fault, that is, step S110.
Compared with the existing protection method, the protection method provided by the invention has the following advantages:
1. the device has higher action speed and meets the requirement on protection rapidity;
2. the calculation is simple and easy to realize, and a complex tool is not needed for extracting the specific frequency component;
3. the invention can identify the unipolar grounding fault and the bipolar short-circuit fault of which the transition resistance is up to 500 ohms, has stronger transition resistance tolerance capability and is not easily influenced by the distributed capacitance current of the line;
4. the method has strong abnormal data resistance and improves the reliability of protection.
The invention provides a method for identifying a fault section of a four-terminal bipolar flexible direct-current power grid, which comprises the following steps as shown in figure 3:
the method comprises the following steps: detecting a protected installation (R)12To) positive and negative electrode voltages Up(k) And Un(k) Wherein subscripts p and n represent positive and negative electrodes, respectively; detecting a protected installation (R)12And R21Of (a) isDirect current imnAnd inmDefining a current imnWith reference to the direction of the bus-pointing line, current inmThe reference direction of the current source is a line pointing bus, the current flowing direction is positive when the current flowing direction is the same as the reference direction, and negative when the current flowing direction is opposite to the reference direction.
Step two: as shown in FIG. 2, it is determined whether | U is satisfiedx(k)|＜0.8UdcWherein x is p and n, UdcIs a dc voltage rating. If yes, starting to execute the step three; if not, the protection is reset.
Step three: calculating the current i at two sides of the linemnAnd inmThe Hausdorff distance value of (1). Protecting the installation position R according to the Hausdorff distance principle12D.c. current imnSubstituting the sampling sequence values (current values of all sampling time points) into the set A to protect the installation site R21D.c. current inmThe sampling sequence value is substituted into the set B, a proper sample data window length is selected for the set A and the set B, and the sample data window length moves forward point by point, so that the current i at two sides can be calculated in real time and outputmnAnd inmThe Hausdorff distance value of (1).
Step four: referring to FIG. 2, the calculated Hausdorff distance is compared with a given threshold value Hset(distance threshold) are compared. For setting the protection threshold value, the sensitivity and reliability of protection should be fully considered. When a fault occurs outside a line area, the protection is prevented from being mistakenly operated due to the influence of any external adverse factor; when any in-zone fault occurs, the protection should be quickly and reliably identified and not rejected. Based on a large number of simulation example simulation system typical position fault conditions, finding out the minimum value of the Hausdorff distance under the condition of an internal fault and the maximum value of the Hausdorff distance under the condition of an external fault, and selecting a proper threshold value H on the basis of reserving a certain marginsetAnd the identification of faults inside and outside the area can be met. If H (A, B) is less than or equal to HsetIf yes, judging that the line is out-of-area fault; if H (A, B) > H is satisfiedsetThen step five is started.
Step five: in the process of calculating the Hausdorff distance value of the current at two ends of the line, the larger one-way Hausdorff distance (h (A, B) sum) in the data window is takenh (B, A) if h (A, B) is larger, judging the current i in the data windowmnThe minimum distance value corresponding to each sampling point is greater than a set distance threshold value HsetThe number of points of (a); if h (B, A) is larger, judging the current i in the data windownmThe minimum distance value corresponding to each sampling point is greater than a set distance threshold value HsetThat is, the distance value of the minimum distance sequence point is greater than the distance threshold value HsetN, is calculated.
Step six: referring to FIG. 2, the overall distance offset of two current waveforms is determined, and n is compared with a given threshold value nset(amplitude threshold) and taking n when taking into account 5 abnormal data points in the extreme sampling time windowsetThe number of abnormal data points in the actual situation is less than 5. If n is less than or equal to nsetJudging as an out-of-area fault; if n is>nsetIf so, the system is judged to be in-zone fault and is protected.
In fig. 3, MMC denotes a modular multilevel converter; line1, Line2, Line3, and Line4 respectively represent a dc Line1, a dc Line2, a dc Line3, and a dc Line 4; r12And R21Respectively representing the protective mounting points, R, at both ends of the DC line113And R31Respectively representing the protective mounting points, R, at both ends of the DC line224And R42Respectively representing the protective mounting points, R, at both ends of the direct current line334And R43Respectively showing the protection installation positions at two ends of the direct current line 4; i.e. imnIs R12Current of (d) inmIs R21The current at (c); to protect the installation site R12For example analysis, F1A fault in one third of the zone of the DC line1, F2Two thirds of faults in zone 1 of the DC line, F3For end faults in zone 1 of the DC line, F4And F5Out-of-range faults in the forward and reverse direction, respectively, of the DC line1, F6For an out-of-range fault near the DC line2, F7For a fault at the midpoint of the DC line4, F8Is a fault at the midpoint of the dc link 3.
According to the invention, the Hausdorff distance value of the current waveforms at the two ends of the direct current transmission line and the integral distance offset amplitude of the waveforms are utilized, and the fault section can be rapidly and accurately identified after the direct current line fault occurs.
The invention also provides a multi-terminal flexible direct-current power grid fault section identification system, which comprises:
the direct current voltage and direct current acquisition module is used for respectively detecting the voltage and current of the protection installation positions at the two ends of each direct current line in the multi-end flexible direct current power grid and acquiring the direct current voltage and the direct current of the protection installation positions at the two ends at each sampling time point;
the first judgment result obtaining module is used for judging whether the direct current voltage is smaller than the direct current voltage threshold value or not and obtaining a first judgment result;
the direct-current line fault-free judging module is used for judging that the direct-current line has no fault if the first judging result shows that the direct-current line has no fault;
the Hausdorff distance value determining module is used for determining the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct current line based on the Hausdorff distance principle according to the direct current at the protection installation positions at the two ends at each sampling time point if the first judgment result indicates that the two protection installation positions are positive;
the second judgment result obtaining module is used for judging whether the Hausdorff distance value is greater than the distance threshold value or not and obtaining a second judgment result;
the direct-current line fault-free judging module is used for judging that the direct-current line has no fault if the second judgment result shows no fault, and the current fault is an out-of-area fault; the outside is the area outside the direct current circuit;
the current waveform overall distance offset amplitude obtaining module is used for obtaining the current waveform overall distance offset amplitude according to the Hausdorff distance value if the second judgment result shows that the current waveform overall distance offset amplitude is positive;
a third judgment result obtaining module, configured to judge whether the overall distance offset amplitude of the current waveform is greater than an amplitude threshold value, and obtain a third judgment result;
the external fault judging module is used for judging that the direct-current line has no fault if the third judgment result shows that the direct-current line has no fault, and the current fault is an external fault;
and the intra-area fault determination module is used for determining that the direct-current line has a fault if the third determination result shows that the direct-current line has the fault.
The Hausdorff distance value determining module specifically comprises:
the first end Euclidean distance calculation submodule is used for calculating the Euclidean distance between the direct current of the first end protection installation position at each sampling time point and the direct current of the second end protection installation position at all the sampling time points;
the first end minimum Euclidean distance obtaining submodule is used for taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current at each sampling time point of the first end protection installation position;
the first one-way Hausdorff distance obtaining submodule is used for selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position as the first one-way Hausdorff distance from the first end protection installation position to the second end protection installation position;
the second end Euclidean distance submodule is used for calculating the Euclidean distance between the direct current of the second end protection installation position at each sampling time point and the direct current of the first end protection installation position at all the sampling time points;
the second-end minimum Euclidean distance submodule is used for taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current at each sampling time point of the second-end protection installation position;
the second unidirectional Hausdorff distance obtaining submodule is used for selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position as the second unidirectional Hausdorff distance from the second end protection installation position to the first end protection installation position;
and the Hausdorff distance value determining submodule is used for determining the maximum value of the first one-way Hausdorff distance and the second one-way Hausdorff distance as the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct current line.
The current waveform overall distance offset amplitude obtaining module specifically comprises:
the first end protection installation position minimum Euclidean distance acquisition submodule is used for acquiring the minimum Euclidean distance of the direct current at each sampling time point at the first end protection installation position if the Hausdorff distance value is the first one-way Hausdorff distance;
the first terminal number counting submodule is used for counting the number of the first terminal protection installation positions, at which the minimum Euclidean distance of the direct current is larger than the distance threshold value at all sampling time points, and taking the number as the integral distance offset amplitude of the current waveform;
the minimum Euclidean distance acquisition submodule at the second end protection installation position is used for acquiring the minimum Euclidean distance of the direct current at each sampling time point at the second end protection installation position if the Hausdorff distance value is the second one-way Hausdorff distance;
and the second end number counting submodule is used for counting the number of the second end protection installation positions, at all sampling time points, of the minimum Euclidean distance of the direct current larger than the distance threshold value, and taking the number as the integral distance offset amplitude of the current waveform.
The dc voltage includes a positive voltage and a negative voltage.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (8)
1. A multi-terminal flexible direct-current power grid fault section identification method is characterized by comprising the following steps:
respectively detecting the voltage and the current of the protection installation positions at the two ends of each direct current line in the multi-end flexible direct current power grid to obtain the direct current voltage and the direct current of the protection installation positions at the two ends at each sampling time point;
judging whether the direct current voltage is smaller than a direct current voltage threshold value or not, and obtaining a first judgment result;
if the first judgment result shows no, judging that the direct current line has no fault;
if the first judgment result shows that the current values are positive, determining the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct current line based on the Hausdorff distance principle according to the direct current at the protection installation positions at the two ends at each sampling time point;
judging whether the Hausdorff distance value is larger than a distance threshold value or not, and obtaining a second judgment result;
if the second judgment result shows no, judging that the direct current line has no fault, and judging that the current fault is an out-of-area fault; the area outside the direct current circuit is an area outside the direct current circuit;
if the second judgment result shows that the current waveform is the integral current waveform, obtaining the integral distance offset amplitude of the current waveform according to the Hausdorff distance value;
judging whether the integral distance offset amplitude of the current waveform is larger than an amplitude threshold value or not, and obtaining a third judgment result;
if the third judgment result shows no, judging that the direct current line has no fault, wherein the current fault is an out-of-area fault;
and if the third judgment result shows that the direct current line is faulty, judging that the direct current line is faulty.
2. The method for identifying the fault section of the multi-terminal flexible direct-current power grid according to claim 1, wherein the determining of the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct-current line based on the Hausdorff distance principle according to the direct current at the protection installation positions at the two ends at each sampling time point specifically comprises:
calculating the Euclidean distance between the direct current of the first end protection installation position at each sampling time point and the direct current of the second end protection installation position at all the sampling time points;
taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current of the first end protection installation position at each sampling time point;
selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position as a first one-way Hausdorff distance from the first end protection installation position to the second end protection installation position;
calculating the Euclidean distance between the direct current of the second end protection installation position at each sampling time point and the direct current of the first end protection installation position at all the sampling time points;
taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current of the second end protection installation position at each sampling time point;
selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position as a second one-way Hausdorff distance from the second end protection installation position to the first end protection installation position;
and determining the maximum value of the first one-way Hausdorff distance and the second one-way Hausdorff distance as the Hausdorff distance value of the direct current at the protection installation position at the two ends of each direct current line.
3. The method for identifying the fault section of the multi-terminal flexible direct-current power grid according to claim 2, wherein the obtaining of the overall distance offset amplitude of the current waveform according to the Hausdorff distance value specifically comprises:
if the Hausdorff distance value is the first one-way Hausdorff distance, acquiring the minimum Euclidean distance of the direct current of the first end protection installation position at each sampling time point;
counting the number of the direct current with the minimum Euclidean distance larger than the distance threshold value at all sampling time points of the first end protection installation position, and taking the number as the integral distance offset amplitude of the current waveform;
if the Hausdorff distance value is the second one-way Hausdorff distance, acquiring the minimum Euclidean distance of the direct current of the second end protection installation position at each sampling time point;
and counting the number of the direct current with the minimum Euclidean distance larger than the distance threshold value at all sampling time points of the second end protection installation position, and taking the number as the integral distance offset amplitude of the current waveform.
4. The method according to claim 1, wherein the direct voltage comprises a positive voltage and a negative voltage.
5. A multi-terminal flexible dc grid fault section identification system, the system comprising:
the direct current voltage and direct current acquisition module is used for respectively detecting the voltage and current of the protection installation positions at the two ends of each direct current line in the multi-end flexible direct current power grid and acquiring the direct current voltage and the direct current of the protection installation positions at the two ends at each sampling time point;
the first judgment result obtaining module is used for judging whether the direct current voltage is smaller than a direct current voltage threshold value or not and obtaining a first judgment result;
the direct-current line fault-free judging module is used for judging that the direct-current line has no fault if the first judging result shows that the direct-current line has no fault;
the Hausdorff distance value determining module is used for determining the Hausdorff distance value of the direct current at the protection installation positions at the two ends of each direct current line based on the Hausdorff distance principle according to the direct current at the protection installation positions at the two ends at each sampling time point if the first judgment result indicates that the two protection installation positions are positive;
the second judgment result obtaining module is used for judging whether the Hausdorff distance value is greater than a distance threshold value or not and obtaining a second judgment result;
the direct-current line fault-free judging module is used for judging that the direct-current line has no fault if the second judging result shows that the direct-current line has no fault, and the current fault is an out-of-area fault; the area outside the direct current circuit is an area outside the direct current circuit;
a current waveform overall distance offset amplitude obtaining module, configured to obtain a current waveform overall distance offset amplitude according to the Hausdorff distance value if the second determination result indicates yes;
a third judgment result obtaining module, configured to judge whether the overall distance offset amplitude of the current waveform is greater than an amplitude threshold value, and obtain a third judgment result;
the external fault determination module is used for determining that the direct-current line has no fault if the third determination result shows that the direct-current line has no fault, and the current fault is an external fault;
and the in-area fault determination module is used for determining that the direct-current line has a fault if the third determination result shows that the direct-current line has the fault.
6. The system for identifying the fault section of the multi-terminal flexible direct-current power grid according to claim 5, wherein the Hausdorff distance value determining module specifically comprises:
the first end Euclidean distance calculation submodule is used for calculating the Euclidean distance between the direct current of the first end protection installation position at each sampling time point and the direct current of the second end protection installation position at all the sampling time points;
the first end minimum Euclidean distance obtaining submodule is used for taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current at each sampling time point of the first end protection installation position;
the first one-way Hausdorff distance obtaining submodule is used for selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the first end protection installation position as the first one-way Hausdorff distance from the first end protection installation position to the second end protection installation position;
the second end Euclidean distance submodule is used for calculating the Euclidean distance between the direct current of the second end protection installation position at each sampling time point and the direct current of the first end protection installation position at all the sampling time points;
the second-end minimum Euclidean distance submodule is used for taking the minimum value of the Euclidean distance as the minimum Euclidean distance of the direct current at each sampling time point of the second-end protection installation position;
the second unidirectional Hausdorff distance obtaining submodule is used for selecting the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position, and taking the maximum value of the minimum Euclidean distances of the direct currents at all sampling time points of the second end protection installation position as the second unidirectional Hausdorff distance from the second end protection installation position to the first end protection installation position;
and the Hausdorff distance value determining submodule is used for determining the maximum value of the first one-way Hausdorff distance and the second one-way Hausdorff distance as the Hausdorff distance value of the direct current at the protection installation positions at two ends of each direct current line.
7. The multi-terminal flexible direct-current power grid fault section identification system according to claim 6, wherein the current waveform overall distance offset amplitude obtaining module specifically comprises:
the first end protection installation position minimum Euclidean distance acquisition submodule is used for acquiring the minimum Euclidean distance of the direct current at each sampling time point at the first end protection installation position if the Hausdorff distance value is the first one-way Hausdorff distance;
the first terminal number counting submodule is used for counting the number of the first terminal protection installation positions, at which the minimum Euclidean distance of the direct current is larger than the distance threshold value at all sampling time points, and taking the number as the integral distance offset amplitude of the current waveform;
the second end protection installation position minimum Euclidean distance obtaining submodule is used for obtaining the minimum Euclidean distance of the direct current at each sampling time point of the second end protection installation position if the Hausdorff distance value is the second one-way Hausdorff distance;
and the second end number counting submodule is used for counting the number of the second end protection installation positions, at all sampling time points, of the minimum Euclidean distance of the direct current larger than the distance threshold value, and taking the number as the integral distance offset amplitude of the current waveform.
8. The multi-terminal flexible direct current grid fault section identification system according to claim 5, wherein the direct current voltage comprises a positive voltage and a negative voltage.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113740664A (en) * | 2021-08-23 | 2021-12-03 | 中国南方电网有限责任公司超高压输电公司广州局 | Direct current system fault positioning method and device, computer equipment and storage medium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109119977A (en) * | 2018-09-20 | 2019-01-01 | 山东大学 | Multiterminal flexible direct current power grid DC line fast protection method and system based on single ended voltage |
| CN109541395A (en) * | 2018-11-23 | 2019-03-29 | 三峡大学 | Distribution Section Location based on Hausdorff under a kind of feature band |
| CN110261706A (en) * | 2019-07-22 | 2019-09-20 | 西南交通大学 | A kind of electric transmission line fault detection method based on neighborhood distance |
| CN110620371A (en) * | 2019-09-27 | 2019-12-27 | 华中科技大学 | Current differential protection method and system for flexible direct current transmission system |
| CN111697548A (en) * | 2020-07-17 | 2020-09-22 | 西安科技大学 | Pilot protection method for identifying internal and external faults of multi-terminal flexible direct current power grid region |
-
2020
- 2020-11-23 CN CN202011320138.1A patent/CN112363023A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109119977A (en) * | 2018-09-20 | 2019-01-01 | 山东大学 | Multiterminal flexible direct current power grid DC line fast protection method and system based on single ended voltage |
| CN109541395A (en) * | 2018-11-23 | 2019-03-29 | 三峡大学 | Distribution Section Location based on Hausdorff under a kind of feature band |
| CN110261706A (en) * | 2019-07-22 | 2019-09-20 | 西南交通大学 | A kind of electric transmission line fault detection method based on neighborhood distance |
| CN110620371A (en) * | 2019-09-27 | 2019-12-27 | 华中科技大学 | Current differential protection method and system for flexible direct current transmission system |
| CN111697548A (en) * | 2020-07-17 | 2020-09-22 | 西安科技大学 | Pilot protection method for identifying internal and external faults of multi-terminal flexible direct current power grid region |
Non-Patent Citations (2)
| Title |
|---|
| YINGYU LIANG 等: "A Novel Similarity-Comparison-Based Directional", 《 2020 IEEE 4TH CONFERENCE ON ENERGY INTERNET AND ENERGY SYSTEM INTEGRATION (EI2)》 * |
| 赵航 等: "基于模量Hausdorff距离波形比较的直流输电线路选择性快速保护方案", 《中国电机工程学报》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113740664A (en) * | 2021-08-23 | 2021-12-03 | 中国南方电网有限责任公司超高压输电公司广州局 | Direct current system fault positioning method and device, computer equipment and storage medium |
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