CN110763940A - Method for estimating oscillation center of power system by using phasor diagram method - Google Patents

Method for estimating oscillation center of power system by using phasor diagram method Download PDF

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CN110763940A
CN110763940A CN201911080223.2A CN201911080223A CN110763940A CN 110763940 A CN110763940 A CN 110763940A CN 201911080223 A CN201911080223 A CN 201911080223A CN 110763940 A CN110763940 A CN 110763940A
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oscillation
vector
line
power system
voltage
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林心
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents

Abstract

The invention discloses a method for estimating an oscillation center of a power system by a phasor diagram method, which relates to the field of power systems and comprises the following steps: firstly, acquiring an impedance angle of the protected line, a first phase angle difference between a first voltage and the line current, and a second phase angle difference between a second voltage and the line current; then, constructing a first matrix and a first vector, and determining a first vector to be identified; then, solving a first estimation value of the first vector to be identified, and extracting the first line distance between the oscillation center and the first end according to the first estimation value; according to the invention, the current and voltage data of two end points of the protection circuit are obtained, the first matrix and the first vector are constructed, and the parameter to be identified is solved, so that the distance from the oscillation center to two ends of the circuit can be identified, and the position of the oscillation fault point can be known.

Description

Method for estimating oscillation center of power system by using phasor diagram method
Technical Field
The invention relates to the field of power systems, in particular to a method for estimating an oscillation center of a power system by a phasor diagram method.
Background
The electric power system is an electric energy production and consumption system which consists of links such as a power plant, a power transmission and transformation line, a power supply and distribution station, power utilization and the like. The function of the device is to convert the primary energy of the nature into electric energy through a power generation device, and then supply the electric energy to each user through power transmission, power transformation and power distribution. In order to realize the function, the power system is also provided with corresponding information and control systems at each link and different levels, and the production process of the electric energy is measured, regulated, controlled, protected, communicated and scheduled so as to ensure that users obtain safe and high-quality electric energy.
In the art, oscillations of the power system are often misjudged as a three-phase short circuit causing the power system to trip. At present, in order to solve the problem that distance protection is susceptible to misoperation caused by oscillation of a power system, widely adopted oscillation locking and fault identification methods in oscillation have certain limitations. Most of the existing methods are based on local information of a protection installation place, effective information of electric power system oscillation and re-fault is not sufficiently utilized, and three-phase short circuit and oscillation are difficult to distinguish in a short time.
In addition, in the prior art, the calculation and the solution are complex, the three-phase short circuit is not judged timely due to long recognition time, the execution speed of the trip protection is not fast, and the method has certain destructiveness to a power system.
Further, in the related art, only the approximate orientation of the oscillation center of the power system can be roughly determined, and it is inconvenient to know the specific position where the oscillation center occurs.
Disclosure of Invention
In view of some defects in the prior art, the present invention provides a method for estimating an oscillation center of an electric power system by using a phasor diagram method, which aims to estimate the occurrence position of the oscillation center, so that relevant personnel can go to relevant positions to perform line troubleshooting, and analyze or eliminate oscillation faults.
In order to achieve the above object, the present invention provides a method for estimating an oscillation center of a power system by a phasor diagram method, including:
step SB1 of collecting a measured first voltage of a protected line between the first and second generator sets of the power system proximate a first end of the first generator setAnd line current
Figure BDA0002263733570000022
Collecting a second voltage measured by the protected line near a second end of the second generator set
Figure BDA0002263733570000023
Step SB2, getImpedance angle of the protected line
Figure BDA0002263733570000024
According to the first voltage
Figure BDA0002263733570000025
And the line currentObtaining the first voltage
Figure BDA0002263733570000027
And the line currentFirst phase angle difference therebetween
Figure BDA0002263733570000029
According to the second voltage
Figure BDA00022637335700000210
And the line current
Figure BDA00022637335700000211
Obtaining the second voltage
Figure BDA00022637335700000212
And the line current
Figure BDA00022637335700000213
Second phase angle difference therebetweenWherein the content of the first and second substances,
Figure BDA00022637335700000215
step SB3, constructing a first matrix
Figure BDA00022637335700000216
Construction of the firstVector quantityDetermining a first vector to be identified
Figure BDA00022637335700000218
The L is a total line distance between the first end and the second end of the protection line; said SCMA first line distance, S, of the first end of the protection line to an oscillation center of the power systemCNThe first matrix X, the first vector y, the first to-be-identified vector η satisfy X η ═ y;
step SB4 of solving a first estimated value of the first to-be-identified vector η
Figure BDA0002263733570000031
And according to the first estimated value
Figure BDA0002263733570000032
Extracting the first line distance S between the oscillation center and the first endCM(ii) a The above-mentioned
Figure BDA0002263733570000033
According to the technical scheme, the current and voltage data of two end points of the protection circuit are obtained, a first matrix and a first vector are constructed, and the parameter to be identified is solved, so that the distance from the oscillation center to two ends of the line can be identified, and the position of the oscillation fault point can be known.
In a specific embodiment, the method further comprises:
step SB5, constructing a second matrix
Figure BDA0002263733570000034
Construction of the second vectorDetermining a second vector to be identified
Figure BDA0002263733570000036
The above-mentioned
Figure BDA0002263733570000037
The second matrix H, the second vector t and the second vector ξ to be identified satisfy the conditions that H ξ is t, the oscillation amplitude of the oscillation center is the oscillation amplitude of the oscillation center, and the second matrix H, the second vector t and the second vector ξ to be identified satisfy the conditions that H ξ is t
Figure BDA0002263733570000038
Step SB6 of solving a second estimate of the second to-be-identified vector ξ
Figure BDA0002263733570000039
And according to said second estimated value
Figure BDA00022637335700000310
Extracting an oscillation amplitude of the oscillation center
Figure BDA00022637335700000311
The above-mentioned
Figure BDA00022637335700000312
In this solution, the impedance angle through the protected lineFirst voltage
Figure BDA00022637335700000314
And line current
Figure BDA00022637335700000315
First phase angle difference therebetween
Figure BDA00022637335700000316
Second voltage
Figure BDA00022637335700000317
And the line current
Figure BDA00022637335700000318
Second phase angle difference therebetween
Figure BDA0002263733570000041
First voltage
Figure BDA0002263733570000042
And a second voltage
Figure BDA0002263733570000043
Realizing the oscillation amplitude of the oscillation center
Figure BDA0002263733570000044
And (4) solving.
In a specific embodiment, before step SB3, the method further comprises: a system oscillation identification step; the system oscillation identifying step includes:
step SA1 of obtaining a first potential of a first generator set at a power transmission end of a power system
Figure BDA0002263733570000045
Acquiring a second potential of a second generator set at a power receiving end of the power systemWherein the content of the first and second substances,
Figure BDA0002263733570000047
the above-mentioned
Figure BDA0002263733570000048
Is the first potential
Figure BDA0002263733570000049
Of said amplitude, saidIs the first potentialThe amplitude of (d);
step SA2, according to the first potential
Figure BDA00022637335700000412
The second potential
Figure BDA00022637335700000413
The first voltage
Figure BDA00022637335700000414
And the line current
Figure BDA00022637335700000415
Solving for the first potential
Figure BDA00022637335700000416
And the second potential
Figure BDA00022637335700000417
System power angle δ therebetween; the power angle of the systemThe above-mentioned
Figure BDA00022637335700000419
Is the first voltage
Figure BDA00022637335700000420
The amplitude of (d);
step SA3, according to the first potential
Figure BDA00022637335700000421
The second potential
Figure BDA00022637335700000422
Setting the power angle delta of the system, and setting a short circuit judgment threshold current ITH(ii) a Wherein, the
Figure BDA00022637335700000423
β is a preset coefficient, β>0, the
Figure BDA00022637335700000424
Step SA4, judging the line current
Figure BDA00022637335700000425
Line current amplitude ofAnd the short circuit judgment threshold current ITHThe magnitude relationship of (1); if the line current amplitude
Figure BDA00022637335700000427
Less than the short circuit judgment threshold current ITHIf yes, judging that the circuit system is in the oscillation mode, and executing step SB 3; if the line current amplitude
Figure BDA00022637335700000428
Greater than or equal to the short circuit judgment threshold current ITHAnd judging that the power system is in a three-phase short circuit mode, executing circuit tripping operation, and inputting a three-phase short circuit prompt.
The technical scheme is based on a formula
Figure BDA0002263733570000051
Solving the system power angle, having high solving speed, improving the oscillation identification speed, and judging the threshold current I by setting the short circuitTHAccording to different first potentials
Figure BDA0002263733570000052
A second potential
Figure BDA0002263733570000053
The power angle delta of the system obtains the corresponding short circuit judgment threshold current ITHSo that when the system power angle delta approaches 180 DEG, the short circuit is judgedThreshold current ITHThe larger the value of the short-circuit judgment threshold current I, the larger the short-circuit judgment threshold current I is, the larger the short-circuit judgment threshold current is, the larger the short-circuitTHThe accuracy of judging the short-circuit current is improved, and the accuracy of judging the state of the power system is improved.
In a specific embodiment, the method further comprises:
step SA5, in a primary oscillation identification operation, after determining that the power system is in a three-phase short-circuit mode and performing a circuit trip operation, determining that the circuit system in the primary oscillation identification operation is in the oscillation mode through manual examination, and adjusting the preset coefficient β.
According to the technical scheme, feedback is carried out through subsequent manual investigation, the preset coefficient is adjusted, and the identification accuracy of the system is improved.
In one embodiment, in step SA5, the adjusting the predetermined coefficient β is to increase the predetermined coefficient β.
In a specific embodiment, in the step SB1, the measured first voltage of the first end portion
Figure BDA0002263733570000054
The line currentAnd the second voltage measured by the second end
Figure BDA0002263733570000056
Measured by a synchrophasor measuring device.
In one embodiment, the first generator set comprises at least one first generator; the second generator set comprises at least one second generator.
In one embodiment, the system power angle δ satisfies: delta is more than or equal to 0 and less than 360 degrees.
In a specific embodiment, the method further comprises a step SC of obtaining the preset coefficient β through a three-phase short circuit experiment, wherein the step SC comprises the following steps:
obtaining a full impedance Z of the power system∑And the first potential of the first generator set
Figure BDA0002263733570000061
Solving the preset coefficient β
Figure BDA0002263733570000062
α is more than or equal to 1.2.
In the technical scheme, the preset coefficient β is preset and solved, and a proper preset coefficient β can be set according to actual requirements so as to identify the oscillation of the power system and the three-phase short-circuit current.
The invention has the beneficial effects that: 1) the method comprises the steps of establishing a first matrix and a first vector by acquiring current and voltage data of two end points of a protection circuit, and solving parameters to be identified so as to identify the distance from an oscillation center to two ends of a line and realize the acquisition of the position of an oscillation fault point; 2) in the present invention, by the formula
Figure BDA0002263733570000063
Solving the system power angle, having high solving speed, improving the oscillation identification speed, and judging the threshold current I by setting the short circuitTHAccording to different first potentials
Figure BDA0002263733570000064
A second potential
Figure BDA0002263733570000065
The power angle delta of the system obtains the corresponding short circuit judgment threshold current ITHSo that the short circuit judgment threshold current I is close to 180 DEG when the system power angle delta approaches toTHThe larger the value of the short-circuit judgment threshold current I, the larger the short-circuit judgment threshold current I is, the larger the short-circuit judgment threshold current is, the larger the short-circuitTHThe accuracy of judging the short-circuit current is improved, and the accuracy of judging the state of the power system is improved.
Drawings
Fig. 1 is a schematic flowchart of a method for estimating an oscillation center of an electric power system by using a phasor diagram method according to an embodiment of the present invention;
FIG. 2 is a diagram of an oscillation analysis model of a power system in accordance with an embodiment of the present invention;
fig. 3 is a voltage-current phasor diagram under system oscillation of a power system according to an embodiment of the present invention.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
as shown in fig. 1 to 3, in a first embodiment of the present invention, a method for estimating an oscillation center of a phasor diagram power system is provided, the method including:
step SB1 of collecting a measured first voltage of a protected line between the first and second generator sets of the power system proximate a first end of the first generator set
Figure BDA0002263733570000071
And line current
Figure BDA0002263733570000072
Collecting a second voltage measured by the protected line near a second end of the second generator set
Figure BDA0002263733570000073
Step SB2 of obtaining the impedance angle of the protected line
Figure BDA0002263733570000074
According to the first voltageAnd the line current
Figure BDA0002263733570000076
Obtaining the first voltage
Figure BDA0002263733570000077
And the line current
Figure BDA0002263733570000078
First phase angle difference therebetween
Figure BDA0002263733570000079
According to the second voltage
Figure BDA00022637335700000710
And the line current
Figure BDA00022637335700000711
Obtaining the second voltage
Figure BDA00022637335700000712
And the line currentSecond phase angle difference therebetweenWherein the content of the first and second substances,
Figure BDA00022637335700000715
step SB3, constructing a first matrixConstructing a first vector
Figure BDA00022637335700000717
Determining a first vector to be identifiedThe L is a total line distance between the first end and the second end of the protection line; said SCMA first line distance, S, of the first end of the protection line to an oscillation center of the power systemCNThe first matrix X, the first vector y, the first to-be-identified vector η satisfy X η ═ y;
step SB4 of solving a first estimated value of the first to-be-identified vector η
Figure BDA0002263733570000081
And according to the first estimated value
Figure BDA0002263733570000082
Extracting the first line distance S between the oscillation center and the first endCM(ii) a The above-mentioned
Figure BDA0002263733570000083
In this embodiment, a first matrix and a first vector are constructed by obtaining current and voltage data of two end points of the protection circuit, and a parameter to be identified is solved, so that the distance from the oscillation center to two ends of the line is identified, and the position of the oscillation fault point is known.
Further, to solve for the oscillation amplitude, the method further comprises:
step SB5, constructing a second matrix
Figure BDA0002263733570000084
Construction of the second vector
Figure BDA0002263733570000085
Determining a second vector to be identified
Figure BDA0002263733570000086
The above-mentioned
Figure BDA0002263733570000087
The second matrix H, the second vector t and the second vector ξ to be identified satisfy the conditions that H ξ is t, the oscillation amplitude of the oscillation center is the oscillation amplitude of the oscillation center, and the second matrix H, the second vector t and the second vector ξ to be identified satisfy the conditions that H ξ is t
Figure BDA0002263733570000088
Step SB6 of solving a second estimate of the second to-be-identified vector ξ
Figure BDA0002263733570000089
And according to said second estimated valueExtracting an oscillation amplitude of the oscillation center
Figure BDA00022637335700000811
The above-mentioned
Figure BDA00022637335700000812
In this embodiment, the impedance angle through the protected line
Figure BDA00022637335700000813
First voltage
Figure BDA00022637335700000814
And line current
Figure BDA00022637335700000815
First phase angle difference therebetween
Figure BDA00022637335700000816
Second voltage
Figure BDA00022637335700000817
And the line current
Figure BDA00022637335700000818
Second phase angle difference therebetween
Figure BDA00022637335700000819
First voltageAnd the firstTwo voltages
Figure BDA00022637335700000821
Realizing the oscillation amplitude of the oscillation center
Figure BDA00022637335700000822
And (4) solving.
It is noted that before identifying the oscillation center, it may be determined whether the power system is in an oscillation state. That is, a step of determining whether or not the power system is in the oscillation state is added before step SB 2.
Therefore, in this embodiment, before step SB3, the method further includes: a system oscillation identification step; the system oscillation identifying step includes:
step SA1 of obtaining a first potential of a first generator set at a power transmission end of a power system
Figure BDA0002263733570000091
Acquiring a second potential of a second generator set at a power receiving end of the power system
Figure BDA0002263733570000092
Wherein the content of the first and second substances,
Figure BDA0002263733570000093
the above-mentioned
Figure BDA0002263733570000094
Is the first potential
Figure BDA0002263733570000095
Of said amplitude, said
Figure BDA0002263733570000096
Is the first potential
Figure BDA0002263733570000097
The amplitude of (d);
step SA2, according to the first potential
Figure BDA0002263733570000098
The second potential
Figure BDA0002263733570000099
The first voltage
Figure BDA00022637335700000910
And the line current
Figure BDA00022637335700000911
Solving for the first potential
Figure BDA00022637335700000912
And the second potential
Figure BDA00022637335700000913
System power angle δ therebetween; the power angle of the system
Figure BDA00022637335700000914
The above-mentioned
Figure BDA00022637335700000915
Is the first voltage
Figure BDA00022637335700000916
The amplitude of (d);
step SA3, according to the first potential
Figure BDA00022637335700000917
The second potential
Figure BDA00022637335700000918
Setting the power angle delta of the system, and setting a short circuit judgment threshold current ITH(ii) a Wherein, the
Figure BDA00022637335700000919
β is a preset coefficient, β>0, the
Figure BDA00022637335700000920
Step SA4, judging the line current
Figure BDA00022637335700000921
Line current amplitude ofAnd the short circuit judgment threshold current ITHThe magnitude relationship of (1); if the line current amplitude
Figure BDA00022637335700000923
Less than the short circuit judgment threshold current ITHIf yes, judging that the circuit system is in the oscillation mode, and executing step SB 3; if the line current amplitude
Figure BDA00022637335700000924
Greater than or equal to the short circuit judgment threshold current ITHAnd judging that the power system is in a three-phase short circuit mode, executing circuit tripping operation, and inputting a three-phase short circuit prompt.
In the present embodiment, the formula is used
Figure BDA0002263733570000101
Solving the system power angle, having high solving speed, improving the oscillation identification speed, and judging the threshold current I by setting the short circuitTHAccording to different first potentials
Figure BDA0002263733570000102
A second potential
Figure BDA0002263733570000103
The power angle delta of the system obtains the corresponding short circuit judgment threshold current ITHSo that the short circuit judgment threshold current I is close to 180 DEG when the system power angle delta approaches toTHThe larger the value of the short-circuit judgment threshold current I, the larger the short-circuit judgment threshold current I is, the larger the short-circuit judgment threshold current is, the larger the short-circuitTHThe accuracy of judging the short-circuit current is improved, and the accuracy of judging the state of the power system is improvedAnd (4) sex.
Further, the method further comprises:
step SA5, in a primary oscillation identification operation, after determining that the power system is in a three-phase short-circuit mode and performing a circuit trip operation, determining that the circuit system in the primary oscillation identification operation is in the oscillation mode through manual examination, and adjusting the preset coefficient β.
Based on this, feedback is carried out through subsequent manual investigation, the preset coefficient is adjusted, and the identification accuracy of the system is improved.
Further, in the step SA5, the adjusting the preset coefficient β is to increase the preset coefficient β.
It is worth mentioning that in the step SB1, the measured first voltage of the first end portion
Figure BDA0002263733570000104
The line current
Figure BDA0002263733570000105
And the second voltage measured by the second end
Figure BDA0002263733570000106
Measured by a synchrophasor measuring device.
In this embodiment, the first generator set includes at least one first generator; the second generator set comprises at least one second generator.
In this embodiment, the system power angle δ satisfies: delta is more than or equal to 0 and less than 360 degrees.
In addition, optionally, the method further comprises a step SC of obtaining the preset coefficient β through a three-phase short circuit experiment, wherein the step SC comprises the following steps:
obtaining a full impedance Z of the power system∑And the first potential of the first generator set
Figure BDA0002263733570000111
Solving the preset coefficient β
Figure BDA0002263733570000112
α is more than or equal to 1.2.
Based on this, by performing the preset solution on the preset coefficient β, an appropriate preset coefficient β can be set according to actual requirements so as to identify the power system oscillation and the three-phase short-circuit current.
In fact, the difference between the three-phase short-circuit current and the oscillating current is large, and a large preset coefficient β can be selected according to actual situations.
The power system of the double generator sets can be equivalent to the power system shown in fig. 2, and comprises two generator sets and a protected line MN between the two generator sets, wherein the M side is a power transmission end, the generator set at the upper end of the protected line is defined as an M generator set, the generator set at the lower end of the generator set is defined as a generator set N, and the impedance of the protected line is ZLThe system impedance of the protection back side at both sides of the protected line is ZM、ZNFull impedance Z of the power system∑＝ZM+ZL+ZNThe impedance angle of the protected line is
Figure BDA0002263733570000113
First potential of first generator set of power transmission end of power system
Figure BDA0002263733570000115
A second potential of a second generator set that is a receiving end of the power system;
Figure BDA0002263733570000116
first voltage
Figure BDA0002263733570000117
And line current
Figure BDA0002263733570000118
Measured at the location of the first end M of the first generator set, a second voltage
Figure BDA0002263733570000119
Measured at a second end of the protected line proximate the second genset;
if the power system is in oscillation state, the oscillation current IoscSatisfies the following conditions:
then it can be obtained: oscillating current IoscAmplitude of
Figure BDA0002263733570000122
The formula shows that: oscillating current IoscAmplitude of | IoscMaximum value of |
Figure BDA0002263733570000123
Oscillating current IoscAmplitude of | IoscThe minimum value of | is
Figure BDA0002263733570000124
Therefore, different oscillation currents I can be obtained according to different values of the system power angle deltaoscAmplitude of | Iosc|；
In the present embodiment, the short-circuit determination threshold current ITHIs set to be in accordance with the oscillating current IoscAmplitude of | IoscI related, oscillating current IoscAmplitude of
Figure BDA0002263733570000125
Wherein the content of the first and second substances,
Figure BDA0002263733570000126
it can be seen as a constant number that,
Figure BDA0002263733570000127
based on this, according to the system power angle deltaConstant variable short circuit judgment threshold current ITHThe high current in the oscillation mode can be prevented from being identified as the three-phase short-circuit current, and the accuracy of system identification is provided.
Meanwhile, a voltage-current phasor diagram under system oscillation is given in fig. 3, and a system power angle δ can be obtained according to the voltage-current phasor diagram:
Figure BDA0002263733570000128
wherein, the O point is a zero point, and the OC is a perpendicular line of △ OMN.
The voltage-current phasor diagram can be used for obtaining:
Figure BDA0002263733570000131
finishing to obtain:
order toOrder to
Figure BDA0002263733570000134
Order to
Figure BDA0002263733570000135
X η ═ y can be obtained
A first estimated value of the first to-be-identified vector η is obtained
Figure BDA0002263733570000136
And further from the first estimate
Figure BDA0002263733570000137
Split to SCM、SCNThe distance between the oscillation center and the two ends of the protected circuit can be obtained:
the voltage-current phasor diagram can be used for obtaining:
Figure BDA0002263733570000138
order to
Figure BDA0002263733570000139
Finishing to obtain:
Figure BDA00022637335700001310
order to
Figure BDA00022637335700001311
Order to
Figure BDA00022637335700001312
Order to
Figure BDA00022637335700001313
Can obtain H ξ ═ t
A second estimate of a second vector to be identified ξ is obtained
Figure BDA0002263733570000141
The oscillation amplitude of the oscillation center can be obtained
Figure BDA0002263733570000142
Specific embodiments of the present invention have been described above in detail. It is to be understood that the specific embodiments of the present invention are not exclusive and that modifications and variations may be made by one of ordinary skill in the art in light of the spirit of the present invention, within the scope of the appended claims. Therefore, technical solutions that can be obtained by a person skilled in the art through logic analysis, reasoning or limited experiments based on the prior art according to the embodiments of the present invention should be within the scope of protection defined by the claims.

Claims (9)

1. A method for estimating an oscillation center of a power system by a phasor diagram method is characterized by comprising the following steps:
step SB1 of collecting a measured first voltage of a protected line between the first and second generator sets of the power system proximate a first end of the first generator set
Figure FDA0002263733560000011
And line current
Figure FDA0002263733560000012
Collecting a second voltage measured by the protected line near a second end of the second generator set
Figure FDA0002263733560000013
Step SB2 of obtaining the impedance angle of the protected line
Figure FDA0002263733560000014
According to the first voltage
Figure FDA0002263733560000015
And the line current
Figure FDA0002263733560000016
Obtaining the first voltageAnd the line current
Figure FDA0002263733560000018
First phase angle difference therebetween
Figure FDA0002263733560000019
According to the second voltage
Figure FDA00022637335600000110
And the line currentObtaining the second voltage
Figure FDA00022637335600000112
And the line current
Figure FDA00022637335600000113
Second phase angle difference therebetween
Figure FDA00022637335600000114
Step SB3, constructing a first matrix
Figure FDA00022637335600000115
Constructing a first vector
Figure FDA00022637335600000116
Determining a first vector to be identifiedThe L is a total line distance between the first end and the second end of the protection line; said SCMA first line distance, S, of the first end of the protection line to an oscillation center of the power systemCNThe first matrix X, the first vector y, the first to-be-identified vector η satisfy X η ═ y;
step SB4 of solving a first estimated value of the first to-be-identified vector η
Figure FDA00022637335600000118
And according to the first estimated value
Figure FDA0002263733560000021
Extracting the first line distance S between the oscillation center and the first endCM(ii) a The above-mentioned
Figure FDA0002263733560000022
2. A method of estimating the center of oscillation of a phasor-diagram power system according to claim 1, said method further comprising:
step SB5, constructing a second matrix
Figure FDA0002263733560000023
Construction of the second vectorDetermining a second vector to be identified
Figure FDA0002263733560000025
The above-mentioned
Figure FDA0002263733560000026
The second matrix H, the second vector t and the second vector ξ to be identified satisfy the conditions that H ξ is t, the oscillation amplitude of the oscillation center is the oscillation amplitude of the oscillation center, and the second matrix H, the second vector t and the second vector ξ to be identified satisfy the conditions that H ξ is t
Figure FDA0002263733560000027
Step SB6 of solving a second estimate of the second to-be-identified vector ξ
Figure FDA0002263733560000028
And according to said second estimated value
Figure FDA0002263733560000029
Extracting an oscillation amplitude of the oscillation center
Figure FDA00022637335600000210
The above-mentioned
Figure FDA00022637335600000211
3. The method according to claim 1, wherein before step SB3, the method further comprises: a system oscillation identification step; the system oscillation identifying step includes:
step SA1 of obtaining a first potential of a first generator set at a power transmission end of a power system
Figure FDA00022637335600000212
Acquiring a second potential of a second generator set at a power receiving end of the power system
Figure FDA00022637335600000213
Wherein the content of the first and second substances,
Figure FDA00022637335600000214
k≥1，
Figure FDA00022637335600000215
the above-mentioned
Figure FDA00022637335600000216
Is the first potential
Figure FDA00022637335600000217
Of said amplitude, said
Figure FDA00022637335600000218
Is the first potentialThe amplitude of (d);
step SA2, according to the first potential
Figure FDA00022637335600000220
The second potential
Figure FDA00022637335600000221
The first voltage
Figure FDA00022637335600000222
And the line currentSolving for the first potentialAnd the second potential
Figure FDA00022637335600000225
System power angle δ therebetween; the power angle of the systemThe above-mentioned
Figure FDA0002263733560000032
Is the first voltage
Figure FDA0002263733560000033
The amplitude of (d);
step SA3, according to the first potential
Figure FDA0002263733560000034
The second potential
Figure FDA0002263733560000035
Setting the power angle delta of the system, and setting a short circuit judgment threshold current ITH(ii) a Wherein, the
Figure FDA0002263733560000036
The β is a pre-set coefficient,the β>0, the
Figure FDA0002263733560000037
Step SA4, judging the line current
Figure FDA0002263733560000038
Line current amplitude of
Figure FDA0002263733560000039
And the short circuit judgment threshold current ITHThe magnitude relationship of (1); if the line current amplitude
Figure FDA00022637335600000310
Less than the short circuit judgment threshold current ITHIf yes, judging that the circuit system is in the oscillation mode, and executing step SB 3; if the line current amplitude
Figure FDA00022637335600000311
Greater than or equal to the short circuit judgment threshold current ITHAnd judging that the power system is in a three-phase short circuit mode, executing circuit tripping operation, and inputting a three-phase short circuit prompt.
4. A method of estimating the center of oscillation of a phasor-diagram power system according to claim 3, said method further comprising:
step SA5, in a primary oscillation identification operation, after determining that the power system is in a three-phase short-circuit mode and performing a circuit trip operation, determining that the circuit system in the primary oscillation identification operation is in the oscillation mode through manual examination, and adjusting the preset coefficient β.
5. The method of claim 4, wherein in the step SA5, the adjusting the predetermined coefficient β is performed by increasing the predetermined coefficient β.
6. The method according to claim 1, wherein in step SB1, the measured first voltage of the first end portion is
Figure FDA0002263733560000041
The line current
Figure FDA0002263733560000042
And the second voltage measured by the second end
Figure FDA0002263733560000043
Measured by a synchrophasor measuring device.
7. The method according to claim 1, wherein the first generator set comprises at least a first generator; the second generator set comprises at least one second generator.
8. The method for estimating the oscillation center of the phasor diagram power system according to claim 2, wherein the system power angle δ satisfies the following condition: delta is more than or equal to 0 and less than 360 degrees.
9. The method for estimating the oscillation center of the phasor diagram power system according to claim 1, wherein the method further comprises a step SC of obtaining the preset coefficient β through a three-phase short circuit experiment, and the step SC comprises:
obtaining a full impedance Z of the power system∑And the first potential of the first generator set
Figure FDA0002263733560000044
Solving the preset coefficient β
Figure FDA0002263733560000045
α is more than or equal to 1.2.
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