Power distribution network short-circuit fault location method and system based on iterative correction of fault point

Abstract

The application discloses a power distribution network short-circuit fault ranging method and system based on iterative correction of fault points, relates to the technical field of power distribution network short-circuit fault ranging, and solves the problem that the fault ranging result is not accurate enough. The application simplifies the calculation process of the fault distance, establishes a simple ranging differential equation by reasonably assuming that the fault distance is the only variable, avoids solving a complex system of simultaneous equations, and is more convenient for engineering application. Moreover, the application adopts an iterative calculation method, which not only simplifies the calculation process, but also can correct errors caused by the assumption, and through multiple iterations, the high ranging accuracy can be ensured. The method has a wide application range, can be used not only for single-phase grounding faults, but also for phase-to-phase short-circuit grounding faults, and has high engineering application value. In addition, the application calculates the ranging result by using the fault voltage variation, can eliminate the influence of the load current on the ranging accuracy, and is beneficial to improving the calculation accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power grid, in particular to a power distribution network short-circuit fault ranging method and system based on iterative correction of fault point. BACKGROUND

[0002] 10-35kV is the main voltage level of the power distribution network in China, with a wide distribution range and bearing the task of directly supplying power to users. Once the power distribution network fails, it will directly affect the reliability of power supply. Statistical data shows that 90% of user power outage accidents are related to power distribution network failures. After the power distribution network fails, maintenance personnel need to quickly find the fault point to eliminate the fault, so accurate fault ranging results are needed to assist maintenance personnel to quickly determine the fault location. Due to the complex structure of the power distribution network, the diverse operating environment, and the rich types of lines, the fault characteristics are also complex, making it difficult to obtain accurate fault ranging results. Therefore, the problem of fault ranging of the power distribution network has long plagued the power supply operation department, and better solutions are urgently needed from a technical perspective.

[0003] Considering the very complex structure of the power distribution network, it is difficult to obtain multi-point synchronous electrical quantity information. From the perspective of practicality, it is suitable to use single-ended ranging method, and it is not suitable to use complex ranging methods such as double-ended ranging and traveling wave ranging. Therefore, a single-ended ranging method that is more in line with the actual characteristics of the power distribution network and easier to implement is needed. SUMMARY

[0004] In view of the problems existing in the prior art, the present application is proposed.

[0005] Therefore, the problem to be solved by the present application is that the structure of the power distribution network is very complex, it is difficult to obtain multi-point synchronous electrical quantity information, from the perspective of practicality, it is suitable to use single-ended ranging method, and it is not suitable to use complex ranging methods such as double-ended ranging and traveling wave ranging, the wide distribution range, complex structure and diverse operating environment of the power distribution network cause the fault ranging result to be not accurate enough.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a power distribution network short-circuit fault ranging method based on iterative correction of fault point, which comprises collecting first parameters of each phase of the power distribution network under normal operation and after the fault occurs;

[0008] According to the fault ranging device, the fault type and fault phase are determined, and the second parameters corresponding to the fault phase are calculated according to the first parameters;

[0009] The ranging equations for single-phase ground fault and inter-phase ground fault are constructed according to the second parameters;

[0010] Setting initial values of the fault point voltage variation and the fault distance according to the first parameter and the second parameter;

[0011] Correcting the values of the fault point voltage variation and the fault distance to obtain a first fault distance and a first fault point voltage variation;

[0012] Substituting the first fault point voltage variation into the distance measurement equation to obtain a second fault distance, and substituting the first fault distance into the distance measurement equation to obtain a second fault point voltage variation;

[0013] Judging whether the distance measurement result converges, if yes, ending the process, and if not, returning to correct the values of the fault point voltage variation and the fault distance.

[0014] As a preferred scheme of the power distribution network short-circuit fault distance measurement method based on iterative correction of fault points, the first parameter of each phase of the power distribution network under normal operation and after the fault occurs is collected, the first parameter including the voltage and current of each phase under normal operation of the circuit, the voltage and current of each phase after a single-phase ground short-circuit fault occurs, and the voltage and current between each phase after a phase-to-ground short-circuit fault occurs; and the second parameter includes the fault phase voltage variation and the fault phase current variation.

[0015] As a preferred scheme of the power distribution network short-circuit fault distance measurement method based on iterative correction of fault points, the distance measurement equation of the single-phase ground fault and the distance measurement equation of the phase-to-ground short-circuit fault are constructed according to the second parameter, and the construction process of the distance measurement equation of the single-phase ground fault is as follows:

[0016] Suppose that the fault occurs in phase A:

[0017] The differential equation taking the fault distance as the unknown quantity is constructed as follows:

[0018]

[0019] where Δi a1 (t), Δi a2 (t), and Δi a0 (t) are the 1-mode, 2-mode, and 0-mode components of the fault phase current variation, Δu f (t) is the fault point voltage variation, R1 and L1 are the 1-mode resistance and inductance of the line between the bus and the fault point, R2 and L2 are the 2-mode resistance and inductance of the line between the bus and the fault point, R0 and L0 are the 0-mode resistance and inductance of the line between the bus and the fault point, and Δu a (t) is the fault voltage variation of phase A.

[0020] Suppose that the line is uniform, i.e., the line impedance value per unit length is constant, so that:

[0021] R1 = r1·L, L1 = l1·L.

[0022] R2 = r2 L, L2 = l2 L;

[0023] R0 = r0 L, L0 = l0 L;

[0024] Wherein, L represents fault distance, r1 is line 1 mode unit length resistance, l1 is line 1 mode unit length inductance, r2 is line 2 mode unit length resistance, l2 is line 2 mode unit length inductance, r0 is line 0 mode unit length resistance, l0 is line 0 mode unit length inductance;

[0025] In addition, in the case of single-phase ground fault, the following conditions occur:

[0026]

[0027] Therefore, the single-phase ground fault ranging equation is:

[0028]

[0029] r ∑ = r1 + r2 + r0, l ∑ = l1 + l2 + l0

[0030] Wherein, Δi a (t) is the A-phase fault current variation.

[0031] As a preferred scheme of the power distribution network short-circuit fault ranging method based on iterative correction of fault point according to the application, wherein: the ranging equation of single-phase ground fault and the ranging equation of inter-phase ground fault are constructed according to the second parameter.

[0032] The construction process of the ranging equation of inter-phase ground fault is as follows:

[0033] Suppose that the fault occurs between AB phases:

[0034] The differential equation with fault distance as unknown quantity is constructed, which is as follows:

[0035]

[0036] Wherein, Δu f (t) is the fault point voltage variation, Δi ab1 (t), Δi ab2 (t), Δi ab0 (t) are respectively the 1-mode, 2-mode and 0-mode components of fault phase current variation, R1, L1 are line 1 mode resistance and inductance between bus and fault point, R2, L2 are line 2 mode resistance and inductance between bus and fault point, R0, L0 are line 0 mode resistance and inductance between bus and fault point, Δu ab(t) is the AB phase-to-phase fault voltage variation;

[0037] Assuming that the line is uniform, that is, the line impedance value per unit length is constant, then:

[0038] R1=r1*L, L1=l1*L;

[0039] R2=r2*L, L2=l2*L;

[0040] R0=r0*L, L0=l0*L;

[0041] Wherein, L represents the fault distance, r1 is the line 1 mode unit length resistance, l1 is the line 1 mode unit length inductance, r2 is the line 2 mode unit length resistance, l2 is the line 2 mode unit length inductance, r0 is the line 0 mode unit length resistance, l0 is the line 0 mode unit length inductance;

[0042] Therefore, the distance measurement equation of the phase-to-ground fault is:

[0043]

[0044] Wherein, Δi ab (t) is the AB phase-to-phase fault current variation, r is the line unit length resistance, and l is the line unit length inductance.

[0045] As a preferred scheme of the power distribution network short-circuit fault distance measurement method based on the iterative correction of the fault point according to the application, wherein: the distance measurement equation of the single-phase ground fault and the distance measurement equation of the phase-to-ground fault are constructed according to the second parameter;

[0046] Wherein, the calculation process of the second fault distance is as follows:

[0047] According to the first parameter and the second parameter, the initial value of the fault point voltage variation and the fault distance is set;

[0048] The initial value of the fault point voltage variation and the fault distance is corrected to obtain the first fault distance and the first fault point voltage variation, wherein the initial value correction step of the fault distance is +0.1km, and the initial value correction step of the amplitude of the fault point voltage variation is-0.01kV;

[0049] Taking the fault distance as the unknown quantity, the first fault point voltage variation is substituted into the distance measurement equation to obtain the second fault distance; taking the fault point voltage variation as the unknown quantity, the first fault distance is substituted into the distance measurement equation to obtain the second fault point voltage variation;

[0050] When the second fault distance needs to be calculated again, the second fault point voltage variation and the second fault distance are taken as the initial value of the fault point voltage variation and the fault distance.

[0051] As a preferred scheme of the power distribution network short-circuit fault location method based on iterative correction of fault point in the application, wherein: the judgment whether the location result converges, if yes, ending the process, if not, returning to correct the value of the fault point voltage variation and the fault distance;

[0052] The judgment basis of judging whether the location result converges is as follows:

[0053] L-L'≤ε

[0054]

[0055] Wherein, L is the fault distance obtained last time, L' is the fault distance obtained next time, ε is the iterative calculation error, L total is the total length of the line.

[0056] As a preferred scheme of the power distribution network short-circuit fault location method based on iterative correction of fault point in the application, wherein: the fault type and the fault phase are judged according to the fault location device, and the fault location device is installed at the head of the line, and when the single-phase ground fault occurs in the line, the voltage sampling value and the current sampling value in the fixed time window before and after the fault occurs are recorded.

[0057] In the second aspect, the embodiment of the application provides a power distribution network short-circuit fault location system based on iterative correction of fault point, which comprises,

[0058] The acquisition module acquires the first parameter of each phase of the power distribution network in normal operation and after the fault occurs;

[0059] The calculation module judges the fault type and the fault phase according to the fault location device, and calculates the second parameter corresponding to the fault phase according to the first parameter;

[0060] The construction module constructs the location equation of the single-phase ground fault and the location equation of the phase-to-ground fault according to the second parameter;

[0061] The setting module sets the initial value of the fault point voltage variation and the fault distance according to the first parameter and the second parameter;

[0062] The correction module corrects the value of the fault point voltage variation and the fault distance to obtain the first fault distance and the first fault point voltage variation;

[0063] The iteration module substitutes the first fault point voltage variation into the location equation to obtain the second fault distance, and substitutes the first fault distance into the location equation to obtain the second fault point voltage variation;

[0064] The judgment module judges whether the location result converges, if yes, ending the process, if not, returning to correct the value of the fault point voltage variation and the fault distance.

[0065] In a third aspect, an embodiment of the present application provides a computer device, comprising a memory and a processor, and the memory stores a computer program, wherein the computer program instructs the processor to implement the steps of the short-circuit fault location method based on iterative correction of fault points for distribution network as described in the first aspect of the present application.

[0066] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, wherein the computer program instructs a processor to implement the steps of the short-circuit fault location method based on iterative correction of fault points for distribution network as described in the first aspect of the present application.

[0067] The present application has the following beneficial effects: the present application simplifies the calculation process of the fault distance, establishes a simple location differential equation by reasonably assuming the fault distance as the only variable, avoids solving a complex system of equations, and is more convenient for engineering application. The iterative calculation method not only simplifies the calculation process, but also corrects the errors caused by the assumption, and through multiple iterations, the high location accuracy can be ensured. The method has a wide range of applications, and can be used not only for single-phase ground fault, but also for phase-to-ground short-circuit fault, and has high engineering application value. The fault voltage variation is used to calculate the location result, which can eliminate the influence of the load current on the location accuracy; the voltage and current variation of the fault phase or the fault phase-to-phase are directly used, which avoids complex decoupling calculation and is also conducive to improving the calculation accuracy.

[0068] In summary, the present application simplifies the calculation method of the fault distance by reasonable assumption and iterative calculation, expands the application range, improves the location accuracy, eliminates the influence of the load current, and is worth popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0069] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0070] Figure 1 The flowchart of the short-circuit fault location method based on iterative correction of fault points for distribution network;

[0071] Figure 2 The computer device diagram of the short-circuit fault location method based on iterative correction of fault points for distribution network;

[0072] Figure 3 The distribution network section positioning schematic diagram of the short-circuit fault location method based on iterative correction of fault points for distribution network. DETAILED DESCRIPTION

[0073] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0074] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application, however, can be practiced in other ways different from those described herein without departing from the scope of the present application. It is understood that variations can be made in view of what is described and understood that it would be within the skill of the art to make additional changes in form and detail.

[0075] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. The "in one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or selectively excluded from other embodiments.

[0076] Embodiment 1

[0077] Reference Figures 1-2 For the first embodiment of the present application, the embodiment provides a power distribution network short-circuit fault location method based on fault point iterative correction, comprising,

[0078] S100: Collecting the first parameters of each phase of the power distribution network during normal operation and after the fault occurs;

[0079] S101: Collecting the first parameters of each phase of the power distribution network during normal operation and after the fault occurs, the first parameters including the voltage and current of each phase during normal operation of the circuit, the voltage and current of each phase after a single-phase ground short-circuit fault occurs, and the voltage and current between each phase after a phase-to-ground short-circuit fault occurs; the second parameters including the fault phase voltage variation and the fault phase current variation.

[0080] S200: Judging the fault type and fault phase according to the fault location device, and calculating the second parameters corresponding to the fault phase according to the first parameters;

[0081] S201: Judging the fault type and fault phase according to the fault location device, wherein the fault location device is installed at the first end of the line, and when a single-phase ground fault occurs in the line, the voltage sampling value and the current sampling value within a fixed time window before and after the fault occurs are recorded.

[0082] S300: Constructing the fault location equation of single-phase ground fault and the fault location equation of phase-to-ground fault according to the second parameters;

[0083] S301: Constructing the fault location equation of single-phase ground fault and the fault location equation of phase-to-ground fault according to the second parameters, wherein the construction process of the fault location equation of single-phase ground fault is as follows:

[0084] Assuming that the fault occurs in phase A:

[0085] The differential equation with fault distance as unknown quantity is constructed as follows:

[0086]

[0087] Where, Δi a1 (t) is the 1-mode component of the fault phase current change, Δi a2 (t) is the 2-mode component of the fault phase current change, and Δi a0 (t) is the 0-mode component of the fault phase current change, Δu f (t) is the fault point voltage change, R1 and L1 are the 1-mode resistance and inductance of the line between the bus and the fault point, R2 and L2 are the 2-mode resistance and inductance of the line between the bus and the fault point, R0 and L0 are the 0-mode resistance and inductance of the line between the bus and the fault point, and Δu a (t) is the A-phase fault voltage change;

[0088] Assuming that the line is uniform, i.e., the line impedance value per unit length is constant, then:

[0089] R1 = r1·L and L1 = l1·L;

[0090] R2 = r2·L and L2 = l2·L;

[0091] R0 = r0·L and L0 = l0·L;

[0092] Where, L represents the fault distance, r1 is the 1-mode unit length resistance of the line, l1 is the 1-mode unit length inductance of the line, r2 is the 2-mode unit length resistance of the line, l2 is the 2-mode unit length inductance of the line, r0 is the 0-mode unit length resistance of the line, and l0 is the 0-mode unit length inductance of the line.

[0093] In addition, in the case of single-phase ground fault, the following conditions exist:

[0094]

[0095] Therefore, the single-phase ground fault distance measurement equation is:

[0096]

[0097] r ∑ = r1 + r2 + r0 and l ∑ = l1 + l2 + l0

[0098] Where, Δi a (t) is the A-phase fault current change.

[0099] S302: Construct the single-phase ground fault distance measurement equation and the phase-to-ground fault distance measurement equation according to the second parameter;

[0100] The construction process of the distance measurement equation of the phase-to-ground fault is as follows:

[0101] Suppose that the fault occurs between phases A and B:

[0102] The differential equation with the fault distance as the unknown quantity is constructed as follows:

[0103]

[0104] where Δu f (t) is the fault point voltage variation, Δi ab1 (t) is the fault phase current variation, Δi ab2 (t) is the fault phase current variation, Δi ab0 (t) is the fault phase current variation, R1 and L1 are the line 1-mode resistance and inductance between the bus and the fault point, R2 and L2 are the line 2-mode resistance and inductance between the bus and the fault point, R0 and L0 are the line 0-mode resistance and inductance between the bus and the fault point, Δu ab (t) is the AB-phase-to-ground fault voltage variation;

[0105] Suppose that the line is uniform, that is, the line impedance value per unit length is constant, so that:

[0106] R1 = r1·L and L1 = l1·L;

[0107] R2 = r2·L and L2 = l2·L;

[0108] R0 = r0·L and L0 = l0·L;

[0109] where L represents the fault distance, r1 is the line 1-mode unit length resistance, l1 is the line 1-mode unit length inductance, r2 is the line 2-mode unit length resistance, l2 is the line 2-mode unit length inductance, r0 is the line 0-mode unit length resistance, and l0 is the line 0-mode unit length inductance;

[0110] Therefore, the distance measurement equation of the phase-to-ground fault is:

[0111]

[0112] where Δi ab (t) is the AB-phase-to-ground fault current variation, r is the line unit length resistance, and l is the line unit length inductance.

[0113] S400: Set the initial values of the fault point voltage variation and the fault distance according to the first parameter and the second parameter;

[0114] S500: Correct the values of the fault point voltage variation and the fault distance to obtain the first fault distance and the first fault point voltage variation;

[0115] S600: substitute the first fault point voltage variation into the distance measurement equation to obtain the second fault distance, and substitute the first fault distance into the distance measurement equation to obtain the second fault point voltage variation;

[0116] S601: construct the distance measurement equation for single-phase ground fault and the distance measurement equation for phase-to-ground fault according to the second parameters;

[0117] The calculation process of the second fault distance is as follows:

[0118] According to the first parameters and the second parameters, the initial values of the fault point voltage variation and the fault distance are set;

[0119] The initial values of the fault point voltage variation and the fault distance are corrected to obtain the first fault distance and the first fault point voltage variation, wherein the initial value correction step of the fault distance is +0.1 km, and the initial value correction step of the amplitude of the fault point voltage variation is-0.01 kV;

[0120] The first fault point voltage variation is substituted into the distance measurement equation to obtain the second fault distance, and the first fault distance is substituted into the distance measurement equation to obtain the second fault point voltage variation;

[0121] When the second fault distance needs to be calculated again, the second fault point voltage variation and the second fault distance are taken as the initial values of the fault point voltage variation and the fault distance.

[0122] S700: judge whether the distance measurement result converges, if yes, end the process, if not, return to correct the values of the fault point voltage variation and the fault distance.

[0123] S701: judge whether the distance measurement result converges, if yes, end the process, if not, return to correct the values of the fault point voltage variation and the fault distance.

[0124] The judgment basis for judging whether the distance measurement result converges is as follows:

[0125] L-L'≤ε

[0126]

[0127] Wherein, L is the fault distance obtained last time, L' is the fault distance obtained next time, ε is the iterative calculation error, L total is the total length of the line.

[0128] Further, the embodiment also provides a power distribution network short-circuit fault distance measurement system based on iterative correction of fault points, comprising,

[0129] The acquisition module acquires the first parameters of each phase of the power distribution network under normal operation and after a fault occurs.

[0130] The calculation module determines the fault type and fault phase according to the fault location device, and calculates the second parameters corresponding to the fault phase according to the first parameters.

[0131] The construction module constructs the single-phase grounding fault ranging equation and the inter-phase grounding fault ranging equation according to the second parameters.

[0132] The setting module sets the initial values of the fault point voltage variation and the fault distance according to the first parameters and the second parameters.

[0133] The correction module corrects the values of the fault point voltage variation and the fault distance to obtain the first fault distance and the first fault point voltage variation.

[0134] The iteration module substitutes the first fault point voltage variation into the ranging equation to obtain the second fault distance, and substitutes the first fault distance into the ranging equation to obtain the second fault point voltage variation.

[0135] The judgment module judges whether the ranging result converges or not, and if yes, the process is ended, and if not, the values of the fault point voltage variation and the fault distance are returned.

[0136] The embodiment also provides a computer device suitable for the power distribution network short-circuit fault ranging method based on fault point iterative correction, which comprises a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to realize the power distribution network short-circuit fault ranging method based on fault point iterative correction as proposed in the above embodiment.

[0137] The computer device can be a terminal, which comprises a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. The processor of the computer device is used to provide calculation and control capabilities. The memory of the computer device comprises a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner. The wireless manner can be realized through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, trackball or touchpad arranged on the shell of the computer device, or an external keyboard, touchpad or mouse, etc.

[0138] The embodiment also provides a storage medium having a computer program stored thereon, the program being executed by a processor to implement the power distribution network short-circuit fault location method based on iterative correction of fault points as proposed in the above embodiment.

[0139] In summary, the parameters after the normal operation and fault occurrence of the power distribution network are collected:

[0140] By collecting voltage, current and other parameters, the operation state of the power distribution network is comprehensively mastered, providing basic data support for subsequent fault location. This step lays a data foundation for the entire location process, which helps to improve the accuracy of subsequent analysis.

[0141] Determine the fault type and phase, and calculate the relevant parameters:

[0142] By determining the fault type and phase through the fault location device, and calculating the corresponding voltage and current variation, the precise identification of the fault condition is achieved. This step can quickly determine the nature of the fault, which is conducive to the subsequent adoption of targeted location strategies and improves the efficiency of fault handling.

[0143] Construct the location equation:

[0144] According to different fault types (single-phase grounding or phase-to-phase short circuit), the corresponding location equation is constructed, and mathematical modeling of complex fault conditions is achieved. This step converts the physical problem into a mathematical problem, providing a theoretical basis for accurate calculation of fault distance, which helps to improve the accuracy of location.

[0145] Set the initial value and perform iterative correction:

[0146] By setting the initial value of the fault point voltage variation and the fault distance, and performing iterative correction, the location result is gradually optimized. This innovative iterative process can continuously correct calculation errors, significantly improve the accuracy of location, and overcome the limitations of traditional single calculation methods.

[0147] Judge convergence and output results:

[0148] By setting the convergence condition, it is determined whether the location result meets the requirements, and the automation and intelligence of the location process are achieved. This step ensures the reliability of the calculation results and improves the efficiency of fault location.

[0149] Improve the location accuracy:

[0150] By using the iterative correction method, the present application can continuously optimize the calculation results, significantly improving the accuracy of fault location. Compared with traditional methods, the location error can be controlled within 0.4%, which is much better than the industry requirement of 0.5% accuracy. This high-precision positioning can help operation and maintenance personnel to find the fault point more quickly and accurately, greatly shortening the fault repair time and improving the power supply reliability.

[0151] Expand the scope of application:

[0152] The present application is not only applicable to single-phase ground fault, but also to phase-to-ground short circuit fault, significantly expanding the scope of application of the method. This universality enables the method to cope with various fault types in the distribution network, improving the flexibility and efficiency of fault handling.

[0153] Simplify the calculation process:

[0154] By establishing a simple distance measurement differential equation with fault distance as the only variable, the complex system of equations is avoided, greatly simplifying the calculation process. This simplification not only improves the calculation efficiency, but also reduces the demand for computing resources, making the method more easily applied and promoted in practical engineering.

[0155] Eliminate the influence of load current:

[0156] The fault voltage change is used to calculate the distance measurement result, effectively eliminating the influence of load current on the distance measurement accuracy. This innovative processing method solves the problem of load current interference in traditional distance measurement methods, further improving the accuracy and reliability of distance measurement.

[0157] Realize intelligent fault location:

[0158] Through automatic data acquisition, fault judgment and iterative calculation, intelligent positioning of short circuit fault in distribution network is realized. This intelligent processing not only improves the efficiency of fault handling, but also reduces the dependence on manual operation, which helps to build a more intelligent and reliable distribution network operation and maintenance system.

[0159] Improve economic efficiency:

[0160] By quickly and accurately locating the fault point, the present application can significantly shorten the fault repair time, reduce the loss of power outage and improve the reliability of power supply. This not only reduces the operation and maintenance cost of power companies, but also improves user satisfaction, bringing significant economic and social benefits.

[0161] In summary, the present application realizes high-precision and intelligent positioning of short circuit fault in distribution network through innovative iterative correction method combined with multiple technical innovations. Compared with existing technologies, the present application has significant improvement in distance measurement accuracy, scope of application, calculation efficiency and practicality, providing strong technical support for safe and reliable operation of distribution network. This unexpected high precision and wide applicability make the present application have important application value and promotion prospect in the field of distribution network fault handling.

[0162] Example 2

[0163] Reference Figure 1 - Figure 2For the second embodiment of the present application, the embodiment provides a power distribution network short-circuit fault location method based on fault point iterative correction. In order to verify the beneficial effects of the present application, economic benefit calculation and simulation experiments are used for scientific demonstration.

[0164] Test sample selection:

[0165] A 10kV power distribution network is selected as the test sample, and its electrical parameters are shown in Table 1.

[0166] Table 1 Electrical parameters of 10kV power distribution network

[0167]

[0168]

[0169] Location results:

[0170] Different distances of A-phase ground faults are set to obtain the location error, and the results are shown in Table 2.

[0171] Table 2 Location results

[0172] Fault setting distance / km Measured distance / km Distance measuring error 4 3.97 0.03 6 6.02 0.02 8 7.96 0.04

[0173] As can be seen from Table 2, the iterative method has smaller location error and higher location accuracy. This is because the iterative method gradually corrects the assumed fault point voltage through multiple calculations, so that the location result tends to be accurate.

[0174] In summary, the method is applied to single-ended location of single-phase ground faults in 10kV power distribution networks, and the average location error is less than 0.4%, which meets the accuracy requirement of 0.5%. The effectiveness of the iterative method is verified, and high-precision single-ended location of short-circuit faults in power distribution networks can be achieved.

[0175] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A power distribution network short-circuit fault location method based on fault point iterative correction, characterized in that: The application relates to a fault distance measurement method and device for a power distribution network. The first parameters of each phase of the power distribution network during normal operation and after fault occurrence are collected; The fault type and fault phase are determined according to the fault distance measurement device, and the second parameters corresponding to the fault phase are calculated according to the first parameters; The first parameters include the voltages and currents of each phase during normal operation of the circuit, the voltages and currents of each phase after single-phase ground short-circuit fault, and the voltages and currents between each phase after phase-to-ground short-circuit fault; the second parameters include the voltage variation of the fault phase and the current variation of the fault phase; The distance measurement equation for single-phase ground fault and the distance measurement equation for phase-to-ground fault are constructed according to the second parameters; The initial values of the fault point voltage variation and the fault distance are set according to the first parameters and the second parameters; The values of the fault point voltage variation and the fault distance are corrected to obtain the first fault distance and the first fault point voltage variation; The first fault point voltage variation is substituted into the distance measurement equation to obtain the second fault distance, and the first fault distance is substituted into the distance measurement equation to obtain the second fault point voltage variation; The calculation process of the second fault distance is as follows: The initial values of the fault point voltage variation and the fault distance are set according to the first parameters and the second parameters; The initial values of the fault point voltage variation and the fault distance are corrected to obtain the first fault distance and the first fault point voltage variation, wherein the initial value correction step length of the fault distance is +0.1 km, and the initial value correction step length of the fault point voltage variation is -0.01 kV; The first fault point voltage variation is substituted into the distance measurement equation to obtain the second fault distance, and the first fault distance is substituted into the distance measurement equation to obtain the second fault point voltage variation; When the second fault distance needs to be calculated again, the second fault point voltage variation and the second fault distance are taken as the initial values of the fault point voltage variation and the fault distance; It is judged whether the distance measurement result converges or not, if yes, the process is ended, and if not, the values of the fault point voltage variation and the fault distance are returned to be corrected; The judgment basis for judging whether the distance measurement result converges or not is as follows: ， ， wherein L is the fault distance obtained at the previous time, is the fault distance obtained at the previous time, is the iteration error, is the total length of the line.

2. The fault point iteration based power distribution network short circuit fault location method according to claim 1, characterized in that: The distance measurement equation for single-phase ground fault and the distance measurement equation for phase-to-ground fault are constructed according to the second parameters, and the construction process of the distance measurement equation for single-phase ground fault is as follows: Suppose that the fault occurs in the A phase: The differential equation with the fault distance as the unknown quantity is constructed, and is as follows: ， wherein, , , are the 1st, 2nd and 0th mode components of the fault phase current variation respectively, is the fault point voltage variation, , are the 1st mode resistance and inductance of the line between the bus and the fault point, , are the 2nd mode resistance and inductance of the line between the bus and the fault point, , are the 0th mode resistance and inductance of the line between the bus and the fault point, is the A phase fault voltage variation; Suppose that the line is uniform, that is, the line impedance value of unit length is constant, so that: ， ； ， ； ， ； wherein, represents the fault distance, is the line 1 mode unit length resistance, is the line 1 mode unit length inductance, is the line 2 mode unit length resistance, is the line 2 mode unit length inductance, is the line 0 mode unit length resistance, is the line 0 mode unit length inductance; In addition, when single-phase ground fault occurs, the following conditions exist: ， Therefore, the distance measurement equation for single-phase ground fault is as follows: ， ， ， wherein, is the A-phase fault current variation.

3. The fault point iteration based power distribution network short circuit fault location method according to claim 2, characterized in that: The distance measurement equation for single-phase ground fault and the distance measurement equation for phase-to-ground fault are constructed according to the second parameters; The construction process of the distance measurement equation for phase-to-ground fault is as follows: Suppose that the fault occurs between the AB phase: The differential equation with the fault distance as the unknown quantity is constructed, and is as follows: ， wherein, is a fault point voltage variation, , , are 1-mode, 2-mode and 0-mode components of a fault phase-to-phase current variation, respectively, , are 1-mode resistance and inductance of a line between a bus and a fault point, , are 2-mode resistance and inductance of a line between a bus and a fault point, , are 0-mode resistance and inductance of a line between a bus and a fault point, is an AB phase-to-phase fault voltage variation; Suppose that the line is uniform, that is, the line impedance value of unit length is constant, so that: ， ； ， ； ， ； wherein, represents the fault distance, is the line 1 mode unit length resistance, is the line 1 mode unit length inductance, is the line 2 mode unit length resistance, is the line 2 mode unit length inductance, is the line 0 mode unit length resistance, is the line 0 mode unit length inductance; Therefore, the distance measurement equation for phase-to-ground fault is as follows: ， wherein, AB interphase fault current variation, is the line unit length resistance, and l is the line unit length inductance.

4. The fault point iteration based power distribution network short circuit fault location method of claim 3, wherein: The fault type and the fault phase are judged according to the fault location device, the fault location device is installed at the line head, when the single-phase grounding fault occurs, the voltage sampling value and the current sampling value in the fixed time window before and after the fault occurrence are recorded.

5. A power distribution network short-circuit fault location system based on iterative correction of fault point, based on the power distribution network short-circuit fault location method based on iterative correction of fault point in any one of claims 1-4, characterized in that: Also include, The acquisition module acquires the first parameters of each phase of the power distribution network during normal operation and after the fault occurs; The calculation module judges the fault type and the fault phase according to the fault location device, and calculates the second parameters corresponding to the fault phase according to the first parameters; The construction module constructs the fault location equation of the single-phase grounding fault and the fault location equation of the phase-to-ground fault according to the second parameters; The setting module sets the initial values of the fault point voltage variation and the fault distance according to the first parameters and the second parameters; The correction module corrects the values of the fault point voltage variation and the fault distance to obtain the first fault distance and the first fault point voltage variation; The iteration module substitutes the first fault point voltage variation into the fault location equation to obtain the second fault distance, and substitutes the first fault distance into the fault location equation to obtain the second fault point voltage variation; The judgment module judges whether the fault location result converges, if yes, the process is ended, if not, the values of the fault point voltage variation and the fault distance are returned to be corrected.

6. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that: The processor executes the computer program to realize the steps of the power distribution network short-circuit fault location method based on the iterative correction of the fault point according to any one of claims 1-4.

7. A computer readable storage medium having stored thereon a computer program, characterized in that: The computer program is executed by the processor to realize the steps of the power distribution network short-circuit fault location method based on the iterative correction of the fault point according to any one of claims 1-4.

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