A method and system for locating short-circuit faults in power transmission lines

Abstract

The present invention provides a method and system for locating a short-circuit fault of a transmission line, the locating method comprising: obtaining a first transient voltage signal generated by a fault at one end of the transmission line and a second transient voltage signal generated by a fault at the other end of the transmission line; obtaining a preliminary first distance between a first fault point and one end of the transmission line according to the first transient voltage signal; obtaining a preliminary second distance between a second fault point and the other end of the transmission line according to the second transient voltage signal; and correcting the position of the real fault point according to the first distance and the second distance to achieve the final positioning of the real fault point. The positioning method provided by the present invention is applicable to transmission lines, and can eliminate the negative effects of line traveling wave velocity changes with frequency and soil resistivity on fault positioning results.

Description

Technical Field

[0001] The present invention belongs to the technical field of transmission line fault location, and in particular relates to a transmission line short circuit fault location method and system. Background Art

[0002] The bare conductors of overhead transmission lines are exposed to the air for a long time. When encountering severe weather conditions (such as low temperature, rain and snow, etc.), line ice or lightning strikes, wet flashover of insulators, dirty flashover, etc. may occur, causing line failures. To ensure the safe operation of transmission lines, it is necessary to quickly locate the location of line faults to shorten the power outage time as much as possible and avoid further expansion of the impact and losses caused by the faults.

[0003] At present, the common methods for locating short-circuit faults in transmission lines mainly include impedance method, traveling wave method and electromagnetic time reversal (EMTR) fault location method. Among them, the realization of fault point location by impedance method is highly dependent on the accurate measurement of normal working conditions such as line impedance, line load and power supply parameters, and is not suitable for situations such as high-resistance grounding, line break faults, and multiple power supply lines. The positioning accuracy of the traveling wave method is greatly affected by the detection accuracy of the traveling wave signal.

[0004] However, the application of the above fault location methods all assumes that the line has stable wave impedance and wave speed, that is, the transmission line parameter model must be constant. For actual lines, due to the existence of problems such as soil resistivity and skin effect, the line inductance and capacitance parameters are frequency-variable, that is, different frequency components will correspond to different wave impedance and wave speed, so the above fault location methods will bring certain errors.

[0005] The study found that the frequency-varying characteristics of the parameters affect the wave velocity at different frequencies, resulting in the fault point location estimated by the single-ended traveling wave positioning method being ahead of the actual fault point location, and the positioning error basically increases linearly with the distance from the fault point to the measurement point. In addition, the greater the soil resistivity, the more obvious the impact of the frequency-varying characteristics of the parameters, and the greater the positioning error.

[0006] Therefore, it is necessary to design a method and system for locating short-circuit faults in power transmission lines to solve the above technical problems. Summary of the invention

[0007] In view of the above problems, the present invention proposes a method for locating a short-circuit fault in a power transmission line, the method comprising:

[0008] Acquire a first transient voltage signal generated by a fault at one end of a transmission line and a second transient voltage signal generated by a fault at the other end of the transmission line;

[0009] Acquire a preliminary first distance between a first fault point and one end of a transmission line according to the first transient voltage signal;

[0010] Acquire a preliminary second distance between a second fault point and the other end of the transmission line according to the second transient voltage signal;

[0011] The position of the real fault point is corrected according to the first distance and the second distance to achieve final positioning of the real fault point.

[0012] Further,

[0013] The position of the actual fault point is corrected by the following formula:

[0014]

[0015] Among them, x f,1 is the first distance, x f,2 is the second distance, L is the total length of the transmission line, x f,real It is the corrected distance between the actual fault point and one end of the transmission line.

[0016] Further,

[0017] The acquiring of the first distance includes:

[0018] According to the first transient voltage signal, a single-ended fault location method is used to obtain a preliminary first distance between a first fault point and one end of the transmission line.

[0019] Further,

[0020] The acquiring of the second distance includes:

[0021] According to the second transient voltage signal, a single-ended fault location method is used to obtain a preliminary second distance between the second fault point and the other end of the transmission line.

[0022] Further,

[0023] The single-ended fault locating method is an EMTR line short-circuit fault locating method.

[0024] Further,

[0025] The single-ended fault location method is a single-ended traveling wave method.

[0026] On the other hand, the present invention also provides a transmission line short circuit fault location system, the location system comprising:

[0027] A signal acquisition module, used to acquire a first transient voltage signal generated by a fault at one end of the transmission line and a second transient voltage signal generated by a fault at the other end of the transmission line;

[0028] A calculation module, configured to obtain a preliminary first distance between a first fault point and one end of a transmission line according to a first transient voltage signal; and obtain a preliminary second distance between a second fault point and the other end of the transmission line according to a second transient voltage signal;

[0029] The correction module is used to correct the position of the real fault point according to the first distance and the second distance to achieve the final positioning of the real fault point.

[0030] Further,

[0031] The position of the actual fault point is corrected by the following formula:

[0032]

[0033] Among them, x f,1 is the first distance, x f,2 is the second distance, L is the total length of the transmission line, x f,real It is the corrected distance between the actual fault point and one end of the transmission line.

[0034] Further,

[0035] The calculation module comprises:

[0036] The first distance calculation module is used to calculate a preliminary first distance between a first fault point and one end of the transmission line according to the first transient voltage signal using a single-ended fault location method.

[0037] Further,

[0038] The calculation module also includes:

[0039] The second distance calculation module is used to calculate a preliminary second distance between a second fault point and the other end of the transmission line according to the second transient voltage signal using a single-ended fault location method.

[0040] A method and system for locating a short-circuit fault in a power transmission line of the present invention can greatly reduce the positioning error by measuring a first transient voltage signal and a second transient voltage signal and using two single-end positioning results (i.e., a first distance and a second distance) for correction.

[0041] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A schematic diagram of a flow chart of a positioning method according to an embodiment of the present invention is shown;

[0044] Figure 2 shows a voltage waveform diagram of a first transient voltage signal according to an embodiment of the present invention;

[0045] Figure 3 FIG. 4 shows a voltage waveform diagram of a second transient voltage signal according to an embodiment of the present invention.

[0046] Figure 4 A positioning error curve diagram is shown between a single-ended EMTR line short-circuit fault positioning method in the prior art and a line short-circuit fault positioning method in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] In addition, in the present invention, the terms “first”, “second” and other similar words are not intended to imply any order, quantity and importance, but are only used to distinguish different elements.

[0049] In transmission lines (such as power transmission lines), due to the inconsistency of wave velocity and wave impedance for different frequency components of the signal, various existing fault location methods will produce errors that increase with the increase of fault distance. Figure 1 As shown, an embodiment of the present invention provides a method for locating a short-circuit fault in a power transmission line, the method comprising:

[0050] Acquire a first transient voltage signal generated by a fault at one end of a transmission line (hereinafter referred to as the line) and a second transient voltage signal generated by the fault at the other end of the transmission line;

[0051] Acquire a preliminary first distance between a first fault point and one end of the line according to the first transient voltage signal;

[0052] Acquire a preliminary second distance between a second fault point and the other end of the line according to the second transient voltage signal;

[0053] The position of the real fault point is corrected according to the first distance and the second distance to achieve final positioning of the real fault point.

[0054] The acquisition of the first distance includes:

[0055] According to the first transient voltage signal, a single-ended fault location method is used to obtain a preliminary first distance between a first fault point and one end of the line.

[0056] The acquisition of the second distance includes:

[0057] According to the second transient voltage signal, a single-ended fault location method is used to obtain a preliminary second distance between the second fault point and the other end of the line.

[0058] In the above steps of obtaining the first distance and the second distance, the single-ended fault location method adopted may be an EMTR line short circuit fault location method or a single-ended traveling wave method. In this embodiment, the EMTR line short circuit fault location method is taken as an example for exemplary description, wherein the EMTR line short circuit fault location method may be a line short circuit fault location method based on direct signal convolution.

[0059] This embodiment uses an EMTR line short-circuit fault location method. Taking a 100km long three-phase transmission line with frequency-variable parameters as an example, a 220kV power frequency voltage is applied to the head end of the 100km long three-phase transmission line, and the power transformer at each end (the head end and the tail end of the 100km long three-phase transmission line) is equivalent to a large resistance of 100kΩ. The soil resistivity is set to 1000Ωm. The steps of a transmission line short-circuit fault location method using a two-terminal signal to correct the influence of frequency-variable parameters are described as follows:

[0060] For different short-circuit fault locations, measurement points are set at both ends of the line to be tested (the two ends of the line) to measure the first transient voltage signal u generated by the fault at both ends of the line. 1 (t) and the second transient voltage signal u 2 (t). That is:

[0061] Assume that one end of the line (i.e. the line to be tested) is end A, and the other end of the line is end B. End A and end B are used as two measuring points of the line. The first transient voltage signal u generated by the fault can be measured at end A. 1 (t), the second transient voltage signal u generated by the fault can be measured at the B end 2 (t).

[0062] Taking the short-circuit fault at 30km as an example, the first transient voltage signal u 1 The voltage waveform of (t) is as follows Figure 2 As shown, the second transient voltage signal u 2 The voltage waveform of (t) is as follows Figure 3 shown.

[0063] For a certain set of first transient voltage signals u 1 (t) and the second transient voltage signal u 2 (t), using the EMTR line short circuit fault location method, the preliminary first fault point x can be obtained f,1 and the second fault point x f,2 , where x f,1 is the first distance (i.e. the distance between the initial first fault point and end A), x f,2 is the second distance (ie, the preliminary distance between the second fault point and the B end).

[0064] Therefore, the correction of the actual fault point location includes:

[0065] Get the total length of the transmission line;

[0066] Calculate, according to the total length of the transmission line, the product of the total length of the transmission line and the first distance as a first calculated value;

[0067] Calculate the sum of the first distance and the second distance as a second calculated value;

[0068] A quotient obtained by dividing the first calculated value by the second calculated value is calculated as the corrected fault point position.

[0069] In this embodiment, the position of the fault point is corrected by the following formula:

[0070]

[0071] Where L is the total length of the transmission line, x f,real It is the corrected distance between the fault point and one end of the transmission line (end A).

[0072] x f,real As the final fault point location. Different fault locations and x f,1 and x f,real The error between Figure 4 As shown in the figure, it can be seen that when considering the wave velocity frequency variation, the error of the single-ended EMTR line short-circuit fault location method is basically proportional to the distance between the fault point and the measurement point. After correction, the location error is greatly reduced and has nothing to do with the fault distance.

[0073] Through the above method, the positioning errors of various existing fault positioning methods are reduced.

[0074] On the other hand, this embodiment also provides a transmission line short circuit fault locating system, the locating system comprising:

[0075] A signal acquisition module, used to acquire a first transient voltage signal generated by a fault at one end of the transmission line and a second transient voltage signal generated by a fault at the other end of the transmission line;

[0076] A calculation module, configured to obtain a preliminary first distance between a first fault point and one end of a transmission line according to a first transient voltage signal; and obtain a preliminary second distance between a second fault point and the other end of the transmission line according to a second transient voltage signal;

[0077] The correction module is used to correct the position of the real fault point according to the first distance and the second distance to achieve the final positioning of the real fault point.

[0078] Wherein, the calculation module includes:

[0079] The first distance calculation module is used to calculate a preliminary first distance between a first fault point and one end of the transmission line according to the first transient voltage signal using a single-ended fault location method.

[0080] Wherein, the calculation module includes:

[0081] The second distance calculation module is used to calculate a preliminary second distance between a second fault point and the other end of the transmission line according to the second transient voltage signal using a single-ended fault location method.

[0082] It should be noted that in this embodiment, in a transmission line short circuit fault locating system, other functions and implementation methods of each module correspond to other functions and implementation methods of a transmission line short circuit fault locating method, and therefore, they are not described in detail here.

[0083] The present invention sets measurement points at both ends, measures the first transient voltage signal and the second transient voltage signal, and uses two single-end positioning results (the first distance and the second distance) for correction, which can greatly reduce the positioning error. In addition, the fault location method provided by the present invention can correct the influence of the frequency variation of the transient traveling wave speed of the transmission line on the fault location result, thereby enhancing the practicality of the fault location method.

[0084] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for locating a short-circuit fault in a power transmission line, characterized in that: The positioning method comprises: Acquire a first transient voltage signal generated by a fault at one end of a transmission line and a second transient voltage signal generated by a fault at the other end of the transmission line; Acquire a preliminary first distance between a first fault point and one end of a transmission line according to the first transient voltage signal; Acquire a preliminary second distance between a second fault point and the other end of the transmission line according to the second transient voltage signal; Correcting the position of the real fault point according to the first distance and the second distance to achieve final positioning of the real fault point; The position of the actual fault point is corrected by the following formula: Among them, x f,1 is the first distance, x f,2 is the second distance, L is the total length of the transmission line, x f,real It is the corrected distance between the actual fault point and one end of the transmission line.

2. A method for locating a short-circuit fault in a power transmission line according to claim 1, characterized in that: The acquiring of the first distance includes: According to the first transient voltage signal, a single-ended fault location method is used to obtain a preliminary first distance between a first fault point and one end of the transmission line.

3. A method for locating a short-circuit fault in a power transmission line according to claim 1, characterized in that: The acquiring of the second distance includes: According to the second transient voltage signal, a single-ended fault location method is used to obtain a preliminary second distance between the second fault point and the other end of the transmission line.

4. A method for locating a short-circuit fault in a power transmission line according to claim 2 or 3, characterized in that: The single-ended fault locating method is an EMTR line short-circuit fault locating method.

5. A method for locating a short-circuit fault in a power transmission line according to claim 2 or 3, characterized in that: The single-ended fault location method is a single-ended traveling wave method.

6. A transmission line short circuit fault location system, characterized in that: The positioning system comprises: A signal acquisition module, used to acquire a first transient voltage signal generated by a fault at one end of the transmission line and a second transient voltage signal generated by a fault at the other end of the transmission line; A calculation module, configured to obtain a preliminary first distance between a first fault point and one end of a transmission line according to a first transient voltage signal; and obtain a preliminary second distance between a second fault point and the other end of the transmission line according to a second transient voltage signal; A correction module, used to correct the position of the real fault point according to the first distance and the second distance, so as to achieve the final positioning of the real fault point; The position of the actual fault point is corrected by the following formula: Among them, x f,1 is the first distance, x f,2 is the second distance, L is the total length of the transmission line, x f,real It is the corrected distance between the actual fault point and one end of the transmission line.

7. A power transmission line short circuit fault location system according to claim 6, characterized in that: The calculation module comprises: The first distance calculation module is used to calculate a preliminary first distance between a first fault point and one end of a transmission line according to a first transient voltage signal by using a single-ended fault location method.

8. A power transmission line short circuit fault location system according to claim 6, characterized in that: The calculation module also includes: The second distance calculation module is used to calculate a preliminary second distance between a second fault point and the other end of the transmission line according to the second transient voltage signal using a single-ended fault location method.

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