CN111929535B - Method and device for detecting fault direction of direct-current side outlet of alternating-current circuit - Google Patents
Method and device for detecting fault direction of direct-current side outlet of alternating-current circuit Download PDFInfo
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- CN111929535B CN111929535B CN202010811774.8A CN202010811774A CN111929535B CN 111929535 B CN111929535 B CN 111929535B CN 202010811774 A CN202010811774 A CN 202010811774A CN 111929535 B CN111929535 B CN 111929535B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/58—Testing of lines, cables or conductors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
Abstract
The application discloses a method and a device for detecting the fault direction of a direct-current side outlet of an alternating-current circuit, wherein the method comprises the following steps: calculating the fundamental wave voltage amplitude value of the direct current side protection installation position of the alternating current line according to the voltage sampling value; when the AC line fault is judged to be a DC side outlet fault according to the fundamental wave voltage amplitude value, calculating the equivalent potential of a receiving end AC system according to a current sampling value, a voltage sampling value, an AC line parameter and a receiving end AC system parameter, wherein the AC line parameter comprises AC line impedance, and the receiving end AC system parameter comprises AC system equivalent impedance; calculating the harmonic content of the equivalent potential of the receiving end alternating current system; and if the harmonic content is greater than the voltage harmonic content threshold value, judging that the outlet fault of the direct current side is a forward outlet fault, otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault. The application provides a reliable and strong technical scheme who detects the direct current side outlet fault direction of the alternating current circuit that links to each other with the contravariant station of suitability.
Description
Technical Field
The application relates to the technical field of power system relay protection, in particular to a method and a device for detecting a fault direction of a direct-current side outlet of an alternating-current circuit.
Background
For a traditional high-voltage direct-current transmission system, a failure of an alternating-current line connected with an inverter station of the system often causes a phase-change failure of the inverter station, and the phase-change failure causes that a traditional direction element based on power frequency quantity cannot correctly judge a fault direction, so that the fault of the alternating-current line cannot be reliably and quickly removed. Under the condition of weak feedback of a receiving-end alternating current system, the locking of an inverter station can be caused by the untimely cutting of the fault of an alternating current line, so that the receiving-end alternating current system has the risk of breakdown. For the alternating current line connected with the inverter station, the direct outlet fault of the direct current side of the alternating current line causes the alternating current bus voltage of the inverter station to be greatly reduced, and the phase change failure of the inverter station is inevitably caused, so that the direct outlet fault of the alternating current line connected with the inverter station has a large influence on the phase change of the inverter station.
Disclosure of Invention
The application provides a method and a device for detecting the fault direction of a direct current side outlet of an alternating current circuit, which are used for providing a technical scheme for accurately and reliably detecting the fault direction of the direct current side outlet of the alternating current circuit connected with an inverter station.
In view of the above, a first aspect of the present application provides a method for detecting a dc-side outlet fault direction of an ac line, including:
calculating the fundamental wave voltage amplitude value of the direct current side protection installation position of the alternating current line according to the voltage sampling value;
when the AC line fault is judged to be a DC side outlet fault according to the fundamental wave voltage amplitude value, calculating the equivalent potential of a receiving end AC system according to a current sampling value, the voltage sampling value, an AC line parameter and a receiving end AC system parameter, wherein the AC line parameter comprises AC line impedance, and the receiving end AC system parameter comprises AC system equivalent impedance;
calculating the harmonic content of the equivalent potential of the receiving end alternating current system;
and if the harmonic content is greater than the voltage harmonic content threshold value, judging that the outlet fault of the direct current side is a forward outlet fault, otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault.
Optionally, the calculating a fundamental voltage amplitude at the dc-side protection installation of the ac line according to the voltage sampling value further includes:
when the AC line has a fault, acquiring a current sampling value and a voltage sampling value of a DC side protection installation position of the AC line.
Optionally, when it is determined that the ac line fault is the dc side outlet fault according to the fundamental wave voltage amplitude, calculating the equivalent potential of the receiving-end ac system according to the current sampling value, the voltage sampling value, the ac line parameter, and the receiving-end ac system parameter, including:
when the fundamental voltage amplitude is smaller than a preset voltage setting value, judging that the alternating current line fault is a direct current side outlet fault;
and when the AC line fault is the DC side outlet fault, calculating the equivalent potential of the receiving end AC system according to the current sampling value, the voltage sampling value, the AC line parameter and the receiving end AC system parameter.
Optionally, when the fundamental voltage amplitude is smaller than the preset voltage setting value, it is determined that the ac line fault is a dc side outlet fault, further including:
and when the fundamental voltage amplitude is greater than or equal to the preset voltage setting value, judging that the alternating current line fault is a non-outlet fault.
Optionally, if the harmonic content is greater than the voltage harmonic content threshold, it is determined that the dc side outlet fault is a forward outlet fault, otherwise, it is determined that the dc side outlet fault is a reverse outlet fault, and then the method further includes:
when the direct-current side outlet fault is judged to be a forward outlet fault, a tripping command is sent to carry out circuit protection;
and when the direct current side outlet fault is judged to be a reverse outlet fault, no tripping command is sent.
This application second aspect provides a direct current side outlet fault direction detection device of alternating current circuit, includes:
the first calculation module is used for calculating the fundamental wave voltage amplitude value of the direct current side protection installation position of the alternating current line according to the voltage sampling value;
the second calculation module is used for calculating the equivalent potential of the receiving end alternating current system according to the current sampling value, the voltage sampling value, the alternating current line parameter and the receiving end alternating current system parameter when the alternating current line fault is judged to be the direct current side outlet fault according to the fundamental wave voltage amplitude value, wherein the alternating current line parameter comprises alternating current line impedance, and the receiving end alternating current system parameter comprises alternating current system equivalent impedance;
the third calculation module is used for calculating the harmonic content of the equivalent potential of the receiving end alternating current system;
and the first judgment module is used for judging that the outlet fault of the direct current side is a forward outlet fault if the harmonic content is greater than the voltage harmonic content threshold value, and otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault.
Optionally, the method further includes:
and the acquisition module is used for acquiring a current sampling value and a voltage sampling value at the direct-current side protection installation position of the alternating-current line when the alternating-current line fails.
Optionally, the second calculating module is specifically configured to:
when the fundamental voltage amplitude is smaller than a preset voltage setting value, judging that the alternating current line fault is a direct current side outlet fault;
and when the AC line fault is the DC side outlet fault, calculating the equivalent potential of the receiving end AC system according to the current sampling value, the voltage sampling value, the AC line parameter and the receiving end AC system parameter.
Optionally, the method further includes:
and the second judgment module is used for judging that the alternating current line fault is a non-outlet fault when the fundamental voltage amplitude is greater than or equal to the preset voltage setting value.
Optionally, the method further includes:
the protection module is used for sending a tripping command to carry out circuit protection when the direct-current side outlet fault is judged to be a forward outlet fault;
and when the direct current side outlet fault is judged to be a reverse outlet fault, a tripping command is not sent.
According to the technical scheme, the embodiment of the application has the following advantages:
in this application, a method for detecting a fault direction of a dc side outlet of an ac line is provided, including: calculating the fundamental wave voltage amplitude value of the direct current side protection installation position of the alternating current line according to the voltage sampling value; when the AC line fault is judged to be a DC side outlet fault according to the fundamental wave voltage amplitude value, calculating the equivalent potential of a receiving end AC system according to a current sampling value, a voltage sampling value, an AC line parameter and a receiving end AC system parameter, wherein the AC line parameter comprises AC line impedance, and the receiving end AC system parameter comprises AC system equivalent impedance; calculating the harmonic content of the equivalent potential of the receiving end alternating current system; and if the harmonic content is greater than the voltage harmonic content threshold value, judging that the outlet fault of the direct current side is a forward outlet fault, otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault.
According to the method for detecting the fault direction of the direct-current side outlet of the alternating-current circuit, calculation analysis is carried out according to the collected voltage data and the collected current data, the fault direction of the direct-current side outlet is accurately detected in a two-step threshold judgment mode, the reliability of a detection result is improved by adopting a data calculation and threshold judgment method, the calculated amount is small, and the method is easy to realize. Therefore, the technical scheme for detecting the fault direction of the direct-current side outlet of the alternating-current line connected with the inverter station is reliable and high in applicability.
Drawings
Fig. 1 is a schematic flowchart of a method for detecting a dc-side outlet fault direction of an ac line according to an embodiment of the present disclosure;
fig. 2 is another schematic flowchart of a method for detecting a dc side outlet fault direction of an ac line according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a dc side outlet fault direction detection apparatus for an ac line according to an embodiment of the present disclosure;
fig. 4 is a schematic system structure diagram of an inversion side of a high-voltage direct-current power transmission system according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
For easy understanding, referring to fig. 1, a first embodiment of a method for detecting a dc side outlet fault direction of an ac line provided by the present application includes:
It should be noted that the voltage sampling value is a voltage value collected from a direct current side protection installation position in an alternating current circuit, and the voltage at the time is affected by a fault and can reflect a certain voltage change characteristic during the fault, so that the fundamental voltage amplitude calculated by using the voltage sampling value has a fault analysis value; the specific principle is that due to the influence of faults, when the fundamental wave voltage amplitude of the direct-current side protection installation position of the alternating-current line is reduced to a certain range, the fault at the moment can be judged to be a direct-current side outlet fault according to the voltage reduction condition. When the AC line fails, a starting element for protecting the DC side of the AC line is operated, and voltage sampling is performed.
102, when the AC line fault is judged to be the DC side outlet fault according to the fundamental wave voltage amplitude, calculating the equivalent potential of the receiving end AC system according to the current sampling value, the voltage sampling value, the AC line parameter and the receiving end AC system parameter, wherein the AC line parameter comprises AC line impedance, and the receiving end AC system parameter comprises AC system equivalent impedance.
It should be noted that, when the ac line fault is a dc-side outlet fault, the receiving-end ac system equivalent potential needs to be calculated to analyze the specific direction of the fault, so as to perform accurate fault direction detection. The ac line parameters generally refer to relevant parameters of components in the line, such as resistance, inductance, and the like, while the receiving-end ac system parameters are parameter values of equivalent resistance and equivalent inductance of the receiving-end ac system, and these parameters can be obtained according to parameters of an actual system.
And 103, calculating the harmonic content of the equivalent potential of the receiving end alternating current system.
It should be noted that, the harmonic analysis may be performed on the equivalent potential of the receiving-end alternating current system by using fast fourier transform, the harmonic content is calculated, and the selection of the harmonic number may be set according to the actual situation, which is not limited herein, and is used for quantitatively characterizing the magnitude of the harmonic content in the equivalent potential of the receiving-end alternating current system. The harmonic content can most visually reflect the nature of the direct-current side outlet fault and can be used for analyzing the direction of the direct-current side outlet fault.
And step 104, if the harmonic content is greater than the voltage harmonic content threshold value, judging that the outlet fault of the direct current side is a forward outlet fault, otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault.
It should be noted that the voltage harmonic content threshold is set according to the actual circuit condition, and is not limited herein; when a forward outlet fault occurs, the fault current flowing through the direct-current side protection installation position of the alternating-current line comes from the inverter station, so that the harmonic content in the equivalent potential is large, while when a reverse outlet fault occurs, the fault current comes from the opposite receiving end alternating-current system, and the harmonic content in the equivalent potential is small, so that when the harmonic content is larger than the voltage harmonic content threshold value, the direct-current side outlet fault is the forward outlet fault, and when the harmonic content is smaller than or equal to the voltage harmonic content threshold value, the direct-current side outlet fault is the reverse outlet fault. The method realizes accurate direction detection of the direct current side outlet fault of the alternating current circuit according to the threshold judgment mode, and is simple and reliable and strong in universality.
According to the method for detecting the fault direction of the direct-current side outlet of the alternating-current circuit, calculation and analysis are carried out according to the collected voltage data and the collected current data, the fault direction of the direct-current side outlet is accurately detected in a two-step threshold judgment mode, the reliability of a detection result is improved by adopting a data calculation and threshold judgment method, the calculated amount is small, and the method is easy to implement. Therefore, the embodiment provides a technical scheme for reliably detecting the fault direction of the direct-current side outlet of the alternating-current line connected with the inverter station, and the technical scheme has strong applicability.
For easy understanding, please refer to fig. 2, the present application provides a second embodiment of a method for detecting a dc side outlet fault direction of an ac line, including:
It should be noted that, when an ac line connected to the inverter station has a fault, the starting element of the dc side protection operates, and a current sampling value and a voltage sampling value at the dc side protection installation location are obtained at the same time, and are used for fault detection and analysis.
It should be noted that, the method adopted for calculating the fundamental voltage amplitude according to the voltage sampling value is a full-period fourier algorithm.
And 203, when the fundamental voltage amplitude is smaller than the preset voltage setting value, judging that the alternating current line fault is a direct current side outlet fault.
It should be noted that the ac line fault is not necessarily a dc-side outlet fault, and therefore before determining the direction of the dc-side outlet fault, it is also necessary to determine according to the fundamental voltage amplitude, to determine whether the ac line fault is the dc-side outlet fault; and then performing different operations according to the preliminarily determined fault result.
And 204, when the fundamental voltage amplitude is greater than or equal to the preset voltage setting value, judging that the alternating current line fault is a non-outlet fault.
It should be noted that, if the fundamental voltage amplitude is determined not to be an outlet fault, that is, although the ac line has a fault, the fundamental voltage amplitude at the dc-side protection installation of the ac line is still greater than or equal to the preset voltage setting value, the ac line fault at this time is not a dc-side outlet fault. Preset voltage setting value U N Can be set according to the actual situation, and the general value range is (0.1,0.2); for the non-exit fault, the non-exit distance protection action needs to be executed, which is not described herein again.
And step 205, when the AC line fault is the DC side outlet fault, calculating the equivalent potential of the receiving end AC system according to the current sampling value, the voltage sampling value, the AC line parameter and the receiving end AC system parameter.
Please refer to fig. 4, which includes an ac bus In _ M of the inverter station, and assuming that the current sampling value is i p (t) a voltage sampling value of u p (t) the AC line parameter comprises AC line resistance R L And an ac line inductance L L The parameters of the receiving end alternating current system comprise equivalent resistance R of the receiving end alternating current system M In addition, the equivalent inductance L of the receiving end alternating current system can be further included M And calculating the equivalent potential of the receiving end alternating current system according to the parameter values:
and step 206, calculating the harmonic content of the equivalent potential of the receiving end alternating current system.
And step 207, if the harmonic content is greater than the voltage harmonic content threshold value, judging that the outlet fault of the direct current side is a forward outlet fault, otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault.
It should be noted that, the harmonic analysis can be performed on the receiving-end alternating-current system equivalent potential by using fast fourier transform, and the way of calculating the harmonic content in the receiving-end alternating-current system equivalent potential is as follows:
wherein i is the harmonic frequency, and m is 7,U i The magnitude of the ith voltage harmonic. Amplitude U to harmonic content h Carrying out threshold analysis, wherein the analysis and judgment process is as follows:
seed of it, U 1 For the fundamental voltage amplitude, Δ is a voltage harmonic content threshold, that is, a setting value of the voltage harmonic content, and the value range is generally (0.1,0.2). Referring to FIG. 4, for a forward outlet fault F1, the current sample i flowing through the DC side protection P p (t) is provided by the inverter station, and the fault current provided by the inverter station contains a large number of harmonic components due to the influence of the nonlinear and alternating current filter and reactive compensation device of the inverter station control system, so that when the direct current side outlet fault is a forward fault, the harmonic content U in the equivalent potential is h_F1 Is large; for a reverse outlet fault F2, a fault current i flows through the DC-side protection P p (t) is provided by an opposite-side alternating current system which mainly takes a synchronous machine as a main part, and the provided fault current mainly comprises a fundamental frequency component and a non-periodic component which is attenuated quickly, so that when the outlet fault of the direct current side is a reverse fault, the harmonic content U in the equivalent potential is h_F2 And the size is small, so that the fault direction of the direct-current side outlet can be judged according to the harmonic content.
And step 208, when the direct current side outlet fault is judged to be the forward outlet fault, sending a tripping command to perform circuit protection, and when the direct current side outlet fault is judged to be the reverse outlet fault, not sending the tripping command.
It should be noted that different fault types can perform different protection operations, and when the outlet fault on the direct current side is a forward outlet fault, a trip instruction is directly sent to perform circuit protection; whereas a reverse egress fault does not require a trip command to be sent.
For easy understanding, please refer to fig. 3, the present application further provides an embodiment of a dc side outlet fault direction detecting apparatus for an ac line, including:
the first calculation module 301 is configured to calculate a fundamental voltage amplitude at a dc-side protection installation location of the ac line according to the voltage sampling value;
the second calculation module 302 is configured to calculate an equivalent potential of the receiving-end alternating-current system according to the current sampling value, the voltage sampling value, the alternating-current line parameter and the receiving-end alternating-current system parameter when it is determined that the alternating-current line fault is the direct-current side outlet fault according to the fundamental wave voltage amplitude value, where the alternating-current line parameter includes an alternating-current line impedance, and the receiving-end alternating-current system parameter includes an alternating-current system equivalent impedance;
the third calculating module 303 is used for calculating the harmonic content of the equivalent potential of the receiving-end alternating-current system;
the first determining module 304 is configured to determine that the dc outlet fault is a forward outlet fault if the harmonic content is greater than the voltage harmonic content threshold, and otherwise determine that the dc outlet fault is a reverse outlet fault.
Further, still include:
the obtaining module 305 is configured to obtain a current sampling value and a voltage sampling value at a dc-side protection installation of the ac line when the ac line fails.
Further, still include:
the obtaining module 305 is configured to obtain a current sampling value and a voltage sampling value at a dc side protection installation location when a dc side of the ac line fails.
Further, the second calculating module 302 is specifically configured to:
when the fundamental voltage amplitude is smaller than a preset voltage setting value, judging that the alternating current line fault is a direct current side outlet fault;
and when the AC line fault is a DC side outlet fault, calculating the equivalent potential of the receiving end AC system according to the current sampling value, the voltage sampling value, the AC line parameter and the receiving end AC system parameter.
Further, the method also comprises the following steps:
and the second judging module 306 is configured to judge that the ac line fault is a non-outlet fault when the fundamental voltage amplitude is greater than or equal to the preset voltage setting value.
Further, still include:
the protection module 307 is configured to send a trip instruction to perform circuit protection when it is determined that the dc side outlet fault is a forward outlet fault;
and when the direct current side outlet fault is judged to be the reverse outlet fault, a tripping command is not sent.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for executing all or part of the steps of the method described in the embodiments of the present application through a computer device (which may be a personal computer, a server, or a network device). And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A method for detecting a fault direction of a direct current side outlet of an alternating current circuit is characterized by comprising the following steps:
calculating the fundamental wave voltage amplitude value of the direct current side protection installation position of the alternating current line according to the voltage sampling value;
when the AC line fault is judged to be a DC side outlet fault according to the fundamental wave voltage amplitude value, calculating the equivalent potential of a receiving end AC system according to a current sampling value, the voltage sampling value, an AC line parameter and a receiving end AC system parameter, wherein the AC line parameter comprises AC line impedance, and the receiving end AC system parameter comprises AC system equivalent impedance;
calculating the harmonic content of the equivalent potential of the receiving end alternating current system;
if the harmonic content is greater than the voltage harmonic content threshold value, judging that the outlet fault of the direct current side is a forward outlet fault, otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault;
harmonic content in equivalent potential of receiving end alternating current system
The calculating method comprises the following steps:
wherein, U h Is the amplitude of the harmonic content in the equivalent potential of the i receiving end alternating current system, i is the harmonic frequency, and m is 7,U i The amplitude of the ith voltage harmonic;
amplitude U to the harmonic content h Carrying out threshold analysis, wherein the analysis and judgment process is as follows:
wherein, U h Is the amplitude of the harmonic content in the equivalent potential of the i receiving end AC system, U 1 And delta is the fundamental voltage amplitude and the voltage harmonic content threshold.
2. The method of claim 1, wherein the calculating a fundamental voltage magnitude at a dc-side protection installation of the ac line from the voltage sample values further comprises:
when the AC line has a fault, acquiring a current sampling value and a voltage sampling value of a DC side protection installation position of the AC line.
3. The method according to claim 1, wherein the calculating the equivalent potential of the receiving-end ac system according to the current sampling value, the voltage sampling value, the ac line parameter and the receiving-end ac system parameter when the ac line fault is determined to be the dc-side outlet fault according to the fundamental wave voltage amplitude comprises:
when the fundamental voltage amplitude is smaller than a preset voltage setting value, judging that the alternating current line fault is a direct current side outlet fault;
and when the AC line fault is the DC side outlet fault, calculating the equivalent potential of the receiving end AC system according to the current sampling value, the voltage sampling value, the AC line parameter and the receiving end AC system parameter.
4. The method of claim 3, wherein the determining that the AC line fault is the DC-side outlet fault if the fundamental voltage amplitude is less than a preset voltage setting value further comprises:
and when the fundamental voltage amplitude is greater than or equal to the preset voltage setting value, judging that the alternating current line fault is a non-outlet fault.
5. The method according to claim 1, wherein the determining that the dc-side outlet fault is a forward outlet fault if the harmonic content is greater than a voltage harmonic content threshold, and otherwise determining that the dc-side outlet fault is a reverse outlet fault further comprises:
when the direct current side outlet fault is judged to be a forward outlet fault, a tripping command is sent to carry out circuit protection;
and when the direct current side outlet fault is judged to be a reverse outlet fault, no tripping command is sent.
6. A direct current side outlet fault direction detection device of an alternating current line is characterized by comprising:
the first calculation module is used for calculating the fundamental wave voltage amplitude value of the direct current side protection installation position of the alternating current line according to the voltage sampling value;
the second calculation module is used for calculating the equivalent potential of the receiving end alternating current system according to the current sampling value, the voltage sampling value, the alternating current line parameter and the receiving end alternating current system parameter when the alternating current line fault is judged to be the direct current side outlet fault according to the fundamental wave voltage amplitude value, wherein the alternating current line parameter comprises alternating current line impedance, and the receiving end alternating current system parameter comprises alternating current system equivalent impedance;
the third calculation module is used for calculating the harmonic content of the equivalent potential of the receiving-end alternating current system;
the first judgment module is used for judging that the outlet fault of the direct current side is a forward outlet fault if the harmonic content is greater than a voltage harmonic content threshold value, and otherwise, judging that the outlet fault of the direct current side is a reverse outlet fault;
harmonic content in equivalent potential of receiving end alternating current system
The calculation method comprises the following steps:
wherein, U h The amplitude of the harmonic content in the equivalent potential of the i receiving end alternating current system is shown, i is the harmonic frequency, and m is 7,U i The amplitude of the ith voltage harmonic;
amplitude U to the harmonic content h Carrying out threshold analysis, wherein the analysis and judgment process comprises the following steps:
wherein, U h Amplitude of harmonic content in i-receiving end AC system equivalent potential, U 1 And delta is the fundamental voltage amplitude and the voltage harmonic content threshold.
7. The ac line dc side outlet fault direction detecting apparatus according to claim 6, further comprising:
and the acquisition module is used for acquiring a current sampling value and a voltage sampling value at the direct-current side protection installation position of the alternating-current line when the alternating-current line fails.
8. The apparatus according to claim 6, wherein the second computing module is specifically configured to:
when the fundamental voltage amplitude is smaller than a preset voltage setting value, judging that the alternating current line fault is a direct current side outlet fault;
and when the AC line fault is the DC side outlet fault, calculating the equivalent potential of the receiving end AC system according to the current sampling value, the voltage sampling value, the AC line parameter and the receiving end AC system parameter.
9. The ac line dc side outlet fault direction detecting apparatus according to claim 8, further comprising:
and the second judgment module is used for judging that the alternating current line fault is a non-outlet fault when the fundamental voltage amplitude is greater than or equal to the preset voltage setting value.
10. The ac line dc side outlet fault direction detecting apparatus according to claim 6, further comprising:
the protection module is used for sending a tripping command to perform circuit protection when the direct-current side outlet fault is judged to be a forward outlet fault;
and when the direct current side outlet fault is judged to be a reverse outlet fault, a tripping command is not sent.
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| CN202010811774.8A CN111929535B (en) | 2020-08-13 | 2020-08-13 | Method and device for detecting fault direction of direct-current side outlet of alternating-current circuit |
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| CN202010811774.8A CN111929535B (en) | 2020-08-13 | 2020-08-13 | Method and device for detecting fault direction of direct-current side outlet of alternating-current circuit |
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| CN111929535B true CN111929535B (en) | 2023-04-18 |
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