CN113572139A - Flexible direct current transmission line single-end quantity fault protection method and device - Google Patents
Flexible direct current transmission line single-end quantity fault protection method and device Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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Abstract
The invention discloses a single-end quantity fault protection method and a single-end quantity fault protection device for a flexible direct current transmission line, wherein the method comprises the following steps: acquiring voltage signals and current signals of the anode and the cathode of the line at the local terminal, and acquiring voltage fault components and current fault components according to the voltage signals at the stable time and the current signals at the stable time; constructing a protection starting criterion by the voltage sudden change of the direct current line; calculating fault voltage reverse wave and high-frequency components thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating the time domain energy value of the fault voltage reverse wave in a preset integration window length; and forming a fault identification criterion inside and outside the region according to the time domain energy value of the fault voltage reverse wave. By collecting voltage and current signals of the anode and the cathode of the local terminal and forming a starting criterion by the voltage mutation of the direct current line, the time domain energy value of the reverse traveling wave of the fault voltage of the local terminal is obtained to form an internal and external fault identification criterion, the internal and external boundaries of the area are obvious, and the quick action and the reliability of the protection of the direct current transmission line are improved.
Description
Technical Field
The invention relates to the technical field of flexible direct current transmission, in particular to a single-end quantity fault protection method and device for a flexible direct current transmission line.
Background
Although the high-voltage direct-current transmission technology in China starts late, through more than twenty years of efforts, the level of the direct-current transmission technology in China is gradually improved, and the installed capacity of the high-voltage direct-current transmission in China is far ahead in the world at present. The flexible direct current transmission is an important hotspot developed in recent years, and as a new generation of direct current transmission technology, the flexible direct current transmission technology has the characteristics of flexibility, robustness and high efficiency, can fully utilize renewable energy sources in actual use, reduces the loss of social resources, and is a necessary trend of the future development of direct current transmission. More importantly, the method has no inevitable commutation failure of the conventional direct current, so the method is widely applied to direct current power transmission and distribution in recent years.
The flexible direct current line fault current has the characteristics of high rising speed and large peak value. For a topological structure of a current converter similar to a north-expanding flexible direct-current all-half-bridge submodule, in order to reduce the impact of over-current on equipment and cause two or more current converters to be locked simultaneously, the specific requirement on the action time of direct-current protection cannot exceed 3 ms. In order to prevent the power electronic components from being damaged due to sudden rise of fault current, a current-limiting reactor is usually connected in series in a direct-current circuit breaker to form a natural boundary of a direct-current circuit, but the change time of the transient process of the fault voltage is prolonged, and the time is won for protecting the direct-current circuit. Based on the characteristic that the transient voltage and current high-frequency components at the protection installation positions at two ends of the line are obviously larger than those of the fault outside the area when the fault inside the area occurs, the invention provides a method and a device for protecting the single-end quantity of the flexible direct-current transmission line.
Disclosure of Invention
The invention aims to provide a single-end fault protection method and a single-end fault protection device for a flexible direct-current transmission line.
In order to solve the above technical problem, a first aspect of an embodiment of the present invention provides a method for protecting a single-ended fault of a flexible dc transmission line, including the following steps:
acquiring voltage signals and current signals of the anode and the cathode of the direct current transmission line at the local end, and obtaining voltage fault components and current fault components according to the voltage signals at the steady state moment and the current signals at the steady state moment;
constructing a protection starting criterion by the voltage sudden change of the direct current line;
calculating fault voltage reverse wave and high-frequency components thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating the time domain energy value of the fault voltage reverse wave in a preset integration window length;
and forming an internal and external fault identification criterion according to the time domain energy value of the fault voltage reverse wave.
Further, the constructing of the protection start criterion by the sudden change of the dc line voltage specifically includes:
in the formula: and delta u (k) is the voltage abrupt change quantity of the direct current line at the current moment, u (k) is a voltage sampling value at the current moment, u (k-1) is the voltage sampling value 1 period before the current moment, and delta 1 is a starting criterion threshold value.
Further, the fault voltage reverse wave is:
ub(t)＝[Δu(t)-zcΔi(t)]/2，
in the formula: z is a radical ofcFor the transmission line wave impedance, Δ u (t) is the voltage fault component, and Δ i (t) is the current fault component.
Further, the fault voltage reverse wave time domain energy value EbThe calculation of (2):
wherein, T0Starting time, T, being a criterion for protecting the startsIs the integration window length.
Further, the inside and outside area fault identification criterion is:
Eb＞k·Emax,
wherein E isbFor transient fault reverse wave time domain energy values, EmaxThe maximum value of the time domain energy of the metallic grounding fault reverse wave of the bus of the outer pole of the region is k, which is a reliability coefficient.
Further, after the criterion for identifying the fault inside and outside the composition area, the method further includes:
and forming a fault pole selection criterion according to the common-mode voltage fault component.
Further, the forming of the fault pole selection criterion according to the common-mode voltage fault component includes:
wherein u is0Is a common mode voltage, up、unVoltages of two poles and positive and negative poles are respectively; Δ u0For common mode voltage fault components, u0(0) Normal operating common mode voltage; and delta 2 is a starting criterion threshold value.
Accordingly, a first aspect of an embodiment of the present invention provides a single-ended fault protection system for a flexible dc transmission line, including:
the acquisition module is used for acquiring voltage signals and current signals of the anode and the cathode of the local-end direct-current transmission line and acquiring voltage fault components and current fault components according to the voltage signals at the steady state moment and the current signals at the steady state moment;
the first judgment module is used for constructing a protection starting criterion according to the voltage sudden change of the direct-current line;
the calculation module is used for calculating fault voltage reverse wave and high-frequency components thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating the time domain energy value of the fault voltage reverse wave in a preset integration window length;
and the second judgment module is used for forming an inside and outside fault identification criterion according to the time domain energy value of the fault voltage reverse wave.
Further, the criterion of the first determination module is specifically:
in the formula: and delta u (k) is the voltage abrupt change quantity of the direct current line at the current moment, u (k) is a voltage sampling value at the current moment, u (k-1) is the voltage sampling value 1 period before the current moment, and delta 1 is a starting criterion threshold value.
Further, the fault voltage reverse wave specifically is:
ub(t)＝[Δu(t)-zcΔi(t)]/2，
in the formula: z is a radical ofcFor the transmission line wave impedance, Δ u (t) is the voltage fault component, and Δ i (t) is the current fault component.
Further, the fault voltage reverse wave time domain energy value EbThe calculation formula of (2) is as follows:
wherein, T0Starting time, T, being a criterion for protecting the startsIs the integration window length.
Further, the inside and outside area fault identification criterion is:
Eb＞k·Emax,
wherein E isbFor transient fault reverse wave time domain energy values, EmaxThe maximum value of the time domain energy of the metallic grounding fault reverse wave of the bus of the outer pole of the region is k, which is a reliability coefficient.
Further, flexible direct current transmission line single-end capacity fault protection device still includes:
and the third judging module is used for forming a fault pole selection criterion according to the common-mode voltage fault component.
Further, the criterion of the third determination module is as follows:
wherein u is0Is a common mode voltage, up、unVoltages of two poles and positive and negative poles are respectively; Δ u0For common mode voltage fault components, u0(0) Normal operating common mode voltage; and delta 2 is a starting criterion threshold value.
The technical scheme of the embodiment of the invention has the following beneficial technical effects:
the method comprises the steps of collecting voltage and current signals of the anode and the cathode of the direct-current transmission line at the local terminal, forming a starting criterion by using the voltage mutation quantity of the direct-current transmission line, further obtaining the time domain energy value of the reverse wave of the fault voltage at the local terminal, forming an inside and outside fault identification criterion, only adopting the voltage and current electrical quantities at the local terminal, having obvious inside and outside boundaries and easy setting, and improving the quick-acting property and the reliability of the protection of the direct-current transmission line.
Drawings
Fig. 1 is a schematic view of a positive direction of a fault in a high voltage direct current transmission system;
FIG. 2 is a diagram of a reverse wave transmission process when a fault occurs outside the two end regions;
fig. 3 is a flowchart of a single-ended fault protection method for a flexible dc transmission line according to an embodiment of the present invention;
fig. 4 is a logic diagram of a single-ended fault protection method for a flexible dc transmission line according to an embodiment of the present invention;
fig. 5 is a block diagram of a single-ended fault protection device of a flexible dc power transmission line according to an embodiment of the present invention.
Reference numerals:
1. the device comprises an acquisition module 2, a first judgment module 3, a calculation module 4, a second judgment module 5 and a third judgment module.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
Fig. 1 is a positive direction schematic diagram of a fault of a high-voltage direct-current transmission system.
Fig. 2 is a diagram of a reverse wave transmission process when a fault occurs outside the two end regions.
Fig. 3 is a flowchart of a single-ended fault protection method for a flexible dc transmission line according to an embodiment of the present invention.
Fig. 4 is a logic diagram of a single-ended fault protection method for a flexible dc transmission line according to an embodiment of the present invention.
Referring to fig. 1, fig. 2, fig. 3, and fig. 4, a first aspect of an embodiment of the present invention provides a method for protecting a single-ended fault of a flexible dc transmission line, including the following steps:
s100, when a direct current line has a fault, generating fault traveling waves transmitted from a fault point to two ends of the line, acquiring voltage signals and current signals of the anode and the cathode of the direct current transmission line at the end, and acquiring voltage fault components and current fault components according to the voltage signals at the steady state moment and the current signals at the steady state moment;
and S200, constructing a protection starting criterion by the voltage sudden change of the direct current line.
Wherein the abrupt change in the dc line voltage represents a change in the sampling interval.
S300, calculating a fault voltage reverse wave and a high-frequency component thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating a time domain energy value of the fault voltage reverse wave from the filtered voltage reverse wave within a preset integration window length.
And S400, forming a fault identification criterion inside and outside the area according to the time domain energy value of the fault voltage reverse wave. If the fault is discriminated, the single-end quantity protection acts, the direct current circuit breakers at two ends of the direct current circuit are tripped, and a fault source is cut off.
The single-ended quantity refers to the electrical quantity of voltage and current of only one station, namely, the information of the station is only used.
According to the single-end fault protection method for the flexible direct-current transmission line, voltage and current signals of the positive electrode and the negative electrode of the direct-current transmission line at the local end are collected, the voltage mutation quantity of the direct-current transmission line forms a starting criterion, the time domain energy value of the reverse traveling wave of the fault voltage at the local end is further obtained, an inside and outside fault identification criterion is formed, only the voltage and current electrical quantity at the local end is adopted, the inside and outside boundaries of the area are obvious, setting is easy, and the speed and the reliability of protection of the direct-current transmission line are improved.
Specifically, the voltage fault component Δ u (t) and the current fault component Δ i (t) in step S100 are calculated by the following formulas:
in the formula: u (t) is the collected voltage signal, i (t) is the collected current signal; u (0) is a steady-state time voltage signal, and i (0) is a steady-state time current signal.
Specifically, the step S200 of constructing the protection start criterion from the sudden change of the dc line voltage specifically includes:
in the formula: Δ u (k) is a sudden change of the voltage of the direct current line at the current moment, u (k) is a voltage sampling value at the current moment, u (k-1) is a voltage sampling value 1 period before the current moment, and Δ 1 is a threshold value of a starting criterion, which is generally 0.02.
Specifically, in step S300, the fault voltage reversal wave is:
ub(t)＝[Δu(t)-zcΔi(t)]/2，
in the formula: z is a radical ofcFor the transmission line wave impedance, Δ u (t) is the voltage fault component, and Δ i (t) is the current fault component.
The high-frequency component means that the voltage reverse traveling wave passes through an 8-order IIR high-pass filtering link, namely, only high-frequency signals above 2KHz are allowed to pass through.
Specifically, the fault voltage inversion wave time domain energy value E in step S300bThe calculation of (2):
wherein, T0Starting time, T, being a criterion for protecting the startsFor the length of the integration window, the value is larger than the time of the traveling wave in the unidirectional transmission of the power transmission line and smaller than the time of the traveling wave in the back and forth direction.
Discretization of the above equation yields:
in the formula: and N is the number of sampling points in the integration window length, and delta t is an execution period.
Specifically, the inside and outside area fault identification criterion in step S400 is:
Eb＞k·Emax,
wherein E isbFor transient fault reverse wave time domain energy values, EmaxThe maximum value of the time domain energy of the metallic grounding fault reversed wave of the bus of the outer pole of the region is obtained, k is a reliability coefficient, and the value is generally 1.2-1.5. If the above formula condition is satisfied, a fault occurs in the direct current line area, otherwise a fault occurs outside the direct current line area.
Further, after the criterion for identifying the faults inside and outside the composition area in step S400, the method further includes:
and S500, forming a fault pole selection criterion according to the common-mode voltage fault component.
Further, the step S500 of forming a fault pole selection criterion according to the common mode voltage fault component includes:
wherein u is0Is a common mode voltage, up、unVoltages of two poles and positive and negative poles are respectively; Δ u0For common mode voltage fault components, u0(0) Normal operating common mode voltage; and delta 2 is a starting criterion threshold value.
When the positive fault occurs to the line, the common mode voltage is a negative value; when a negative fault occurs to the line, the common-mode voltage is a positive value; when a bipolar fault occurs in the line, the common mode voltage is a value tending to 0.
When a fault occurs outside the area in the direct current line area, the transient fault reverse wave time domain energy value characteristics at two ends of the line are different. When a fault occurs in the line area, the two ends can detect the reverse traveling wave, and the energy of the reverse traveling wave is related to the attenuation constant of the line and the fault position of the line; when out-of-line fault occurs, in-productSub-window length TsIn the method, only one end can detect the reverse wave, so that the protection criterion is formed according to the difference of time domain energy of the reverse wave of the fault inside and outside the region.
Fig. 5 is a block diagram of a single-ended fault protection device of a flexible dc power transmission line according to an embodiment of the present invention.
Accordingly, referring to fig. 5, a first aspect of an embodiment of the present invention provides a single-ended fault protection system for a flexible dc transmission line, including:
the acquisition module 1 is used for acquiring voltage signals and current signals of the anode and the cathode of the local-end direct-current transmission line and acquiring voltage fault components and current fault components according to the voltage signals at the steady state moment and the current signals at the steady state moment;
the first judgment module 2 is used for constructing a protection starting criterion according to the voltage mutation quantity of the direct-current line;
the calculation module 3 is used for calculating the fault voltage reverse wave and the high-frequency component thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating the time domain energy value of the fault voltage reverse wave within a preset integration window length;
and the second judgment module 4 is used for forming an inside and outside fault identification criterion according to the time domain energy value of the fault voltage reverse wave.
Further, the criterion of the first determination module 2 is specifically:
in the formula: and delta u (k) is a sudden change of the direct current line voltage at the current moment, u (k) is a voltage sampling value at the current moment, u (k-1) is a voltage sampling value 1 period before the current moment, and delta 1 is a starting criterion threshold value.
Further, the fault voltage reverse wave specifically is:
ub(t)＝[Δu(t)-zcΔi(t)]/2，
in the formula: z is a radical ofcFor the transmission line wave impedance, Δ u (t) is the voltage fault component, and Δ i (t) is the current fault component.
Further, the fault voltage reverse wave time domain energy value EbThe calculation formula of (2) is as follows:
wherein, T0Starting time, T, being a criterion for protecting the startsIs the integration window length.
Further, the internal and external fault identification criteria are as follows:
Eb＞k·Emax,
wherein E isbFor transient fault reverse wave time domain energy values, EmaxThe maximum value of the time domain energy of the metallic grounding fault reverse wave of the bus of the outer pole of the region is k, which is a reliability coefficient.
Further, flexible direct current transmission line single-end capacity fault protection device still includes:
and the third judging module 5 is used for forming a fault pole selection criterion according to the common-mode voltage fault component.
Further, the third determination module 5 has the following criteria:
wherein u is0Is a common mode voltage, up、unVoltages of two poles and positive and negative poles are respectively; Δ u0For common mode voltage fault components, u0(0) Normal operating common mode voltage; and delta 2 is a starting criterion threshold value.
The single-end fault protection device for the flexible direct-current transmission line has the advantages that the voltage and current signals of the positive electrode and the negative electrode of the direct-current transmission line at the local end are collected, the voltage mutation quantity of the direct-current transmission line forms the starting criterion, the time domain energy value of the reverse wave of the fault voltage at the local end is further obtained, the internal and external fault identification criteria are formed, only the voltage and current electrical quantities at the local end are adopted, the internal and external boundaries of the area are obvious, the setting is easy, and the quick-acting performance and the reliability of the protection of the direct-current transmission line are improved.
Accordingly, a third aspect of the embodiments of the present invention further provides an electronic device, including: at least one processor; and a memory coupled to the at least one processor; wherein the memory stores instructions executable by the one processor to cause the at least one processor to perform the method for single ended fault protection of a flexible direct current power transmission line.
Furthermore, a fourth aspect of the embodiments of the present invention further provides a computer-readable storage medium, on which computer instructions are stored, and the computer instructions, when executed by a processor, implement the method for single-ended fault protection of a flexible direct current transmission line.
The embodiment of the invention aims to protect a single-end quantity fault protection method and a single-end quantity fault protection device for a flexible direct-current transmission line, wherein the method comprises the following steps: acquiring voltage signals and current signals of the anode and the cathode of the direct current transmission line at the local end, and obtaining voltage fault components and current fault components according to the voltage signals at the steady state moment and the current signals at the steady state moment; constructing a protection starting criterion by the voltage sudden change of the direct current line; calculating fault voltage reverse wave and high-frequency components thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating the time domain energy value of the fault voltage reverse wave in a preset integration window length; and forming a fault identification criterion inside and outside the region according to the time domain energy value of the fault voltage reverse wave. The technical scheme has the following effects:
the method comprises the steps of collecting voltage and current signals of the anode and the cathode of the direct-current transmission line at the local terminal, forming a starting criterion by using the voltage mutation quantity of the direct-current transmission line, further obtaining the time domain energy value of the reverse wave of the fault voltage at the local terminal, forming an inside and outside fault identification criterion, only adopting the voltage and current electrical quantities at the local terminal, having obvious inside and outside boundaries and easy setting, and improving the quick-acting property and the reliability of the protection of the direct-current transmission line.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (14)
1. A single-end quantity fault protection method for a flexible direct current transmission line is characterized by comprising the following steps:
acquiring voltage signals and current signals of the anode and the cathode of the direct current transmission line at the local end, and obtaining voltage fault components and current fault components according to the voltage signals at the steady state moment and the current signals at the steady state moment;
constructing a protection starting criterion by the voltage sudden change of the direct current line;
calculating fault voltage reverse wave and high-frequency components thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating the time domain energy value of the fault voltage reverse wave in a preset integration window length;
and forming an internal and external fault identification criterion according to the time domain energy value of the fault voltage reverse wave.
2. The single-ended fault protection method of the flexible direct-current transmission line according to claim 1, wherein a protection start criterion is constructed by a sudden change of a direct-current line voltage, and specifically comprises:
in the formula: and delta u (k) is the voltage abrupt change quantity of the direct current line at the current moment, u (k) is a voltage sampling value at the current moment, u (k-1) is the voltage sampling value 1 period before the current moment, and delta 1 is a starting criterion threshold value.
3. The method of claim 1, wherein the fault voltage reversal wave is:
ub(t)＝[Δu(t)-zcΔi(t)]/2，
in the formula: z is a radical ofcFor the transmission line wave impedance, Δ u (t) is the voltage fault component, and Δ i (t) is the current fault component.
4. The method of claim 1, wherein the fault voltage inverse wave time domain energy value E is a single-ended quantity fault protection method of the flexible dc transmission linebThe calculation of (2):
wherein, T0Starting time, T, being a criterion for protecting the startsIs the integration window length.
5. The single-ended fault protection method of a flexible direct current transmission line according to claim 1, wherein the intra-area and extra-area fault identification criteria are:
Eb＞k·Emax,
wherein E isbFor transient fault reverse wave time domain energy values, EmaxThe maximum value of the time domain energy of the metallic grounding fault reverse wave of the bus of the outer pole of the region is k, which is a reliability coefficient.
6. The single-ended fault protection method of the flexible direct current transmission line according to claim 1, wherein after the forming of the intra-area and extra-area fault identification criterion, the method further comprises:
and forming a fault pole selection criterion according to the common-mode voltage fault component.
7. The method of claim 6, wherein the forming the fault selection criterion based on the common mode voltage fault component comprises:
wherein u is0Is a common mode voltage, up、unVoltages of two poles and positive and negative poles are respectively; Δ u0For common mode voltage fault components, u0(0) Normal operating common mode voltage; and delta 2 is a starting criterion threshold value.
8. The utility model provides a flexible direct current transmission line single-end volume fault protection device which characterized in that includes:
the acquisition module is used for acquiring voltage signals and current signals of the anode and the cathode of the local-end direct-current transmission line and acquiring voltage fault components and current fault components according to the voltage signals at the steady state moment and the current signals at the steady state moment;
the first judgment module is used for constructing a protection starting criterion according to the voltage sudden change of the direct-current line;
the calculation module is used for calculating fault voltage reverse wave and high-frequency components thereof according to the wave impedance, the voltage fault component and the current fault component of the direct-current transmission line, and further calculating the time domain energy value of the fault voltage reverse wave in a preset integration window length;
and the second judgment module is used for forming an inside and outside fault identification criterion according to the time domain energy value of the fault voltage reverse wave.
9. The single-ended fault protection device of claim 8, wherein the first determination module specifically determines the following criteria:
in the formula: and delta u (k) is the voltage abrupt change quantity of the direct current line at the current moment, u (k) is a voltage sampling value at the current moment, u (k-1) is the voltage sampling value 1 period before the current moment, and delta 1 is a starting criterion threshold value.
10. The single-ended fault protection device of claim 8, wherein the fault voltage reversal wave is specifically:
ub(t)＝[Δu(t)-zcΔi(t)]/2，
in the formula: z is a radical ofcFor the transmission line wave impedance, Δ u (t) is the voltage fault component, and Δ i (t) is the current fault component.
11. The flexible direct current transmission line single ended fault protection device of claim 8, wherein said fault voltage reversed wave time domain energy value EbThe calculation formula of (2) is as follows:
wherein, T0Starting time, T, being a criterion for protecting the startsIs the integration window length.
12. The flexible direct current transmission line single ended fault protection device of claim 8, wherein said in-zone and out-of-zone fault identification criteria are:
Eb＞k·Emax,
wherein E isbFor transient fault reverse wave time domain energy values, EmaxThe maximum value of the time domain energy of the metallic grounding fault reverse wave of the bus of the outer pole of the region is k, which is a reliability coefficient.
13. The flexible direct current transmission line single ended fault protection device of claim 8, further comprising:
and the third judging module is used for forming a fault pole selection criterion according to the common-mode voltage fault component.
14. The single-ended fault protection device of claim 13, wherein the third decision module has the criteria:
wherein u is0Is a common mode voltage, up、unVoltages of two poles and positive and negative poles are respectively; Δ u0For common mode voltage fault components, u0(0) Normal operating common mode voltage; and delta 2 is a starting criterion threshold value.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114597876A (en) * | 2022-03-15 | 2022-06-07 | 西安交通大学 | Flexible direct-current transmission line protection method based on reverse wave curvature |
| CN115015686A (en) * | 2022-01-26 | 2022-09-06 | 昆明理工大学 | LCC-VSC hybrid high-voltage direct-current transmission line fault distance measurement method and system |
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