CN115000924B - 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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CN115000924B
CN115000924B CN202210828518.9A CN202210828518A CN115000924B CN 115000924 B CN115000924 B CN 115000924B CN 202210828518 A CN202210828518 A CN 202210828518A CN 115000924 B CN115000924 B CN 115000924B
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line
admittance
current
criterion
voltage
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CN115000924A (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 to ground admittance 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 is widely adopted in a configuration scheme in which 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 relay protection device of a plurality of alternating current collecting lines is reduced already occurs when large-scale new energy is sent out of a power grid in a centralized mode. 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 admittance to the ground 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
Figure 911524DEST_PATH_IMAGE001
、
Figure 810210DEST_PATH_IMAGE002
、
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, obtaining 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 admittance to ground before and after the line fails, a line admittance protection action criterion is constructed, which comprises:
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
Then determineAnd (4) judging 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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、
Figure 17681DEST_PATH_IMAGE041
，
Figure DEST_PATH_IMAGE042
、
Figure 417701DEST_PATH_IMAGE043
、
Figure 751730DEST_PATH_IMAGE044
(ii) a Three-phase current sampling values on two sides of the line 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
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 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 the high-proportion new energy access system are reduced. As 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, and 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 fault occurs inside and outside the area, thereby solving the problem that the sensitivity of the existing current differential protection is influenced by the power failure characteristics.
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 the result of the ac line fault line admittance protection action of the new energy sent out via the flexible direct island mode according to the embodiment of the present invention;
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 fault line admittance protection operation in the 100% input area of the controllable reactor 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 according to an embodiment of the present invention;
fig. 14 shows the result of the intra-area fault line admittance protection action according to the 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 be embodied in many different forms than those herein set forth and should be readily appreciated by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
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 voltage phasor values and current phasor values at two sides of the line are obtained by measuring voltage and current sampling values at two sides of the line. The three-phase voltage on both sides of the line is sampled as
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、
Figure 444191DEST_PATH_IMAGE052
、
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 line 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 a 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:
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
for electric conductionA value;
criterion for a user
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 line admittance protection action criterion is satisfied, carrying out admittance protection action, specifically:
when the temperature is higher than the set temperature
Figure 31512DEST_PATH_IMAGE037
Or
Figure 416357DEST_PATH_IMAGE038
Then, the fault in the line generation area to be judged is determined and judged, and the protection action is admitted.
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 the 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 the rated voltage.
Through 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 220kV. 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 acts 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 fig. 9, a series compensation capacitor is not put into the system diagram, when the controllable reactor is put into the circuit diagram at 100%, AN AN single-phase earth fault occurs in a circuit area, as shown in fig. 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 67%, AN single-phase ground fault in a circuit area occurs, as shown in fig. 11, a non-shaded part in the figure is AN action area, and the ground admittance enters the action area in 1.67 ms.
(2) AC circuit with series compensation capacitor
In a system diagram of a circuit with a series compensation capacitor installed, as shown in fig. 9, the series compensation capacitor is put into, and AN single-phase ground fault occurs in a circuit area, as shown in fig. 12, a non-shaded portion in the diagram is AN action area, a relative ground admittance enters the action area at 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 area 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 the conventional transmission line normally operates, the action condition of the line admittance protection is shown in fig. 16, wherein a non-shaded part is an action area, the ground admittance is always in a shaded part, and the 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 values at both sides of the line;
a differential current and voltage phasor sum determination unit 171 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 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 constructing unit 173 is configured to construct a criterion of line admittance protection action 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
Figure 859375DEST_PATH_IMAGE098
、
Figure 570979DEST_PATH_IMAGE099
、
Figure 170588DEST_PATH_IMAGE100
，
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
、
Figure 886685DEST_PATH_IMAGE108
、
Figure 836187DEST_PATH_IMAGE109
。
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 348202DEST_PATH_IMAGE110
Or
Figure 470879DEST_PATH_IMAGE111
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 a line admittance protection criterion construction device for a high-proportion new energy system, which have the advantages of strong protection fault identification capability, high action speed, no need of manual setting of fixed values, convenient device realization, application to lines of different voltage levels, no need of compensating capacitance current, no influence of a drawing-out characteristic, no influence of a system operation mode and a power failure characteristic, and adaptation to the condition of access of a large amount of new energy 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 so forth) 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 foregoing 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 (9)

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;
according to the change characteristics of the amplitude and the phase of the line admittance to the ground before and after the line fails, a line admittance protection action criterion is constructed, and comprises the following steps:
the line admittance protection criterion is constructed as follows:
Figure 724776DEST_PATH_IMAGE001
in the formula:
Figure 572646DEST_PATH_IMAGE002
the value of the susceptance is fixed,
Figure 232298DEST_PATH_IMAGE003
determining a value for the electrical conductance;
criterion for a user
Figure 456606DEST_PATH_IMAGE004
Reflecting the increase of admittance magnitude, criterion
Figure 127890DEST_PATH_IMAGE005
Reflecting the change in admittance phase.
2. The method of claim 1, further comprising, prior to the step of obtaining the voltage phasor and the current value phasor across the line:
three-phase voltage sampling values on both sides of the measuring line are
Figure 146661DEST_PATH_IMAGE006
，
Figure 293609DEST_PATH_IMAGE007
(ii) a Three-phase current sampling values on two sides of the line are
Figure 321608DEST_PATH_IMAGE008
，
Figure 237611DEST_PATH_IMAGE009
。
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 286339DEST_PATH_IMAGE010
，
Figure 186162DEST_PATH_IMAGE011
Figure 486693DEST_PATH_IMAGE012
(ii) a Current phasor of
Figure DEST_PATH_IMAGE013
，
Figure 257203DEST_PATH_IMAGE014
。
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 DEST_PATH_IMAGE015
in the formula (I), the compound is shown in the specification,
Figure 227564DEST_PATH_IMAGE016
in order to be a differential current flow,
Figure DEST_PATH_IMAGE017
。
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 349104DEST_PATH_IMAGE018
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 DEST_PATH_IMAGE019
in the formula:
Figure 187747DEST_PATH_IMAGE020
，
Figure DEST_PATH_IMAGE021
in order to allow the line to be admittance to ground,
Figure 967091DEST_PATH_IMAGE022
in order to conduct the electricity of the line to ground,
Figure DEST_PATH_IMAGE023
is the line-to-ground susceptance.
6. The method of claim 1, wherein after the step of constructing the line admittance protection action criterion, further comprising:
substituting the variable quantity of the amplitude or the phase of the ground admittance of the line to be judged into the 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_IMAGE025
Or
Figure 826462DEST_PATH_IMAGE026
And determining to judge the fault in the line generation area to be judged, and carrying out admittance protection action.
7. 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;
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 a line fault, and comprises the following steps:
the line admittance protection criterion is constructed as follows:
Figure DEST_PATH_IMAGE027
in the formula:
Figure 169719DEST_PATH_IMAGE028
the value of the susceptance is fixed,
Figure DEST_PATH_IMAGE029
determining a value for the electrical conductance;
the criteria are used as a basis for determining,
Figure 421840DEST_PATH_IMAGE030
reflecting the increase of admittance magnitude, criterion
Figure DEST_PATH_IMAGE031
Reflecting the change in admittance phase.
8. The apparatus of claim 7, further comprising:
a measuring unit for measuring three-phase voltage sampling values of two sides of the line
Figure 25996DEST_PATH_IMAGE032
，
Figure DEST_PATH_IMAGE033
Figure 728373DEST_PATH_IMAGE034
(ii) a Three-phase current sampling values on two sides of the line are
Figure DEST_PATH_IMAGE035
，
Figure 558926DEST_PATH_IMAGE036
。
9. The apparatus of claim 7, 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 DEST_PATH_IMAGE037
Or
Figure 623527DEST_PATH_IMAGE038
And determining to judge the fault in the line generation area to be judged, and carrying out admittance protection action.
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