A submarine cable line distance measurement method and system based on dual-end steady-state information

Abstract

The present invention discloses a submarine cable line distance measurement method and system based on double-end steady-state quantity information, which relates to the field of line distance measurement technology. The steps are: measuring the voltage sampling value and current sampling value on both sides of the submarine cable line, and obtaining the voltage phasor value and the current phasor value according to the voltage sampling value and the current sampling value; calculating the voltage sampling value change and the current sampling value change on both sides of the submarine cable line at a fixed time after the fault, and obtaining the voltage change phasor value and the current change phasor value according to the voltage sampling value change and the current sampling value change; calculating the propagation coefficient and wave impedance of the submarine cable line; iteratively calculating the voltage phasor value, the current phasor value, the voltage change phasor value, and the current change phasor value according to the propagation coefficient and the wave impedance to obtain the correction value; combining the iterative result with the correction value to continuously iterate and obtain the distance measurement result. The method of the present invention is simple in principle, can accurately identify the fault point, and realize accurate distance measurement of the line.

Description

Technical Field

[0001] The present invention relates to the technical field of line distance measurement, and more particularly to a submarine cable line distance measurement method and system based on dual-end steady-state quantity information. Background Art

[0002] As my country's economy develops, its power grid is becoming increasingly complex. Due to the country's diverse and complex topography, transmission lines are often located between mountains and rivers, crossing extremely wide waterways and straits, and employing numerous submarine cables. With the increasing complexity of the transmission network, quickly and accurately locating faults in high-voltage lines and promptly resolving them to eliminate potential safety hazards are crucial for ensuring the safety and stability of my country's power system and the operation of the national economy across vast swathes of the country.

[0003] Numerous methods have been proposed for detecting line faults, with power line fault location based on power frequency electrical quantities being a representative one. However, this method is susceptible to external instability, resulting in significant errors in fault location, hindering its widespread application on hybrid high-voltage overhead and cable lines. Therefore, for those skilled in the art, accurately measuring distance and identifying fault points on submarine cables is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the present invention provides a submarine cable line ranging method and system based on dual-end steady-state quantity information to solve the problems encountered in the background technology.

[0005] To achieve the above-mentioned object, the present invention adopts the following technical solution: a submarine cable line ranging method based on dual-end steady-state information, the specific steps of which include the following:

[0006] Measuring voltage sampling values ​​and current sampling values ​​on both sides of the submarine cable line, and obtaining voltage phasor values ​​and current phasor values ​​according to the voltage sampling values ​​and current sampling values;

[0007] Calculating the voltage sampling value changes and current sampling value changes on both sides of the submarine cable line at a fixed time after the fault, and obtaining the voltage change phasor value and the current change phasor value according to the voltage sampling value changes and the current sampling value changes;

[0008] Calculate the propagation coefficient and wave impedance of submarine cable lines;

[0009] Performing iterative calculation based on the propagation coefficient, the wave impedance, the voltage phasor value, the current phasor value, the voltage variation phasor value, and the current variation phasor value to obtain a correction value;

[0010] The correction value is used in combination with the iterative result to perform continuous iteration to obtain the ranging result.

[0011] Optionally, the propagation coefficient is calculated as follows:

[0012]

[0013] Among them, r sc is the unit resistance, x sc is the unit reactance, b sc The unit is susceptance, jb sc is the unit admittance.

[0014] Optionally, the wave impedance is calculated as follows:

[0015]

[0016] Optionally, the iterative calculation process is:

[0017] The distance from the fault point to the m side is represented by lkm. The distance measurement result is obtained by iteratively calculating l. In the first iteration, let Where: L submarine cable is the length of the submarine cable line;

[0018] The voltage value at a point 11 km away from the m side of the submarine cable line is calculated based on the voltage and current phasor values ​​on the m side of the submarine cable line: in, is the voltage phasor value on side m, is the current phasor value on side m; ψ=a, b, c are the fault phases;

[0019] The voltage variation value at a point 11 km away from the m side of the submarine cable line is calculated from the voltage variation phasor value and the current variation phasor value on the m side of the submarine cable line: in, is the phasor value of the voltage change on side m, is the phasor value of the current change on side m;

[0020] The voltage value at a point 11 km away from the n side of the submarine cable line is calculated based on the voltage and current phasor values ​​on the n side of the submarine cable line: in, is the voltage phasor value on the n side, is the current phasor value on the n side;

[0021] The voltage variation value at a point 11 km away from the n side of the submarine cable line is calculated from the voltage variation phasor value and the current variation phasor value on the n side of the submarine cable line: in, is the phasor value of the voltage change on the n side, is the phasor value of the current change on the n side;

[0022] Based on the results of the first iterative calculation, the correction value Δl is calculated:

[0023] Among them, Z sc is the unit impedance, Z sc =r sc +jx sc .

[0024] Optional, The value of If the difference is greater than the first threshold, the second iteration sets l2 = l1 + Δl; if it is less than the first threshold, the second iteration sets l2 = l1 - Δl; when When the iteration ends, ε is a constant value, ε=100v, and the l N is the ranging result.

[0025] Optionally, the voltage phasor value, the current phasor value, the voltage change phasor value, and the current change phasor value are calculated according to a Fourier series algorithm.

[0026] On the other hand, a submarine cable line distance measurement system based on double-end steady-state information is provided, comprising a sampling module, a phasor value calculation module, a variation calculation module, a variation phasor value calculation module, a submarine cable parameter calculation module, an iteration module, and a distance measurement result output module; wherein,

[0027] The sampling module is used to measure the voltage sampling values ​​and current sampling values ​​on both sides of the submarine cable line;

[0028] The phasor value calculation module is used to obtain the voltage phasor value and the current phasor value according to the voltage sampling value and the current sampling value;

[0029] The variation calculation module is used to calculate the variation of the voltage sampling values ​​and the current sampling values ​​on both sides of the submarine cable line at a fixed time after the fault;

[0030] The variation phasor value calculation module is used to obtain the voltage variation phasor value and the current variation phasor value according to the voltage sampling value variation and the current sampling value variation;

[0031] The submarine cable parameter calculation module is used to calculate the propagation coefficient and wave impedance of the submarine cable line;

[0032] The iterative module is configured to perform iterative calculation based on the propagation coefficient, the wave impedance, the voltage phasor value, the current phasor value, the voltage variation phasor value, and the current variation phasor value to obtain a correction value;

[0033] The distance measurement result output module is used to combine the iteration result and use the correction value to perform continuous iteration to obtain the distance measurement result.

[0034] It can be seen from the above technical solution that compared with the prior art, the present invention discloses a method and system for submarine cable line distance measurement based on dual-end steady-state information, which uses iterative calculation of the short-circuit point voltage to determine the short-circuit point location. The method has a simple principle, can accurately identify the fault point, and realize accurate distance measurement of the line. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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 merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0036] Figure 1 is a flow chart of the method of the present invention;

[0037] Figure 2 It is a simulation structure diagram of the present invention;

[0038] Figure 3 This is a system structure diagram of the present invention. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0040] The embodiment of the present invention discloses a method for measuring the distance of a submarine cable line based on double-end steady-state information. Figure 1 As shown, the specific steps include:

[0041] S1, use voltage transformer to measure the voltage sampling value on both sides of the submarine cable line; the voltage sampling value on the m side of the submarine cable line is u ma ,u mb ,u mc ; The voltage sampling value on the n side of the submarine cable line is: u na ,u nb ,u nc .

[0042] S2. Calculate the variation of the sampling value of the voltage on both sides of the submarine cable line, and obtain the fault time t from the starting element of the protection device. s , calculate T after fault B The change in the sampling value of the voltage on both sides of the submarine cable line at time.

[0043] The change of the voltage sampling value on the m side of the submarine cable line is:

[0044]

[0045] The change of the voltage sampling value on the n side of the submarine cable line is:

[0046]

[0047] Where, T is the power frequency period, which is 20ms in this embodiment, and t is T B modT,T B =100ms.

[0048] S3. Using the voltage sampling values ​​on both sides of the submarine cable line, the phasor value is calculated according to the Fourier series algorithm:

[0049] S4. Using the voltage variation sampling values ​​on both sides of the submarine cable line, the phasor value is calculated according to the Fourier series algorithm:

[0050] S5. Use current transformers to measure the current sampling values ​​on both sides of the submarine cable line; the current sampling value on the m side of the submarine cable line is: i ma ,i mb ,i mc ; The voltage sampling value on the n side of the submarine cable line is: i na ,i nb ,i nc .

[0051] S6. Calculate the change in the sampling value of the current on both sides of the submarine cable line, using T B Taking the moment as an example, calculate T B The change in the sampling value of the current on both sides of the submarine cable line at that moment.

[0052] The change of the current sampling value on the m side of the submarine cable line is:

[0053]

[0054] The change of the current sampling value on the n side of the submarine cable line is:

[0055]

[0056] S7. Using the current sampling values ​​on both sides of the submarine cable line, the phasor value is calculated according to the Fourier series algorithm:

[0057] S8. Using the current variation sampling values ​​on both sides of the submarine cable line, the phasor value is calculated according to the Fourier series algorithm:

[0058] S9. Calculate the propagation coefficient of the submarine cable line. According to the parameters of the submarine cable line, the unit resistance is r sc , the unit reactance is x sc , the unit impedance is Z sc =r sc +jx sc ; The unit of conductivity is g sc , the unit of susceptance is b sc , the unit admittance is y sc =g sc +jb sc , usually the submarine cable line conductivity g sc =0, then the unit admittance can be written as y sc =jb sc The propagation coefficient is calculated as

[0059] S10. Calculate the wave impedance of the submarine cable line. According to the parameters of the submarine cable line, the wave impedance is calculated to be

[0060] S11, Figure 2 For example, the fault point is the submarine cable line outlet fault. The submarine cable line is 20 km long. The distance from the fault point to the m side is represented by lkm. l is calculated by iteration. In the first iteration, l=l1=10;

[0061] The voltage value at a point 11 km away from the m side of the submarine cable line is calculated based on the voltage and current phasor values ​​on the m side of the submarine cable line: Where: ψ=a, b, c are fault phases;

[0062] The voltage variation value at a point 11 km away from the m side of the submarine cable line is calculated from the voltage variation phasor value and the current variation phasor value on the m side of the submarine cable line:

[0063] The voltage value at a point 11 km away from the m side of the submarine cable line is calculated based on the voltage and current phasor values ​​on the n side of the submarine cable line:

[0064] The voltage variation value at the point 11 km away from the m side of the submarine cable line is calculated based on the voltage variation phasor value and current variation phasor value on the n side of the submarine cable line:

[0065] S12. Based on the result of the first iterative calculation, the correction value Δl is calculated:

[0066]

[0067] S13, if the voltage Leading current About 90° (i.e. The phase of this voltage phasor leads The phase of this current phasor is about 90°). Then in the second iteration, let l2=l1+Δl; if the voltage Hysteresis current About 90°, when Then in the second iteration, let l2 = l1 - Δl. Calculate l2=l1-Δl=10-9.9195=0.0805.

[0068] S14, when When , the iteration ends, let ε=5; calculate At this time, l2=0.0805 is the distance measurement result.

[0069] Embodiment 2 of the present invention discloses a submarine cable line ranging system based on dual-end steady-state information. Figure 3 As shown, it includes a sampling module, a phasor value calculation module, a change calculation module, a change phasor value calculation module, a submarine cable parameter calculation module, an iteration module, and a ranging result output module; wherein,

[0070] Sampling module, used to measure the voltage sampling value and current sampling value on both sides of the submarine cable line;

[0071] A phasor value calculation module is used to obtain voltage phasor values ​​and current phasor values ​​according to voltage sampling values ​​and current sampling values;

[0072] The variation calculation module is used to calculate the variation of the voltage sampling values ​​and the current sampling values ​​on both sides of the submarine cable line at a fixed time after the fault;

[0073] The variation phasor value calculation module is used to obtain the voltage variation phasor value and the current variation phasor value according to the voltage sampling value variation and the current sampling value variation;

[0074] Submarine cable parameter calculation module, used to calculate the propagation coefficient and wave impedance of the submarine cable line;

[0075] An iterative module is used to perform iterative calculation based on the propagation coefficient, wave impedance, voltage phasor value, current phasor value, voltage change phasor value, and current change phasor value to obtain a correction value;

[0076] The ranging result output module is used to combine the iterative results with the correction value to perform continuous iterations to obtain the ranging results.

[0077] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0078] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A submarine cable line distance measurement method based on dual-end steady-state information, characterized in that: The specific steps include the following: Measuring voltage sampling values ​​and current sampling values ​​on both sides of the submarine cable line, and obtaining voltage phasor values ​​and current phasor values ​​according to the voltage sampling values ​​and current sampling values; Calculating the voltage sampling value changes and current sampling value changes on both sides of the submarine cable line at a fixed time after the fault, and obtaining the voltage change phasor value and the current change phasor value according to the voltage sampling value changes and the current sampling value changes; Calculate the propagation coefficient and wave impedance of submarine cable lines; Performing iterative calculation based on the propagation coefficient, the wave impedance, the voltage phasor value, the current phasor value, the voltage variation phasor value, and the current variation phasor value to obtain a correction value; The correction value is used in combination with the iterative result to continuously iterate to obtain the ranging result; The calculation formula of the propagation coefficient is: Among them, r sc is the unit resistance, x sc is the unit reactance, b sc The unit is susceptance, jb sc is the unit admittance; The calculation formula of the wave impedance is: The iterative calculation process is: The distance from the fault point to the m side is represented by lkm. The distance measurement result is obtained by iteratively calculating l. In the first iteration, let Where: L submarine cable is the length of the submarine cable line; The voltage value at a point 11 km away from the m side of the submarine cable line is calculated based on the voltage and current phasor values ​​on the m side of the submarine cable line: in, is the voltage phasor value on side m, is the current phasor value on side m; ψ=a, b, c are the fault phases; The voltage variation value at a point 11 km away from the m side of the submarine cable line is calculated from the voltage variation phasor value and the current variation phasor value on the m side of the submarine cable line: in, is the phasor value of the voltage change on side m, is the phasor value of the current change on side m; The voltage value at a point 11 km away from the n side of the submarine cable line is calculated based on the voltage and current phasor values ​​on the n side of the submarine cable line: in, is the voltage phasor value on the n side, is the current phasor value on the n side; The voltage variation value at a point 11 km away from the n side of the submarine cable line is calculated from the voltage variation phasor value and the current variation phasor value on the n side of the submarine cable line: in, is the phasor value of the voltage change on the n side, is the phasor value of the current change on the n side; Based on the results of the first iterative calculation, the correction value Δl is calculated: Among them, Z sc is the unit impedance, Z sc =r sc +jx sc ; Will The value of If the difference is greater than the first threshold, the second iteration sets l2 = l1 + Δl; if it is less than the first threshold, the second iteration sets l2 = l1 - Δl; when When the iteration ends, ε is a constant value, ε=100v, and the l N is the ranging result.

2. A method for measuring distance of a submarine cable line based on dual-end steady-state information according to claim 1, characterized in that: The voltage phasor value, the current phasor value, the voltage variation phasor value, and the current variation phasor value are calculated according to a Fourier series algorithm.

3. A submarine cable line ranging system based on dual-end steady-state quantity information, applied to a submarine cable line ranging method based on dual-end steady-state quantity information according to any one of claims 1-2, characterized in that: It includes sampling module, phasor value calculation module, variation calculation module, variation phasor value calculation module, submarine cable parameter calculation module, iteration module, and ranging result output module; among them, The sampling module is used to measure the voltage sampling values ​​and current sampling values ​​on both sides of the submarine cable line; The phasor value calculation module is used to obtain the voltage phasor value and the current phasor value according to the voltage sampling value and the current sampling value; The variation calculation module is used to calculate the variation of the voltage sampling values ​​and the current sampling values ​​on both sides of the submarine cable line at a fixed time after the fault; The variation phasor value calculation module is used to obtain the voltage variation phasor value and the current variation phasor value according to the voltage sampling value variation and the current sampling value variation; The submarine cable parameter calculation module is used to calculate the propagation coefficient and wave impedance of the submarine cable line; The iterative module is configured to perform iterative calculation based on the propagation coefficient, the wave impedance, the voltage phasor value, the current phasor value, the voltage variation phasor value, and the current variation phasor value to obtain a correction value; The distance measurement result output module is used to combine the iteration result and use the correction value to perform continuous iteration to obtain the distance measurement result.

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