Fault location method, device, equipment and computer storage medium

Abstract

The application discloses a fault location method and device, equipment and computer storage medium, and relates to the technical field of power systems. The fault location method comprises the following steps: obtaining target data of a measuring point after a fault occurs in a power transmission line; the target data comprises voltage phasors and current phasors of positive sequences, negative sequences and zero sequences of the measuring point after the fault occurs; based on a fault boundary condition of a fault point in the power transmission line, a target composite sequence network is constructed; based on the target composite sequence network, a target Kirchhoff voltage (KVL) equation set is constructed; and the target data is substituted into the target KVL equation set, so that the position of the fault point in the power transmission line is solved. According to the embodiment of the application, the influence of a fault transition resistance on single-end location accuracy can be eliminated, the problem of insufficient single-end fault location information under high-resistance grounding fault is solved, and the reliability of fault location is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power systems, and particularly relates to a fault distance measurement method, device, equipment and computer storage medium. BACKGROUND

[0002] In the relay protection of a power system, accurate fault distance measurement for a high-voltage overhead transmission line is of great significance to the safe and stable operation of the power system. At present, fault distance measurement methods for high-voltage overhead transmission lines are mainly divided into three types in terms of principle, including a fault analysis distance measurement method based on power frequency electrical quantities, a traveling wave distance measurement method, and a distance measurement method based on high-frequency transient quantities. At present, the traveling wave distance measurement method is a relatively accurate method among the above distance measurement methods, but this method often requires accurate wideband linear voltage and current transformers, and also requires the collection of wideband voltage and current signals. In addition, the traveling wave distance measurement applied to an AC line also has problems such as the uncertainty of the generation of traveling waves, the extraction of traveling wave signals, the frequency variation effect of parameters, and the determination of wave speed, so its cost and uncertainty are relatively high. In comparison, the above fault analysis distance measurement method based on power frequency electrical quantities is usually dominated by impedance methods, and the distance measurement cost is relatively low, and has great engineering practical value.

[0003] For the above fault analysis distance measurement method based on power frequency electrical quantities, it can be further divided into single-end distance measurement method and double-end distance measurement method according to the different data used. Generally, the double-end method is more accurate than the single-end method, but the double-end method requires stable communication and time synchronization, which further increases the cost and uncertainty. Therefore, in general, the single-end fault distance measurement method based on power frequency electrical quantities is relatively simple and economical, and has greater engineering practical value.

[0004] However, although the above single-end fault distance measurement method based on power frequency electrical quantities has good engineering practical value, it has poor resistance to transition resistance, so the fault distance measurement has obvious precision defects in the case of transition resistance fault. SUMMARY

[0005] The embodiments of the present application provide a fault distance measurement method, device, equipment and computer storage medium, which can eliminate the influence of fault transition resistance on single-end distance measurement accuracy, solve the problem of insufficient single-end fault distance measurement information under high-resistance grounding fault, and improve the reliability of fault distance measurement.

[0006] In a first aspect, the embodiments of the present application provide a fault distance measurement method, which comprises:

[0007] Obtaining target data of a measurement point after a fault occurs in a transmission line; the target data includes voltage phasors and current phasors of positive sequence, negative sequence and zero sequence of the measurement point after the fault occurs;

[0008] Construct a target composite sequence network based on the fault boundary condition of the fault point in the transmission line;

[0009] Construct a target Kirchhoff voltage (KVL) equation set based on the target composite sequence network;

[0010] Substitute the target data into the target KVL equation set to obtain the position of the fault point in the transmission line.

[0011] In some possible implementations, constructing a target Kirchhoff voltage (KVL) equation set based on the target composite sequence network comprises:

[0012] Constructing the target KVL equation set based on the negative sequence network loop, the zero sequence network loop, and the target network loop in the target composite sequence network;

[0013] The target network loop is a composite sequence network loop composed of the zero sequence network loop, the positive sequence network loop, and the negative sequence network loop in the target composite sequence network.

[0014] In some possible implementations, substituting the target data into the target KVL equation set to obtain the position of the fault point in the transmission line comprises:

[0015] Substituting the target data into the target KVL equation set;

[0016] Performing real part solution and imaginary part solution on the target KVL equation set after substituting the target data to obtain the position of the fault point in the transmission line.

[0017] In some possible implementations, when the length of the transmission line is greater than or equal to a preset threshold, constructing a target composite network based on the fault boundary condition of the fault point in the transmission line comprises:

[0018] Constructing a target composite sequence network based on the fault boundary condition of the fault point in the transmission line and the π-type equivalent circuit of the transmission line.

[0019] In some possible implementations, before obtaining the target data of the measurement point after the transmission line fails, the fault location method further comprises:

[0020] In the case where the transmission line fails, collecting the instantaneous values of three-phase voltages and the instantaneous values of three-phase currents of the measurement point in the transmission line;

[0021] Performing full-cycle Fourier transform and phase sequence transform on the instantaneous values of three-phase voltages and the instantaneous values of three-phase currents to obtain the target data.

[0022] In some possible implementations, when the fault is a single-phase ground fault, the target KVL equation set comprises:

[0023]

[0024] wherein M, N are the two ends of the transmission line, M is the measurement point, and F is the fault point;

[0025] unit length positive sequence and zero sequence impedance of the transmission line z1, z0; zero sequence, positive sequence, and negative sequence impedance of the line MF segment in the transmission line Z LMi zero sequence, positive sequence, and negative sequence impedance of the line FN segment in the transmission line Z LNi zero sequence, positive sequence, and negative sequence system impedance of the transmission line M, N side Z Mi , Z Ni zero sequence, positive sequence, and negative sequence voltage phasor at the measurement point M zero sequence, positive sequence, and negative sequence current phasor at the measurement point M

[0026] x is the distance between the fault point F and the measurement point M; R f is the fault transition resistance; Z N2 is the opposite end system negative sequence impedance of the transmission line; Z N0 is the opposite end system zero sequence impedance of the transmission line; is the positive sequence component of the fault current.

[0027] In some possible embodiments, when the fault is a single-phase ground fault and the full length of the transmission line is greater than or equal to a preset threshold, the target KVL equation set includes:

[0028]

[0029]

[0030]

[0031] wherein M, N are the two ends of the transmission line, M is the measurement point, and F is the fault point;

[0032]

[0033]

[0034] unit length positive sequence and zero sequence impedance of the transmission line z1, z0; unit length positive sequence and zero sequence admittance of the transmission line y1, y0; zero sequence, positive sequence, and negative sequence impedance of the line MF segment in the transmission line Z LMi zero sequence, positive sequence, and negative sequence admittance of the line MF segment in the transmission line Y LMi zero sequence, positive sequence, and negative sequence impedance of the line FN segment in the transmission line Z LNi(i=0, 1, 2); zero sequence, positive sequence, negative sequence admittance Y of the line FN section in the transmission line LNi (i=0, 1, 2); zero sequence, positive sequence, negative sequence system impedance Z of the M, N side of the transmission line Mi , Z Ni (i=0, 1, 2); zero sequence, positive sequence, negative sequence system admittance Y of the M, N side of the transmission line Mi , Y Ni (i=0, 1, 2); zero sequence, positive sequence, negative sequence voltage phasor at the measurement point M zero sequence, positive sequence, negative sequence current phasor at the measurement point M

[0035] x is the distance between the fault point F and the measurement point M; R f is the fault transition resistance; Z N2 is the opposite end system negative sequence impedance of the transmission line; Z N0 is the opposite end system zero sequence impedance of the transmission line; is the positive sequence component of the fault current.

[0036] In a second aspect, the embodiments of the present application provide a fault location device, which comprises:

[0037] A first obtaining module is configured to obtain target data of a measurement point after a fault occurs in a transmission line; the target data comprises positive sequence, negative sequence and zero sequence voltage phasors and current phasors of the measurement point after the fault occurs;

[0038] A first constructing module is configured to construct a target composite sequence network based on a fault boundary condition of a fault point in the transmission line;

[0039] A second constructing module is configured to construct a target Kirchhoff voltage law (KVL) equation set based on the target composite sequence network;

[0040] A first obtaining module is configured to obtain target data of a measurement point after a fault occurs in a transmission line; the target data comprises positive sequence, negative sequence and zero sequence voltage phasors and current phasors of the measurement point after the fault occurs;

[0041] In a third aspect, the embodiments of the present application provide a fault location device, which comprises:

[0042] A processor and a memory storing computer program instructions;

[0043] The processor executes the computer program instructions to implement the fault location method provided in any one of the above embodiments of the present application.

[0044] In a fourth aspect, an embodiment of the present application provides a computer storage medium, which stores computer program instructions. When the computer program instructions are executed by a processor, the fault location method according to any one of the above embodiments of the present application is implemented.

[0045] 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 performs the fault location method according to any one of the above embodiments of the present application.

[0046] The fault location method, the device, the equipment and the computer storage medium provided by the embodiments of the present application construct a target composite sequence network through the boundary condition of the fault point in the fault point of the power transmission line, and solve the position of the fault point in the power transmission line according to the KVL equation set written according to the constructed target composite sequence network. The fault location method, the device, the equipment and the computer storage medium provided by the embodiments of the present application construct a target composite sequence network to write a KVL equation set. In this step, the fault transition resistance is actually included in the equation set as an unknown quantity to be solved subsequently. In this way, in the present application, the influence of the fault transition resistance on the single-end fault location accuracy is substantially eliminated, thereby effectively solving the problem of insufficient fault location information of the single-end method under high-resistance grounding fault, and improving the reliability of fault location. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced. Those skilled in the art can obtain other drawings according to these drawings without creating any creative labor.

[0048] Figure 1 FIG. 1 is a flowchart of a fault location method according to an embodiment of the present application;

[0049] Figure 2 FIG. 2 is a single-line diagram of a typical power transmission line fault according to an embodiment of the present application;

[0050] Figure 3 FIG. 3 is a composite sequence network diagram of a single-phase grounding fault according to an embodiment of the present application;

[0051] Figure 4 FIG. 4 is a composite sequence network diagram of a single-phase grounding fault considering distributed capacitance according to an embodiment of the present application;

[0052] Figure 5 FIG. 5 is a fault location result and a fault location error of a simulation experiment of a fault location method according to an embodiment of the present application;

[0053] Figure 6is a structural schematic diagram of a fault location device provided by an embodiment of the present application.

[0054] Figure 7 is a structural schematic diagram of a fault location device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0055] The features and exemplary embodiments of various aspects of the present application will be described in detail below with reference to the drawings. The following detailed description is merely intended to explain the present application, and is not intended to limit the present application. The present application can be implemented without some of the specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application through showing examples of the present application.

[0056] It should be noted that, in this document, the terms such as first and second are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" 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 not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, 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.

[0057] As described in the background section, although the above-mentioned single-ended fault location method based on power frequency electrical quantity has good engineering practical value, the single-ended impedance location method needs to assume that the fault current flowing through the fault transition resistance and the current at the measurement point are in phase, which is not necessarily true when passing through the transition resistance, thereby bringing errors to the measurement results. For high-resistance grounding faults with a transition resistance of tens of ohms or even hundreds of ohms, the error is more serious.

[0058] To solve the problems in the prior art, the embodiments of the present application provide a fault location method, device, equipment, storage medium and computer program product. It should be noted that the embodiments provided by the present application are not intended to limit the scope of the present application.

[0059] The fault location method provided by the embodiments of the present application will be introduced first.

[0060] Figure 1A flowchart of a fault location method provided by an embodiment of the present application is shown. The fault location method is applied to an electronic device, which can include a server or a user terminal, etc. As shown in Figure 1 The fault location method includes the following steps:

[0061] S110, obtaining target data of a measurement point after a fault occurs in a power transmission line; the target data includes voltage phasors and current phasors of positive sequence, negative sequence and zero sequence of the measurement point after the fault occurs;

[0062] S120, constructing a target composite sequence network based on a fault boundary condition of a fault point in the power transmission line;

[0063] S130, constructing a target Kirchhoff voltage law (KVL) equation set based on the target composite sequence network;

[0064] S140, substituting the target data into the target KVL equation set to obtain a location of the fault point in the power transmission line.

[0065] The fault location method of the embodiment of the present application constructs a target composite sequence network based on a fault boundary condition of a fault point in a power transmission line, and writes a KVL equation set according to the constructed target composite sequence network, so as to obtain a location of the fault point in the power transmission line. The fault location method provided by the embodiment of the present application writes a KVL equation set based on a constructed target composite sequence network, and in this step, the fault transition resistance is actually taken as an unknown quantity to be listed in the equation set for subsequent solving. In this way, in the present application, the influence of the fault transition resistance on the single-end location accuracy is substantially eliminated, thereby effectively solving the problem of insufficient fault location information of a single-end method under a high-resistance grounding fault, and improving the reliability of fault location.

[0066] In S110, when specifically implemented, the measurement point position of the power transmission line can be pre-provided with a related data acquisition device, which can acquire and process related electrical quantities of the measurement point after a fault occurs in the power transmission line. In this way, the target data of the measurement point after the fault occurs in the power transmission line can be obtained through the above-mentioned related data acquisition device.

[0067] The target data can specifically include voltage phasors and current phasors of positive sequence, negative sequence and zero sequence of the measurement point of the power transmission line after the fault occurs.

[0068] In some possible implementations, in order to more reasonably obtain the target data of the measurement point, before obtaining the target data of the measurement point after the fault occurs in the power transmission line, the fault location method can further include:

[0069] In the case of a fault in the power transmission line, instantaneous values of three-phase voltages and instantaneous values of three-phase currents at a measuring point in the power transmission line are collected;

[0070] The instantaneous values of three-phase voltages and the instantaneous values of three-phase currents are subjected to full-cycle Fourier transform and phase sequence transform to obtain target data.

[0071] In a specific implementation, a single-end measuring point of the power transmission line can be pre-installed with a current transformer, a voltage transformer, etc. In this way, in the case of a fault in the power transmission line, instantaneous values of three-phase voltages and instantaneous values of three-phase currents at a measuring point in the power transmission line are collected by a current transformer, a voltage transformer, etc.

[0072] After the instantaneous values of three-phase voltages and the instantaneous values of three-phase currents are collected, the voltage and current phasors of positive sequence, negative sequence, and zero sequence are calculated by full-cycle Fourier transform and phase sequence transform, i.e., the above-mentioned target data are obtained, so as to facilitate subsequent specific calculation.

[0073] It should be noted that, considering the time delay of line three-phase signals, in order to make the subsequent fault distance calculation result more accurate, the above-mentioned voltages and currents can be collected after a preset time period after the fault occurs. Exemplarily, the sampling values of the single-end electrical quantities can be instantaneous values of three-phase voltages and instantaneous values of three-phase currents at the 5th cycle after the fault of the power transmission line.

[0074] In S120, exemplarily, considering the diversity of fault types in the power transmission line, and high-resistance ground faults are more likely to occur in single-phase ground faults, the subsequent steps will be specifically introduced mainly taking single-phase ground faults as an example.

[0075] Please refer to Figure 2 , Figure 2 which is a typical single-line diagram of a power transmission line fault provided by an embodiment of the present application. Taking a single-phase ground fault of a double-power supply as shown in Figure 2 as an example. Figure 2 In , MN is an output circuit, M is a measuring point, F is a fault point, and it is assumed that a single-phase ground fault of phase A occurs at the F point. are respectively the Thevenin equivalent sources on the M side and the N side; Z M , Z N are respectively the system impedances on the M side and the N side.

[0076] In a specific implementation of S120, in combination with the above-mentioned scenario, if a fault occurring in the power transmission line is a single-phase ground fault, a target composite sequence network of the single-phase ground fault is constructed based on a fault boundary condition of the fault point F in the power transmission line MN. The target composite sequence network can be specifically referred to Figure 3 , Figure 3This is a schematic diagram of a composite sequence network for a single-phase grounding fault provided in an embodiment of this application.

[0077] like Figure 3 As shown, Figure 3 In the target composite sequence network, the known quantities include: Z LMi (i = 0, 1, 2) represent the zero-sequence, positive-sequence, and negative-sequence impedances of the MF segment of the transmission line; Z LNi (i = 0, 1, 2) represent the zero-sequence, positive-sequence, and negative-sequence impedances of the FN segment of the transmission line; Z Mi Z Ni (i = 0, 1, 2) represent the zero-sequence, positive-sequence, and negative-sequence system impedances on the M and N sides, respectively; These are the zero-sequence, positive-sequence, and negative-sequence voltage phasors at measurement point M; Let M be the zero-sequence, positive-sequence, and negative-sequence current phasors at the measurement point M.

[0078] The unknown quantity is: the fault transition resistance is R. f , These are the zero-sequence, positive-sequence, and negative-sequence components of the fault current.

[0079] The fault boundary conditions at fault point F are as shown in Equation 1:

[0080]

[0081] It should be noted that, considering the complexity and miniaturization of various electrical quantities in actual transmission lines, in order to ensure the calculability of the single-ended fault location scheme of this application, this application makes the following approximations without affecting the actual location accuracy as much as possible: the fault transition resistance is a pure resistance; the positive sequence impedance and negative sequence impedance of the line are equal; and the distributed capacitance of the line is ignored when the transmission line is a short line; the impedance angle of the power system is known, and since the reactance in the actual system is much greater than the resistance, this application approximates the system impedance as a pure reactance.

[0082] In S130, in specific implementation, if the fault in the transmission line is a single-phase ground fault, then, after obtaining... Figure 2 After the target composite sequence network shown, the target Kirchhoff voltage KVL equations can be directly constructed based on the target composite sequence network according to Kirchhoff's laws.

[0083] In some possible implementations, considering that the Thevenin equivalent power source in the positive sequence network loop needs to be solved, and to facilitate the subsequent calculation of the fault location and avoid introducing more unknowns to increase the complexity of solving the subsequent equations, the above-mentioned construction of the target Kirchhoff voltage KVL equations based on the target composite sequence network may include:

[0084] Based on the negative sequence network loop, the zero sequence network loop and the target network loop in the target composite sequence network, a target KVL equation set is constructed;

[0085] The target network loop can be a composite sequence network loop composed of the zero sequence network loop, the positive sequence network loop and the negative sequence network loop in the target composite sequence network.

[0086] In some possible implementation manners, specifically, when the fault is a single-phase ground fault, the target KVL equation set can be specifically as shown in the following formula 2:

[0087]

[0088] Wherein, M and N are two ends of a power transmission line, M is a measurement point, and F is a fault point.

[0089] In the formula (2), the known quantities include: positive sequence and zero sequence impedance per unit length of the power transmission line z1, z0; zero sequence, positive sequence and negative sequence impedance Z LMi (i=0, 1, 2) of the line MF segment in the power transmission line; zero sequence, positive sequence and negative sequence impedance Z LNi (i=0, 1, 2) of the line FN segment in the power transmission line; zero sequence, positive sequence and negative sequence system impedance Z Mi , Z Ni (i=0, 1, 2) of the power transmission line; zero sequence, positive sequence and negative sequence voltage phasor Zero sequence, positive sequence and negative sequence current phasor at the measurement point M

[0090] The unknown quantities include: x is the distance between the fault point F and the measurement point M; R f is a fault transition resistance; Z N2 is the opposite end system negative sequence impedance of the power transmission line; Z N0 is the opposite end system zero sequence impedance of the power transmission line; is the positive sequence component of the fault current.

[0091] It should be understood that, considering that the target data has been obtained in step 110, i.e., the voltage phasor and the current phasor of the measurement point after the fault occurs, therefore, for the convenience of understanding, the parameters in the target KVL equation set shown in the formula (2) are directly taken as the known quantities when introducing the parameters in the target KVL equation set shown in the formula (2), but this does not conflict with the subsequent step 140 of substituting the target data into the target KVL equation set for solving.

[0092] In S140, when specifically implemented, the target data obtained in the foregoing step 110 can be substituted into the target KVL equation set shown in the formula (2), so as to solve the above-mentioned multiple unknown quantities.

[0093] The distance between the fault point F and the measuring point M can be obtained after solving, and the position of the fault point in the power transmission line is determined.

[0094] In a more specific embodiment, in order to better solve the position of the fault point in the power transmission line, the above-mentioned target data is substituted into the target KVL equation set, and the position of the fault point in the power transmission line is solved, which can specifically include:

[0095] Substitute the target data into the target KVL equation set;

[0096] The target KVL equation set after substituting the target data is subjected to real part solution and imaginary part solution, and the position of the fault point in the power transmission line is solved.

[0097] In the embodiment, the target KVL equation set shown in the above-mentioned formula (2) is taken as an example. Although the target KVL equation set shown in the formula (2) is three equations in form, in actual calculation, one complex equation can be decomposed into two equations of real part and imaginary part. Specifically, in the formula (2), the unknown quantity x and R f are single variables; Z N2 and Z N0 are complex numbers and the real part and the imaginary part are unknown, which can be decomposed into two variables of real part and imaginary part.

[0098] In this way, the real part solution and the imaginary part solution of the target KVL equation set are carried out around the complex number , and the original five unknown quantities are expanded to six. At the same time, the above-mentioned target KVL equation set can finally obtain a new equation set containing six equations through the real part solution and the imaginary part solution. Finally, the number of equations in the new equation set is the same as the number of unknown quantities (to be solved), which guarantees the solvability of the new equation set.

[0099] Specifically, the above-mentioned new equation set can be shown in the following formula (3):

[0100]

[0101] In the above-mentioned formula (3), the to-be-solved quantities in the new equation set are: the fault position (the distance between the fault point F and the measuring point M) x, the fault transition resistance R f , the imaginary part Im[Z N2 ] of the negative sequence impedance of the opposite system of the power transmission line, the imaginary part Im[Z N0 ] of the zero sequence impedance of the opposite system of the power transmission line, the real part and the imaginary part

[0102] ​In this embodiment, considering that the new equation set is a nonlinear equation set, it is difficult to solve directly, and therefore a numerical calculation method can be used for iterative solution. Specifically, the present application uses the "fsolve" function in the MATLAB calculation software for solution, and the specific algorithm is the Trust Region Method, so that the equation set can be solved to obtain the position of the fault point in the power transmission line.

[0103] It should be noted that in other embodiments, other methods for solving nonlinear equation sets can also be used to solve the new equation set shown in equation (3), and the present application does not make specific limitations thereto.

[0104] In some possible implementations, considering that if the distributed capacitance is ignored in the case of a long power transmission line, a large ranging error is easily caused. Therefore, in order to guarantee the accuracy of single-ended fault ranging, when the full length of the power transmission line is greater than or equal to a preset threshold, a target composite network is constructed based on the fault boundary condition of the fault point in the power transmission line, which can include:

[0105] Based on the fault boundary condition of the fault point in the power transmission line and the π-type equivalent circuit of the power transmission line, a target composite sequence network is constructed.

[0106] The above-mentioned preset threshold can be set by a person skilled in the art in combination with actual power system fault experience, and the present application does not make specific limitations thereto.

[0107] In this embodiment, considering the distributed capacitance existing in the power transmission line, the target composite sequence network is constructed in combination with the fault boundary condition of the fault point in the power transmission line and the π-type equivalent circuit of the power transmission line. Specifically, please refer to Figure 4 , Figure 4 is a composite sequence network schematic diagram of single-phase ground fault considering distributed capacitance provided by an embodiment of the present application.

[0108] As shown in Figure 4 , under the premise of considering the line distributed capacitance, the target composite sequence network is constructed by using the characteristics of the π-type equivalent circuit of the power transmission line. Figure 4 In the above-mentioned equation (4), it is assumed that the distance between the measuring point M and the fault point F is x; the unit length positive sequence and zero sequence impedance of the power transmission line are known quantities z1 and z0; and the unit length positive sequence and zero sequence ground admittance of the power transmission line are known quantities y1 and y0.

[0109] Further, in a more specific implementation, when the fault in the power transmission line is single-phase ground fault and the full length of the power transmission line is greater than or equal to a preset threshold, the above-mentioned target KVL equation set can be as shown in equation (4):

[0110]

[0111]

[0112]

[0113] In the target KVL equation group shown in formula (4), M and N are two ends of the transmission line, M is a measurement point, and F is a fault point;

[0114]

[0115]

[0116] In the target KVL equation group shown in formula (4), the known quantities include: the positive sequence and zero sequence impedance per unit length of the transmission line z1, z0; the positive sequence and zero sequence ground admittance of the transmission line y1, y0; the zero sequence, positive sequence and negative sequence impedance of the line MF segment in the transmission line Z LMi (i=0, 1, 2), which can be calculated in combination with formula (5); the zero sequence, positive sequence and negative sequence admittance of the line MF segment in the transmission line Y LMi (i=0, 1, 2); the zero sequence, positive sequence and negative sequence impedance of the line FN segment in the transmission line Z LNi (i=0, 1, 2), which can be calculated in combination with formula (6); the zero sequence, positive sequence and negative sequence admittance of the line FN segment in the transmission line Y LNi (i=0, 1, 2); the zero sequence, positive sequence and negative sequence system impedance of the transmission line M and N sides Z Mi , Z Ni (i=0, 1, 2); the zero sequence, positive sequence and negative sequence system admittance of the transmission line M and N sides Y Mi , Y Ni (i=0, 1, 2), which can be calculated in combination with formula (5) and formula (6); the zero sequence, positive sequence and negative sequence voltage phasor at the measurement point M the zero sequence, positive sequence and negative sequence current phasor at the measurement point M

[0117] The unknown quantities include: x is the distance between the fault point F and the measurement point M; R f is a fault transition resistance; Z N2 is the opposite end system negative sequence impedance of the transmission line; Z N0 is the opposite end system zero sequence impedance of the transmission line; is the positive sequence component of the fault current.

[0118] After the above formula (4) is obtained by considering the distributed capacitance, it can be solved by means of the method shown in the foregoing description for ignoring the line distributed capacitance. Specifically, in the target KVL equation set shown in formula (4), one complex equation can be decomposed into two equations of real part and imaginary part, and therefore the target KVL equation set shown in formula (4) can finally be converted into a new equation set including 14 equations. Since the above equation set is a nonlinear equation set, it is difficult to be solved directly, and needs to be solved iteratively by using a numerical calculation method. In this embodiment, the "fsolve" function in the calculation software MATLAB is used for solving, and the specific algorithm is Trust Region Method. In this way, the specific position of the fault point in the transmission line can be determined by solving the new equation set.

[0119] In order to fully reflect the feasibility and reliability of the fault location method provided in the embodiments of the present application, a simulation model of a power transmission system as shown in Figure 1 is built by using the PSCAD / EMTDC electromagnetic transient simulation program to specifically simulate and verify the above fault location method.

[0120] In the specific simulation experiment, different fault positions and fault resistances are set for simulation and calculation. The Bergeron model is used for the transmission line, the total length of the line is set to 100 km, and the fault transition resistances are set to 0.001 Ω, 20 Ω, 50 Ω, 100 Ω, 200 Ω and 500 Ω respectively. The fault type is set to single-phase ground fault, and the A phase is the fault phase. The sampling values of the measurement point M of the single-ended electrical quantity are set to the instantaneous values of the three-phase voltage and the three-phase current at the 5th cycle after the fault, and the sampling frequency is 10 kHz.

[0121] After the single-phase ground fault occurs in the transmission line, the instantaneous values of the three-phase voltage and the three-phase current at the 5th cycle after the fault of the measurement point M in the transmission line are measured, the positive sequence, negative sequence and zero sequence voltage phasors and current phasors are calculated through full-cycle Fourier transform and phase sequence transform, and are substituted into the equation set in the foregoing description of the present application for numerical solution, so as to determine the distance between the fault and the measurement point.

[0122] For details, please refer to Figure 5 , Figure 5 The fault location result and the location error of the simulation experiment of the fault location method provided in an embodiment of the present application are shown in the table. Figure 5 It can be seen from the table that the fault location result obtained by the fault location method of the present application has good accuracy. Especially when the distance between the fault position and the measurement point is less than half of the total length of the transmission line, the location error is basically less than 0.5 km.

[0123] Further, from Figure 5It can be seen from the shown distance measurement error result that in the simulation experiment of different fault transition resistances, the resistance value of the fault transition resistance does not obviously affect the distance measurement precision of the fault distance measurement method, which fully reflects the superiority of the single-end fault distance measurement algorithm in the high-resistance grounding fault case.

[0124] It can be seen that the fault distance measurement method provided in the embodiment of the application establishes a circuit relationship equation set according to a sequence component network after an asymmetric fault of a line, introduces mutual inductance information in a traditional impedance distance measurement algorithm by using network equations of a zero sequence network and a negative sequence network, and eliminates the influence of a fault resistance and a terminal impedance on the single-end fault distance measurement precision by using the assumption that the terminal impedance of the line is generally approximately a pure reactance. The fault distance measurement method provided in the embodiment of the application eliminates the influence of the fault resistance and the terminal impedance on the single-end distance measurement precision, solves the problem of insufficient single-end fault distance measurement information in the high-resistance grounding fault case, and improves the reliability of fault distance measurement. The fault distance measurement method provided in the embodiment of the application provides an effective improvement and expansion for the existing single-end fault distance measurement means of a power transmission line.

[0125] Based on the fault distance measurement method provided in the above embodiment, the application further provides a fault distance measurement device corresponding to the fault distance measurement method. Figure 6 The fault distance measurement device is described in detail.

[0126] Figure 6 The structure schematic diagram of the fault distance measurement device provided in the embodiment of the application is shown. Figure 6 The shown fault distance measurement device 600 includes:

[0127] The first obtaining module 610 is configured to obtain target data of a measurement point after a fault of a power transmission line; the target data includes voltage phasors and current phasors of positive sequences, negative sequences and zero sequences of the measurement point after the fault;

[0128] The first constructing module 620 is configured to construct a target composite sequence network based on a fault boundary condition of a fault point in the power transmission line.

[0129] The second constructing module 630 is configured to construct a target Kirchhoff voltage (KVL) equation set based on the target composite sequence network.

[0130] The first obtaining module 640 is configured to substitute the target data into the target KVL equation set to obtain a position of the fault point in the power transmission line.

[0131] The fault location device provided in the embodiments of the present application can construct a target composite sequence network based on the boundary conditions of the fault point in the power transmission line, and write KVL equation sets according to the constructed target composite sequence network, so as to obtain the position of the fault point in the power transmission line. The fault location device provided in the embodiments of the present application writes KVL equation sets through the constructed target composite sequence network, and in this step, the fault transition resistance is actually taken as an unknown quantity and included in the equation sets for subsequent solving. Therefore, in the present application, the influence of the fault transition resistance on the single-end fault location accuracy is substantially eliminated, thereby effectively solving the problem of insufficient fault location information of the single-end method under high-resistance ground fault, and improving the reliability of fault location.

[0132] In some possible implementation manners, considering that the Thevenin equivalent source in the positive sequence network loop needs to be solved, based on this, in order to facilitate the subsequent calculation and solving of the position of the fault point, more unknown quantities are avoided to increase the complexity of subsequent equation set solving, the above second construction module 630 can be configured to construct a target KVL equation set based on the negative sequence network loop, the zero sequence network loop and the target network loop in the target composite sequence network.

[0133] The target network loop can be a composite sequence network loop composed of the zero sequence network loop, the positive sequence network loop and the negative sequence network loop in the target composite sequence network.

[0134] In some possible implementation manners, in order to better solve the position of the fault point in the power transmission line, the above first obtaining module 640 can specifically include:

[0135] The substitution sub-module can be configured to substitute the target data into the target KVL equation set.

[0136] The solving sub-module can be configured to perform real part solving and imaginary part solving on the target KVL equation set after the target data is substituted, and obtain the position of the fault point in the power transmission line.

[0137] In some possible implementation manners, considering that if the distributed capacitance is ignored, a larger fault location error is easily caused in the case of a long power transmission line. Therefore, in order to guarantee the accuracy of single-end fault location, when the full length of the power transmission line is greater than or equal to a preset threshold, the above first construction module 620 can specifically include:

[0138] Constructing a target composite sequence network based on the fault boundary conditions of the fault point in the power transmission line and the π-type equivalent circuit of the power transmission line.

[0139] In some possible implementation manners, in order to more reasonably obtain the target data of the measurement point, before obtaining the target data of the measurement point after the fault of the power transmission line occurs, the fault location device can further include:

[0140] The first acquisition module can be used for acquiring the instantaneous values of three-phase voltages and the instantaneous values of three-phase currents of the measuring point in the power transmission line in the case where the power transmission line has a fault;

[0141] The second obtaining module can be used for performing full-cycle Fourier transform and phase sequence transform on the instantaneous values of three-phase voltages and the instantaneous values of three-phase currents to obtain target data.

[0142] In some possible implementation manners, specifically, when the fault is a single-phase ground fault, the above target KVL equation set can include:

[0143]

[0144] wherein M and N are two ends of the power transmission line, M is the measuring point, and F is the fault point;

[0145] unit length positive sequence and zero sequence impedance z1 and z0 of the power transmission line; zero sequence, positive sequence and negative sequence impedance ZMF of the line MF segment in the power transmission line LMi (i=0, 1, 2); zero sequence, positive sequence and negative sequence impedance ZFN of the line FN segment in the power transmission line LNi (i=0, 1, 2); zero sequence, positive sequence and negative sequence system impedance ZMN of the power transmission line on the M and N sides Mi , Z Ni (i=0, 1, 2); zero sequence, positive sequence and negative sequence voltage phasor at the measuring point M zero sequence, positive sequence and negative sequence current phasor at the measuring point M

[0146] x is a distance between the fault point F and the measuring point M; R f is a fault transition resistance; Z N2 is a counter terminal system negative sequence impedance of the power transmission line; Z N0 is a counter terminal system zero sequence impedance of the power transmission line; is a positive sequence component of the fault current.

[0147] In some possible implementation manners, specifically, when the fault is a single-phase ground fault and the full length of the power transmission line is greater than or equal to a preset threshold, the above target KVL equation set can include:

[0148]

[0149]

[0150]

[0151] wherein M and N are two ends of the power transmission line, M is the measuring point, and F is the fault point;

[0152]

[0153]

[0154] Positive and zero sequence impedance per unit length of the transmission line z1, z0; Positive and zero sequence admittance per unit length of the transmission line y1, y0; Zero sequence, positive sequence and negative sequence impedance of the line MF section in the transmission line Z LMi (i = 0, 1, 2); Zero sequence, positive sequence and negative sequence admittance of the line MF section in the transmission line Y LMi (i = 0, 1, 2); Zero sequence, positive sequence and negative sequence impedance of the line FN section in the transmission line Z LNi (i = 0, 1, 2); Zero sequence, positive sequence and negative sequence admittance of the line FN section in the transmission line Y LNi (i = 0, 1, 2); Zero sequence, positive sequence and negative sequence system impedance of the M, N side of the transmission line Z Mi , Z Ni (i = 0, 1, 2); Zero sequence, positive sequence and negative sequence system admittance of the M, N side of the transmission line Y Mi , Y Ni (i = 0, 1, 2); Zero sequence, positive sequence and negative sequence voltage phasor at the measurement point M Zero sequence, positive sequence and negative sequence current phasor at the measurement point M

[0155] x is the distance between the fault point F and the measurement point M; R f is the fault transition resistance; Z N2 is the opposite end system negative sequence impedance of the transmission line; Z N0 is the opposite end system zero sequence impedance of the transmission line; is the positive sequence component of the fault current.

[0156] Figure 7 is a structural schematic diagram of a fault location device provided by an embodiment of the application.

[0157] The fault location device can include a processor 701 and a memory 702 having computer program instructions stored therein.

[0158] Specifically, the processor 701 described above can include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or can be configured as one or more integrated circuits that implement the embodiments of the application.

[0159] The memory 702 can include mass storage for data or instructions. As an example and not by way of limitation, the memory 702 can include a hard disk drive (HDD), a floppy disk drive, flash memory, an optical disc (e.g., a compact disc (CD) or a digital versatile disc (DVD)), a solid-state drive (SSD), a USB drive, or a combination of two or more of these. Where appropriate, the memory 702 can include removable or non-removable (or fixed) media. Where appropriate, the memory 702 can be internal or external to the integrated gateway disaster recovery device. In particular embodiments, the memory 702 is non-volatile, solid-state memory.

[0160] The memory can include read-only memory (ROM), random-access memory (RAM), magnetic disk storage mediums, optical storage mediums, flash memory devices, electrical, optical, or other physical / tangible memory storage devices. Thus, in general, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., a memory device) encoded with software that, when executed (by one or more processors), is operable to access the data and / or instructions that enable the operations described with reference to the methods according to the aspects of the present disclosure.

[0161] The processor 701 implements any of the fault location methods described above by reading and executing computer program instructions stored in the memory 702.

[0162] In one example, the data fault location device can also include a communication interface 703 and a bus 710. As shown, the processor 701, the memory 702, and the communication interface 703 are connected through the bus 710 and accomplish the communication between each other. Figure 7

[0163] The communication interface 703 is mainly used to realize the communication between each module, device, unit and / or equipment in the embodiments of the present application.

[0164] ​Bus 710 includes a hardware, software, or both that couples components of the fault location device to each other. As an example and not by way of limitation, the bus can include an accelerated graphics port (AGP) or other graphics bus, an enhanced industry standard architecture (EISA) bus, a front-side bus (FSB), a HyperTransport (HT) interconnect, an industry standard architecture (ISA) bus, an infiniband (IB) interconnect, a low pin count (LPC) bus, a memory bus, a microchannel architecture (MCA) bus, a peripheral component interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a serial advanced technology attachment (SATA) bus, a video electronics standards board (VLB) bus, or another suitable bus or a combination of two or more of these. Where suitable, bus 710 can include one or more buses. Although this application describes and illustrates a particular bus, this application contemplates any suitable bus or interconnect.

[0165] The fault location device performs the fault location method in the embodiments of the application, thereby achieving Figure 1 the fault location method described.

[0166] In addition, in combination with the fault location method in the above embodiments, the embodiments of the application can provide a computer storage medium to implement. The computer storage medium has computer program instructions stored thereon; the computer program instructions are executed by a processor to implement any one of the fault location methods in the above embodiments.

[0167] Based on the fault location method in the above embodiments, the embodiments of the application provide a computer program product, instructions in the computer program product are executed by a processor of an electronic device, so that the electronic device executes the fault location method provided by any one of the above embodiments of the application.

[0168] It needs to be clear that the application is not limited to the specific configurations and processes described above and shown in the drawings. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the 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 steps, after understanding the spirit of the application.

[0169] The functions noted in the description of the structural block diagrams above can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, and the like. When implemented in software, the elements of the present application are program or code segments that are used to perform the required tasks. The program or code segments can be stored in a machine-readable medium, or transmitted through a data signal carried in a carrier wave over a transmission medium or communication link. A "machine-readable medium" includes any medium that can store or transport 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, fiber optic media, radio frequency (RF) links, and the like. The code segments can be downloaded via computer networks such as the Internet, intranets, and the like.

[0170] It is also important to note that the examples mentioned in the present application describe some methods or systems based on a series of steps or devices. However, the present application is not limited to the order of the steps mentioned above, that is, the steps can be performed in the order mentioned in the examples, or in an order different from the examples, or several steps can be performed simultaneously.

[0171] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. These computer program instructions can also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other processing device to operate in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks. The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. These computer program instructions can also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other processing device to operate in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0172] The above merely describes a specific implementation of the present application. Those skilled in the art can clearly understand the specific working processes of the system, modules and units described above for the convenience and brevity of description, and can refer to the corresponding processes in the foregoing method embodiments, which will not be described herein again. It should be understood that the protection scope of the present application is not limited to this, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application.

Claims

1. A fault location method, characterized in that, include: Acquire target data of measurement points after a power transmission line fault occurs; The target data includes positive-sequence, negative-sequence, and zero-sequence voltage and current phasors at the measurement points after the fault occurs. Based on the fault boundary conditions of the fault points in the transmission line, a target composite sequence network is constructed. Based on the target composite sequence network, construct the target KVL equation system; Substitute the target data into the target KVL equations to solve for the location of the fault point in the transmission line. The step of substituting the target data into the target KVL equation system to solve for the location of the fault point in the transmission line includes: Substitute the target data into the target KVL equation system; The real and imaginary parts of the target KVL equations after substituting the target data are solved to obtain the location of the fault point in the transmission line; the number of equations after real and imaginary solutions is the same as the number of unknowns; When the total length of the transmission line is greater than or equal to a preset threshold, the construction of the target composite network based on the fault boundary conditions of the fault points in the transmission line includes: Based on the fault boundary conditions of the fault points in the transmission line and the π-type equivalent circuit of the transmission line, the target composite sequence network is constructed. The transmission line is approximated as follows: the fault transition resistance is a pure resistance; the positive sequence impedance and negative sequence impedance of the transmission line are equal; and the distributed capacitance of the line is ignored when the transmission line is a short line; the power system impedance is approximated as a pure reactance.

2. The method according to claim 1, characterized in that, The construction of the target Kirchhoff voltage KVL equations based on the target composite sequence network includes: Based on the negative-order network loop, zero-order network loop, and target network loop in the target composite order network, the target KVL equation system is constructed. The target network loop is a composite sequence network loop in the target composite sequence network, which is composed of the zero-sequence network loop, the positive-sequence network loop, and the negative-sequence network loop.

3. The method according to claim 1, characterized in that, Before acquiring the target data of the measurement point after the transmission line fault occurs, the method further includes: In the event of the aforementioned fault in the transmission line, the instantaneous values ​​of the three-phase voltage and the three-phase current at the measurement points in the transmission line are collected. The target data is obtained by performing full-cycle Fourier transform and phase sequence transform on the instantaneous values ​​of the three-phase voltage and the instantaneous values ​​of the three-phase current.

4. The method according to claim 2, characterized in that, When the fault is a single-phase ground fault, the target KVL equation set includes: Wherein, M and N are the two ends of the transmission line, M is the measurement point, and F is the fault point; The positive-sequence and zero-sequence impedances z1 and z0 per unit length of the transmission line; the zero-sequence, positive-sequence, and negative-sequence impedances Z of the MF segment of the transmission line. LMi (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence impedances Z of the FN segment of the transmission line. LNi (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence system impedances Z on the M and N sides of the transmission line. Mi Z Ni (i = 0, 1, 2); The zero-sequence, positive-sequence, and negative-sequence voltage phasors at measurement point M The zero-sequence, positive-sequence, and negative-sequence current phasors at measurement point M x is the distance between the fault point F and the measurement point M; R f For fault transition resistance; Z N2 Z is the negative sequence impedance of the system at the opposite end of the transmission line; N0 The zero-sequence impedance of the system at the opposite end of the transmission line; This represents the positive sequence component of the fault current.

5. The method according to claim 2, characterized in that, When the fault is a single-phase ground fault and the total length of the transmission line is greater than or equal to a preset threshold, the target KVL equation set includes: Wherein, M and N are the two ends of the transmission line, M is the measurement point, and F is the fault point; The positive-sequence and zero-sequence impedances per unit length of the transmission line are z1 and z0; the positive-sequence and zero-sequence admittances to ground per unit length of the transmission line are known quantities y1 and y0; the zero-sequence, positive-sequence, and negative-sequence impedances Z of the MF segment of the transmission line are... LMi (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence admittances Y of the MF segment of the transmission line. LMi (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence impedances Z of the FN segment of the transmission line. LNi (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence admittances Y of the FN segment of the transmission line. LNi (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence system impedances Z on the M and N sides of the transmission line. Mi Z Ni (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence system admittances Y on the M and N sides of the transmission line. Mi Y Ni (i = 0, 1, 2); the zero-sequence, positive-sequence, and negative-sequence voltage phasors at the measurement point M. The zero-sequence, positive-sequence, and negative-sequence current phasors at measurement point M x is the distance between the fault point F and the measurement point M; R f For fault transition resistance; Z N2 Z is the negative sequence impedance of the system at the opposite end of the transmission line; N0 The zero-sequence impedance of the system at the opposite end of the transmission line; This represents the positive sequence component of the fault current.

6. A fault location device, characterized in that, The device includes: The first acquisition module is used to acquire target data of the measurement point after a fault occurs in the transmission line; the target data includes positive sequence, negative sequence, and zero sequence voltage phasors and current phasors of the measurement point after the fault occurs; The first construction module is used to construct a target composite sequence network based on the fault boundary conditions of the fault points in the transmission line; The second construction module is used to construct the target KVL equation system based on the target composite sequence network; The first obtaining module is used to substitute the target data into the target KVL equation system and solve for the location of the fault point in the transmission line; The first obtaining module includes: a substitution submodule, used to substitute the target data into the target KVL equation system; The solution submodule is used to solve the target KVL equations after substituting the target data into real and imaginary solutions to obtain the location of the fault point in the transmission line; the number of equations after real and imaginary solutions is the same as the number of unknowns; When the total length of the transmission line is greater than or equal to a preset threshold, the construction of the target composite network based on the fault boundary conditions of the fault points in the transmission line includes: Based on the fault boundary conditions of the fault points in the transmission line and the π-type equivalent circuit of the transmission line, the target composite sequence network is constructed. The transmission line is approximated as follows: the fault transition resistance is a pure resistance; the positive sequence impedance and negative sequence impedance of the transmission line are equal; and the distributed capacitance of the line is ignored when the transmission line is a short line; the power system impedance is approximated as a pure reactance.

7. A fault location device, characterized in that, The device includes: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the fault location method as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, which, when executed by a processor, implement the fault location method as described in any one of claims 1-5.

9. A computer program product, characterized in that, When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device performs the fault location method as described in any one of claims 1-5.

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