CN115000924A - Line admittance protection criterion construction method and device for high-proportion new energy system - Google Patents

Line admittance protection criterion construction method and device for high-proportion new energy system Download PDF

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CN115000924A
CN115000924A CN202210828518.9A CN202210828518A CN115000924A CN 115000924 A CN115000924 A CN 115000924A CN 202210828518 A CN202210828518 A CN 202210828518A CN 115000924 A CN115000924 A CN 115000924A
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line
admittance
current
ground
criterion
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CN115000924B (en
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周泽昕
李明节
郭雅蓉
刘宇
王兴国
徐凯
王书扬
刘丹
刘佳琪
戴飞扬
于溯
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means

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Abstract

The invention discloses a method and a device for constructing a line admittance protection criterion for a high-proportion new energy system, wherein the method comprises the following steps: acquiring voltage phasor and current phasor at two sides of a line; determining differential current of the line based on current phasors at two sides of the line; determining the sum of the voltage phasors of the line based on the voltage phasors at the two sides of the line; calculating the ground admittance of the line according to the relation between the differential current and the sum of the voltage phasors; and constructing a line admittance protection action criterion according to the amplitude and phase change characteristics of the line admittance to the ground before and after the line fails. The technical problem that fault identification sensitivity is insufficient due to the fact that short-circuit current is limited after new energy is accessed is solved, and the reliability of protection and response to access of novel equipment such as controllable parallel reactance or series compensation capacitor is improved.

Description

Line admittance protection criterion construction method and device for high-proportion new energy system
Technical Field
The invention relates to the field of relay protection of power systems, in particular to a method and a device for constructing a line admittance protection criterion for a high-proportion new energy system.
Background
With the access of large-scale new energy and power electronics to a power grid, the existing protection faces two problems of sensitivity reduction and insufficient protection adaptability of novel power equipment after the access.
The line protection in the existing ac system adopts a widely adopted configuration scheme that current differential protection is used as main protection, and distance protection is used as backup protection.
Aiming at current differential protection, with the large-scale access of new energy in a novel power system, under the influence of a control system strategy after a new energy power supply fault, a fault current shows the characteristic of limited amplitude, the fault characteristic of a new energy side is weakened, and the sensitivity of the current differential protection principle for identifying faults through the fault current characteristic is greatly reduced. In addition, for a scene that new energy is sent out through a flexible direct current and alternating current collecting line, an alternating current outlet fault has a drawing-out characteristic, and currents on two sides of the line show an outside fault characteristic when an inside fault occurs, so that the action performance of current differential protection is seriously influenced.
For distance protection, the action characteristics of the distance protection are affected by a control strategy of a new energy power supply and a flexible and straight system, so that the existing distance protection may have operation failure or misoperation.
The existing protection can not be adapted due to the above conditions, even incorrect protection action can occur, and faults can not be timely removed, so that the stability of the system is influenced. At present, the problem that the sensitivity of a plurality of alternating current collecting line relay protection devices is reduced when large-scale new energy is sent out of a power grid in a centralized mode is solved. Aiming at the problem of insufficient protection sensitivity and reliability, the line protection principle adapting to high-proportion new energy access needs to be researched urgently, and the fault of a novel power system is rapidly and accurately identified.
Disclosure of Invention
In order to solve the technical problem, the invention provides a line admittance protection criterion construction method for a high-proportion new energy system, which comprises the following steps:
acquiring voltage phasor and current phasor at two sides of a line;
determining differential current of the line based on current phasors at two sides of the line; determining the sum of the voltage phasors of the line based on the voltage phasors at the two sides of the line;
calculating the ground admittance of the line according to the relation between the differential current and the sum of the voltage phasors;
and constructing a line admittance protection action criterion according to the amplitude and phase change characteristics of the line to ground admittance before and after the line fails.
Further, before the step of obtaining the voltage phasor and the current phasor at two sides of the line, the method further comprises the following steps:
three-phase voltage sampling values of two sides of the measuring line are
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、
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、
Figure 520677DEST_PATH_IMAGE003
，
Figure 264642DEST_PATH_IMAGE004
、
Figure 360643DEST_PATH_IMAGE005
、
Figure 164651DEST_PATH_IMAGE006
(ii) a Three-phase current sampling values on two sides of the circuit are
Figure 627993DEST_PATH_IMAGE007
、
Figure 175649DEST_PATH_IMAGE008
、
Figure 893200DEST_PATH_IMAGE009
，
Figure 868110DEST_PATH_IMAGE010
、
Figure 287590DEST_PATH_IMAGE011
、
Figure 435674DEST_PATH_IMAGE012
。
Further, acquiring voltage phasor and current phasor at two sides of the line includes:
based on Fourier recursion algorithm, calculating voltage phasor at two sides of the line as
Figure 257000DEST_PATH_IMAGE013
、
Figure 652078DEST_PATH_IMAGE014
、
Figure 558854DEST_PATH_IMAGE015
，
Figure 448313DEST_PATH_IMAGE016
、
Figure 389724DEST_PATH_IMAGE017
、
Figure 722747DEST_PATH_IMAGE018
(ii) a The current phasor is
Figure 116819DEST_PATH_IMAGE019
、
Figure 606707DEST_PATH_IMAGE020
、
Figure 137045DEST_PATH_IMAGE021
，
Figure 890237DEST_PATH_IMAGE022
、
Figure 755294DEST_PATH_IMAGE023
、
Figure 252135DEST_PATH_IMAGE024
。
Further, based on the current phasors at both sides of the line, the differential current of the line is determined, and the expression of the differential current is as follows:
Figure 902559DEST_PATH_IMAGE025
in the formula (I), the compound is shown in the specification,
Figure 357811DEST_PATH_IMAGE026
in order to be a differential current flow,
Figure 726475DEST_PATH_IMAGE027
。
further, calculating the line-to-ground admittance according to the relationship between the differential current and the sum of the voltage phasors, comprising:
transforming the expression of the differential current to obtain the following expression of the differential current:
Figure 506300DEST_PATH_IMAGE028
according to the relation between the differential current and the sum of the voltage phasors, determining a line-to-ground admittance expression as follows:
Figure 11231DEST_PATH_IMAGE029
in the formula:
Figure 840647DEST_PATH_IMAGE030
，
Figure 696607DEST_PATH_IMAGE031
in order to allow the line to be conducted to ground,
Figure 331988DEST_PATH_IMAGE032
in order to conduct the electricity of the line to ground,
Figure 940693DEST_PATH_IMAGE033
is the line-to-ground susceptance.
Further, according to the amplitude and phase variation characteristics of the line to ground admittance before and after the line fails, a line admittance protection action criterion is constructed, which includes:
the line admittance protection criterion is constructed as follows:
Figure DEST_PATH_IMAGE034
in the formula:
Figure 675431DEST_PATH_IMAGE035
the value of the susceptance is fixed,
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determining a value for the electrical conductance;
criterion
Figure 707103DEST_PATH_IMAGE037
Reflecting the increase of admittance magnitude, criterion
Figure DEST_PATH_IMAGE038
Reflecting the change in admittance phase.
Further, after the step of constructing the line admittance protection action criterion, the method further comprises:
substituting the variable quantity of the amplitude or the phase of the ground admittance of the line to be judged into a line admittance protection action criterion, and when any one line admittance protection action criterion is satisfied, carrying out admittance protection action, specifically:
when in use
Figure 83858DEST_PATH_IMAGE037
Or
Figure 563380DEST_PATH_IMAGE038
And determining to judge the fault in the line generation area to be judged, and carrying out admittance protection action.
The invention also provides a line admittance protection criterion construction device for the high-proportion new energy system, which comprises the following steps:
the phasor value acquisition unit is used for acquiring voltage phasor and current phasor at two sides of the line;
a differential current and voltage phasor sum determination unit for determining a differential current of the line based on the current phasors at both sides of the line; determining the sum of the voltage phasors of the line based on the voltage phasors at the two sides of the line;
the admittance calculating unit is used for calculating the admittance of the line to the ground according to the relation between the differential current and the sum of the voltage phasors;
and the criterion construction unit is used for constructing a line admittance protection action criterion according to the amplitude and phase change characteristics of the line admittance to the ground before and after the line fails.
Further, the method also comprises the following steps:
a measuring unit for measuring three-phase voltage sampling values of two sides of the line
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、
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、
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，
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、
Figure 417701DEST_PATH_IMAGE043
、
Figure 751730DEST_PATH_IMAGE044
(ii) a Three-phase current sampling values on two sides of the circuit are
Figure 359429DEST_PATH_IMAGE045
、
Figure 411699DEST_PATH_IMAGE046
、
Figure 379524DEST_PATH_IMAGE047
，
Figure 833639DEST_PATH_IMAGE048
、
Figure 612239DEST_PATH_IMAGE049
、
Figure 151805DEST_PATH_IMAGE050
。
Further, the method also comprises the following steps:
the protection action unit is used for substituting the variable quantity of the amplitude or the phase of the ground admittance of the line to be judged into a line admittance protection action criterion, and when any one line admittance protection action criterion is satisfied, admittance protection action is performed, specifically:
when in use
Figure 424785DEST_PATH_IMAGE037
Or
Figure 733407DEST_PATH_IMAGE038
And determining to judge the fault in the line generation area to be judged, and carrying out admittance protection action.
The invention provides a line admittance protection criterion construction method and device for a high-proportion new energy system, and provides a line admittance protection principle for identifying faults by using changes of line admittance parameters aiming at the problem that the line protection sensitivity and adaptability of a high-proportion new energy access system are reduced. Because the admittance parameters are inherent parameters of the equipment, the protection principle is not influenced by the operation mode of a system and the power failure characteristics, when the amplitude of the failure current is limited or the phase is changed, the failure can still be identified through the change of the property of the admittance parameters when the area is in failure or the area is out of failure, and the problem that the sensitivity of the existing current differential protection is influenced by the power failure characteristics is solved.
Drawings
Fig. 1 is a schematic flow chart of a method for constructing a line admittance protection criterion for a high-proportion new energy system according to an embodiment of the present invention;
FIG. 2 is a line admittance model according to an embodiment of the present invention;
FIG. 3 is an admittance protection action zone according to an embodiment of the present invention;
FIG. 4 is a logic diagram of admittance protection actions according to an embodiment of the present invention;
fig. 5 is a high-scale new energy access scenario according to an embodiment of the present invention;
fig. 6 shows the admittance protection action result of the high-scale new energy access scenario according to the embodiment of the present invention;
fig. 7 is a scene in which new energy is sent out through a soft route according to an embodiment of the present invention;
fig. 8 shows a new energy source according to an embodiment of the present invention sending out an ac line fault line admittance protection operation result via a flexible-direct island mode;
FIG. 9 is a circuit diagram of a controllable shunt reactor and series compensation capacitor according to an embodiment of the present invention;
FIG. 10 shows the result of the admittance protection action of the fault line in the area where the controllable reactor is 100% put into the area according to the embodiment of the present invention;
fig. 11 shows the result of the admittance protection action of the fault line in the area where 67% of the controllable reactor according to the embodiment of the present invention is put into;
fig. 12 shows the result of the fault line admittance protection in the line area with the series compensation capacitors according to the embodiment of the present invention;
FIG. 13 is a system diagram of a conventional power access scenario to which embodiments of the present invention relate;
fig. 14 shows the result of the intra-area fault line admittance protection action according to an embodiment of the present invention;
fig. 15 shows the result of the admittance protection action of the out-of-area faulty line according to an embodiment of the present invention;
FIG. 16 shows the result of normal operation line admittance protection actions according to an embodiment of the present invention;
fig. 17 is a schematic structural diagram of a line admittance protection criterion construction for a high-scale new energy system according to an embodiment of the present invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather construed as limited to the embodiments set forth herein.
Example 1
Fig. 1 is a schematic flow chart of a method for constructing a line admittance protection criterion for a high-proportion new energy system according to an embodiment of the present invention, and the method provided by the present invention is described in detail below with reference to fig. 1.
And step S101, acquiring voltage phasor and current phasor at two sides of the line.
And acquiring voltage phasor values and current phasor values of two sides of the line by measuring voltage and current sampling values of the two sides of the line. The three-phase voltage on both sides of the line is sampled as
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、
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、
Figure 566868DEST_PATH_IMAGE053
，
Figure 979263DEST_PATH_IMAGE054
、
Figure 99666DEST_PATH_IMAGE055
、
Figure 613824DEST_PATH_IMAGE056
(ii) a Three-phase current sampling values on two sides of the circuit are
Figure 477875DEST_PATH_IMAGE057
、
Figure 240383DEST_PATH_IMAGE058
、
Figure 797266DEST_PATH_IMAGE059
，
Figure 533141DEST_PATH_IMAGE060
、
Figure 200882DEST_PATH_IMAGE061
、
Figure 322291DEST_PATH_IMAGE062
。
Based on Fourier recursion algorithm, calculating voltage phase values at two sides of the line as
Figure 50076DEST_PATH_IMAGE063
、
Figure 476509DEST_PATH_IMAGE064
、
Figure 433095DEST_PATH_IMAGE065
，
Figure 425322DEST_PATH_IMAGE066
、
Figure 324007DEST_PATH_IMAGE067
、
Figure 768895DEST_PATH_IMAGE068
(ii) a The current phasor value is
Figure 27707DEST_PATH_IMAGE069
、
Figure 140020DEST_PATH_IMAGE070
、
Figure 944028DEST_PATH_IMAGE071
，
Figure 141791DEST_PATH_IMAGE072
、
Figure 486184DEST_PATH_IMAGE073
、
Figure 203736DEST_PATH_IMAGE074
。
Step S102, determining differential current of the line based on current phasor values at two sides of the line; the sum of the voltage phasors for the line is determined based on the voltage phasors across the line.
The expression for the differential current of the line is:
Figure 178645DEST_PATH_IMAGE075
in the formula (I), the compound is shown in the specification,
Figure 863704DEST_PATH_IMAGE076
in order to be a differential current flow,
Figure 215051DEST_PATH_IMAGE077
。
and step S103, calculating the admittance to the ground of the line according to the relation between the differential current and the sum of the voltage phasors.
Converting the expression of the differential current according to the relationship between the differential current of the line and the phasor sum of the voltages at two sides of the line to obtain the following expression of the differential current:
Figure 285644DEST_PATH_IMAGE078
as shown in fig. 2, according to the relationship between the differential current and the sum of the voltage phasors, determining a line-to-ground admittance expression as follows:
Figure 697034DEST_PATH_IMAGE079
in the formula:
Figure 603810DEST_PATH_IMAGE080
，
Figure 493269DEST_PATH_IMAGE081
in order to allow the line to be admittance to ground,
Figure 185412DEST_PATH_IMAGE082
in order to conduct the electricity of the line to ground,
Figure 236545DEST_PATH_IMAGE083
is the line-to-ground susceptance.
And step S104, constructing a line admittance protection action criterion according to the amplitude and phase change characteristics of the line admittance to the ground before and after the line fails.
And constructing a line admittance protection action criterion by using the obvious difference of the amplitude and the phase of the line admittance to the ground when the line fails in the region and the region.
When the system normally operates or an out-of-area fault occurs, the line-to-ground admittance reflects the line-to-ground capacitance, the amplitude is less than 1mS, and the phase is capacitive.
When an internal fault occurs, the admittance of the line to the ground reflects the parallel connection of the conductance (the reciprocal of the transition resistance) and the susceptance (the reciprocal of the capacitive reactance to the ground), the amplitude is greater than 100mS, and the phase presents the inductive or the resistance-capacitance property.
I.e. both the amplitude and phase of the admittance to ground change significantly before and after a line fault.
The line admittance protection criterion is constructed as follows:
Figure 630617DEST_PATH_IMAGE034
in the formula:
Figure 323767DEST_PATH_IMAGE035
the value of the susceptance is fixed,
Figure 916422DEST_PATH_IMAGE036
determining a value for the electrical conductance;
criterion
Figure 918882DEST_PATH_IMAGE037
Reflecting the increase of admittance magnitude, criterion
Figure 800250DEST_PATH_IMAGE038
Reflecting the change in admittance phase.
Substituting the ground admittance of the line to be judged into a line admittance protection action criterion, and when any one line admittance protection action criterion is satisfied, carrying out admittance protection action, specifically:
when in use
Figure 31512DEST_PATH_IMAGE037
Or
Figure 416357DEST_PATH_IMAGE038
And determining to judge the fault in the line generation area to be judged, and carrying out admittance protection action.
The line admittance protection does not need manual setting, and the fixed value in the protection criterion can be solidified in the protection device. The key constant value setting method comprises the following steps:
(1) key constant 1: constant value of susceptance
Figure 85323DEST_PATH_IMAGE084
Figure 719567DEST_PATH_IMAGE085
The setting principle is that the maximum capacitance of the line is set, i.e. the line is set
Figure 754519DEST_PATH_IMAGE086
Avoiding the setting of the maximum setting capacitance current, wherein the setting principle is as follows:
Figure 259450DEST_PATH_IMAGE087
in the formula:
Figure 603712DEST_PATH_IMAGE088
line-to-ground susceptance per kilometer;
Figure 459673DEST_PATH_IMAGE089
the longest AC line without parallel reactance compensation;
Figure 32737DEST_PATH_IMAGE090
is a setting margin.
(2) Key constant 2: electric conductivity value
Figure 392174DEST_PATH_IMAGE091
Figure 408802DEST_PATH_IMAGE091
The setting principle is to set according to the maximum transition resistance, i.e. according to
Figure 486480DEST_PATH_IMAGE092
The sensitivity is set, and the setting principle is as follows:
Figure 128814DEST_PATH_IMAGE094
in the formula:
Figure 608337DEST_PATH_IMAGE095
a minimum short circuit current identifiable for admittance protection;
Figure 294402DEST_PATH_IMAGE097
is a rated voltage.
By the key constant value setting method, the shaded portion in fig. 3 is an out-of-area fault, and the remaining portion is an in-area fault.
And after the fault occurs, the admittance of the line to the ground enters an action area, and the admittance protection acts. Admittance protection action logic is shown in fig. 4.
Example 2
The following scenarios are selected below to verify the reliability of the line admittance protection.
1. High-proportion new energy access scene
The high-proportion new energy access scene is that offshore wind power is sent out through a submarine cable, CN single-phase earth fault occurs in a submarine cable generation area, and the system voltage level is 220 kV. The system diagram is shown in fig. 5, the result of the admittance protection action is shown in fig. 6, the unshaded part in the diagram is the action zone, a is relatively admittance and B are relatively admittance not to enter the action zone, and C is relatively admittance to enter the action zone in 5 ms. The line admittance protection operates reliably.
2. New energy direct-sending scene through soft
The new energy is sent out through a flexible direct-out scene in a flexible direct island mode, namely the new energy access proportion is 100%, and AB interphase faults in an alternating-current outgoing line generation area are avoided. The system diagram is shown in fig. 7, the result of the admittance protection action is shown in fig. 8, the unshaded part in the diagram is the action zone, a relatively admittance enters the action zone at 3.33ms, B relatively admittance enters the action zone at 2.5ms, and C relatively admittance does not enter the action zone. The line admittance protection operates reliably.
3. Power electronic device access scene
(1) AC line with controllable shunt reactance
A system diagram of a circuit provided with a controllable shunt reactor is shown in figure 9, a series compensation capacitor is not put into the system diagram, when the controllable reactor is put into the system diagram at 100%, AN (AN) single-phase ground fault in a circuit area occurs, as shown in figure 10, a non-shaded part in the diagram is AN action area, a relative ground admittance enters the action area within 1.67ms, and B relative ground admittance and C relative ground admittance do not enter the action area.
When the controllable reactor is switched in at 67%, AN single-phase ground fault occurs in the circuit area, as shown in fig. 11, the non-shaded part in the figure is the action area, and the admittance to the ground enters the action area at 1.67 ms.
(2) AC circuit with series compensation capacitor
The system diagram of a circuit provided with a series compensation capacitor is shown in fig. 9, the series compensation capacitor is put into, AN AN single-phase ground fault occurs in a circuit area, as shown in fig. 12, the non-shaded part in the diagram is AN action area, A relative ground admittance enters the action area within 1.67ms, and B relative ground admittance and C relative ground admittance do not enter the action area.
4. Conventional power access scenarios
The conventional power source access scenario is that the power sources on both sides of the line are conventional power sources, and a system diagram is shown in fig. 13, which discusses the conditions of the line in-zone fault, the out-of-zone fault and the normal operation respectively.
(1) In-zone fault
AN single-phase ground fault occurs in the line area, and the action condition of the line admittance protection is shown in fig. 14. The unshaded part of the figure is the action zone, A relatively admits into the action zone at 1.67ms, B relatively admits and C relatively admits into the action zone.
(2) Out-of-range fault
When a line external fault occurs on the line, the operation of the line admittance protection is as shown in fig. 15, in which the non-shaded part is the operation area, the ground admittance is always shaded, and the protection does not operate.
(3) Normal operation
When a conventional power transmission line normally runs, the action condition of line admittance protection is shown in fig. 16, a non-shaded part in the figure is an action area, ground admittance is always in a shaded part, and protection does not act.
Example 3
Based on the same inventive concept, the present invention also provides a line admittance protection criterion construction apparatus 17 for a high-proportion new energy system, as shown in fig. 17, including:
a phasor value acquisition unit 170 for acquiring voltage phasor and current phasor at both sides of the line;
a differential current and voltage phasor sum determination unit 171 for determining the differential current of the line based on the current phasors at both sides of the line; determining the sum of the voltage phasors of the line based on the voltage phasors at the two sides of the line;
the admittance calculating unit 172 is used for calculating the wire admittance to the ground according to the relation between the differential current and the sum of the voltage phasors;
the criterion construction unit 173 is configured to construct a line admittance protection action criterion according to the amplitude and phase variation characteristics of the line admittance to ground before and after a fault occurs in the line.
Further, the method also comprises the following steps:
a measuring unit for measuring three-phase voltage sampling values of two sides of the line
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、
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、
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，
Figure 778287DEST_PATH_IMAGE101
、
Figure 581289DEST_PATH_IMAGE102
、
Figure 299846DEST_PATH_IMAGE103
(ii) a Three-phase current sampling values on two sides of the circuit are
Figure 753961DEST_PATH_IMAGE104
、
Figure 266982DEST_PATH_IMAGE105
、
Figure 55816DEST_PATH_IMAGE106
，
Figure 578064DEST_PATH_IMAGE107
、
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、
Figure 836187DEST_PATH_IMAGE109
。
Further, the method also comprises the following steps:
a protection action unit, configured to substitute a variation of an amplitude or a phase of a ground admittance of a line to be determined into a line admittance protection action criterion, where, when any one of the line admittance protection action criteria is satisfied, an admittance protection action is performed, specifically:
when the temperature is higher than the set temperature
Figure 348202DEST_PATH_IMAGE110
Or
Figure 470879DEST_PATH_IMAGE111
Then, the fault in the line generation area to be judged is determined and judged, and the protection action is admitted.
The invention provides a line admittance protection criterion construction method and a line admittance protection criterion construction device for a high-proportion new energy system, which have the advantages of strong protection fault recognition capability, high action speed, no need of manual setting of a fixed value, convenient device realization, no need of compensating capacitor current for lines with different voltage levels, no influence from a drawing-out characteristic, no influence from a system operation mode and a power supply fault characteristic, and adaptability to the conditions of access of a large number of new energy resources and power electronic equipment of a power system. The technical problem that fault identification sensitivity is insufficient due to the fact that short-circuit current is limited after new energy is connected is solved, the reliability of protection response on connection of novel equipment such as controllable parallel reactance or series compensation capacitor is improved, support is provided for stability of a novel power system, conditions are created for large-scale clean energy consumption, and the method has high practical value and wide application prospect.
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: although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention.

Claims (10)

1. A line admittance protection criterion construction method for a high-proportion new energy system is characterized by comprising the following steps:
acquiring voltage phasor and current phasor at two sides of a line;
determining differential current of the line based on current phasors at two sides of the line; determining the sum of the voltage phasors of the line based on the voltage phasors at the two sides of the line;
calculating the ground admittance of the line according to the relation between the differential current and the sum of the voltage phasors;
and constructing a line admittance protection action criterion according to the amplitude and phase change characteristics of the line admittance to the ground before and after the line fails.
2. The method of claim 1, further comprising, prior to the step of obtaining voltage phasor and current phasor values across the line:
three-phase voltage sampling values of two sides of the measuring line are
Figure 134271DEST_PATH_IMAGE001
、
Figure 936005DEST_PATH_IMAGE002
、
Figure 15956DEST_PATH_IMAGE003
，
Figure 11988DEST_PATH_IMAGE004
、
Figure 810179DEST_PATH_IMAGE005
、
Figure 884446DEST_PATH_IMAGE006
(ii) a Three-phase current sampling values on two sides of the line are
Figure 694270DEST_PATH_IMAGE007
、
Figure 218792DEST_PATH_IMAGE008
、
Figure 878181DEST_PATH_IMAGE009
，
Figure 146352DEST_PATH_IMAGE010
、
Figure 341841DEST_PATH_IMAGE011
、
Figure 302843DEST_PATH_IMAGE012
。
3. The method of claim 1, wherein obtaining voltage phasor and current phasor values across a line comprises:
based on Fourier recursion algorithm, calculating voltage phasor at two sides of the line as
Figure 685414DEST_PATH_IMAGE013
、
Figure 757276DEST_PATH_IMAGE014
、
Figure 807271DEST_PATH_IMAGE015
，
Figure 876858DEST_PATH_IMAGE016
、
Figure 136938DEST_PATH_IMAGE017
、
Figure 117883DEST_PATH_IMAGE018
(ii) a Current phasor of
Figure 412598DEST_PATH_IMAGE019
、
Figure 325190DEST_PATH_IMAGE020
、
Figure 72567DEST_PATH_IMAGE021
，
Figure 689493DEST_PATH_IMAGE022
、
Figure 448501DEST_PATH_IMAGE023
、
Figure 187787DEST_PATH_IMAGE024
。
4. The method of claim 1, wherein the differential current of the line is determined based on current phasors across the line, the differential current being expressed as:
Figure 32246DEST_PATH_IMAGE025
in the formula (I), the compound is shown in the specification,
Figure 187284DEST_PATH_IMAGE026
in order to be a differential current flow,
Figure 191012DEST_PATH_IMAGE027
。
5. the method of claim 1, wherein calculating a line-to-ground admittance from the differential current versus sum of voltage phasors comprises:
transforming the expression of the differential current to obtain the following expression of the differential current:
Figure 209522DEST_PATH_IMAGE028
according to the relation between the differential current and the sum of the voltage phasors, determining a line-to-ground admittance expression as follows:
Figure 665911DEST_PATH_IMAGE029
in the formula:
Figure 624640DEST_PATH_IMAGE030
，
Figure 358240DEST_PATH_IMAGE031
in order to allow the line to be admittance to ground,
Figure 173750DEST_PATH_IMAGE032
in order to conduct the electricity of the line to ground,
Figure 258380DEST_PATH_IMAGE033
is the line-to-ground susceptance.
6. The method of claim 1, wherein constructing a line admittance protection action criterion according to the amplitude and phase variation characteristics of the line admittance to ground before and after a fault occurs comprises:
the line admittance protection criterion is constructed as follows:
Figure 755221DEST_PATH_IMAGE034
in the formula:
Figure 467962DEST_PATH_IMAGE035
the value of the susceptance is fixed,
Figure 329738DEST_PATH_IMAGE036
determining a value for the electrical conductance;
criterion
Figure 26299DEST_PATH_IMAGE037
Reflecting the increase of admittance magnitude, criterion
Figure 500399DEST_PATH_IMAGE038
Reflecting the change in admittance phase.
7. The method according to claim 1 or 6, further comprising, after the step of constructing a line admittance protection action criterion:
substituting the variable quantity of the amplitude or the phase of the ground admittance of the line to be judged into a line admittance protection action criterion, and when any one line admittance protection action criterion is satisfied, carrying out admittance protection action, specifically:
when in use
Figure DEST_PATH_IMAGE039
Or
Figure 802067DEST_PATH_IMAGE040
Then, the fault in the line generation area to be judged is determined and judged, and the protection action is admitted.
8. A line admittance protection criterion construction device for a high-proportion new energy system is characterized by comprising the following steps:
the phasor value acquisition unit is used for acquiring voltage phasor and current phasor at two sides of the line;
a differential current and voltage phasor sum determination unit for determining a differential current of the line based on the current phasors at both sides of the line; determining the sum of the voltage phasors of the line based on the voltage phasors at the two sides of the line;
the admittance calculating unit is used for calculating the admittance of the line to the ground according to the relation between the differential current and the sum of the voltage phasors;
and the criterion construction unit is used for constructing a line admittance protection action criterion according to the amplitude and phase change characteristics of the line to ground admittance before and after the line fails.
9. The apparatus of claim 8, further comprising:
a measuring unit for measuring three-phase voltage sampling values of two sides of the line
Figure DEST_PATH_IMAGE041
、
Figure 365904DEST_PATH_IMAGE042
、
Figure 159548DEST_PATH_IMAGE043
，
Figure 60508DEST_PATH_IMAGE044
、
Figure 623207DEST_PATH_IMAGE045
、
Figure 951420DEST_PATH_IMAGE046
(ii) a Three-phase current sampling values on two sides of the line are
Figure 294677DEST_PATH_IMAGE047
、
Figure 373229DEST_PATH_IMAGE048
、
Figure 180648DEST_PATH_IMAGE049
，
Figure 555129DEST_PATH_IMAGE050
、
Figure 182419DEST_PATH_IMAGE051
、
Figure 34969DEST_PATH_IMAGE052
。
10. The apparatus of claim 8, further comprising:
the protection action unit is used for substituting the variable quantity of the amplitude or the phase of the ground admittance of the line to be judged into a line admittance protection action criterion, and when any one line admittance protection action criterion is satisfied, admittance protection action is performed, specifically:
when in use
Figure 900156DEST_PATH_IMAGE054
Or
Figure 570172DEST_PATH_IMAGE056
And determining to judge the fault in the line generation area to be judged, and carrying out admittance protection action.
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CN111682546A (en) * 2020-06-01 2020-09-18 国网河北省电力有限公司石家庄供电分公司 DC power flow improvement algorithm based on sensitivity analysis
CN112713576A (en) * 2020-12-21 2021-04-27 西安理工大学 Short-circuit protection method for radiation direct-current micro-grid
CN114204525A (en) * 2021-11-10 2022-03-18 华中科技大学 Pilot protection method for direct-current transmission line and application thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5170308A (en) * 1989-01-20 1992-12-08 Hitachi, Ltd. Method and system of transformer protection and method and system of detecting a defective winding
CN101068079A (en) * 2007-06-18 2007-11-07 北京交通大学 Method for realizing transmission line protection based on admittance principle
CN101106266A (en) * 2007-06-18 2008-01-16 北京交通大学 A method for realizing transformer protection based on guiding nano principle
CN101136549A (en) * 2007-10-12 2008-03-05 清华大学 Power system separation decision space screening method
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CN111682546A (en) * 2020-06-01 2020-09-18 国网河北省电力有限公司石家庄供电分公司 DC power flow improvement algorithm based on sensitivity analysis
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