Method, device and equipment for detecting fault distance of power transmission line and medium

Abstract

The invention discloses a power transmission line fault distance detection method and device, equipment and a medium. The method comprises the following steps: when it is detected that a single-phase line of a power transmission line has a fault, obtaining an electrical quantity of a first end of the power transmission line and a zero-sequence suppression constraint condition of a second end in the power transmission line; according to the electrical quantity of the first end and the fault distance, a target electrical quantity function of the electrical quantity of the second end of the power transmission line is constructed, and the fault distance is the distance between the line fault point and the first end; and under a zero-sequence suppression constraint condition, calculating a function value of the target electrical quantity function to obtain a fault distance. According to the scheme provided by the invention, the accuracy of fault distance detection of the power transmission line can be improved.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of Chinese patent application 202311095150.0, filed on August 28, 2023, entitled “On-site protection scheme for the opposite side of inverter power lines”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the technical field of power systems, and in particular, relates to a method, device, equipment and medium for detecting a fault distance of a transmission line. Background Art

[0004] With the increasing prominence of environmental issues and the development of power electronics technology, inverter-based renewable energy generation and DC transmission lines have been increasingly used. Distance protection is the main protection and backup protection of transmission lines.

[0005] In traditional AC systems, the performance of distance protection during non-metallic faults can be improved by means of boundary adjustment, impedance complex plane and voltage phasor plane. Since the fault current provided by the inverter power supply is limited, the harmonic content is large, and the phase is not fixed, the distance protection of the line connected to the inverter power supply cannot accurately detect the fault, resulting in false operation or refusal of the distance protection. Summary of the invention

[0006] The embodiments of the present application provide a method, device, equipment and medium for detecting fault distance of a power transmission line, which can improve the accuracy of fault distance detection of the power transmission line.

[0007] In a first aspect, an embodiment of the present application provides a method for detecting a fault distance of a transmission line, the method comprising: when a single-phase line of the transmission line is detected to have a fault, obtaining an electrical quantity at a first end of the transmission line and a zero-sequence suppression constraint at a second end of the transmission line; constructing a target electrical quantity function of the electrical quantity at the second end of the transmission line based on the electrical quantity at the first end and the fault distance, wherein the fault distance is the distance between a line fault point of the transmission line and the first end; and calculating a function value of the target electrical quantity function under the zero-sequence suppression constraint to obtain the fault distance.

[0008] In a second aspect, an embodiment of the present application provides a device for detecting a fault distance of a transmission line, the device comprising: a data acquisition module, for acquiring the electrical quantity of the first end of the transmission line and the zero-sequence suppression constraint of the second end of the transmission line when a single-phase line fault is detected in the transmission line; a function construction module, for constructing a target electrical quantity function of the electrical quantity of the second end of the transmission line according to the electrical quantity of the first end and the fault distance, wherein the fault distance is the distance between the line fault point of the transmission line and the first end; and a distance detection module, for calculating the function value of the target electrical quantity function under the zero-sequence suppression constraint to obtain the fault distance.

[0009] In a third aspect, an embodiment of the present application provides an electronic device, comprising: a processor and a memory storing computer program instructions; when the processor executes the computer program instructions, the method for detecting the fault distance of a transmission line as described in the first aspect is implemented.

[0010] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having computer program instructions stored thereon. When the computer program instructions are executed by a processor, the method for detecting a fault distance of a transmission line as described in the first aspect is implemented.

[0011] In a fifth aspect, an embodiment of the present application provides a computer program product. When instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the method for detecting a fault distance of a power transmission line as described in the first aspect.

[0012] As can be seen from the above content, in the embodiment of the present application, the electrical quantity at one end is used to estimate the electrical quantity at the other end to construct an electrical quantity function, which is a function of the fault distance. Under the zero-sequence suppression constraint, the electrical quantity function is solved to obtain the fault distance. This process does not require the acquisition of the fault current, thereby avoiding the problem of inaccurate fault distance identification caused by the large harmonic content and non-fixed phase of the fault current provided by the inverter power supply in the related art, thereby improving the accuracy of fault distance detection of the transmission line. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0014] Figure 1 This is a diagram of a detection architecture for a power transmission line fault distance provided by an embodiment of the present application;

[0015] Figure 2It is a flow chart of a method for detecting a fault distance of a power transmission line provided by an embodiment of the present application;

[0016] Figure 3 is a schematic diagram of a single-phase fault of a power transmission line provided by an embodiment of the present application;

[0017] Figure 4 is a sequence network diagram of module 1 of a power transmission line MN provided by an embodiment of the present application;

[0018] Figure 5 is a sequence network diagram of module 2 of a power transmission line MN provided by an embodiment of the present application;

[0019] Figure 6 is a module 0 sequence network diagram of a power transmission line MN provided by an embodiment of the present application;

[0020] Figure 7 is a schematic structural diagram of a device for detecting a fault distance of a power transmission line provided by another embodiment of the present application;

[0021] Figure 8 It is a structural schematic diagram of an electronic device provided in yet another embodiment of the present application. DETAILED DESCRIPTION

[0022] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating the examples of the present application.

[0023] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0024] For ease of understanding, before explaining the solution provided in this application, the background involved in the solution provided in this application is first explained.

[0025] Distance protection is the main protection and backup protection of transmission lines. However, due to the influence of inverter control, the fault current provided by renewable energy stations and DC inverter interfaces has large amplitude limitation and harmonic content, which is very different from the current provided by synchronous generators. In traditional AC systems, methods to improve the performance of distance protection during non-metallic faults mainly include distance protection based on boundary adjustment, impedance complex plane and voltage phasor plane. Since the fault current provided by the inverter power supply is limited in size, has large harmonic content and is not fixed in phase, the distance protection of the line connected to the inverter power supply cannot accurately detect the fault, and the protection may malfunction or refuse to operate.

[0026] Since the single-end protection is affected by the opposite-end system, if the protection algorithm can estimate the opposite-end electrical quantity through the local electrical quantity, the boundary constraints of the opposite-end system can be used to set the protection scheme. However, this scheme has a higher probability of large transition resistance in single-phase faults, which makes it more likely to misjudge the protection.

[0027] In order to solve the problems of the prior art, the embodiments of the present application provide a method, device, equipment and medium for detecting the fault distance of a transmission line. Figure 1 The detection architecture diagram of the transmission line fault distance provided by the embodiment of the present application is shown in FIG. Figure 1 In the figure, S is the inverter power supply, and DG (Distribution Generation) is the generator at the opposite end of the inverter power supply. Figure 1 It can be seen that in the embodiment of the present application, the fault resistance and fault distance are first set; then, the electrical quantities at the opposite end of the inverter power supply are estimated by the electrical quantities at the local end of the inverter power supply line; then, the fault resistance and fault distance are calculated using the estimated electrical quantities at the opposite end and the zero-sequence suppression constraints of the inverter power supply system, rather than boundary constraints; finally, the fault resistance and fault distance are detected according to the preset fault judgment criteria to perform fault judgment on the inverter power supply system and determine the fault type.

[0028] Figure 2 FIG. 1 is a flow chart showing a method for detecting a fault distance of a power transmission line provided by an embodiment of the present application. Figure 2 As shown, the method comprises the following steps:

[0029] Step S201, when a single-phase line fault of a transmission line is detected, obtaining electrical quantities at a first end of the transmission line and zero-sequence suppression constraint conditions at a second end of the transmission line.

[0030] In step S201, the transmission line is a transmission line where the inverter power system is located. In the embodiment of the present application, the transmission line is a three-phase line, wherein a phase line of the transmission line fails. It should be noted that the fault distance detection method proposed in the embodiment of the present application is implemented in the scenario where a single-phase fault occurs in the transmission line and the fault line in the three-phase line is known.

[0031] In addition, in step S201, the electrical quantities of the transmission line may include but are not limited to voltage and current. Figure 3 In the schematic diagram of a single-phase fault of a transmission line shown in FIG. 1 , M and N are busbars at both ends of the transmission line. In the embodiment of the present application, M is used as the first end and N is used as the second end (i.e., the opposite end). Figure 3 In , F is the location where the fault occurs in the transmission line, that is, the line fault point; P and Q are the endpoints on both sides of the line fault point, where P is the endpoint close to the M end and Q is the endpoint close to the N end. Figure 3 In the example, the electrical quantity corresponding to the first phase line at the M end is u MA (t) and i MA (t); the electrical quantity corresponding to the second phase line at the M end is u MB (t) and i MB (t); the electrical quantity corresponding to the third phase line at the M end is u MC (t) and i MC (t); the electrical quantity corresponding to the first phase line at the N end is u NA (t) and i NA (t); the electrical quantity corresponding to the second phase line at the N end is u NB (t) and i NB (t); the electrical quantity corresponding to the third phase line at the N end is u NC (t) and i NC (t); the electrical quantity corresponding to the first phase line at the P end is u PA (t) and i PA (t); the electrical quantity corresponding to the second phase line at the P end is u PB (t) and i PB (t); the electrical quantity corresponding to the third phase line at the P end is u PC (t) and i PC (t); the electrical quantity corresponding to the first phase circuit at the Q end is u QA (t) and i QA (t); the electrical quantity corresponding to the second phase line at the Q end is u QB (t) and i QB (t); the electrical quantity corresponding to the third phase line at the Q end is u QC (t) and i QC (t); the ground current corresponding to the line fault point F is iFA (t). Figure 3 In, L MP is the distance between the line fault point F and the M end; L NQ is the distance between the line fault point F and the N end; the direction indicated by x is the positive direction of each electrical quantity. In the embodiment of the present application, the propagation direction of the traveling wave in the transmission line can be taken as the positive direction.

[0032] It should be noted that in Figure 3 Among the electrical quantities shown, except for the electrical quantity at the M end which is a known electrical quantity, the rest are unknown electrical quantities. Figure 3 The distance in is also an unknown quantity.

[0033] Step S202: constructing a target electrical quantity function of the electrical quantity at the second end of the transmission line according to the electrical quantity at the first end and the fault distance.

[0034] In step S202, the fault distance is the distance between the line fault point and the first end of the transmission line, that is, Figure 3 L MP .

[0035] As an example, assuming that the fault distance is known, the electrical quantity at the second end can be estimated based on the electrical quantity at the first end and the fault distance according to the transmission characteristics of the traveling wave in the transmission line. Since the fault distance is unknown, the electrical quantity at the second end is essentially a function (i.e., the target electrical quantity function) containing the unknown quantity (fault distance). By solving this function, the fault distance can be obtained.

[0036] Step S203, under the zero-sequence suppression constraint condition, the function value of the target electrical quantity function is calculated to obtain the fault distance.

[0037] It should be noted that under the zero-sequence suppression constraint, the zero-sequence current at the N terminal is 0. Under this constraint, the target electrical quantity function is solved to obtain the fault distance. The solution process is calculated based on the zero-sequence suppression constraint, not based on the boundary conditions of the opposite system, thus avoiding the problem of poor accuracy in fault distance determination due to large transition resistance during single-phase faults.

[0038] In addition, since negative-sequence suppression control methods are installed in many new energy stations and DC converter stations, for the opposite-end system with negative-sequence suppression current, in an embodiment of the present application, the negative-sequence current of zero can be used as a boundary condition and combined with the estimated value of the opposite-end electrical quantity to construct a protection criterion. The specific process is similar to the above steps S201 to S203, and the only difference is that the constraints are different.

[0039] Based on the scheme defined by the above steps S201 to S203, it can be known that in the embodiment of the present application, the electrical quantity at one end is used to estimate the electrical quantity at the other end to construct an electrical quantity function, which is a function of the fault distance. Under the zero-sequence suppression constraint, the electrical quantity function is solved to obtain the fault distance. This process does not require the acquisition of the fault current, thereby avoiding the problem of inaccurate fault distance identification caused by the large harmonic content and non-fixed phase of the fault current provided by the inverter power supply in the related art, thereby improving the accuracy of fault distance detection of the transmission line.

[0040] The following is a detailed explanation of each step of the method provided in the embodiments of the present application.

[0041] After obtaining the electrical quantity at the first end of the transmission line, firstly, Karenberg transformation is performed on the electrical quantity at the first end to obtain a first converted electrical quantity corresponding to the electrical quantity at the first end.

[0042] In the above embodiment, the electrical quantity at the first end includes: the first phase electrical quantity of the single-phase line with fault, the second phase electrical quantity of the other phase lines without fault, and the third phase electrical quantity, and the first converted electrical quantity includes: the first mode electrical quantity, the second mode electrical quantity, and the zero mode electrical quantity. That is, through the Karenbel transformation, the electrical quantity of the three-phase line can be converted into the electrical quantity of 1, 2, and 0 modes.

[0043] Specifically, the difference between the first-phase electrical quantity and the second-phase electrical quantity is calculated, and the product is multiplied by a preset coefficient to obtain a first-mode electrical quantity; the difference between the first-phase electrical quantity and the third-phase electrical quantity is calculated, and the product is multiplied by a preset coefficient to obtain a second-mode electrical quantity; the average value of the first-phase electrical quantity, the second-phase electrical quantity and the third-phase electrical quantity is calculated to obtain a zero-mode electrical quantity.

[0044] The above conversion process can be expressed as follows:

[0045]

[0046] In the above formula, u M1 (t) and i M1 (t) is a modulus electrical quantity (corresponding to the electrical quantity of 1 modulus), u M2 (t) and i M2 (t) is the second-mode electrical quantity (corresponding to the electrical quantity of the 2nd mode), u M0 (t) and i M0 (t) is the zero-mode electrical quantity (corresponding to the 0-mode electrical quantity).

[0047] It should be noted that by performing Karenberg transformation on electrical quantities, imaginary-part coupled electrical quantities can be converted into imaginary-part uncoupled electrical quantities, which is convenient for subsequent calculations.

[0048] It should be noted that by using the above method to perform Karenberg conversion on the electrical quantity at the second end and the electrical quantity at both ends of the line fault point, the corresponding converted electrical quantities can be obtained. The specific conversion method is similar to the above, and will not be listed here one by one.

[0049] After performing Karen Bell transformation on the electrical quantities at each end, the voltage traveling wave of the first transformed electrical quantity is calculated to obtain the first voltage traveling wave; then, based on the first voltage traveling wave and the fault distance, a first voltage traveling wave function corresponding to the first fault end of the fault point is constructed, wherein the fault point includes the first fault end (such as Figure 3 The P end in the figure) and the second fault end (such as Figure 3 Q end in the diagram), the distance between the first fault end and the first end is greater than the distance between the second fault end and the first end; then, a voltage traveling wave function of the second end is constructed based on the first voltage traveling wave; and based on the voltage traveling wave function of the second end and the fault distance, a second voltage traveling wave function corresponding to the second fault end is constructed; finally, under the constraints of the boundary conditions corresponding to the fault point, the first voltage traveling wave function and the second voltage traveling wave function are combined to obtain the target electrical quantity function.

[0050] In one example, Figure 4 , Figure 5 and Figure 6 The sequence diagrams of mode 1, mode 2 and mode 0 of the transmission line MN are shown respectively. Figure 4 The sequence diagram of mode 1 shown can determine the mode 1 voltage traveling wave at the M, P, Q, and N terminals:

[0051]

[0052]

[0053] In the above formula, u M1 + (t) and u M1 - (t) is the positive sequence component of the first voltage traveling wave, where u M1 + (t) is the positive voltage traveling wave, u M1 - (t) is a negative voltage traveling wave; u P1 + (t) and u P1 - (t) is the positive sequence component of the first voltage traveling wave function; u Q1 + (t) and u Q1 - (t) is the positive sequence component of the second voltage traveling wave function; u N1 + (t) and u N1- (t) is the positive sequence component of the voltage traveling wave function at the second end; Z L1 represents the positive-sequence wave impedance, which is a known quantity; γ1 is the positive-sequence traveling wave propagation coefficient.

[0054] Figure 5 The mode 2 sequence diagram shown can determine the mode 2 voltage traveling wave at the M, P, Q, and N terminals:

[0055]

[0056]

[0057] In the above formula, u M2 + (t) and u M2 - (t) is the negative sequence component of the first voltage traveling wave; u P2 + (t) and u P2 - (t) is the negative sequence component of the first voltage traveling wave function; u Q2 + (t) and u Q2 - (t) is the negative sequence component of the second voltage traveling wave function; u N2 + (t) and u N2 - (t) is the negative sequence component of the voltage traveling wave function at the second terminal.

[0058] Figure 6 The mode 0 sequence diagram shown can determine the mode 2 voltage traveling wave at the M, P, Q, and N terminals:

[0059]

[0060]

[0061] In the above formula, u M0 + (t) and u M0 - (t) is the zero-sequence component of the first voltage traveling wave; Z L0 represents the zero-sequence wave impedance, which is a known quantity; γ0 is the zero-sequence traveling wave propagation coefficient. P0 + (t) and u P0 - (t) is the zero-sequence component of the first voltage traveling wave function; u Q0 + (t) and u Q0 - (t) is the zero-sequence component of the second voltage traveling wave function; uN0 + (t) and u N0 - (t) is the zero-sequence component of the voltage traveling wave function at the second end.

[0062] As an example, the boundary conditions corresponding to the fault point include:

[0063] u PA (t) = u FA (t) = u QA (t)

[0064] u FA (t) = R F i FA (t)

[0065] u PA (t) = u P1 (t)+u P2 (t)+u P0 (t)

[0066] =u P1 + (t)+u P2 + (t)+u P0 + (t)+uP1 - (t)+u P2 - (t)+u P2 - (t)+u P0 - (t)

[0067] i FB (t) = 0

[0068] i FC (t) = 0

[0069]

[0070]

[0071] Among them, u PA (t) is the voltage between the first terminal and the first fault terminal at time t; u FA (t) is the voltage between the first terminal and the fault point at time t; u QA (t) is the voltage between the first terminal and the second fault terminal at time t; R F is the fault resistance corresponding to the fault point. In the embodiment of the present application, R F is the unknown quantity; i FA(t) is the current between the first end of the first phase line where the fault occurs and the fault point at time t; i FB (t) is the current between the first end and the fault point in the second phase line where no fault occurs at time t; i FC (t) is the current between the first end of the third phase line without fault and the fault point at time t; u P1 (t),u P2 (t),u P0 (t) are respectively the first mode voltage, the second mode voltage and the third mode voltage of the first fault end; i F0 (t) is the zero-sequence current at the fault point; is the forward traveling wave current at the first fault end at time t; is the negative traveling wave current at the first fault end at time t; is the forward traveling wave current at the second fault terminal at time t; is the negative traveling wave current at the second fault end at time t.

[0072] Based on the above formula, combined with the sequence network diagram of M, P, Q, and N, the following formula can be obtained:

[0073]

[0074] Jointly available,

[0075] i M0 + (t-(L NQ +L MP ) / v)-i N0 + (t)=0.5i F0 (tL NQ / v)

[0076] i N0 - (t-(L NQ +L MP ) / v)-i N0 -(t)=0.5i F0 (tL MP / v)

[0077]

[0078] It should be noted that, in the above formula, v represents the propagation velocity of the traveling wave in the transmission line, wherein v1 is the propagation velocity of the positive sequence, and v0 is the propagation velocity of the zero sequence.

[0079] The N-side zero-sequence current can be derived from the above formula:

[0080]

[0081] In a specific scenario: the line length is short, and the opposite end N side is a neutral point ungrounded system, then the zero-sequence current on the opposite end N side is zero, and the transmission time is very short. All quantities can be expressed by the voltage and current values ​​and the first-order derivatives at time t. The zero-sequence current on the N side is expressed as follows:

[0082]

[0083] Among them, i N0 (t) is the zero-sequence current at the second end; i M0 + (t) is the positive zero-sequence current at the first end; L MP is the distance between the first end and the first fault end; L NQ is the distance between the second end and the second fault end; C0 is the line parameter of the transmission line; u ′ M0 (t) is the derivative of the voltage in the zero-mode electrical quantity at the first end; u MA (t) is the voltage of the first phase line at the first end; i ′ M1 (t) is the derivative of the current in the first-mode electrical quantity at the first end; i ′ M2 (t) is the derivative of the current in the second mode electrical quantity at the first end; i ′ M0 (t) is the derivative of the current in the zero-mode electrical quantity at the first end; L1 is the reactance corresponding to the first-mode electrical quantity; L2 is the reactance corresponding to the second-mode electrical quantity; L0 is the reactance corresponding to the zero-mode electrical quantity.

[0084] The specific derivation process of the above formula is as follows:

[0085]

[0086] From the above formula, we can see that only R F , L MP Two unknown quantities. When each quantity is expressed in phasor form, there are two equations with zero real part and zero imaginary part. These two unknown quantities can be solved to obtain the fault distance R F .

[0087] Furthermore, the function value of the target electrical quantity function includes the fault distance and the fault resistance, wherein after the function value of the target electrical quantity function is calculated to obtain the fault distance, the fault type can be determined based on the fault distance and the fault resistance.

[0088] Specifically, it is detected whether the fault distance is within a preset fault distance range, and the fault resistance is within a preset fault resistance range; when the fault distance is within the preset fault distance range, and the fault resistance is within the preset fault resistance range, the fault type of the fault point is determined to be an intra-zone fault, wherein the intra-zone fault is a fault that can be resolved by performing local protection at the first end; when the fault distance is outside the preset fault distance range, and / or the fault resistance is outside the preset fault resistance range, the fault type of the fault point is determined to be an out-of-zone fault or a line disturbance.

[0089] If 0 <R F <R set , and 0≤L MP ≤L MN , then the fault is determined to be an internal fault, otherwise it is determined to be an external fault or a line disturbance.

[0090] It can be seen from the above that in the scheme provided in the embodiment of the present application, the fault resistance and fault distance are assumed, the electrical quantity on the inverter power supply side is estimated by the electrical quantity on the opposite side of the inverter power supply line, the fault resistance and fault distance are calculated using the estimated electrical quantity on the inverter power supply side and the zero-sequence suppression constraint of the inverter power supply system, and the fault discrimination is completed according to the calculation results of the fault resistance and fault distance. The protection scheme calculates the fault distance and fault resistance of the single-phase fault through the local voltage and current information and the constraint that the zero-sequence current of the opposite inverter power supply is zero, and forms a protection criterion according to the calculated fault resistance and fault distance to realize fault discrimination. The scheme provided in the embodiment of the present application realizes the local protection of the single-phase fault on the opposite side of the inverter power supply line, meets the rapidity and selectivity of the line protection, and improves the power supply reliability of the line containing power electronic equipment.

[0091] The present application also provides a device for detecting a fault distance of a power transmission line. Figure 7 As shown, the device 700 includes: a data acquisition module 701, a function construction module 702 and a distance detection module 703.

[0092] The data acquisition module 701 is used to acquire the electrical quantity of the first end of the transmission line and the zero-sequence suppression constraint condition of the second end of the transmission line when a single-phase line fault of the transmission line is detected;

[0093] A function construction module 702 is used to construct a target electrical quantity function of the electrical quantity of the second end of the transmission line according to the electrical quantity of the first end and the fault distance, wherein the fault distance is the distance between the line fault point of the transmission line and the first end;

[0094] The distance detection module 703 is used to calculate the function value of the target electrical quantity function under the zero-sequence suppression constraint condition to obtain the fault distance.

[0095] In one example, the device for detecting the fault distance of a power transmission line further includes: a transformation module, configured to perform a Karenberg transformation on the electrical quantity at the first end to obtain a first converted electrical quantity corresponding to the electrical quantity at the first end.

[0096] In one example, the electrical quantities at the first end include: the first-phase electrical quantities of the single-phase line where the fault occurs, the second-phase electrical quantities of other phase lines where the fault occurs, and the third-phase electrical quantities, and the first converted electrical quantities include: a first-mode electrical quantity, a second-mode electrical quantity, and a zero-mode electrical quantity, wherein the transformation module is specifically used to calculate the difference between the first-phase electrical quantity and the second-phase electrical quantity, and multiply it by a preset coefficient to obtain a first-mode electrical quantity; calculate the difference between the first-phase electrical quantity and the third-phase electrical quantity, and multiply it by a preset coefficient to obtain a second-mode electrical quantity; calculate the average value of the first-phase electrical quantity, the second-phase electrical quantity, and the third-phase electrical quantity to obtain a zero-mode electrical quantity.

[0097] In one example, the function construction module is specifically used to calculate the voltage traveling wave of the first converted electrical quantity to obtain the first voltage traveling wave; based on the first voltage traveling wave and the fault distance, construct a first voltage traveling wave function corresponding to the first fault end of the fault point, wherein the fault point includes the first fault end and the second fault end, and the distance between the first fault end and the first end is greater than the distance between the second fault end and the first end;

[0098] A voltage traveling wave function of the second end is constructed based on the first voltage traveling wave; a second voltage traveling wave function corresponding to the second fault end is constructed based on the voltage traveling wave function of the second end and the fault distance; under the constraints of the boundary conditions corresponding to the fault point, the first voltage traveling wave function and the second voltage traveling wave function are combined to obtain the target electrical quantity function.

[0099] In one example, the boundary conditions corresponding to the fault point include:

[0100] u PA (t) = u FA (t) = u QA (t)

[0101] u FA (t) = R F i FA (t)

[0102] u PA (t) = u P1 (t)+u P2 (t)+u P0 (t)

[0103] i FB (t) = 0

[0104] i FC (t) = 0

[0105]

[0106]

[0107] Among them, u PA (t) is the voltage between the first terminal and the first fault terminal at time t; u FA (t) is the voltage between the first terminal and the fault point at time t; u QA (t) is the voltage between the first terminal and the second fault terminal at time t; R F is the fault resistance corresponding to the fault point; i FA (t) is the current between the first end of the first phase line where the fault occurs and the fault point at time t; i FB (t) is the current between the first end and the fault point in the second phase line where no fault occurs at time t; i FC (t) is the current between the first end of the third phase line without fault and the fault point at time t; u P1 (t),u P2 (t),u P0 (t) are respectively the first mode voltage, the second mode voltage and the third mode voltage of the first fault end; i F0 (t) is the zero-sequence current at the fault point; is the forward traveling wave current at the first fault end at time t; is the negative traveling wave current at the first fault end at time t; is the forward traveling wave current at the second fault terminal at time t; is the negative traveling wave current at the second fault end at time t.

[0108] In one example, the target electrical quantity function is expressed as follows:

[0109]

[0110] Among them, i N0 (t) is the zero-sequence current at the second terminal; is the positive zero-sequence current at the first end; L MP is the distance between the first end and the first fault end; L NQ is the distance between the second end and the second fault end; C0 is the line parameter of the transmission line; u ′ M0 (t) is the derivative of the voltage in the zero-mode electrical quantity at the first end; u MA (t) is the voltage of the first phase line at the first end; i ′ M1 (t) is the derivative of the current in the first-mode electrical quantity at the first end; i ′M2 (t) is the derivative of the current in the second mode electrical quantity at the first end; i ′ M0 (t) is the derivative of the current in the zero-mode electrical quantity at the first end; L1 is the reactance corresponding to the first-mode electrical quantity; L2 is the reactance corresponding to the second-mode electrical quantity; L0 is the reactance corresponding to the zero-mode electrical quantity.

[0111] In one example, the function value of the target electrical quantity function includes the fault distance and the fault resistance, wherein the detection device for the fault distance of the transmission line further includes: a fault discrimination module, used to detect whether the fault distance is within a preset fault distance range, and the fault resistance is within a preset fault resistance range; when the fault distance is within the preset fault distance range, and the fault resistance is within the preset fault resistance range, the fault type of the fault point is determined to be an intra-zone fault, wherein the intra-zone fault is a fault that can be resolved by performing local protection at the first end; when the fault distance is outside the preset fault distance range, and / or the fault resistance is outside the preset fault resistance range, the fault type of the fault point is determined to be an out-of-zone fault or a line disturbance.

[0112] The device for detecting the fault distance of a power transmission line provided in the embodiment of the present application can implement each process implemented in the aforementioned method embodiment, and will not be described again here to avoid repetition.

[0113] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0114] Figure 8 A schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present application is shown.

[0115] The electronic device may include a processor 801 and a memory 802 storing computer program instructions.

[0116] Specifically, the processor 801 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0117] The memory 802 may include a large capacity memory for data or instructions. By way of example and not limitation, the memory 802 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. In appropriate cases, the memory 802 may include a removable or non-removable (or fixed) medium. In appropriate cases, the memory 802 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 802 is a non-volatile solid-state memory.

[0118] The memory may include read-only memory (ROM), random access memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical or other physical / tangible memory storage devices. Thus, typically, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to an aspect of the present disclosure.

[0119] The processor 801 reads and executes the computer program instructions stored in the memory 802 to implement any one of the methods for detecting the fault distance of a power transmission line in the above embodiments.

[0120] In one example, the electronic device may further include a communication interface 803 and a bus 810. Figure 8 As shown, the processor 801, the memory 802, and the communication interface 803 are connected via a bus 810 and communicate with each other.

[0121] The communication interface 803 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0122] Bus 810 includes hardware, software or both, and the parts of electronic equipment are coupled to each other.For example, but not limitation, bus may include accelerated graphics port (AGP) or other graphics bus, enhanced industrial standard architecture (EISA) bus, front side bus (FSB), hypertransport (HT) interconnection, industrial standard architecture (ISA) bus, infinite bandwidth interconnection, low pin count (LPC) bus, memory bus, micro channel architecture (MCA) bus, peripheral component interconnection (PCI) bus, PCI-Express (PCI-X) bus, serial advanced technology attachment (SATA) bus, video electronics standard association local (VLB) bus or other suitable bus or two or more of these combinations. In appropriate cases, bus 810 may include one or more buses. Although the present application embodiment describes and shows a specific bus, the application considers any suitable bus or interconnection.

[0123] In addition, in combination with the method for detecting the fault distance of a power transmission line in the above embodiment, the embodiment of the present application may provide a computer-readable storage medium for implementation. The computer-readable storage medium stores computer program instructions; when the computer program instructions are executed by a processor, any one of the methods for detecting the fault distance of a power transmission line in the above embodiment is implemented.

[0124] In addition, in combination with the method for detecting the fault distance of a power transmission line in the above embodiment, the embodiment of the present application may provide a computer program product for implementation. When the instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes and implements any of the methods for detecting the fault distance of a power transmission line in the above embodiment.

[0125] It should be clear that the present application is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present application.

[0126] The functional modules shown in the above-described block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present application are programs or code segments that are used to perform the required tasks. Programs or code segments can be stored in machine-readable media, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable media" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0127] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps, that is, the steps can be performed in the order mentioned in the embodiment, or in a different order from the embodiment, or several steps can be performed simultaneously.

[0128] The above describes various aspects of the present disclosure with reference to the flowchart and / or block diagram of the detection method, device, equipment and medium of the transmission line fault distance according to the embodiment of the present disclosure. It should be understood that each box in the flowchart and / or block diagram and the combination of each box in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine so that these instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the functions / actions specified in one or more boxes of the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field programmable logic circuit. It can also be understood that each box in the block diagram and / or flowchart and the combination of boxes in the block diagram and / or flowchart can also be implemented by dedicated hardware that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0129] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A method for detecting a fault distance of a power transmission line, characterized in that: include: In the case where a single-phase line of a transmission line is detected to have a fault, obtaining an electrical quantity at a first end of the transmission line and a zero-sequence suppression constraint condition at a second end of the transmission line; constructing a target electrical quantity function of the electrical quantity of the second end of the transmission line according to the electrical quantity of the first end and the fault distance, wherein the fault distance is the distance between the line fault point of the transmission line and the first end; Under the zero-sequence suppression constraint condition, the function value of the target electrical quantity function is calculated to obtain the fault distance.

2. The method according to claim 1, characterized in that After obtaining the electrical quantity at the first end of the transmission line, the method further includes: Performing a Karenberg transformation on the electrical quantity at the first end to obtain a first converted electrical quantity corresponding to the electrical quantity at the first end.

3. The method according to claim 2, characterized in that The electrical quantity at the first end includes: a first-phase electrical quantity of a single-phase line with a fault, a second-phase electrical quantity of other phase lines without a fault, and a third-phase electrical quantity, and the first converted electrical quantity includes: a first-mode electrical quantity, a second-mode electrical quantity, and a zero-mode electrical quantity, wherein the electrical quantity at the first end is subjected to a Karenberg transformation to obtain a first converted electrical quantity corresponding to the electrical quantity at the first end, including: Calculate the difference between the first-phase electrical quantity and the second-phase electrical quantity, and multiply it by a preset coefficient to obtain the first-mode electrical quantity; Calculate the difference between the first-phase electrical quantity and the third-phase electrical quantity, and multiply the difference by the preset coefficient to obtain the second-mode electrical quantity; The average value of the first phase electrical quantity, the second phase electrical quantity and the third phase electrical quantity is calculated to obtain the zero-mode electrical quantity.

4. The method according to claim 3, characterized in that Constructing a target electrical quantity function of the electrical quantity at the second end of the transmission line according to the electrical quantity at the first end and the fault distance, comprising: Calculating a voltage traveling wave of the first converted electrical quantity to obtain a first voltage traveling wave; Based on the first voltage traveling wave and the fault distance, constructing a first voltage traveling wave function corresponding to a first fault end of the fault point, wherein the fault point includes the first fault end and a second fault end, and the distance between the first fault end and the first end is greater than the distance between the second fault end and the first end; Constructing a voltage traveling wave function at the second end based on the first voltage traveling wave; constructing a second voltage traveling wave function corresponding to the second fault end based on the voltage traveling wave function of the second end and the fault distance; Under the constraint of the boundary conditions corresponding to the fault point, the first voltage traveling wave function and the second voltage traveling wave function are combined to obtain the target electrical quantity function.

5. The method according to claim 4, characterized in that The boundary conditions corresponding to the fault point include: u PA (t)=u FA (t)=u QA (t) u FA (t)=R F i FA (t) u PA (t)=u P1 (t)+u P2 (t)+u P0 (t) i FB (t)=0 i FC (t)=0 Among them, u PA (t) is the voltage between the first terminal and the first fault terminal at time t; u FA (t) is the voltage between the first end and the fault point at time t; u QA (t) is the voltage between the first terminal and the second fault terminal at time t; R F is the fault resistance corresponding to the fault point; i FA (t) is the current between the first end of the first phase line where the fault occurs and the fault point at time t; i FB (t) is the current between the first end of the second phase line where no fault occurs and the fault point at time t; i FC (t) is the current between the first end of the third phase line where no fault occurs and the fault point at time t; u P1 (t),u P2 (t),u P0 (t) are respectively a first mode voltage, a second mode voltage and a third mode voltage of the first fault end; i F0 (t) is the zero-sequence current of the fault point; is the forward traveling wave current of the first fault end at time t; is the negative traveling wave current at the first fault end at time t; is the forward traveling wave current of the second fault end at time t; is the negative traveling wave current at the second fault end at time t.

6. The method according to claim 5, characterized in that The target electrical quantity function is expressed by the following formula: Among them, i N0 (t) is the zero-sequence current of the second terminal; i M0 + (t) is the positive zero-sequence current of the first end; L MP is the distance between the first end and the first fault end; L NQ is the distance between the second end and the second fault end; C0 is the line parameter of the transmission line; u ′ M0 (t) is the derivative of the voltage in the zero-mode electrical quantity at the first end; u MA (t) is the voltage of the first phase line of the first end; i ′ M1 (t) is the derivative of the current in the first-mode electrical quantity at the first end; i ′ M2 (t) is the derivative of the current in the second mode electrical quantity of the first end; i ′ M0 (t) is the derivative of the current in the zero-mode electrical quantity at the first end; L1 is the reactance corresponding to the one-mode electrical quantity; L2 is the reactance corresponding to the two-mode electrical quantity; L0 is the reactance corresponding to the zero-mode electrical quantity.

7. The method according to claim 1, characterized in that The function value of the target electrical quantity function includes the fault distance and the fault resistance. After calculating the function value of the target electrical quantity function and obtaining the fault distance, the method further includes: Detecting whether the fault distance is within a preset fault distance range, and whether the fault resistance is within a preset fault resistance range; When the fault distance is within the preset fault distance range and the fault resistance is within the preset fault resistance range, determining that the fault type of the fault point is an intra-zone fault, wherein the intra-zone fault is a fault that can be resolved by performing local protection at the first end; When the fault distance is outside the preset fault distance range and / or the fault resistance is outside the preset fault resistance range, the fault type of the fault point is determined to be an out-of-zone fault or a line disturbance.

8. A device for detecting fault distance of a power transmission line, characterized in that: include: A data acquisition module, configured to acquire electrical quantities at a first end of the transmission line and zero-sequence suppression constraints at a second end of the transmission line when a single-phase line fault is detected in the transmission line; a function construction module, configured to construct a target electrical quantity function of the electrical quantity of the second end of the transmission line according to the electrical quantity of the first end and the fault distance, wherein the fault distance is the distance between a line fault point of the transmission line and the first end; The distance detection module is used to calculate the function value of the target electrical quantity function under the zero-sequence suppression constraint condition to obtain the fault distance.

9. An electronic device, characterized in that: The electronic device comprises: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, the method for detecting the fault distance of a power transmission line according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: Computer program instructions are stored on the computer-readable storage medium, and when the computer program instructions are executed by the processor, the method for detecting the fault distance of the power transmission line according to any one of claims 1 to 7 is implemented.

11. A computer program product, characterized in that When the instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the method for detecting the fault distance of a power transmission line as described in any one of claims 1 to 7.

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