Fault point determination method, electronic equipment and computer readable storage medium

Abstract

The invention relates to the technical field of power system relay protection, in particular to a fault point determination method, electronic equipment and a computer readable storage medium, and the method comprises the steps: obtaining multi-phase voltages and multi-phase currents corresponding to a multi-phase line, and enabling the multi-phase voltages, the multi-phase currents and the multi-phase line to be in one-to-one correspondence; and according to the multi-phase current, determining a multi-phase negative sequence current. According to the multi-phase negative sequence current, the multi-phase current, the multi-phase voltage and the line distance, multiple fault distances are determined, the multiple fault distances are in one-to-one correspondence with the multi-phase lines, and the line distance is used for representing the corresponding length of the multi-phase lines. According to the multiple fault distances and the line distance, a fault point and the distance between the fault point and the line protection device are determined and are in positive correlation with a first fault distance, and the first fault distance is the distance corresponding to the fault line in the multiple fault distances. According to the invention, the fault point can be accurately positioned, a maintainer can conveniently determine the fault position, the fault maintenance time is shortened, and the operation stability of the new energy transmission line is improved.

Description

Technical Field

[0001] This application relates to the technical field of power system relay protection, and particularly to a fault point determination method, an electronic device, and a computer-readable storage medium. Background Art

[0002] In the field of power system relay protection, distance protection is an important protection method, and distance protection realizes fault detection by measuring voltage and current in the power system. The single-ended fault location method is a fault location technology based on the principle of distance protection, and can realize fault distance measurement through the voltage and current of the line.

[0003] In the traditional technical solution, when a single-phase grounding fault occurs on the line, the line protection device can calculate the measured impedance through the collected voltage and current. And according to the proportional relationship between the measured impedance and the line impedance, the position of the fault point is determined, so as to realize the location of the fault point.

[0004] However, when a single-phase grounding fault occurs on the line, there is usually a transition resistance at the fault point. The measured impedance calculated by the line protection device according to the collected voltage and current is inaccurate, resulting in an inaccurate position of the fault point determined by the line protection device. Summary of the Invention

[0005] This application provides a fault point determination method, device, electronic device, and computer-readable storage medium. It can accurately locate the fault point, facilitate the maintenance personnel to determine the fault location, shorten the fault maintenance time, and improve the operation stability of the new energy transmission line.

[0006] In a first aspect, this application provides a fault point determination method, which is applied to a line protection device for monitoring the line state of a multi-phase line. The method includes: obtaining multi-phase voltages and multi-phase currents corresponding to the multi-phase line, where the multi-phase voltages, multi-phase currents, and multi-phase line correspond one by one. Determining multi-phase negative sequence currents according to the multi-phase currents, where the multi-phase negative sequence currents correspond to the multi-phase currents one by one. Determining multiple fault distances according to the multi-phase negative sequence currents, multi-phase currents, multi-phase voltages, and line distance, where the multiple fault distances correspond to the multi-phase line one by one, and the line distance is used to represent the length corresponding to the multi-phase line. Determining the fault point according to the multiple fault distances and the line distance, where the distance between the fault point and the line protection device is positively correlated with the first fault distance, and the first fault distance is the distance corresponding to the fault line among the multiple fault distances.

[0007] In some embodiments, determining a plurality of fault distances according to polyphase negative sequence current, polyphase current, polyphase voltage, and line distance includes: determining a plurality of real parts of voltage and a plurality of imaginary parts of voltage according to the polyphase negative sequence current, where the plurality of real parts of voltage are the real parts of voltage corresponding to the polyphase fault point voltage, the plurality of imaginary parts of voltage are the imaginary parts of voltage corresponding to the polyphase fault point voltage, and the angular values of the plurality of voltage angles corresponding to the polyphase fault point voltage are the same as the angular values of the plurality of current angles corresponding to the polyphase negative sequence current. Determining the plurality of fault distances according to the plurality of real parts of voltage, the plurality of imaginary parts of voltage, the polyphase current, the polyphase voltage, and the line distance.

[0008] In some embodiments, determining a plurality of fault distances according to the plurality of real parts of voltage, the plurality of imaginary parts of voltage, the polyphase current, the polyphase voltage, and the line distance includes: obtaining a preset positive sequence impedance and a preset zero sequence impedance, where the preset positive sequence impedance is the positive sequence impedance corresponding to the line distance, and the preset zero sequence impedance is the zero sequence impedance corresponding to the line distance. Determining the ratio of the difference between the preset zero sequence impedance and the preset positive sequence impedance to three times the preset positive sequence impedance as the zero sequence compensation coefficient. Determining the plurality of fault distances according to the preset positive sequence impedance, the zero sequence compensation coefficient, the plurality of real parts of voltage, the plurality of imaginary parts of voltage, the polyphase current, the polyphase voltage, and the line distance.

[0009] In some embodiments, determining a plurality of fault distances according to the preset positive sequence impedance, the zero sequence compensation coefficient, the plurality of real parts of voltage, the plurality of imaginary parts of voltage, the polyphase current, the polyphase voltage, and the line distance includes: determining the sum of the polyphase currents as the zero sequence current. Determining the plurality of fault distances according to the zero sequence current, the preset positive sequence impedance, the zero sequence compensation coefficient, the plurality of real parts of voltage, the plurality of imaginary parts of voltage, the polyphase current, the polyphase voltage, and the line distance.

[0010] In some embodiments, the above method further includes: when detecting that the current device state is the startup state, recording the current moment as the first moment.

[0011] In some embodiments, determining a fault point according to the plurality of fault distances and the line distance includes: continuously obtaining multiple groups of fault distances within a first preset time period, where the starting moment of the first preset time period is the second moment, the second moment is after the first moment and is the moment separated from the first moment by a second preset time period. Determining a plurality of average distances according to the multiple groups of fault distances, and the average distances correspond to the polyphase lines one by one. If the first average distance is greater than or equal to 0 and less than the line distance, and all the multiple second average distances are greater than or equal to the line distance or less than 0, then determining the line point corresponding to the first average distance in the first line as the fault point, where the first line is the polyphase line corresponding to the first average distance, the first average distance is one of the multiple average distances, and the multiple second average distances are the average distances different from the first average distance among the multiple average distances.

[0012] In some embodiments, the first set of fault distances includes at least a first fault distance corresponding to a first-phase line, a second fault distance corresponding to a second-phase line, and a third fault distance corresponding to a third-phase line. The first-phase line, the second-phase line, and the third-phase line are lines in a multi-phase line, and the first set of fault distances is any one of multiple sets of fault distances.

[0013] In some embodiments, the multiple average distances include at least an average first fault distance, an average second fault distance, and an average third fault distance. The average first fault distance is the mean of multiple first fault distances, the average second fault distance is the mean of multiple second fault distances, and the average third fault distance is the mean of multiple third fault distances. The first average distance is one of the average first fault distance, the average second fault distance, and the average third fault distance.

[0014] In a second aspect, the present application provides a fault point determination device. The fault point determination device may be a line protection device, and the line protection device is used to monitor the line state of a multi-phase line. The fault point determination device includes: an acquisition module and a calculation module.

[0015] The acquisition module is used to acquire the multi-phase voltage and multi-phase current corresponding to the multi-phase line, and the multi-phase voltage, the multi-phase current, and the multi-phase line all correspond one by one.

[0016] The calculation module is used to determine the multi-phase negative sequence current according to the multi-phase current, and the multi-phase negative sequence current corresponds to the multi-phase current one by one.

[0017] The calculation module is further used to determine multiple fault distances according to the multi-phase negative sequence current, the multi-phase current, the multi-phase voltage, and the line distance. The multiple fault distances correspond to the multi-phase line one by one, and the line distance is used to represent the length corresponding to the multi-phase line.

[0018] The calculation module is further used to determine the fault point according to the multiple fault distances and the line distance. The distance between the fault point and the line protection device is positively correlated with the first fault distance, and the first fault distance is the distance corresponding to the faulty line among the multiple fault distances.

[0019] In a third aspect, the present application provides an electronic device, including a processor and a memory. The processor is used to execute a computer program stored in the memory to implement the method in any one of the above first aspects.

[0020] In a fourth aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements the method in any one of the above first aspects.

[0021] In the technical solution provided by this application, a line protection device can obtain polyphase voltages and polyphase currents corresponding to a polyphase line, and the polyphase voltages, polyphase currents, and polyphase line all correspond one by one. Then, according to the polyphase currents, polyphase negative-sequence currents are determined, and the polyphase negative-sequence currents correspond to the polyphase currents one by one. Next, according to the polyphase negative-sequence currents, polyphase currents, polyphase voltages, and line distances, multiple fault distances are determined, and the multiple fault distances correspond to the polyphase line one by one. The line distance is used to represent the length corresponding to the polyphase line. Finally, according to the multiple fault distances and the line distance, a fault point is determined. The distance between the fault point and the line protection device is positively correlated with the first fault distance, and the first fault distance is the distance corresponding to the faulty line among the multiple fault distances. The technical solution provided by the embodiments of this application can accurately locate the fault point, facilitate maintenance personnel to determine the fault location, shorten the fault repair time, and improve the operation stability of the new energy transmission line. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 FIG. is a schematic diagram of an application scenario of a fault point determination method provided by an embodiment of this application;

[0024] Figure 2 FIG. is a schematic flowchart of a fault point determination method provided by an embodiment of this application;

[0025] Figure 3 FIG. is another schematic flowchart of a fault point determination method provided by an embodiment of this application;

[0026] Figure 4 FIG. is a schematic diagram of the fault distance of a fault point determination method provided by an embodiment of this application passing through a 0.01 Ω transition resistance;

[0027] Figure 5 FIG. is a schematic diagram of the fault distance of a fault point determination method provided by an embodiment of this application passing through a 100 Ω transition resistance;

[0028] Figure 6 FIG. is a schematic diagram of a fault point determination device provided by an embodiment of this application;

[0029] Figure 7 FIG. is a schematic diagram of an electronic device provided by an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from obscuring the description of the present application.

[0031] It should be understood that when used in the specification and appended claims of the present application, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0032] It should also be understood that the term "and / or" as used in the specification and appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0033] As used in the specification and appended claims of the present application, the term "if" can be interpreted as "when", "once", "in response to determining", or "in response to detecting" depending on the context. Similarly, the phrase "if determined" or "if [the described condition or event] is detected" can be interpreted as meaning "once determined", "in response to determining", "once [the described condition or event] is detected", or "in response to detecting [the described condition or event]" depending on the context.

[0034] In addition, in the description of the specification and appended claims of the present application, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0035] The reference to "one embodiment" or "some embodiments" etc. described in the specification of the present application means that a specific feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. The terms "comprising", "including", "having", and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way.

[0036] The new energy transmission line refers to the transmission line from a new energy power station (such as a photovoltaic power station, a wind farm, etc.) to a substation. Its main function is to transmit the electricity generated by the new energy power station to the power grid for users in other regions. When a fault occurs in the line (the new energy transmission line), maintenance personnel can determine the fault point through line fault location methods. There are two common fault location methods: one is the double-end fault location method through optical fiber differential protection, and the other is the single-end fault location method through distance protection.

[0037] Among them, the double-end fault location method through optical fiber differential protection usually transmits and exchanges signals through optical fibers. When a fault occurs in the optical fiber channel, the line protection devices cannot transmit and exchange signals through optical fibers. And the double-end fault location method through optical fiber differential protection is usually used in voltage levels of 110 kV and above. Since the new energy transmission line usually uses a 35 kV low-voltage line to transmit electric energy to the power grid. Therefore, the new energy transmission line usually does not configure the optical fiber differential protection function.

[0038] In the application process of the single-end fault location method through distance protection, when a fault occurs in the line, affected by the transition resistance, the measured impedance calculated by the line protection device based on the collected voltage and current is inaccurate. Figure 1 This is a schematic diagram of an application scenario provided by an embodiment of the present application. As Figure 1 shown, the new energy transmission line can be an inverter-type new energy transmission line, and line protection devices can be installed on the new energy side and the grid side of the new energy transmission line respectively. When a fault occurs at point F1, there will be a transition resistance R f , and the current flow directions are as shown by I f and I 2 shown. The fault distance calculated by the line protection device through voltage and current will also have an error, resulting in an inaccurate fault point position determined by the line protection device. The maintenance personnel cannot determine the accurate fault position, the maintenance time will be extended, and there are potential safety hazards in the operation stability of the new energy transmission line.

[0039] In view of this, an embodiment of the present application provides a fault point location method, an electronic device, and a computer-readable storage medium, which can accurately locate the fault point, facilitate the maintenance personnel to determine the fault position, shorten the fault maintenance time, and improve the operation stability of the new energy transmission line.

[0040] The technical solutions of the embodiments of the present application will be described below with reference to the examples in the drawings.

[0041] The technical solutions provided by the embodiments of the present application can be applied to the line protection device on the grid side of the inverter-type new energy transmission line.

[0042] Figure 2A schematic flow chart provided by an embodiment of the present application. The process for the line protection device to determine the fault point may include the following steps:

[0043] Step S201: Obtain the polyphase voltage and polyphase current corresponding to the polyphase line.

[0044] In the embodiment of the present application, the polyphase line may be a three-phase line. For example, the polyphase lines may be the A-phase line, the B-phase line, and the C-phase line respectively. The polyphase voltage may be: the voltage of the A-phase line, the voltage of the B-phase line, and the voltage of the C-phase line, respectively represented as: U A 、U B and U C . The polyphase current may be: the current flowing through the A-phase line, the current flowing through the B-phase line, and the current flowing through the C-phase line, respectively represented as: I A 、I B and I C .

[0045] The line protection device may obtain the polyphase current corresponding to the polyphase line through multiple CTs (Current Transformers). Obtain the polyphase voltage corresponding to the polyphase line through multiple PTs (Potential Transformers).

[0046] In some embodiments, the line protection device may also calculate the polyphase voltage and polyphase current through the full-cycle Fourier transform method. The present application does not limit the acquisition methods of the polyphase current and polyphase voltage.

[0047] Step S202: Determine the polyphase negative-sequence current according to the polyphase current.

[0048] In the embodiment of the present application, the line protection device may calculate the polyphase negative-sequence current through the following formula:

[0049] I 2a =I A +I B / a+I C ·a;

[0050] I 2b =I A ·a+I B +I C / a;

[0051] I 2c =I A / a+I B ·a+I C ;

[0052] Among them, I 2a represents the negative-sequence current corresponding to the A-phase line, I2b represents the negative-sequence current corresponding to the B-phase line, I 2c represents the negative-sequence current corresponding to the C-phase line. a represents a complex number, which can be a = -0.5 + 0.886, and j represents the imaginary unit.

[0053] Step S203: Determine multiple real parts of voltage and multiple imaginary parts of voltage according to the polyphase negative-sequence current.

[0054] When the line protection device detects that the current device state is the startup state, it can record the current moment as the first moment and use the angle of the polyphase negative-sequence current as the angle of the polyphase fault point voltage at the virtual fault point.

[0055] In the embodiment of the present application, when a single-phase grounding fault occurs in the line, the positive-sequence network, negative-sequence network, and zero-sequence network of the power system are equivalent to a series relationship in the equivalent composite sequence power grid. When a fault occurs in the grid-connected outgoing line, the inverter-type new energy outgoing line will adopt a control strategy of suppressing negative-sequence current, and the negative-sequence current generated by the fault will flow to the grid side. Then, the line protection device installed on the grid side can collect all the negative-sequence current. Therefore, the negative-sequence current collected by the line protection device installed on the grid side can be equivalent to the fault zero-sequence current. And the transition resistance of the single-phase grounding is a resistor, and the voltage across the resistor is in phase with the flowing current. Therefore, the line protection device can use the angle of the polyphase negative-sequence current as the angle of the polyphase fault point voltage at the virtual fault point.

[0056] The calculation formulas for the multiple real parts of voltage corresponding to the polyphase fault point voltage can be respectively:

[0057] U FAR = Acosθ A ;

[0058] U FBR = Acosθ B ;

[0059] U FCR = Acosθ C ;

[0060] where, U FAR 、U FBR and U FCR are respectively used to represent the real part of the voltage of the fault point voltage corresponding to the A-phase line, the real part of the voltage of the fault point voltage corresponding to the B-phase line, and the real part of the voltage of the fault point voltage corresponding to the C-phase line. A is used to represent the effective value of the fault point voltage. θ A 、θ B 、θ C respectively represent the angle of the A-phase negative-sequence current, the angle of the B-phase negative-sequence current, and the angle of the C-phase negative-sequence current.

[0061] The calculation formulas for the multiple voltage imaginary parts corresponding to the polyphase fault point voltages can be respectively as follows:

[0062] U FAX = Asinθ A ;

[0063] U FBX = Asinθ B ;

[0064] U FCX = Asinθ C ;

[0065] Among them, U FAX , U FBX and U FCX are respectively used to represent the voltage imaginary part of the fault point voltage corresponding to the A-phase line, the voltage imaginary part of the fault point voltage corresponding to the B-phase line, and the voltage imaginary part of the fault point voltage corresponding to the C-phase line. A is used to represent the effective value of the fault point voltage.

[0066] For example, when a fault occurs at 40 km of the A-phase line, the polyphase currents corresponding to the A-phase line, B-phase line, and C-phase line are 5.433 A∠0°, 0.079 A∠55.8°, and 0.081 A∠77.4° respectively. The line protection device calculates the polyphase negative sequence currents corresponding to the A-phase line, B-phase line, and C-phase line based on the polyphase currents as follows: 5.391 A∠-1°, 5.391 A∠119°, 5.391 A∠239°. Then the multiple voltage real parts corresponding to the polyphase fault point voltages are respectively: U FAR = Acos(-1°), U FBR = Acos(119°), and U FCR = Acos(239°). The multiple voltage imaginary parts corresponding to the polyphase fault point voltages are respectively: U FAX = Asin(-1°), U FBX = Asin(119°), and U FCX = Asin(239°).

[0067] Step S204: Determine the zero-sequence current according to the polyphase current.

[0068] In the embodiment of the present application, the line protection device can calculate the zero-sequence current through the following formula:

[0069] 3I 0 = I A + I B + I C ;

[0070] Among them, I A , I B and I Crespectively represent the currents corresponding to the A-phase line, B-phase line, and C-phase line.

[0071] Step S205: Obtain the preset positive-sequence impedance and preset zero-sequence impedance.

[0072] In the embodiment of the present application, the line protection device can obtain the line distance (the full length of the line L), the preset positive-sequence impedance (the full-length positive-sequence impedance of the line), and the preset zero-sequence impedance (the full-length zero-sequence impedance of the line).

[0073] Step S206: Determine the zero-sequence compensation coefficient according to the preset positive-sequence impedance and the preset zero-sequence impedance.

[0074] In the embodiment of the present application, the calculation formula of the zero-sequence compensation coefficient can be:

[0075]

[0076] where Z 0 represents the preset zero-sequence impedance, and Z 1 represents the preset positive-sequence impedance.

[0077] For example, when the line distance is 80 km, the preset positive-sequence impedance corresponding to this line distance is 5.615 Ω∠85.8°, the preset zero-sequence impedance corresponding to this line distance is 17.02 Ω∠76°, and the zero-sequence compensation coefficient

[0078] Step S207: Determine a plurality of fault distances according to the zero-sequence current, the preset positive-sequence impedance, the zero-sequence compensation coefficient, the plurality of real parts of the voltage, the plurality of imaginary parts of the voltage, the polyphase current, the polyphase voltage, and the line distance.

[0079] In the embodiment of the present application, the line protection device can construct a calculation formula for calculating a plurality of fault distances according to the preset zero-sequence impedance, the preset positive-sequence impedance, the line distance, the polyphase voltage, and the polyphase current. Among them, the calculation formula for the fault distance corresponding to the A-phase line is:

[0080]

[0081] where U A represents the voltage corresponding to the A-phase line, I A represents the current corresponding to the A-phase line, K r represents the zero-sequence compensation coefficient, 3I 0 represents the zero-sequence current. Z 1 represents the preset positive-sequence impedance, X A represents the fault distance corresponding to the A-phase line, L represents the line distance, and U FA represents the fault point voltage corresponding to the A-phase line. The fault point voltage U FA, can be expressed as the real part of the voltage U of the fault point corresponding to the A-phase line FAR + the imaginary part of the voltage U of the fault point corresponding to the A-phase line FAX , the product with the imaginary unit j.

[0082] The calculation formula for the fault distance corresponding to the B-phase line is:

[0083]

[0084] Among them, U B represents the voltage corresponding to the B-phase line, I B represents the current corresponding to the B-phase line, X B represents the fault distance corresponding to the B-phase line, U FB represents the voltage of the fault point corresponding to the B-phase line. The voltage U of the fault point corresponding to the B-phase line FB , can be expressed as the real part of the voltage U of the fault point corresponding to the B-phase line FBR + the imaginary part of the voltage U of the fault point corresponding to the B-phase line FBX , the product with the imaginary unit j.

[0085] The calculation formula for the fault distance corresponding to the C-phase line is:

[0086]

[0087] Among them, U C represents the voltage corresponding to the C-phase line, I C represents the current corresponding to the C-phase line, X C represents the fault distance corresponding to the C-phase line, U FC represents the voltage of the fault point corresponding to the C-phase line. The voltage U of the fault point corresponding to the C-phase line FC , can be expressed as the real part of the voltage U of the fault point corresponding to the C-phase line FCR + the imaginary part of the voltage U of the fault point corresponding to the C-phase line FCX , the product with the imaginary unit j.

[0088] The line protection device can calculate the fault distances corresponding to the A-phase line, B-phase line, and C-phase line respectively according to multiple calculation formulas for the fault distances.

[0089] Exemplarily, the method for the line protection device to calculate the fault distance corresponding to the A-phase line according to the calculation formula for the fault distance corresponding to the A-phase line can be:

[0090] According to

[0091] It can be known that

[0092] Then there is

[0093] Among them, (I A +K r ·3I 0 )·Z 1 =I AR +jI AX . U AR and U AX respectively represent the real part and the imaginary part of the voltage U A , that is, U AR +jU AX =U A .

[0094] It can be obtained that:

[0095]

[0096] Combined, it can be obtained that:

[0097] It can be known that the fault distance corresponding to the A-phase line is:

[0098] In the embodiment of the present application, the line protection device can also determine the fault distance corresponding to the B-phase line and the fault distance corresponding to the C-phase line according to the above method, which are respectively:

[0099]

[0100] For example, the line protection device can determine I A +K r ·3I 0 )·Z 1 =I AR +jI AX , and determine that I AR and I AX are 8.854 and 50.212 respectively, and then substitute the line distance L = 80km and the A-phase voltage U A =4.096 + j25.288 into the expression It can be obtained that It can be known that the fault distance corresponding to the A-phase line is 40.28km.

[0101] Step S208: Continuously obtain multiple groups of fault distances within the first preset time period.

[0102] In the embodiment of the present application, the starting moment of the first preset time period can be the second moment, and the second moment is the moment after the first moment and at an interval of the second preset time period from the first moment.

[0103] Exemplarily, the line protection device can set a first preset time period according to the actual application scenario. For example, the first preset time period can be set to 5 ms.

[0104] The line protection device can set the duration of the second preset time period according to the calculation time period of the full-cycle Fourier transform. For example, the line protection device can set the duration of the second preset time period to one cycle wave of 20 ms of the calculation time of the full-cycle Fourier transform. It can reduce the error caused by the calculation time window of the full-cycle Fourier transform being less than one cycle wave during the fault transient period, thereby improving the accuracy of the calculation result.

[0105] The line protection device can collect polyphase current and polyphase voltage at a preset sampling frequency within the first preset time period. Multiple sets of fault distances are calculated based on the polyphase current and polyphase voltage. For any one of the multiple sets of fault distances (such as the first set of fault distances), the first set of fault distances at least includes a first fault distance corresponding to the first-phase line, a second fault distance corresponding to the second-phase line, and a third fault distance corresponding to the third-phase line. The first-phase line, the second-phase line, and the third-phase line are lines in the polyphase line.

[0106] For example, when the polyphase lines are the A-phase line, the B-phase line, and the C-phase line respectively, the first set of fault distances includes the A-phase fault distance, the B-phase fault distance, and the C-phase fault distance. The multiple sets of fault distances include multiple A-phase fault distances, multiple B-phase fault distances, and multiple C-phase fault distances.

[0107] Step S209: Determine multiple average distances according to the multiple sets of fault distances, and the average distances correspond to the polyphase lines one by one.

[0108] The multiple average distances at least include an average first fault distance, an average second fault distance, and an average third fault distance. The average first fault distance is the mean value of the multiple first fault distances, the average second fault distance is the mean value of the multiple second fault distances, and the average third fault distance is the mean value of the multiple third fault distances.

[0109] For example, when the multiple sets of fault distances include multiple A-phase fault distances, multiple B-phase fault distances, and multiple C-phase fault distances, the average first fault distance is the mean value of the multiple A-phase fault distances, the average second fault distance is the mean value of the multiple B-phase fault distances, and the average third fault distance is the mean value of the multiple C-phase fault distances.

[0110] The line protection device determines multiple average distances according to the multiple sets of fault distances within the first preset time period, and determines the fault point according to the multiple average distances, which can avoid the influence of single calculation error on the fault point discrimination result, thereby improving the accuracy of the fault point discrimination result and further improving the stability of line operation.

[0111] Step S2010: If the first average distance is greater than or equal to 0 and less than the line distance, and multiple second average distances are all greater than or equal to the line distance or less than 0, then determine that the line point corresponding to the first average distance in the first line is the fault point.

[0112] The first line is the line corresponding to the first average distance among the polyphase lines. The first average distance is one of the multiple average distances, and the multiple second average distances are the average distances different from the first average distance among the multiple average distances.

[0113] Exemplarily, the first average distance is one of the average first fault distance, average second fault distance, and average third fault distance.

[0114] For example, if the line distance is 80 km, and the multiple average distances corresponding to the A-phase line, B-phase line, and C-phase line are 40.28 km, 80 km, and 80 km respectively, then the line protection device can determine that the line point 40.28 km away from the line protection device in the A-phase line is the fault point.

[0115] In the technical solution provided by the embodiment of the present application, the line protection device can obtain polyphase voltages and polyphase currents corresponding to the polyphase lines, and the polyphase voltages, polyphase currents, and polyphase lines correspond one by one. And determine polyphase negative sequence currents according to the polyphase currents, and the polyphase negative sequence currents correspond to the polyphase currents one by one. Then determine multiple fault distances according to the polyphase negative sequence currents, polyphase currents, polyphase voltages, and the line distance, and the multiple fault distances correspond to the polyphase lines one by one. The line distance is used to represent the length corresponding to the polyphase line. Finally, determine the fault point according to the multiple fault distances and the line distance. The distance between the fault point and the line protection device is positively correlated with the first fault distance, and the first fault distance is the distance corresponding to the faulty line among the multiple fault distances. The technical solution provided by the embodiment of the present application can accurately locate the fault point, facilitate the maintenance personnel to determine the fault location, shorten the fault maintenance time, and improve the operation stability of the new energy transmission line.

[0116] According to the technical solution provided in the above steps S201 to S2010, the embodiment of the present application provides a flowchart of another method for determining a fault point, as Figure 3 shown, including the following steps:

[0117] Step S301: Obtain polyphase voltages and polyphase currents corresponding to the polyphase lines, and the polyphase voltages, polyphase currents, and polyphase lines correspond one by one.

[0118] The line protection device can obtain the polyphase voltages and polyphase currents corresponding to the polyphase lines through the method in step S201 above, and the present application will not elaborate here.

[0119] Step S302: Determine polyphase negative-sequence currents based on the polyphase currents, where the polyphase negative-sequence currents correspond one-to-one to the polyphase currents.

[0120] The line protection device can determine the polyphase negative-sequence currents through the method in step S202 above, which is not elaborated herein in this application.

[0121] Step S303: Determine multiple fault distances based on the polyphase negative-sequence currents, polyphase currents, polyphase voltages, and line distances, where the multiple fault distances correspond one-to-one to the polyphase lines, and the line distance is used to characterize the length corresponding to the polyphase line.

[0122] The line protection device can determine the multiple fault distances through the methods in steps S203 to S207 above, which is not elaborated herein in this application.

[0123] Step S304: Determine the fault point based on the multiple fault distances and the line distance. The distance between the fault point and the line protection device is positively correlated with the first fault distance. The first fault distance is the distance corresponding to the faulty line among the multiple fault distances.

[0124] The line protection device can determine the fault point through the methods in steps S208 to S2010 above, which is not elaborated herein in this application.

[0125] Exemplarily, through the technical solutions provided in steps S301 to S303 above, the line protection device calculates the distance of the position point corresponding to the A-phase line at 40 km from the line protection device with a fault through a 0.01 Ω transition resistance as Figure 4 shown. It can be seen that within the 20 ms time period after the line protection device starts, for the fault distance corresponding to the A-phase line at 40 km from the line protection device, due to the calculation time window of the full-cycle Fourier transform being less than one cycle, the fault distance fluctuates greatly. After the calculation time window reaches one cycle, the fault distance stabilizes at 40 km.

[0126] Through the technical solutions provided in steps S301 to S303 above, the line protection device calculates the distance of the position point corresponding to the A-phase line at 40 km from the line protection device with a fault through a 100 Ω transition resistance as Figure 5 shown. It can be seen that within the 20 ms time period after the line protection device starts, for the fault distance corresponding to the A-phase line at 40 km from the line protection device, due to the calculation time window of the full-cycle Fourier transform being less than one cycle, the fault distance fluctuates greatly. After the calculation time window reaches one cycle, the fault distance stabilizes at 40 km.

[0127] It can be known that the accuracy rate of the calculation result of the fault distance provided by this application is not affected by the magnitude of the transition resistance at the fault point.

[0128] It should be understood that, on the premise of no logical conflict, the above-mentioned application embodiments can be combined and implemented with each other to meet the actual application requirements. The specific embodiments or implementation schemes obtained after these combinations still fall within the protection scope of the present application.

[0129] Corresponding to the fault point determination method in the above embodiments, an embodiment of the present application provides a fault point determination device 60. The fault point determination device 60 can be a line protection device. The fault point determination device 60 can be implemented by software, hardware, or a combination of both to become part or all of a computer device, and is used to execute the steps in the fault point determination method in the above embodiments.

[0130] Figure 6 The structure diagram of a fault point determination device provided by an embodiment of the present application is shown. For the convenience of description, only the parts related to the embodiments of the present application are shown.

[0131] Referring to Figure 6 , the fault point determination device 60 includes an acquisition module 610 and a calculation module 620.

[0132] The acquisition module 610 is used to acquire polyphase voltages and polyphase currents corresponding to a polyphase line, and the polyphase voltages, polyphase currents, and polyphase lines correspond to each other one by one.

[0133] The calculation module 620 is used to determine polyphase negative sequence currents according to the polyphase currents, and the polyphase negative sequence currents correspond to the polyphase currents one by one.

[0134] The calculation module 620 is further used to determine a plurality of fault distances according to the polyphase negative sequence currents, polyphase currents, polyphase voltages, and line distances. The plurality of fault distances correspond to the polyphase lines one by one, and the line distance is used to represent the length corresponding to the polyphase line.

[0135] The calculation module 620 is further used to determine a fault point according to the plurality of fault distances and the line distance. The distance between the fault point and the line protection device is positively correlated with the first fault distance, and the first fault distance is the distance corresponding to the faulty line among the plurality of fault distances.

[0136] In some embodiments, the calculation module 620 is specifically used to: determine a plurality of voltage real parts and a plurality of voltage imaginary parts according to the polyphase negative sequence currents. The plurality of voltage real parts are the plurality of voltage real parts corresponding to the polyphase fault point voltages, and the plurality of voltage imaginary parts are the plurality of voltage imaginary parts corresponding to the polyphase fault point voltages. The angular values of the plurality of voltage angles corresponding to the polyphase fault point voltages are the same as the angular values of the plurality of current angles corresponding to the polyphase negative sequence currents. Determine a plurality of fault distances according to the plurality of voltage real parts, the plurality of voltage imaginary parts, the polyphase currents, the polyphase voltages, and the line distance.

[0137] In some embodiments, the calculation module 620 is specifically configured to: obtain a preset positive sequence impedance and a preset zero sequence impedance, where the preset positive sequence impedance is the positive sequence impedance corresponding to the line distance, and the preset zero sequence impedance is the zero sequence impedance corresponding to the line distance. Determine the ratio of the difference between the preset zero sequence impedance and the preset positive sequence impedance to three times the preset positive sequence impedance as the zero sequence compensation coefficient. Determine multiple fault distances according to the preset positive sequence impedance, the zero sequence compensation coefficient, multiple real parts of voltage, multiple imaginary parts of voltage, polyphase current, polyphase voltage, and line distance.

[0138] In some embodiments, the calculation module 620 is specifically configured to: determine the sum of polyphase currents as the zero sequence current. Determine multiple fault distances according to the zero sequence current, the preset positive sequence impedance, the zero sequence compensation coefficient, multiple real parts of voltage, multiple imaginary parts of voltage, polyphase current, polyphase voltage, and line distance.

[0139] In some embodiments, the calculation module 620 is further configured to: when detecting that the current device state is the startup state, record the current moment as the first moment.

[0140] In some embodiments, the calculation module 620 is specifically configured to: continuously obtain multiple sets of fault distances within a first preset time period, where the starting moment of the first preset time period is the second moment, and the second moment is after the first moment and is the moment separated from the first moment by a second preset time period. Determine multiple average distances according to the multiple sets of fault distances, and the average distances correspond to the polyphase lines one by one. If the first average distance is greater than or equal to 0 and less than the line distance, and multiple second average distances are all greater than or equal to the line distance or less than 0, then determine the line point corresponding to the first average distance in the first line as the fault point, where the first line is the line corresponding to the first average distance among the polyphase lines, the first average distance is one of the multiple average distances, and the multiple second average distances are the average distances different from the first average distance among the multiple average distances.

[0141] In some embodiments, the first set of fault distances includes at least a first fault distance corresponding to the first phase line, a second fault distance corresponding to the second phase line, and a third fault distance corresponding to the third phase line. The first phase line, the second phase line, and the third phase line are lines in the polyphase line, and the first set of fault distances is any one of the multiple sets of fault distances.

[0142] In some embodiments, the multiple average distances include at least an average first fault distance, an average second fault distance, and an average third fault distance. The average first fault distance is the mean of multiple first fault distances, the average second fault distance is the mean of multiple second fault distances, and the average third fault distance is the mean of multiple third fault distances. The first average distance is one of the average first fault distance, the average second fault distance, and the average third fault distance.

[0143] It should be noted that for the information interaction, execution process, etc. between the above-mentioned devices / units, since they are based on the same inventive concept as the method embodiments of the present application, for their specific functions and the technical effects brought, reference can be specifically made to the method embodiment part, and details will not be elaborated here.

[0144] It should be understood that the sequence numbers of the steps in the above embodiments do not mean the order of execution. The execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0145] Based on the same inventive concept, the embodiments of the present application also provide an electronic device.

[0146] Figure 7 It is a schematic structural diagram of the electronic device provided by the embodiments of the present application. As Figure 7 shown, the electronic device 70 of this embodiment includes: at least one processor 710 ( Figure 7 only one is shown in the figure), a memory 720, and a communication module 740. A computer program 730 that may run on the processor 710 is stored in the memory 720. When the processor 710 executes the computer program 730, it implements the steps in the above-mentioned method embodiments for determining the fault point. For example, Figure 2 the steps S201 to step S2010 shown in Figure 3 or the steps S301 to step S304 shown in Figure 6 When the processor 710 executes the computer program 730, it implements the functions of each module / unit in the above-mentioned device embodiments. For example

[0147] The functions of the modules 810 to 820 shown in Figure 7 The communication module 740 may be a separate communication unit for communicating with an external server or a terminal device.

[0148] The processor 710 may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0149] In some embodiments, the memory 720 may be an internal storage unit of the electronic device 70, such as the hard disk or memory of the electronic device 70. The memory 720 may also be an external storage device of the electronic device 70, such as a plug-in hard disk equipped on the electronic device 70, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. The memory 720 may also include both the internal storage unit of the electronic device 70 and the external storage device. The memory 720 is used to store an operating system, application programs, a BootLoader, data, and other programs, such as the program code of the computer program 730. The memory 720 may also be used to temporarily store data that has been sent or will be sent.

[0150] In addition, those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the above division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. In each embodiment of the present application, each functional unit may be integrated in a processing unit, or each unit may exist physically alone, or two or more units may be integrated in one unit. The above integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0151] The embodiments of the present application provide a computer-readable storage medium storing a computer program, and when the computer program runs on an electronic device, the electronic device is enabled to execute the steps in the above method embodiments.

[0152] An embodiment of the present application provides a chip, which includes a processor and a memory. A computer program is stored in the memory, and when the computer program is executed by the processor, the steps in the above-mentioned method embodiments are implemented.

[0153] An embodiment of the present application provides a computer program product. When the computer program product runs on an electronic device, the electronic device is caused to execute the steps in the above-mentioned method embodiments.

[0154] It should be understood that the processor mentioned in the embodiments of the present application may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0155] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchlink dynamic random access memory (SLDRAM), and direct rambus random access memory (DR RAM).

[0156] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is used as an example. In practical applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiments can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of the present application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0157] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For parts not detailed or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0158] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional technician can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0159] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in an electrical, mechanical or other forms.

[0160] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] In addition, the functional units in each embodiment of this application can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0162] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-described embodiment methods of this application, a computer program can be used to instruct relevant hardware to complete. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-described various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can at least include: any entity or device that can carry the computer program code to the large-screen device, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk, or an optical disc, etc. In some jurisdictions, according to legislation and patent practice, the computer-readable medium cannot be an electrical carrier signal and a telecommunication signal.

[0163] Finally, it should be noted that the above are only specific embodiments of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A method for determining a fault point, characterized in that: Applied to a line protection device, the line protection device is used to monitor the line status of a multi-phase line, the method comprises: Acquire a multiphase voltage and a multiphase current corresponding to the multiphase line, wherein the multiphase voltage, the multiphase current and the multiphase line all correspond one to one; Determine a multi-phase negative sequence current according to the multi-phase current, wherein the multi-phase negative sequence current corresponds to the multi-phase current in a one-to-one manner; Determine a plurality of fault distances according to the multi-phase negative sequence current, the multi-phase current, the multi-phase voltage and the line distance, wherein the plurality of fault distances correspond to the multi-phase lines one by one, and the line distance is used to characterize the length corresponding to the multi-phase line; A fault point is determined according to the multiple fault distances and the line distance, and the distance between the fault point and the line protection device is positively correlated with a first fault distance, which is a distance corresponding to the fault line among the multiple fault distances.

2. The method for determining a fault point according to claim 1, characterized in that: The determining of multiple fault distances according to the multi-phase negative sequence current, the multi-phase current, the multi-phase voltage and the line distance comprises: Determine a plurality of real voltage parts and a plurality of imaginary voltage parts according to the multi-phase negative-sequence current, the plurality of real voltage parts are a plurality of real voltage parts corresponding to the multi-phase fault point voltage, the plurality of imaginary voltage parts are a plurality of imaginary voltage parts corresponding to the multi-phase fault point voltage, and the angle values ​​of the plurality of voltage angles corresponding to the multi-phase fault point voltage are the same as the angle values ​​of the plurality of current angles corresponding to the multi-phase negative-sequence current; A plurality of fault distances are determined based on the plurality of real voltage parts, the plurality of imaginary voltage parts, the multi-phase currents, the multi-phase voltages, and the line distances.

3. The method for determining a fault point according to claim 2, characterized in that: The determining of multiple fault distances according to the multiple voltage real parts, the multiple voltage imaginary parts, the multi-phase currents, the multi-phase voltages and the line distances comprises: Obtaining a preset positive-sequence impedance and a preset zero-sequence impedance, wherein the preset positive-sequence impedance is the positive-sequence impedance corresponding to the line distance, and the preset zero-sequence impedance is the zero-sequence impedance corresponding to the line distance; Determine a ratio of a difference between the preset zero-sequence impedance and the preset positive-sequence impedance to three times the preset positive-sequence impedance as a zero-sequence compensation coefficient; A plurality of fault distances are determined according to the preset positive-sequence impedance, the zero-sequence compensation coefficient, the plurality of real parts of voltages, the plurality of imaginary parts of voltages, the multi-phase currents, the multi-phase voltages and the line distance.

4. The method for determining a fault point according to claim 3, characterized in that: The determining of multiple fault distances according to the preset positive-sequence impedance, the zero-sequence compensation coefficient, the multiple voltage real parts, the multiple voltage imaginary parts, the multi-phase current, the multi-phase voltage and the line distance comprises: Determining the sum of the multi-phase currents as a zero-sequence current; A plurality of fault distances are determined according to the zero-sequence current, the preset positive-sequence impedance, the zero-sequence compensation coefficient, the plurality of real parts of voltages, the plurality of imaginary parts of voltages, the multi-phase current, the multi-phase voltage and the line distance.

5. The method for determining a fault point according to any one of claims 1 to 4, characterized in that: The method further comprises: When it is detected that the current device state is the startup state, the current time is recorded as the first time.

6. The method for determining a fault point according to claim 5, characterized in that: The determining of the fault point according to the multiple fault distances and the line distance comprises: Continuously acquiring multiple groups of fault distances within a first preset time period, wherein the start time of the first preset time period is a second time period, and the second time period is a time period after the first time period and separated from the first time period by a second preset time period; Determine a plurality of average distances according to the plurality of groups of fault distances, wherein the average distances correspond one-to-one to the multi-phase lines; If the first average distance is greater than or equal to 0 and less than the line distance, and multiple second average distances are all greater than or equal to the line distance, or less than 0, then it is determined that the line point corresponding to the first average distance in the first line is the fault point, the first line is the line in the multi-phase line corresponding to the first average distance, the first average distance is one of the multiple average distances, and the multiple second average distances are average distances in the multiple average distances that are different from the first average distance.

7. The method for determining a fault point according to claim 6, characterized in that: The first group of fault distances includes at least a first fault distance corresponding to a first phase line, a second fault distance corresponding to a second phase line, and a third fault distance corresponding to a third phase line. The first phase line, the second phase line, and the third phase line are lines in the multi-phase line, and the first group of fault distances is any one of the multiple groups of fault distances.

8. The method for determining a fault point according to claim 7, characterized in that: The multiple average distances include at least an average first fault distance, an average second fault distance, and an average third fault distance, wherein the average first fault distance is an average of multiple first fault distances, the average second fault distance is an average of multiple second fault distances, and the average third fault distance is an average of multiple third fault distances; The first average distance is one of the average first fault distance, the average second fault distance, and the average third fault distance.

9. An electronic device, characterized in that: The system comprises a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the fault point determination method as described in any one of claims 1 to 8.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the fault point determination method as described in any one of claims 1 to 8 is implemented.

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