CN107968384B - Same-pole multi-loop zero-sequence current protection method and device - Google Patents

Same-pole multi-loop zero-sequence current protection method and device Download PDF

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CN107968384B
CN107968384B CN201710987276.7A CN201710987276A CN107968384B CN 107968384 B CN107968384 B CN 107968384B CN 201710987276 A CN201710987276 A CN 201710987276A CN 107968384 B CN107968384 B CN 107968384B
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line
zero sequence
adjacent
current
phase
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CN107968384A (en
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陈建民
邱智勇
姜宪国
李仲青
王兴国
姚斌
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Sgcc East China Branch
State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
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Sgcc East China Branch
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
    • H02H7/267—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 parallel lines and wires

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Abstract

The invention relates to a same-pole multi-loop zero-sequence current protection method and a device, wherein the method comprises the following steps: determining zero sequence current of a line and adjacent lines thereof; acquiring zero sequence mutual inductance coefficients of the adjacent lines to the lines, and determining compensation coefficients of the adjacent lines according to the zero sequence mutual inductance coefficients of the adjacent lines to the lines; determining zero sequence current after line compensation by using zero sequence current of the line and adjacent lines thereof and compensation coefficients of the adjacent lines; according to the zero sequence current of the circuit and the zero sequence current after the compensation of the circuit, the zero sequence current protection action is started on the circuit.

Description

Same-pole multi-loop zero-sequence current protection method and device
Technical Field
The invention relates to the field of relay protection of power systems, in particular to a method and a device for protecting zero-sequence current of a same-pole multi-circuit line.
Background
With the increasing of domestic power load, the electric power construction is rapidly developed, and transmission corridor is increasingly in short supply, and the same-tower double-circuit, three-circuit and four-circuit lines can share the corridor, so that occupied land resources are saved, and the solar energy power transmission corridor is more and more widely applied. In the same-tower multi-circuit line erection, due to the limitation of practical conditions, a large number of projects adopt the erection form of different-tower transposition, and in addition, part of lines adopt the erection mode of local same tower, so that three phases of all circuit lines cannot be completely symmetrical.
The asymmetry of parameters of each line of the same tower and the electromagnetic coupling relation between the lines and adjacent lines can generate a large unbalanced component in load current flowing through the lines of the same tower, wherein the influence of the unbalanced component of zero sequence on protection is the most prominent. According to research, the zero sequence current amplitude is overlarge due to the influences of unbalanced line parameters and mutual inductance in complex same-tower multi-circuit line engineering, and zero sequence current protection misoperation can be caused in serious cases. Therefore, it is necessary to research a new zero sequence current protection method to avoid the influence of the adjacent lines on the current line.
Disclosure of Invention
The invention provides a method and a device for protecting zero sequence current of multiple loops on the same pole, aiming at effectively compensating the zero sequence current, reducing the influence of adjacent lines on the zero sequence current of the line, avoiding the false action of the zero sequence current protection of the line due to the influence of the adjacent lines and improving the safety of the zero sequence current protection.
The purpose of the invention is realized by adopting the following technical scheme:
the improvement of a same-pole multi-loop zero-sequence current protection method is that the method comprises the following steps:
determining zero sequence current of a line and adjacent lines thereof;
acquiring zero sequence mutual inductance coefficients of the adjacent lines to the lines, and determining compensation coefficients of the adjacent lines according to the zero sequence mutual inductance coefficients of the adjacent lines to the lines;
determining zero sequence current after line compensation by using zero sequence current of the line and adjacent lines thereof and compensation coefficients of the adjacent lines;
and judging whether to start zero sequence current protection action on the line according to the zero sequence current of the line and the zero sequence current compensated by the line.
Preferably, the determining zero sequence currents of the line and its adjacent lines includes:
determining zero sequence current of the line according to the following formula
Figure BDA0001440780340000021
Figure BDA0001440780340000022
In the above formula, the first and second carbon atoms are,
Figure BDA0001440780340000023
for the a-phase current phasor of the line,
Figure BDA0001440780340000024
for the phase B current phasor of the line,
Figure BDA0001440780340000025
is the C-phase current phasor of the line;
determining zero sequence current of the x-th adjacent line of the line according to the following formula
Figure BDA0001440780340000026
Figure BDA0001440780340000027
Wherein: x is the [1,4 ]]，
Figure BDA0001440780340000028
The a-phase current phasor for the x-th adjacent line of the line,
Figure BDA0001440780340000029
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA00014407803400000210
the phase quantity of the C-phase current of the x-th adjacent line of the lines.
Preferably, the obtaining zero sequence mutual inductance of the adjacent line to the line, and determining the compensation coefficient of the adjacent line according to the zero sequence mutual inductance of the adjacent line to the line includes:
determining zero sequence mutual inductance of the adjacent line to the line according to the following formula, including:
Figure BDA00014407803400000211
wherein: kxAZero sequence mutual inductance coefficient, K, of phase A current of said adjacent x-th line to said linexBZero sequence mutual inductance coefficient, K, of phase B current of said adjacent x-th line to said linexCFor the zero sequence mutual inductance coefficient of the adjacent x-th line C-phase current to the line,
Figure BDA00014407803400000212
is the zero-sequence current of the line,
Figure BDA00014407803400000213
the a-phase current phasor for the x-th adjacent line of the line,
Figure BDA00014407803400000214
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA00014407803400000215
for the phase quantity of C phase current of the x-th adjacent line of the line, x is the [1,4 ]]；
Determining the compensation coefficient K of the x-th adjacent line of the line according to the following formulax：
Kx＝(KxA+KxB+KxC)/3
Preferably, the determining the zero sequence current after line compensation by using the zero sequence current of the line and the adjacent line and the compensation coefficient of the adjacent line includes:
determining the zero sequence current after line compensation according to the following formula:
Figure BDA0001440780340000031
wherein:
Figure BDA0001440780340000032
is the zero sequence current of the line, KxFor the compensation coefficients of the x-th adjacent line of said lines,
Figure BDA0001440780340000033
zero sequence current of the x-th adjacent line of the line.
Preferably, the determining whether to start a protection action on the line according to the zero sequence current of the line and the zero sequence current compensated by the line includes:
if the zero sequence current of the line and the zero sequence current after line compensation meet the protection condition, starting protection action on the line, wherein the protection condition is determined according to the following formula:
Figure BDA0001440780340000034
b:t＞T0dz
wherein: i is0dzIs a zero sequence current constant value, T0dzIs a zero sequence time fixed value and t is the duration time satisfying the condition a.
The improvement of a same-pole multi-loop zero-sequence current protection device is that the device comprises:
the first determination unit is used for determining zero sequence currents of the line and the adjacent line;
the second determining unit is used for acquiring the zero sequence mutual inductance coefficient of the adjacent line to the line and determining the compensation coefficient of the adjacent line according to the zero sequence mutual inductance coefficient of the adjacent line to the line;
the third determining unit is used for determining zero sequence current after line compensation by using zero sequence current of the line and adjacent lines thereof and the compensation coefficient of the adjacent lines;
and the protection unit is used for judging whether to start zero sequence current protection action on the line according to the zero sequence current of the line and the zero sequence current compensated by the line.
Preferably, the first determining unit includes:
a first determining module for determining zero sequence current of the line according to the following formula
Figure BDA0001440780340000035
Figure BDA0001440780340000041
In the above formula, the first and second carbon atoms are,
Figure BDA0001440780340000042
for the a-phase current phasor of the line,
Figure BDA0001440780340000043
for the phase B current phasor of the line,
Figure BDA0001440780340000044
is the C-phase current phasor of the line;
a second determining module for determining zero sequence current of the x-th adjacent line of the line according to the following formula
Figure BDA0001440780340000045
Figure BDA0001440780340000046
Wherein: x is an element of [1, X ]]，
Figure BDA0001440780340000047
The a-phase current phasor for the x-th adjacent line of the line,
Figure BDA0001440780340000048
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA0001440780340000049
the phase quantity of the C-phase current of the x-th adjacent line of the lines.
Preferably, the second determination unit includes:
a third determination module: for determining zero sequence mutual inductance of said adjacent line pair said line according to the following equation, comprising:
Figure BDA00014407803400000410
wherein: kxAZero sequence mutual inductance coefficient, K, of phase A current of said adjacent x-th line to said linexBZero sequence mutual inductance coefficient, K, of phase B current of said adjacent x-th line to said linexCFor the zero sequence mutual inductance coefficient of the adjacent x-th line C-phase current to the line,
Figure BDA00014407803400000411
is the zero-sequence current of the line,
Figure BDA00014407803400000412
the a-phase current phasor for the x-th adjacent line of the line,
Figure BDA00014407803400000413
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA00014407803400000414
for the phase quantity of C phase current of the x-th adjacent line of the line, x is the [1,4 ]]；
A fourth determining module for determining the compensation coefficient K of the xth adjacent line of the line according to the following formulax：
Kx＝(KxA+KxB+KxC)/3
Preferably, the third determining unit includes:
a fifth determining module, configured to determine the zero-sequence current after the line compensation according to the following formula:
Figure BDA0001440780340000051
wherein:
Figure BDA0001440780340000052
is the zero sequence current of the line, KxFor the compensation coefficients of the x-th adjacent line of said lines,
Figure BDA0001440780340000053
zero sequence current of the x-th adjacent line of the line.
Preferably, the protection unit includes:
the protection module is used for starting protection action on the line if the zero sequence current of the line and the zero sequence current compensated by the line meet protection conditions, wherein the protection conditions are determined according to the following formula:
Figure BDA0001440780340000054
b:t＞T0dz
wherein: i is0dzIs a zero sequence current constant value, T0dzIs a zero sequence time fixed value and t is the duration time satisfying the condition a.
The invention has the beneficial effects that:
according to the technical scheme provided by the invention, the zero sequence current of the adjacent line is introduced into the zero sequence current protection of the line by determining the zero sequence current of the adjacent line after compensation and comprehensively considering the zero sequence current of the line. Based on the technical scheme provided by the invention, the zero-sequence current can be effectively compensated, the influence of adjacent lines on the zero-sequence current of the line can be reduced, the false action of the zero-sequence current protection of the line due to the influence of the adjacent lines can be avoided, and the safety of the zero-sequence current protection is improved.
Drawings
FIG. 1 is a connection diagram of 500kV 5415, 5416 and 5810 lines in the embodiment of the invention;
FIG. 2 is a phasor diagram of three-phase currents and zero-sequence currents of 5415 and 5416 lines in an embodiment of the invention;
FIG. 3 is a flow chart of a same-pole multi-loop zero-sequence current protection method provided by the invention;
FIG. 4 is a diagram of zero sequence mutual inductance of the I loop line A relative to the II loop line in the embodiment of the present invention;
FIG. 5 is a diagram of zero sequence mutual inductance of the I loop line B relative to the II loop line in the embodiment of the present invention;
FIG. 6 is a diagram of zero sequence mutual inductance of the I loop circuit C relative to the II loop circuit according to the embodiment of the present invention;
fig. 7 is a schematic structural diagram of a same-pole multi-loop zero-sequence current protection device provided by the invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
At present, the construction of a power transmission network is increasingly complex, and the three-phase parameter asymmetry of a line is easily caused by a complex line erecting mode, so that the occurrence of unbalanced current in the line is further caused. For example, as shown in fig. 1, the load of the same-tower three-circuit line sent by a certain power station is increased due to the fact that the same-tower three-circuit line is pulled away from the vicinity of the same-tower three-circuit line, so that the zero-sequence unbalanced current exceeds 300A, the zero-sequence inverse time-lag protection limit value is adjusted urgently, an operation risk is caused, and even the zero-sequence current reaches the limit value under some operation conditions, so that a power grid outage accident is caused.
The current secondary values of Qin from line 5415 and Qin fist line 5416 are shown in Table 1.
TABLE 15415 and 5416 line current secondary values (CT ratio 2500:1)
Figure BDA0001440780340000061
The secondary current reaches 0.11A, corresponding to the primary zero sequence current 275A, and approaches 300A action constant value.
As shown in fig. 2, which is a phase diagram of three-phase current and zero-sequence current of 5415 and 5416 lines, due to the influence of the same-pole line, the three-phase current of the line is asymmetric, and the zero-sequence current is large, so it is necessary to research a new zero-sequence current protection method to avoid the influence of the adjacent line on the zero-sequence current of the line.
The invention provides a same-pole multi-loop zero-sequence current protection method, which is used for avoiding the influence of adjacent lines on zero-sequence current protection of a line, and as shown in fig. 3, the method comprises the following steps:
101. determining zero sequence current of a line and adjacent lines thereof;
102. acquiring zero sequence mutual inductance coefficients of the adjacent lines to the lines, and determining compensation coefficients of the adjacent lines according to the zero sequence mutual inductance coefficients of the adjacent lines to the lines;
103. determining zero sequence current after line compensation by using zero sequence current of the line and adjacent lines thereof and compensation coefficients of the adjacent lines;
104. and judging whether to start zero sequence current protection action on the line according to the zero sequence current of the line and the zero sequence current compensated by the line.
For example: taking the same line in a certain area in east China as an example, 3 adjacent lines are used.
Specifically, the step 101 includes:
determining zero sequence current of the line according to the following formula
Figure BDA0001440780340000071
Figure BDA0001440780340000072
In the above formula, the first and second carbon atoms are,
Figure BDA0001440780340000073
for the a-phase current phasor of the line,
Figure BDA0001440780340000074
for the phase B current phasor of the line,
Figure BDA0001440780340000075
is the C-phase current phasor of the line;
determining zero sequence current of the x-th adjacent line of the line according to the following formula
Figure BDA0001440780340000076
Figure BDA0001440780340000077
Wherein: x is the [1,4 ]]，
Figure BDA0001440780340000078
The a-phase current phasor for the x-th adjacent line of the line,
Figure BDA0001440780340000079
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA00014407803400000710
the phase quantity of the C-phase current of the x-th adjacent line of the lines.
In this embodiment: obtaining the three-phase current of the line: i isA、IB、IC(ii) a Obtaining three-phase current I of first adjacent line1A、I1B、I1CObtaining three-phase current I of a second adjacent line2A、I2B、I2CObtaining three-phase current I of a third adjacent line3A、I3B、I3C(ii) a And the phasor values of the respective currents are calculated using fourier methods. And then determining the zero sequence current of each adjacent line by using the three-phase current phasor values of each adjacent line:
Figure BDA00014407803400000711
Figure BDA00014407803400000712
Figure BDA00014407803400000713
determining the zero sequence current of the line:
Figure BDA00014407803400000714
after determining the zero sequence current of the line and its adjacent lines, acquiring the zero sequence mutual inductance of the adjacent lines to the line, and determining the compensation coefficient of the adjacent lines according to the zero sequence mutual inductance of the adjacent lines to the line, therefore, the step 102 includes:
determining zero sequence mutual inductance of the adjacent line to the line according to the following formula, including:
Figure BDA0001440780340000081
wherein: kxAZero sequence mutual inductance coefficient, K, of phase A current of said adjacent x-th line to said linexBZero sequence mutual inductance coefficient, K, of phase B current of said adjacent x-th line to said linexCFor the zero sequence mutual inductance coefficient of the adjacent x-th line C-phase current to the line,
Figure BDA0001440780340000082
is the zero-sequence current of the line,
Figure BDA0001440780340000083
the a-phase current phasor for the x-th adjacent line of the line,
Figure BDA0001440780340000084
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA0001440780340000085
for the phase quantity of C phase current of the x-th adjacent line of the line, x is the [1,4 ]]；
Determining the compensation coefficient K of the x-th adjacent line of the line according to the following formulax：
Kx＝(KxA+KxB+KxC)/3
In the embodiment provided by the invention: the constant values of the compensation coefficients of the adjacent lines are respectively K1、K2、K3The zero sequence mutual inductance coefficient K of the three-phase current of each line to the line needs to be calculated by an EMTP simulation systemA、KB、KCAnd then averaged. Namely:
K1＝(K1A+K1B+K1C)/3
K2＝(K2A+K2B+K2C)/3
K3＝(K3A+K3B+K3C)/3
the method comprises the following steps of obtaining a zero sequence mutual inductance coefficient of A phase current of an adjacent line to a line through an EMTP simulation system:
for example: in the example shown in fig. 1, assuming 5810 is open, the effect of I loop 5415 on II loop 5416 is studied, I loop being the adjacent line of II loop;
when the A phase of the I-loop circuit operates independently, the mutual inductance zero sequence current of the II-loop circuit is measured, the mutual inductance coefficient of the A phase of the I-loop circuit relative to the II-loop circuit is calculated, and K is obtained through calculation1A-0.147, as shown in fig. 4, where the coefficient is II for the loop 3I0And calculating the ratio of the phase A current of the I loop circuit, and dividing the mutual inductance coefficient by 3 on the basis, wherein the following steps are the same.
The zero sequence mutual inductance coefficient of the B-phase current to the line is acquired through an EMTP simulation system: when the phase B of the I-loop circuit runs independently, the mutual inductance zero-sequence current of the phase II circuit is measured, the mutual inductance coefficient of the phase I circuit B relative to the phase II circuit is calculated, and K is obtained through calculation1B-0.138 as shown in fig. 5.
The zero sequence mutual inductance coefficient of the C-phase current to the line is acquired through an EMTP simulation system: when the C phase of the I-loop circuit operates independently, the mutual inductance zero-sequence current of the II-loop circuit is measured, the mutual inductance coefficient of the C phase of the I-loop circuit relative to the II-loop circuit is calculated, and K is obtained through calculation1C-0.161 as shown in fig. 6.
Acquiring zero sequence mutual inductance coefficient of the adjacent line to the line, and further calculating zero sequence compensation coefficient of the adjacent line to the line:
K1＝(K1A+K1B+K1C)/3
determining the zero sequence current of the compensated line by combining the zero sequence compensation coefficients of the adjacent line to the line, so that the step 103 includes:
determining the zero sequence current after line compensation according to the following formula:
Figure BDA0001440780340000091
wherein:
Figure BDA0001440780340000092
is the zero sequence current of the line, KxFor the compensation coefficients of the x-th adjacent line of said lines,
Figure BDA0001440780340000093
zero sequence current of the x-th adjacent line of the line.
In the embodiment provided by the invention: determining the zero sequence current after compensation:
Figure BDA0001440780340000094
in combination with
Figure BDA0001440780340000095
And
Figure BDA0001440780340000096
and judging the compensation zero sequence current protection.
After determining the zero-sequence current after the line compensation, it is necessary to determine that the zero-sequence current satisfies the condition, so that the step 104 includes:
if the zero sequence current of the line and the zero sequence current after line compensation meet the protection condition, starting protection action on the line, wherein the protection condition is determined according to the following formula:
Figure BDA0001440780340000097
b:t＞T0dz
wherein: i is0dzIs a zero sequence current constant value, T0dzIs a zero sequence time fixed value and t is the duration time satisfying the condition a.
And when the condition a and the condition b are met, the zero sequence current protection sends a tripping instruction.
A same-pole multi-loop zero-sequence current protection device, as shown in fig. 7, includes:
the first determination unit is used for determining zero sequence currents of the line and the adjacent line;
the second determining unit is used for acquiring the zero sequence mutual inductance coefficient of the adjacent line to the line and determining the compensation coefficient of the adjacent line according to the zero sequence mutual inductance coefficient of the adjacent line to the line;
the third determining unit is used for determining zero sequence current after line compensation by using zero sequence current of the line and adjacent lines thereof and the compensation coefficient of the adjacent lines;
and the protection unit is used for judging whether to start zero sequence current protection action on the line according to the zero sequence current of the line and the zero sequence current compensated by the line.
Preferably, the first determining unit includes:
a first determining module for determining zero sequence current of the line according to the following formula
Figure BDA0001440780340000101
Figure BDA0001440780340000102
In the above formula, the first and second carbon atoms are,
Figure BDA0001440780340000103
for the a-phase current phasor of the line,
Figure BDA0001440780340000104
for the phase B current phasor of the line,
Figure BDA0001440780340000105
is the C-phase current phasor of the line;
a second determining module for determining zero sequence current of the x-th adjacent line of the line according to the following formula
Figure BDA0001440780340000106
Figure BDA0001440780340000107
Wherein: x is an element of [1, X ]]，
Figure BDA0001440780340000108
The a-phase current phasor for the x-th adjacent line of the line,
Figure BDA0001440780340000109
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA00014407803400001010
the phase quantity of the C-phase current of the x-th adjacent line of the lines.
Preferably, the second determination unit includes:
a third determination module: for determining zero sequence mutual inductance of said adjacent line pair said line according to the following equation, comprising:
Figure BDA0001440780340000111
wherein: kxAZero sequence mutual inductance coefficient, K, of phase A current of said adjacent x-th line to said linexBZero sequence mutual inductance coefficient, K, of phase B current of said adjacent x-th line to said linexCFor the zero sequence mutual inductance coefficient of the adjacent x-th line C-phase current to the line,
Figure BDA0001440780340000112
is the zero-sequence current of the line,
Figure BDA0001440780340000113
the a-phase current phasor for the x-th adjacent line of the line,
Figure BDA0001440780340000114
for the phase B current phasor of the x-th adjacent line of the line,
Figure BDA0001440780340000115
for the phase quantity of C phase current of the x-th adjacent line of the line, x is the [1,4 ]]；
A fourth determining module for determining the compensation coefficient K of the xth adjacent line of the line according to the following formulax：
Kx＝(KxA+KxB+KxC)/3
Wherein: kxAPhase A current phasor, K, for the x-th adjacent line of the linexBPhase B current phasor, K, for the x-th adjacent line of said linexCFor the phase quantity of C phase current of the X-th adjacent line of the line, X belongs to [1, X ∈]And X is the total number of adjacent lines of the line.
Preferably, the third determining unit includes:
a fifth determining module, configured to determine the zero-sequence current after the line compensation according to the following formula:
Figure BDA0001440780340000116
wherein:
Figure BDA0001440780340000117
is the zero sequence current of the line, KxFor the compensation coefficients of the x-th adjacent line of said lines,
Figure BDA0001440780340000118
zero sequence current of the x-th adjacent line of the line.
Preferably, the protection unit includes:
the protection module is used for starting protection action on the line if the zero sequence current of the line and the zero sequence current compensated by the line meet protection conditions, wherein the protection conditions are determined according to the following formula:
Figure BDA0001440780340000119
b:t＞T0dz
wherein: i is0dzIs a zero sequence current constant value, T0dzIs a zero sequence time fixed value and t is the duration time satisfying the condition a.
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 (6)

1. A same-pole multi-loop zero-sequence current protection method is characterized by comprising the following steps:
determining zero sequence current of a line and adjacent lines thereof;
acquiring zero sequence mutual inductance coefficients of the adjacent lines to the lines, and determining compensation coefficients of the adjacent lines according to the zero sequence mutual inductance coefficients of the adjacent lines to the lines;
determining zero sequence current after line compensation by using zero sequence current of the line and adjacent lines thereof and compensation coefficients of the adjacent lines;
judging whether to start a zero sequence current protection action on the line according to the zero sequence current of the line and the zero sequence current compensated by the line;
acquiring zero sequence mutual inductance of the adjacent line to the line, and determining a compensation coefficient of the adjacent line according to the zero sequence mutual inductance of the adjacent line to the line, wherein the method comprises the following steps:
determining zero sequence mutual inductance of the adjacent line to the line according to the following formula, including:
Figure FDA0003415056780000011
wherein: kxAZero sequence mutual inductance coefficient, K, of phase A current of said adjacent x-th line to said linexBZero sequence mutual inductance coefficient, K, of phase B current of said adjacent x-th line to said linexCFor the zero sequence mutual inductance coefficient of the adjacent x-th line C-phase current to the line,
Figure FDA0003415056780000012
is the zero-sequence current of the line,
Figure FDA0003415056780000013
the a-phase current phasor for the x-th adjacent line of the line,
Figure FDA0003415056780000014
for the phase B current phasor of the x-th adjacent line of the line,
Figure FDA0003415056780000015
for the phase quantity of C phase current of the x-th adjacent line of the line, x is the [1,4 ]]；
Determining the compensation coefficient K of the x-th adjacent line of the line according to the following formulax：
Kx＝(KxA+KxB+KxC)/3；
The determining the zero sequence current after the line compensation by using the zero sequence current of the line and the adjacent line and the compensation coefficient of the adjacent line comprises the following steps:
determining the zero sequence current after line compensation according to the following formula:
Figure FDA0003415056780000016
wherein:
Figure FDA0003415056780000017
is the zero sequence current of the line, KxFor the compensation coefficients of the x-th adjacent line of said lines,
Figure FDA0003415056780000021
zero sequence current of the x-th adjacent line of the line.
2. The method of claim 1, wherein the determining zero sequence currents of the line and its neighbors comprises:
determining zero sequence current of the line according to the following formula
Figure FDA0003415056780000022
Figure FDA0003415056780000023
In the above formula, the first and second carbon atoms are,
Figure FDA0003415056780000024
for the a-phase current phasor of the line,
Figure FDA0003415056780000025
for the phase B current phasor of the line,
Figure FDA0003415056780000026
is the C-phase current phasor of the line;
determining zero sequence current of the x-th adjacent line of the line according to the following formula
Figure FDA0003415056780000027
Figure FDA0003415056780000028
Wherein: x is the [1,4 ]]，
Figure FDA0003415056780000029
The a-phase current phasor for the x-th adjacent line of the line,
Figure FDA00034150567800000210
for the phase B current phasor of the x-th adjacent line of the line,
Figure FDA00034150567800000211
the phase quantity of the C-phase current of the x-th adjacent line of the lines.
3. The method of claim 1, wherein the determining whether to initiate a protective action on the line based on the zero sequence current of the line and the compensated zero sequence current of the line comprises:
if the zero sequence current of the line and the zero sequence current after line compensation meet the protection condition, starting protection action on the line, wherein the protection condition is determined according to the following formula:
Figure FDA00034150567800000212
b:t＞T0dz
wherein: i is0dzIs a zero sequence current constant value, T0dzIs a zero sequence time fixed value and t is the duration time satisfying the condition a.
4. A same-pole multi-loop zero-sequence current protection device is characterized by comprising:
the first determination unit is used for determining zero sequence currents of the line and the adjacent line;
the second determining unit is used for acquiring the zero sequence mutual inductance coefficient of the adjacent line and determining the compensation coefficient of the adjacent line according to the zero sequence mutual inductance coefficient of the adjacent line;
the third determining unit is used for determining zero sequence current after line compensation by using zero sequence current of the line and adjacent lines thereof and the compensation coefficient of the adjacent lines;
the protection unit is used for judging whether to start zero sequence current protection action on the line according to the zero sequence current of the line and the zero sequence current compensated by the line;
the second determination unit includes:
a third determination module: for determining zero sequence mutual inductance of said adjacent line pair said line according to the following equation, comprising:
Figure FDA0003415056780000031
wherein: kxAZero sequence mutual inductance coefficient, K, of phase A current of said adjacent x-th line to said linexBFor the adjacent x-th line B-phase current to the lineZero sequence mutual inductance coefficient of (K)xCFor the zero sequence mutual inductance coefficient of the adjacent x-th line C-phase current to the line,
Figure FDA0003415056780000032
is the zero-sequence current of the line,
Figure FDA0003415056780000033
the a-phase current phasor for the x-th adjacent line of the line,
Figure FDA0003415056780000034
for the phase B current phasor of the x-th adjacent line of the line,
Figure FDA0003415056780000035
for the phase quantity of C phase current of the x-th adjacent line of the line, x is the [1,4 ]]；
A fourth determining module for determining the compensation coefficient K of the xth adjacent line of the line according to the following formulax：
Kx＝(KxA+KxB+KxC)/3；
The third determination unit includes:
a fifth determining module, configured to determine the zero-sequence current after the line compensation according to the following formula:
Figure FDA0003415056780000036
wherein:
Figure FDA0003415056780000037
is the zero sequence current of the line, KxFor the compensation coefficients of the x-th adjacent line of said lines,
Figure FDA0003415056780000038
zero sequence current of the x-th adjacent line of the line.
5. The apparatus of claim 4, wherein the first determining unit comprises:
a first determining module for determining zero sequence current of the line according to the following formula
Figure FDA0003415056780000039
Figure FDA00034150567800000310
In the above formula, the first and second carbon atoms are,
Figure FDA00034150567800000311
for the a-phase current phasor of the line,
Figure FDA00034150567800000312
for the phase B current phasor of the line,
Figure FDA00034150567800000313
is the C-phase current phasor of the line;
a second determining module for determining zero sequence current of the x-th adjacent line of the line according to the following formula
Figure FDA0003415056780000041
Figure FDA0003415056780000042
Wherein: x is the [1,4 ]]，
Figure FDA0003415056780000043
The a-phase current phasor for the x-th adjacent line of the line,
Figure FDA0003415056780000044
for the phase B current phasor of the x-th adjacent line of the line,
Figure FDA0003415056780000045
the phase quantity of the C-phase current of the x-th adjacent line of the lines.
6. The apparatus of claim 4, wherein the protection unit comprises:
the protection module is used for starting protection action on the line if the zero sequence current of the line and the zero sequence current compensated by the line meet protection conditions, wherein the protection conditions are determined according to the following formula:
Figure FDA0003415056780000046
b:t＞T0dz
wherein: i is0dzIs a zero sequence current constant value, T0dzIs a fixed value of the zero sequence time,
Figure FDA0003415056780000047
is the minimum value of the zero sequence current amplitude and the compensated zero sequence current amplitude, and t is the duration time satisfying the condition a.
CN201710987276.7A 2017-10-20 2017-10-20 Same-pole multi-loop zero-sequence current protection method and device Active CN107968384B (en)

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