CN112436494B - Circuit breaker fault backup protection method suitable for high-voltage direct-current power grid - Google Patents
Circuit breaker fault backup protection method suitable for high-voltage direct-current power grid Download PDFInfo
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- CN112436494B CN112436494B CN202011347947.1A CN202011347947A CN112436494B CN 112436494 B CN112436494 B CN 112436494B CN 202011347947 A CN202011347947 A CN 202011347947A CN 112436494 B CN112436494 B CN 112436494B
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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
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Abstract
The application provides a breaker fault backup protection method suitable for a high-voltage direct-current power grid, which is used for starting a main protection action when a fault of the high-voltage direct-current power grid occurs; sequentially collecting data samples according to a preset sampling interval; wherein the data samples include a system current and a voltage; determining a current threshold and a voltage threshold according to the system current and voltage; comparing a current threshold value, a voltage threshold value and a scalar value according to preset delay time, and judging whether the fault is cleared; when the fault is not cleared, starting backup protection; the method shortens the time of the high-voltage direct-current power grid for bearing low voltage and large current, thereby reducing the influence of faults on the system, further improving the safe operation level of the power grid, and ensuring the safe operation of the power grid by using an efficient and accurate protection scheme.
Description
Technical Field
The application relates to the field of protection of direct-current transmission systems, in particular to a circuit breaker fault backup protection method suitable for a high-voltage direct-current power grid.
Background
The direct current has the advantages of no inductive reactance, no synchronization problem and the like, and the high-voltage direct current transmission realizes high-power long-distance direct current transmission by utilizing the characteristic; high voltage direct current transmission technology is used for long distance transmission of electric energy through overhead lines and submarine cables; high voltage direct current transmission is used for long or ultra-long distance transmission because it is more economical than conventional alternating current transmission; by applying the high-voltage direct-current transmission system, both the grade and the direction of electric energy can be quickly and accurately controlled, and the performance can improve the performance and the efficiency of an alternating-current power grid connected with the high-voltage direct-current transmission system.
However, the fault clearing time of the alternating current power grid circuit breaker protection is long, and the direct current fault current cannot be directly used for the protection of the high-voltage direct current power grid, and the traditional protection scheme has strict requirements on parameters of protection equipment such as a circuit breaker and the like, so that the fault detection time is too long, and continuous risks are brought to the operation of the high-voltage direct current power grid.
Disclosure of Invention
The application provides a breaker fault backup protection method suitable for a high-voltage direct-current power grid, and aims to solve the technical problem that current is rapidly increased after a fault occurs in the high-voltage direct-current power grid.
In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions:
the method for the fault backup protection of the circuit breaker suitable for the high-voltage direct-current power grid is provided, and when a fault of the high-voltage direct-current power grid occurs, the method comprises the following steps:
starting a main protection action;
sequentially collecting data samples according to a preset sampling interval; wherein the data samples include a system current and a voltage;
determining a current threshold and a voltage threshold according to the system current and voltage;
comparing a current threshold value, a voltage threshold value and a scalar value according to preset delay time, and judging whether the fault is cleared;
when the fault is not cleared, starting backup protection;
wherein the current threshold and the voltage threshold are determined by a linear discriminant analysis method that:
wherein the content of the first and second substances,
in the formula i Threshold value As current threshold, u Threshold value Is a voltage threshold value, alpha is a differentiation parameter>
And
for cleared fault sample X 1 And primary protection uncleared fault sample X 2 Reduced dimension changed Y 1 And Y 2 Of the final sample.
Optionally, the system current and voltage in the data samples comprise:
system current i when primary protection has cleared fault in data sample c And voltage u c ；
System current i when primary protection has not cleared fault in data sample uc And voltage u uc 。
Optionally, the obtaining of the final sample comprises:
obtaining a primary protection cleared fault sample X 1 And primary protection uncleared fault sample X 2 ：
X 1 ＝{(i c (Δt),u c (Δt)),(i c (2Δt),u c (2Δt)),…,(i c (nΔt),u c (nΔt))}
X 2 ＝{(i uc (Δt),u uc (Δt)),(i uc (2Δt),u uc (2Δt)),…,(i uc (nΔt),u uc (nΔt))}
Where Δ t is a predetermined sampling interval, i c And u c For the system current and voltage at which the primary protection has cleared the fault in the data sample i uc And u uc The system current and voltage when the main protection has not cleared the fault in the data sample;
obtaining a definition matrix M i And a variability parameter α:
in the formula (I), the compound is shown in the specification,
is X i I =1,2; m s ＝M 1 +M 2 ；
Clear fault sample X to the primary protection 1 And said primary protection uncleared fault sample X 2 Performing dimensionality reduction to obtain Y 1 And Y 2 And the dimensionality reduction change is as follows:
Y i ＝α T X i
wherein i =1,2.
Optionally, the initiating a primary protection action: and controlling the adjacent circuit breakers to trip through the main protection.
Optionally, the initiating a backup protection action: controlling the tripping of its adjacent circuit breakers by said backup protection
The application provides a breaker fault backup protection method suitable for a high-voltage direct-current power grid, which is used for starting a main protection action when a high-voltage direct-current power grid fault occurs; sequentially collecting data samples according to a preset sampling interval; wherein the data samples include a system current and a voltage; determining a current threshold and a voltage threshold according to the system current and voltage; comparing a current threshold value, a voltage threshold value and a scalar value according to preset delay time, and judging whether the fault is cleared; when the fault is not cleared, starting backup protection; the method shortens the time of the high-voltage direct-current power grid for bearing low voltage and large current, thereby reducing the influence of faults on the system, further improving the safe operation level of the power grid, and ensuring the safe operation of the power grid by using an efficient and accurate protection scheme.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for backup protection of a fault of a circuit breaker in an embodiment of the present application, where the method is applied to a high-voltage dc power grid;
fig. 2 is a schematic action time diagram of a method for protecting a breaker failure backup suitable for a high-voltage direct-current power grid according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a protection scheme according to an embodiment of the present application;
FIG. 4 is a graph of the data distribution of cleared faults and uncleared faults for line AB of the embodiment of FIG. 3 of the present application;
fig. 5 is a schematic diagram illustrating an implementation effect of a method for backup protection of a fault of a circuit breaker, which is suitable for a high-voltage direct-current power grid according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all 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 application.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the accompanying drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be implemented in sequences other than those illustrated or described herein. Moreover, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The present application is described in further detail below with reference to the attached drawing figures:
the embodiment of the application provides a breaker fault backup protection method suitable for a high-voltage direct-current power grid, which is used for referring to fig. 1 when a fault of the high-voltage direct-current power grid occurs, and the method comprises the following steps:
and S100, starting a main protection action.
S200, sequentially collecting data samples according to a preset sampling interval; wherein the data samples comprise system current and voltage; the system currents and voltages in the data samples include: system current i when primary protection has cleared fault in data sample c And voltage u c (ii) a System current i when primary protection has not cleared fault in data sample uc And voltage u uc 。
Obtaining a primary protection cleared fault sample X 1 And primary protection uncleared fault sample X 2 ：
X 1 ＝{(i c (Δt),u c (Δt)),(i c (2Δt),u c (2Δt)),…,(i c (nΔt),u c (nΔt))}
X 2 ＝{(i uc (Δt),u uc (Δt)),(i uc (2Δt),u uc (2Δt)),…,(i uc (nΔt),u uc (nΔt))}
Where Δ t is a predetermined sampling interval, i c And u c For the system current and voltage at which the primary protection has cleared the fault in the data sample i uc And u uc The system current and voltage at which the fault is not cleared for the primary protection in the data sample.
Obtaining a definition matrix M i And a variability parameter α:
in the formula (I), the compound is shown in the specification,
is X i I =1,2; m is a group of s ＝M 1 +M 2 。
Clear fault sample X to the primary protection 1 And said primary protection uncleared fault sample X 2 Obtaining Y after dimension reduction and change 1 And Y 2 And the dimensionality reduction change is as follows:
Y i ＝α T X i
wherein i =1,2.
And S300, determining a current threshold and a voltage threshold according to the system current and the system voltage.
S400, comparing a current threshold value, a voltage threshold value and a scalar value according to preset delay time, and judging whether the fault is cleared; the current threshold and the voltage threshold are determined by a linear discriminant analysis method that:
wherein the content of the first and second substances,
in the formula i Threshold value Is a current threshold value u Threshold value Is a voltage threshold value, alpha is a differentiation parameter>
And
for cleared fault sample X 1 And primary protection uncleared fault sample X 2 Reduced dimension changed Y 1 And Y 2 The final sample of (1).
And S500, starting backup protection when the fault is not cleared.
And controlling the adjacent circuit breakers to trip through the main protection. And controlling the adjacent circuit breakers to trip through the backup protection.
As shown in FIG. 2, t f Indicating the start time of the fault, the main protection at t d And detecting that a fault occurs at any moment. The current protection method is through the main protection breaker at t o The moment is normal, then t c The fault is cleared by the primary protection at that time. If the primary protection breaker fails, backup protection will be at t' d Detecting a fault t 'without clearing of main protection at all times' o The circuit breakers adjacent to each other at time point are operated and finally at t' c The fault is cleared all of the time. The backup protection method proposed by the application is at t o Then, the fault of which the main protection is not cleared begins to be detected, so that the fault detection time is shortened, t br Representing the minimum time required between primary protection fault detection and backup protection actions.
As shown in fig. 3, to explain in detail, when a fault occurs on the line AB, first the main protection is started
Act to send a trip signal to the circuit breaker at A and start a timer and backup protection->
Is added with a delay time t Δ . Then judging whether the fault is cleared or not, if so, enabling the main protection action to be effective; otherwise the primary protection fails. Then backup protection->
By using electric current and electricityThe voltage measurement value is used to distinguish the cleared fault from the uncleared fault, and the current threshold value, the voltage threshold value and the scalar value are compared according to the preset delay time through step S400 to judge whether the fault is cleared. The profile of the fault cleared and fault uncleared data for line AB is shown in fig. 4. If the fault is not yet cleared, the circuit breakers at C and D trip, thereby blocking the effects of fault current from other parts of the system.
According to the method for protecting the circuit breaker fault backup suitable for the high-voltage direct-current power grid, the effect schematic diagram shown in the figure 5 is obtained by using the method for determining the voltage threshold and the current threshold. According to the method and the device, the fault detection time is shortened, the risk of damage of the power electronic element is reduced, and the reliability and effectiveness of the high-voltage direct-current power grid protection system can be effectively improved.
The application provides a breaker fault backup protection method suitable for a high-voltage direct-current power grid, which is used for starting a main protection action when a fault of the high-voltage direct-current power grid occurs; sequentially collecting data samples according to a preset sampling interval; wherein the data samples include a system current and a voltage; determining a current threshold and a voltage threshold according to the system current and voltage; comparing a current threshold value, a voltage threshold value and a scalar value according to preset delay time, and judging whether the fault is cleared; when the fault is not cleared, starting backup protection; the method shortens the time of the high-voltage direct-current power grid for bearing low voltage and large current, thereby reducing the influence of faults on the system, further improving the safe operation level of the power grid, and ensuring the safe operation of the power grid by using an efficient and accurate protection scheme.
The above contents are only for illustrating the technical idea of the present application, and the protection scope of the present application is not limited thereby, and any modification made on the basis of the technical idea presented in the present application falls within the protection scope of the claims of the present application.
Additionally, the order in which elements and sequences of the processes described herein are processed, the use of alphanumeric characters, or the use of other designations, is not intended to limit the order of the processes and methods described herein, unless explicitly claimed. While various presently contemplated embodiments have been discussed in the foregoing disclosure by way of example, it should be understood that such detail is solely for that purpose and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover all modifications and equivalent arrangements that are within the spirit and scope of the embodiments herein. For example, although the system components described above may be implemented by hardware devices, they may also be implemented by software-only solutions, such as installing the described system on an existing server or mobile device.
Similarly, it should be noted that in the preceding description of embodiments of the application, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the embodiments. This method of disclosure, however, is not intended to require more features than are expressly recited in the claims. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.
Each patent, patent application publication, and other material, such as articles, books, specifications, publications, documents, and the like, cited in this application is hereby incorporated by reference in its entirety. Except where the application is filed in a manner inconsistent or contrary to the present disclosure, and except where the claim is filed in its broadest scope (whether present or later appended to the application) as well. It is noted that the descriptions, definitions and/or use of terms in this application shall control if they are inconsistent or contrary to the statements and/or uses of the present application in the material attached to this application.
Claims (4)
1. A breaker fault backup protection method suitable for a high-voltage direct-current power grid is used when a fault of the high-voltage direct-current power grid occurs, and the method comprises the following steps:
starting a main protection action;
sequentially collecting data samples according to a preset sampling interval; wherein the data samples include a system current and a voltage;
determining a current threshold and a voltage threshold according to the system current and voltage;
comparing the current threshold value, the voltage threshold value and the scalar value according to the preset delay time, and judging whether the fault is cleared;
when the fault is not cleared, starting backup protection;
wherein the current threshold and the voltage threshold are determined by a linear discriminant analysis method that:
wherein, the first and the second end of the pipe are connected with each other,
in the formula (I), the reaction is carried out,
as a result of the current threshold value,
in order to be the voltage threshold value of the voltage,
in order to be a difference parameter,
and
cleared fault samples for primary protection
And primary protection uncleared fault samples
After the dimensionality reduction is changed
And
the final sample of (a);
wherein the obtaining of the final sample comprises:
obtaining the primary protection cleared fault sample
And primary protection uncleared fault samples
：
In the formula (I), the compound is shown in the specification,
is a pre-set sampling interval of time,
and
for the system current and voltage in the data sample at which the primary protection has cleared the fault,
and
the system current and voltage when the main protection has not cleared the fault in the data sample;
obtaining a definition matrix
And a difference parameter
：
In the formula (I), the compound is shown in the specification,
is composed of
The average value of (a) of (b),
；
；
clear fault samples to the primary protection
And the primary protection uncleared fault sample
Is subjected to dimensionality reduction to obtain
And
and the dimensionality reduction change is as follows:
in the formula (I), the compound is shown in the specification,
。
2. the method of claim 1, wherein the system current and voltage in the data samples comprise:
system current when primary protection has cleared fault in data sample
And voltage
；
System current when primary protection has not cleared fault in data sample
And voltage
。
3. The method for fault backup protection of a circuit breaker applied to a high-voltage direct-current power grid according to claim 1, wherein the initiating of the main protection action comprises:
and controlling the adjacent circuit breakers to trip through the main protection.
4. The method for fault backup protection of a circuit breaker applied to a high-voltage direct-current power grid according to claim 1, wherein the starting backup protection action comprises:
and controlling the adjacent circuit breakers to trip through the backup protection.
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2020
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