CN112684375A - Fault analysis method for two-phase broken line of four-circuit line erected on same extra-high voltage pole - Google Patents

Fault analysis method for two-phase broken line of four-circuit line erected on same extra-high voltage pole Download PDF

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CN112684375A
CN112684375A CN202011255492.0A CN202011255492A CN112684375A CN 112684375 A CN112684375 A CN 112684375A CN 202011255492 A CN202011255492 A CN 202011255492A CN 112684375 A CN112684375 A CN 112684375A
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phase
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陆政君
童理
石桂学
韦昌伟
黄宗启
杨嘉靖
石怀强
赵铎
庞泽
覃雪梅
覃正红
唐纬
施运宾
韦紫君
唐广
甘琦
杨超群
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Datang Hydropower Science and Technology Research Institute Co Ltd
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Abstract

The invention relates to a fault analysis method for two-phase broken lines of a four-circuit line erected on the same extra-high voltage pole, which comprises the following steps: step 1, calculating a composite fault sequence network diagram of two phase line breaks of a return line under the condition of only voltage constraint or current constraint according to boundary conditions of the two phase line breaks of the return line; step 2, calculating to obtain a sequence network diagram only containing an unknown sequence voltage component according to the two-phase broken line composite fault sequence network diagram of the loop
Figure DDA0002772991580000011
The equation of (1); and 3, calculating other sequence voltages and sequence currents according to the voltage-current constraint relation based on the equation, and further calculating the breakThe voltage between the two points of the line and the normal phase current. The invention fills the blank of broken line fault analysis and provides a solid foundation for the researches of fault location, protection configuration and the like.

Description

Fault analysis method for two-phase broken line of four-circuit line erected on same extra-high voltage pole
Technical Field
The invention belongs to the technical field of power transmission, and particularly relates to a fault analysis method for two-phase line breakage of a four-circuit line erected on an ultrahigh voltage same pole.
Background
The same-pole four-circuit transmission technology is widely applied to developed countries with developed economy and densely populated areas, but research data on the aspects of a phase-mode conversion method, a fault analysis method, relay protection configuration, a fault line selection method, a fault distance measurement principle and the like disclosed abroad is less, and the same-pole four-circuit transmission technology is a relatively new research subject in China.
The four circuit lines on the same pole are 12 lines in total, the coupling condition is complex, the mutual inductance between complex lines greatly increases the difficulty of line decoupling, and the original research method cannot be applied to the four circuit lines on the same pole. The four-circuit line fault on the same pole has various types, and besides a single-circuit line fault, a cross-line fault can occur, so that the work of line selection, setting and the like of relay protection is difficult. Zero-sequence mutual inductance between lines cannot be eliminated by means of a traditional symmetric component method and a six-sequence component method, and in order to eliminate the influence of mutual inductance between four circuit lines on the same pole on fault analysis and fault location, a decoupling method of mutual inductance between lines and mutual inductance between phases must be further researched.
At present, a 12-order component method is adopted for analyzing short circuit faults of four circuit lines on the same pole, and the method is popularized and applied in the aspects of fault location, fault analysis and relay protection and the like. The 12-order component method firstly solves the decoupling of mutual inductance between four loops on the same pole. The mutual inductance between the loops can be eliminated firstly by adopting the step-by-step matrix transformation, and then the mutual inductance between the phases is eliminated, so that the independent 12-order components are obtained. The meaning and the characteristic of each sequence component can be obtained in the matrix transformation process, and the system impedance correction method is calculated, so that each sequence network in short circuit fault is established, a fault boundary condition equation is established, and each sequence voltage and current of a short circuit point are calculated by solving an equation set, so that the short circuit voltage and current at any position in the system can be obtained, and the short circuit fault calculation of four circuit lines on the same pole is completed. However, the method only aims at short-circuit faults, and for disconnection faults, the sequence network diagrams and the sequence fault component equations are different from the short-circuit faults, so that the contents of the sequence network drawings, the boundary condition equation set algorithm, the composite sequence network drawings and the like of the disconnection faults need to be deeply researched, the blank of disconnection fault analysis is filled, and a solid foundation is provided for the researches of fault location, protection configuration and the like.
Disclosure of Invention
The invention aims to provide a fault analysis method for two phase broken lines of an extra-high voltage four-circuit line erected on the same pole, which is used for drawing a 12-sequence component sequence network diagram during the broken line fault according to a 12-sequence component method decoupling thought and a system impedance correction method. According to the characteristic of the e1 ordered network active, an equation of each ordered component is provided. Drawing a composite sequence network diagram under the condition of voltage constraint or current constraint according to the boundary condition when the wire is broken, and quickly calculating the composite sequence network diagram
Figure BDA0002772991560000021
And further calculating the voltage and the current of each sequence according to the voltage-current relationship, and further calculating the fracture voltage and the normal phase current.
The invention provides a fault analysis method for two-phase broken lines of an ultrahigh-voltage four-circuit line erected on the same pole, which comprises the following steps:
step 1, calculating a composite fault sequence network diagram of two phase line breaks of a return line under the condition of only voltage constraint or current constraint according to boundary conditions of the two phase line breaks of the return line;
step 2, calculating to obtain a sequence network diagram only containing an unknown sequence voltage component according to the two-phase broken line composite fault sequence network diagram of the loop
Figure BDA0002772991560000022
The equation of (2):
Figure BDA0002772991560000023
in the formula (I), the compound is shown in the specification,
Figure BDA0002772991560000024
for the integrated electromotive force at the broken line looking into the system,
Figure BDA0002772991560000025
e is equivalent electromotive force on two sides of the line, and delta is a phase angle between the electromotive force on the two sides of the line; ze0Is the e0 series impedance; ze1Is the e1 series impedance; ze2Is the e2 series impedance; zf0Is f0 order impedance；Zf1F1 series impedance; zf2F2 series impedance;
and 3, calculating other sequence voltages and sequence currents according to the voltage-current constraint relation based on the equation, and further calculating the voltage between two points of the broken line and the normal phase current.
By means of the scheme, the voltage and current constraint relation is obtained by a fault analysis method of two-phase broken lines of a four-circuit line erected on the same extra-high voltage pole through simplifying a boundary condition equation set, a composite sequence network diagram is drawn, and according to the sequence network diagram, the voltage and current constraint relation containing one unknown sequence voltage component can be calculated quickly
Figure BDA0002772991560000026
Equation (2)
Figure BDA0002772991560000027
According to the voltage and current constraint relation, other sequence voltages and sequence currents can be rapidly calculated, and further, voltages and normal phase currents between two points of the broken line can be calculated, so that the blank of broken line fault analysis is filled, and a solid foundation is provided for researches such as fault location, protection configuration and the like.
The foregoing is a summary of the present invention, and in order to provide a clear understanding of the technical means of the present invention and to be implemented in accordance with the present specification, the following is a detailed description of the preferred embodiments of the present invention.
Drawings
FIG. 1 is a diagram of impedance structure of four loops on the same pole;
FIG. 2 is a normal positive order net diagram and an e-order net diagram; in fig. 2, a) is a positive sequence (012) net diagram; b) is an e-sequence network diagram;
FIG. 3 is a sequence diagram of the 12-order fault components of the present invention; in FIG. 3, a) is a net diagram of e1 and e 2; b) is an e0 net view; c) f1, f2, g1, g2, h1 and h2 sequence net pictures; d) f0, g0 and h0 sequence diagrams;
FIG. 4 is a composite sequence net diagram of an IBC disconnection fault in an embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
The embodiment provides a fault analysis method for two-phase broken lines of a four-circuit line erected on the same extra-high voltage pole, which is characterized by comprising the following steps:
step 1, calculating a composite fault sequence network diagram of two phase line breaks of a return line under the condition of only voltage constraint or current constraint according to boundary conditions of the two phase line breaks of the return line;
step 2, calculating to obtain a sequence network diagram only containing an unknown sequence voltage component according to the two-phase broken line composite fault sequence network diagram of the loop
Figure BDA0002772991560000031
The equation of (2):
Figure BDA0002772991560000032
in the formula (I), the compound is shown in the specification,
Figure BDA0002772991560000033
for the integrated electromotive force at the broken line looking into the system,
Figure BDA0002772991560000034
e is equivalent electromotive force on two sides of the line, and delta is a phase angle between the electromotive force on the two sides of the line; ze0Is the e0 series impedance; ze1Is the e1 series impedance; ze2Is the e2 series impedance; zf0F0 series impedance; zf1F1 series impedance; zf2F2 series impedance;
and 3, calculating other sequence voltages and sequence currents according to the voltage-current constraint relation based on the equation, and further calculating the voltage between two points of the broken line and the normal phase current.
The present invention is described in further detail below.
Referring to the four-circuit line on the same pole shown in FIG. 1, let the self-impedance of the line be zsThe mutual impedances of the lines are equal to each other and are all zmThe mutual impedance between different loops is also equal and is denoted as zx。
In the four-wire on the same pole shown in fig. 1, the phase voltage and the phase current of the four wires have a matrix equation (1-1) between the impedances:
Figure BDA0002772991560000041
it is briefly described as
Figure BDA0002772991560000042
Figure BDA0002772991560000043
For the same pole four loop line voltage drop,
Figure BDA0002772991560000044
phase current column vector of four loops on the same pole, [ Z ]]The impedance matrix of four loops is shown, the elements on the diagonal line represent the self-impedance of each phase, and the elements on the non-diagonal line represent the inter-phase mutual impedance of each phase on the single loop and the inter-line mutual impedance of each loop respectively. Because mutual inductance exists between 12 electrical quantities of the ABC three phases of the four loops on the same pole, the decoupling needs to be researched firstly when the four loops are researched, namely the mutual inductance is eliminated. The decoupling is carried out in two steps: and the mutual inductance between the outside lines of the loops is eliminated, and then the mutual inductance between the phases inside the loops is eliminated. The impedance matrix is transformed into a diagonal matrix, namely, other elements except the diagonal are zero, 12 electrical quantities are decoupled into independent 12-sequence components, and mutual inductance does not exist any more.
Let the decoupling matrix be
Figure BDA0002772991560000051
Wherein
Figure BDA0002772991560000055
The decoupled voltage and current matrix is:
Figure BDA0002772991560000052
the two-loop phase-mode transformation is noted as:
Figure BDA0002772991560000053
from the formula (1-2), it can be deduced
Figure BDA0002772991560000054
The formula (1-3) is developed to
Figure BDA0002772991560000061
Wherein z ise0＝zs+2zm+9zx，zf0＝zg0＝zh0＝zs+2zm-3zx
ze1＝zf1＝zg1＝zh1＝ze2＝zf2＝zg2＝zh2＝zs-zm
It can be seen from the inverse matrix of M that the e-sequence component reflects the co-current of the four lines, and the f-sequence component, g-sequence component and h-sequence component reflect the loop current in the four lines on the same pole. The f-sequence component, the g-sequence component and the h-sequence component only circulate in the same pole four-circuit line and do not flow out of the same pole four-circuit line, so that the voltages of the sequence components f, g and h on the buses at two ends of the same pole four-circuit line are zero, and only e-sequence voltage and current exist outside the same pole four-circuit line.
The connection between the four-circuit line on the same pole and the external system is embodied by the e-sequence component, but the e-sequence component is not directly connected with the positive sequence network of the external system but needs to be correspondingly processed. From the inverse matrix of M:
Figure BDA0002772991560000062
wherein, (i ═ 0,1, 2).
As can be seen from the equation, the e1 sequence voltage is equal to the positive sequence voltage of the four-circuit line divided by 4, i.e., the average value. Referring to the positive sequence (012) diagram of fig. 2, since the four lines are all connected to the line left end bus M, the positive sequence voltages of the four lines are equal, and thus the voltage at bus M, e1 is equal to the normal positive sequence voltage. For current, the e1 current flowing through the system impedance is equal to the sum of the positive sequence currents of the four-circuit line divided by 4, whereas the positive sequence current flowing through the system impedance in a normal positive sequence network is the sum of the positive sequence currents of the four-circuit line, so the e1 sequence current is 1/4 of the normal positive sequence current. According to ohm's law, the left system impedance in the e1 sequence net diagram should be corrected to 4 times the value of the system impedance of the normal positive sequence net. The same applies to the e0 procedure and the e2 procedure, and the N-side system impedance correction method is the same as the M-side. The common positive net-ordering diagram and the e-net-ordering diagram of the four-circuit line on the same pole can be seen in fig. 2.
According to the sequence network diagrams of the short-circuit faults, the sequence network diagrams of the broken line faults can be drawn, but when the broken line faults are different from the short-circuit faults, the sequence impedance is in a series relation when the broken line faults are seen from the broken port. A 12-order fault component sequence net diagram is shown in fig. 3.
From the 12-sequence component method, only the e1 sequence is an active network, and the other sequence components are passive networks. The voltage and current equations at the line break are as follows:
Figure BDA0002772991560000071
Figure BDA0002772991560000072
respectively, the voltage components of each sequence at the broken line,
Figure BDA0002772991560000073
for the combined electromotive force of the broken wire looking into the system, wherein
Figure BDA0002772991560000074
E is the equivalent electromotive force on both sides of the line, delta is the phase angle between the electromotive forces on both sides of the line,
Figure BDA0002772991560000075
respectively, the current components of each sequence at the broken line, zkei、zkfi、zkgi、zkhiEach sequence impedance is seen from the broken line to the system (i is 0,1, 2).
Taking the disconnection fault of B-phase and C-phase of I-loop as an example, the boundary condition is
Figure BDA0002772991560000076
By substituting formula (2-1) for formula (1-2), the relationship between the respective sequence components can be found as follows:
Figure BDA0002772991560000081
through simplification, the product is obtained
Figure BDA0002772991560000082
According to the voltage constraint and the current constraint conditions, a composite sequence network diagram of the I loop in the case of the disconnection fault of the B phase and the C phase can be drawn, and as shown in fig. 4, the specific analysis is as follows:
according to voltage relation
Figure BDA0002772991560000083
The series connection of the e0, e1 and e2 voltages is required. According to the voltage relation Uf0＝3Ue0,Uf1＝3Ue1,Uf2＝3Ue2The voltage of the f0 sequence is connected in parallel with the voltage of the e0 sequence after passing through a transformer with a transformation ratio (1:3), the voltage of the f1 sequence is connected in parallel with the voltage of the e1 sequence after passing through a transformer with a transformation ratio (1:3), and the voltage of the f2 sequence is connected in parallel with the voltage of the e2 sequence after passing through a transformer with a transformation ratio (1: 3).
In addition to the e1 sequence, the other 11-sequence components are passive networks,according to the current relation
Figure BDA0002772991560000084
Currents of the sequences g0, g1, g2, h0, h1 and h2 are 0, the sequences e0 and f0 are firstly connected in parallel, the sequences e1 and f1 are firstly connected in parallel, and the sequences e2 and f2 are firstly connected in parallel and then finally connected in series. For maintaining secondary sequence current of transformer
Figure BDA0002772991560000085
And
Figure BDA0002772991560000086
the f0, f1 and f2 series impedances need to be corrected. Secondary side I of transformerf0After passing through a transformer with a transformation ratio of (1:3), the primary side current becomes If0/3, maintaining the sequence voltage on the sequence impedance
Figure BDA0002772991560000087
I.e. the primary voltage of the transformer is not changed, the f 0-sequence impedance is corrected to be 3Zf0. The f1 and f2 sequence impedance correction method is the same as f 0.
From FIG. 4, it can be quickly deduced
Figure BDA0002772991560000091
The other voltages and currents of the respective stages can be calculated by the equation (2-4) of (1), and the voltage between the two points of disconnection and the normal phase current can be calculated by the equation (2-3).
Figure BDA0002772991560000092
The fault analysis method includes the steps of calculating a composite fault sequence network diagram of the B-phase and C-phase disconnection of the I-loop according to a voltage and current constraint relation, and calculating the composite fault sequence network diagram of the B-phase and C-phase disconnection of the I-loop according to the composite fault sequence network diagram of the B-phase and C-phase disconnection of the I-loop
Figure BDA0002772991560000093
The equation of (2) fills the blank of the broken line fault analysis, and provides a solid foundation for the researches of fault location, protection configuration and the like.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims (1)

1. A fault analysis method for two-phase broken lines of a four-circuit line erected on the same extra-high voltage pole is characterized by comprising the following steps:
step 1, calculating a composite fault sequence network diagram of two phase line breaks of a return line under the condition of only voltage constraint or current constraint according to boundary conditions of the two phase line breaks of the return line;
step 2, calculating to obtain a sequence network diagram only containing an unknown sequence voltage component according to the two-phase broken line composite fault sequence network diagram of the loop
Figure FDA0002772991550000014
The equation of (2):
Figure FDA0002772991550000011
in the formula (I), the compound is shown in the specification,
Figure FDA0002772991550000012
for the integrated electromotive force at the broken line looking into the system,
Figure FDA0002772991550000013
e is equivalent electromotive force on two sides of the line, and delta is a phase angle between the electromotive force on the two sides of the line; ze0Is the e0 series impedance; ze1Is the e1 series impedance; ze2Is the e2 series impedance; zf0F0 series impedance; zf1F1 series impedance; zf2F2 series impedance;
and 3, calculating other sequence voltages and sequence currents according to the voltage-current constraint relation based on the equation, and further calculating the voltage between two points of the broken line and the normal phase current.
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