CN112653136B - Power electronic multi-feed-in power system key line identification method and system - Google Patents
Power electronic multi-feed-in power system key line identification method and system Download PDFInfo
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- H—ELECTRICITY
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- H—ELECTRICITY
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- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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Abstract
The invention discloses a method and a system for identifying a key circuit of a power electronic multi-feed-in power system, wherein the method comprises the following steps: obtaining an extended admittance matrix of the power electronic multi-feed-in power system; wherein obtaining information on which the extended admittance matrix is based comprises: the feed-in capacity and the grid structure of the power electronic multi-feed-in power system; according to the eigenvalue of the extended admittance matrix, the power electronic multi-feed power system is equivalent to a plurality of power electronic single-feed power systems with the same small interference stability; the minimum eigenvalue of the extended admittance matrix is the generalized short-circuit ratio of the power electronic multi-feed-in power system; obtaining sensitivity of the generalized short-circuit ratio relative to each network line admittance by combining the characteristic value and the characteristic vector property; and identifying the key circuit of the power electronic multi-feed power system according to the obtained sensitivity sequence. The invention can effectively reduce the problem of small interference stability in practical engineering application.
Description
Technical Field
The invention belongs to the technical field of new energy planning and design, and particularly relates to a method and a system for identifying a key circuit of a power electronic multi-feed-in power system.
Background
With the aggravation of global energy crisis and the increasing severity of environmental protection situation, the proportion of new energy units in the power system is gradually increased; different from large-scale new energy access in-situ balance and consumption in Europe and America, the energy load distribution in China is unbalanced, areas with rich wind energy resources are located in the northwest and far away from the load center in the east, the requirement of large-scale remote transmission of electric energy exists for a long time, and the cluster grid connection of a high-proportion multiple new energy unit becomes an important trend for future development. Research shows that after a new energy source unit with increasingly larger capacity is connected, a power system presents obvious power electronization characteristics, the problem of small interference stability is easily caused, and great challenges are provided for safe and stable operation of the system.
In order to ensure the stable operation of the grid-connected system of the new energy unit, key lines of the system need to be identified according to the characteristics of the grid-connected new energy unit, so that important attention is paid to planning and control. In summary, a new method and system for identifying critical circuits of a power electronic multi-feed power system are needed.
Disclosure of Invention
The present invention is directed to a method and system for identifying a critical circuit of a power electronic multi-feeding power system, so as to solve one or more of the above-mentioned problems. The invention provides a method and a system for identifying key circuits of a power electronic multi-feed power system based on small interference stability according to generalized short-circuit ratio indexes, the calculation idea is clear, the process is simple, and the identification of the key circuits of the power electronic multi-feed power system can be completed under the condition that certain new energy unit feed-in capacity and a grid structure can be explored; the method provides guidance for planning and operation of the new energy power station from the aspect of small interference stability, and contributes to comprehensiveness of planning and design consideration of the power system.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention discloses a method for identifying a key circuit of a power electronic multi-feed-in power system, which comprises the following steps:
obtaining an extended admittance matrix of the power electronic multi-feed-in power system; wherein obtaining information on which the extended admittance matrix is based comprises: the feed-in capacity and the grid structure of the power electronic multi-feed-in power system;
according to the eigenvalue of the extended admittance matrix, the power electronic multi-feed power system is equivalent to a plurality of power electronic single-feed power systems with the same small interference stability; the minimum eigenvalue of the extended admittance matrix is the generalized short-circuit ratio of the power electronic multi-feed-in power system; obtaining sensitivity of the generalized short-circuit ratio relative to each network line admittance by combining the characteristic value and the characteristic vector property;
and identifying the key circuit of the power electronic multi-feed-in power system according to the obtained sequence of the sensitivity.
The invention discloses a method for identifying a key circuit of a power electronic multi-feed-in power system, which comprises the following steps:
and 3, finishing identification of the key lines of the power electronic multi-feed power system based on the sequence of the sensitivities obtained in the step 2.
The further improvement of the present invention is that, in step 1, the step of calculating the extended admittance matrix based on the impedance parameters and the grid structure of the power electronic multi-feed-in power system specifically includes:
from each feed-in pointCapacity diagonal matrix S formed by rated capacity of power electronic equipment B (ii) a Obtaining an equivalent admittance matrix B from alternating current power grid impedance parameters and a topological structure of the power electronic multi-feed-in power system initial Obtaining a reduced order node admittance matrix B through a Schur complement operation;
extended admittance matrix J eq The expression of (a) is as follows,
in a further improvement of the present invention, in step 1, the step of obtaining the generalized short-circuit ratio of the power electronic multi-feed power system through eigenvalue decomposition specifically includes:
obtaining a minimum eigenvalue of the extended admittance matrix; the minimum characteristic value is a generalized short-circuit ratio gSCR of the power electronic multi-feed power system, and the expression is,
gSCR＝minλ(J eq )，
wherein λ (J) eq ) To expand the admittance matrix J eq The characteristic value of (2).
The invention has the further improvement that the step 2 specifically comprises the following steps:
judging node classification at two ends of each network line; wherein the classifying includes: power electronic device nodes, passive nodes and infinite nodes;
calculating the sensitivity of the generalized short circuit ratio gSCR on each network line admittance according to different node classifications; wherein the content of the first and second substances,
both nodes are power electronic equipment nodes, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
denotes the ith 1 An n x 1 dimensional matrix with 1 element and 0 elements,
i th of phi 1 N is the number of nodes of the power electronic equipment, i 1 ，j 1 Representing two power electronics nodes in the system, b i1j1 Is a node i 1 、j 1 Line admittance therebetween;
wherein psi and phi are respectively the extended admittance matrix J eq The left and right eigenvectors corresponding to the eigenvalues gsrc,
one node is a power electronic device node and the other node is an infinite node, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
wherein the content of the first and second substances,
denotes the ith 2 An n × 1-dimensional matrix in which each element is 1 and the remaining elements are 0,
i th of phi 2 N is the number of nodes of the power electronic equipment, i 2 As power electronics nodes, j 2 Being an infinite node, b i2j2 Is a node i 2 、j 2 Line admittance therebetween;
both nodes are passive nodes, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
represents the (i) th 3 N) an m x 1 dimensional matrix with 1 elements and 0 remaining elements, m being the number of passive nodes,
denotes the (j) th 3 N) m x 1 dimensional matrices of elements 1 and 0 for the remaining elements, i 3 ，j 3 Are all passive nodes, n is the number of nodes of the power electronic equipment, b i3j3 Is a node i 3 、j 3 Line admittance between, ρ i3 Is B' ac Ith of (2) 3 Element of rho j3 Is B' ac J (d) of 3 An element;
one node is a passive node and the other node is an infinite node, the sensitivity of the generalized short-circuit ratio to the line admittance is,
in the formula (I), the compound is shown in the specification,
represents the (i) th 4 -n) m x 1 dimensional matrices with elements 1 and the remaining elements 0, m being the number of passive nodes, n being the number of power electronics nodes, i 4 Is a passive node, j 4 As a power electronics node, b i4j4 Is a node i 4 、j 4 Line admittance between, p i4 Is B' ac Ith of (2) 4 Element of rho j4 Is B' ac J (d) of 4 An element;
one node is a power electronic device node and the other node is a passive node, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
denotes the ith 5 An n x 1 dimensional matrix with 1 element and 0 elements,
i of phi 5 Each element, n being the number of power electronics nodes,
denotes the (j) th 5 -n) m x 1 dimensional matrices with 1 elements and 0 remaining elements, m being the number of passive nodes, i 5 As power electronics nodes, j 5 Being a passive node, b i5j5 Is a node i 5 、j 5 Admittance of the connection line, p j5 Is B' ac J (d) of 5 And (4) each element.
The invention discloses a power electronic multi-feed-in power system key line identification system, which comprises:
the generalized short-circuit ratio acquisition module is used for calculating to obtain an extended admittance matrix based on impedance parameters and a grid structure of the power electronic multi-feed-in power system; decomposing the characteristic values to obtain a generalized short-circuit ratio of the power electronic multi-feed-in power system;
the sensitivity acquisition module is used for calculating the sensitivity of the generalized short-circuit ratio of the power electronic multi-feed-in power system to each network line admittance;
and the identification module is used for completing identification of the key circuit of the power electronic multi-feed power system based on the obtained sensitivity sequence.
Compared with the prior art, the invention has the following beneficial effects:
the method is based on the generalized short-circuit ratio index of the power electronic multi-feed-in power system, obtains the key circuit of the system of the power electronic equipment under the large-scale grid-connected condition from the small-interference stability angle, can provide guidance for planning and running of a new energy unit, contributes to comprehensiveness of planning and designing of the power system, and can effectively reduce the small-interference stability problem in practical engineering application. The method has clear calculation idea and simple process, and can explore the identification of the key circuit of the power electronic multi-feed power system under certain new energy unit feed-in capacity and a grid structure.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a schematic diagram of an equivalent circuit of a power electronic multi-feed power system in simulation verification according to an embodiment of the present invention;
FIG. 2 is a block diagram of power electronics control in simulation verification according to an embodiment of the present invention;
fig. 3 is a schematic flowchart of a method for identifying a critical line in a power electronic multi-feed power system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a generalized short-circuit ratio of a critical line and a non-critical line according to a variation trace of a line admittance in a simulation verification according to an embodiment of the present invention; wherein, fig. 4 (a) is a schematic diagram of a change track of a generalized short-circuit ratio of a critical line along with a line admittance, and fig. 4 (b) is a schematic diagram of a change track of a generalized short-circuit ratio of a non-critical line along with a line admittance;
FIG. 5 is a schematic diagram illustrating a comparison of variation trajectories of dominant feature roots of a critical line and a non-critical line along with line admittance in simulation verification according to an embodiment of the present invention; fig. 5 (a) is a schematic diagram of a variation trajectory of a key line dominant feature root along with line admittance, and fig. 5 (b) is a schematic diagram of a variation trajectory of a non-key line dominant feature root along with line admittance;
FIG. 6 is a schematic voltage waveform comparison diagram during single-loop disconnection disturbance of a critical line and a non-critical line in simulation verification according to an embodiment of the present invention; fig. 6 (a) is a schematic voltage waveform diagram when the critical line single circuit line is disconnected and disturbed, and fig. 6 (b) is a schematic voltage waveform diagram when the non-critical line single circuit line is disconnected and disturbed.
Detailed Description
In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the following clearly and completely describes the technical solution of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention; it is to be understood that the described embodiments are only some of the embodiments of the present invention. Other embodiments, which can be derived by one of ordinary skill in the art from the disclosed embodiments without inventive faculty, are intended to be within the scope of the invention.
Referring to fig. 3, a method for identifying a key circuit of a power electronic multi-feed power system according to an embodiment of the present invention includes the following steps:
1) Obtaining an equivalent admittance matrix B from impedance parameters and a topological structure of an alternating current power grid initial Obtaining a reduced order node admittance matrix B through a Schuler's complement operation;
2) Capacity diagonal matrix S formed by rated capacity of each feed-in point power electronic equipment B Obtaining an extended admittance matrix from the formula (1), obtaining a minimum eigenvalue of the extended admittance matrix from the formula (2), namely the generalized short-circuit ratio gSCR of the power electronic multi-feed-in power system, and calculating a right eigenvector phi of the generalized short-circuit ratio gSCR;
gSCR＝minλ(J eq )， (2)
3) Computing adjoint matrices
And operation matrix
4) According to different classes of nodes at two ends of the line, the method specifically comprises the following steps: the two nodes are power electronic equipment nodes, and the sensitivity of the generalized short circuit comparison to the line admittance is as shown in formula (3); one node is a power electronic equipment node, the other node is an infinite node, and the sensitivity of the generalized short circuit ratio to the line admittance is as shown in the formula (4); the two nodes are passive nodes, and the sensitivity of the generalized short circuit ratio to the line admittance is as shown in a formula (5); one node is a passive node, the other node is an infinite node, and the sensitivity of the generalized short circuit ratio to the line admittance is as shown in the formula (6); one node is a power electronic equipment node, the other node is a passive node, and the sensitivity of the generalized short circuit ratio to the line admittance is as shown in the formula (7);
in the formula (I), the compound is shown in the specification,
an n x 1-dimensional matrix representing the ith element as 1 and the remaining elements as 0,
i element of phi, n is the number of power electronic device nodes, i, j represents two electronic device nodes in the system, b ij Is the line admittance between nodes i, j;
wherein psi and phi are respectively the extended admittance matrix J eq Left and right eigenvectors corresponding to eigenvalues gSCR,
ψJ eq ＝gSCRψ
J eq Φ＝gSCRΦ；
wherein the content of the first and second substances,
an n x 1-dimensional matrix representing the ith element as 1 and the remaining elements as 0,
is the ith element of phi, n is the number of power electronic device nodes, i is a power electronic device node, j is an infinite node, b ij Is the line admittance between nodes i, j;
in the formula (I), the compound is shown in the specification,
an m x 1-dimensional matrix representing the i-th to n-th elements as 1 and the remaining elements as 0, m being the number of passive nodes,
representing the m multiplied by 1 dimensional matrix with the i to n elements as 1 and the rest elements as 0, wherein i and j are passive nodes, n is the number of nodes of the power electronic equipment, b ij For line admittance, p, between nodes i, j i Is B' ac The ith element of (2);
wherein, the first and the second end of the pipe are connected with each other,
subscripts 1,2,3 and 4 respectively represent admittance matrixes among nodes of the power electronic equipment, between nodes of the power electronic equipment and passive nodes, between nodes of the passive nodes and the power electronic equipment and between the passive nodes,
in order to be a companion matrix, the system is,
is an operation matrix;
wherein, the first and the second end of the pipe are connected with each other,
an m × 1 dimensional matrix representing the i-th to n-th elements as 1 and the rest elements as 0, wherein m is the number of passive nodes, n is the number of power electronic device nodes, i is the passive node, j is the power electronic device node, b ij For line admittance between nodes i, j, p i Is B' ac The ith element of (1);
wherein, the first and the second end of the pipe are connected with each other,
an n x 1-dimensional matrix representing the ith element as 1 and the remaining elements as 0,
is the i-th element of phi, p i Is B' ac The ith element of (2); i is a power electronic device node, j is a passive node, b ij Connecting line admittances for nodes i, j;
5) The admittance sensitivity of the generalized short-circuit ratio gSCR to each line is arranged in a descending order, and the line arranged in front is the key line of the system.
The method provided by the embodiment of the invention is based on the generalized short-circuit ratio index of the power electronic multi-feed-in power system, obtains the key circuit of the system under the large-scale grid-connected condition of the power electronic equipment from the small-interference stability angle, provides guidance for planning and running of a new energy unit, contributes to comprehensiveness of planning and design consideration of the power system, and can effectively reduce the occurrence of the small-interference stability problem in practical engineering application.
The invention provides a method for identifying a key circuit of a power electronic multi-feed-in power system based on small interference stability, which comprises the following steps:
1) Aiming at a power electronic multi-feed-in power system with certain parameters and grid structure, calculating to obtain an extended admittance matrix J eq Decomposing the characteristic value to obtain a generalized short-circuit ratio gSCR of the power electronic multi-feed power system;
2) Calculating an adjoint matrix and an operation matrix required by subsequent calculation;
3) And calculating the sensitivity of the generalized short-circuit ratio gSCR of the power electronic multi-feed-in power system on each network line admittance, and sequencing the sensitivities in a descending order, wherein the network line corresponding to the sensitivity arranged in the front is a key line.
In another embodiment of the present invention, the step 1) specifically includes:
1.1 Rated capacity of input power electronics constitutes a capacity diagonal matrix S B Forming a node admittance matrix B initial And calculating a reduced node admittance matrix B.
1.2 Extend the admittance matrix as
1.3 Through the pair J eq Decomposing the characteristic value to obtain the characteristic value lambda 1 ,λ 2 ,L,λ n The minimum characteristic value is the generalized short-circuit ratio gsrc of the power electronic multi-feed power system.
In another embodiment of the present invention, the step 2) specifically includes:
2.1 Partitioning the node admittance matrix according to the order reduction requirement;
2.2 Computing a companion matrix;
2.3 Computing an operation matrix;
in another embodiment of the present invention, the step 3) specifically includes:
3.1 Phi and phi are respectively the extended admittance matrix J eq Left and right eigenvectors corresponding to the eigenvalues gSCR;
3.2 Judging the classification of nodes at two ends of each line, and dividing the classification into power electronic equipment nodes, passive nodes and infinite nodes;
3.3 According to different node classes, calculating the sensitivity of generalized short-circuit ratio gSCR about each network line admittance, and arranging the sensitivity in descending order, wherein the network line corresponding to the sensitivity arranged in the front is the key line.
In the embodiment of the present invention, calculating the sensitivity of the generalized short circuit ratio gsrc with respect to each network line admittance according to different node classifications specifically includes:
3.3.1 Both nodes are power electronics nodes, the sensitivity of the generalized short-circuit ratio to the line admittance is,
wherein the content of the first and second substances,
an n x 1-dimensional matrix representing the ith element as 1 and the remaining elements as 0,
the ith element of phi is the same as the following;
3.3.2 One node is a power electronics node and the other node is an infinite node, the sensitivity of the generalized short-circuit ratio to the line admittance is,
3.3.3 Both nodes are passive nodes, and the sensitivity of the generalized short-circuit ratio to the line admittance is
Where ρ is i Is B' ac The ith element of (1), the same below;
3.3.4 One node is a passive node and the other node is an infinite node, and the sensitivity of the generalized short-circuit ratio to the line admittance is
3.3.5 One node is a power electronics node and the other node is a passive node, the sensitivity of the generalized short-circuit ratio to the line admittance is,
in summary, the invention discloses a method for identifying a key circuit of a power electronic multi-feed-in power system based on small interference stability. Aiming at a power electronic multi-feed-in power system, an extended admittance matrix of the system can be obtained from information such as feed-in capacity, a grid structure and the like; according to the eigenvalue of the extended admittance matrix, the power electronic multi-feed power system can be equivalent to a plurality of power electronic single-feed power systems with the same small interference stability; the minimum eigenvalue of the extended admittance matrix is the generalized short-circuit ratio of the power electronic multi-feed-in power system, the sensitivity of the generalized short-circuit ratio on each network circuit admittance can be obtained by combining the eigenvalue and the eigenvector property, and the key circuit of the power electronic multi-feed-in power system is identified according to the sensitivity. The invention provides a small-interference-stability-based power electronic multi-feed-in power system key line identification method, which is clear in calculation thought and simple in process, aims to identify a power electronic multi-feed-in power system key line under the condition of exploring a certain feed-in capacity and a grid structure, provides guidance for planning and operation of a new energy power station from the small-interference stability perspective, and contributes to comprehensiveness of power system planning design consideration.
The specific verification examples of the invention are as follows:
a power electronic three-feed power system is built in Matlab/Simulink software, and is shown in figure 1. The power electronics in a three-feed system is a typical inverter. The inverter outer loop employs PQ control as shown in fig. 2. The physical meanings of the variables in fig. 2 are shown in table 1 below.
Table 1.Pq controlled inverter variable correspondence table
The parametric values for the PQ-controlled inverter variables are shown in table 2 below.
TABLE 2 parameter values of inverter variables in example simulation verification
| Active power P in /p.u. | 1 |
| Reactive power Q in /p.u. | 0 |
| PQ controlled PI link parameter K ppq | 0.1 |
| PQ control PI |
10 |
| Current inner loop PI link parameter K pi | 0.3 |
| Current inner loop PI |
10 |
| Phase-locked loop PI link parameter K ppll | 30 |
| Phase-locked loop PI link parameter K ipll | 3400 |
| Filter inductance L f /p.u. | 0.05 |
| Filter capacitor C f /p.u. | 0.05 |
The ac network parameters of the power electronic three-feed system are shown in table 3 below.
Table 3. AC power grid parameters in simulation verification of embodiment
| Line impedance Z 12 /p.u. | 0.4 |
| Line impedance Z 13 /p.u. | 0.5 |
| Line impedance Z 15 /p.u. | 0.06 |
| Line impedance Z 24 /p.u. | 0.064 |
| Line impedance Z 34 /p.u. | 0.096 |
| Line impedance Z 46 /p.u. | 0.021 |
Rated capacity of given power electronic three-feed-in system is S B = diag (3,1,1.5), system generalized short-circuit ratio gsscr =5.656, greater than the critical generalized short-circuit ratio 4.40.
The generalized short-circuit ratio of the power electronic three-feed system to the admittance sensitivity of each line is shown in table 4.
TABLE 4 generalized short-circuit comparison of admittance sensitivity of various lines
| Line impedance Z 34 /p.u. | 0.3350 |
| Line impedance Z 15 /p.u. | 0.3140 |
| Line impedance Z 12 /p.u. | 0.0505 |
| Line impedance Z 13 /p.u. | 0.0387 |
| Line impedance Z 46 /p.u. | 0.0318 |
| Line impedance Z 24 /p.u. | 0.0248 |
As can be seen from the table, the sensitivity values of the first two lines (lines 3-4 and lines 1-5) are larger, and the difference between the sensitivity values of the first two lines and the sensitivity values of the last four lines is larger, so that the lines 3-4 and lines 1-5 are the key lines of the system.
Two lines with similar admittance conditions, namely a line 3-4 and a line 2-4 are selected for comparison, wherein the line 3-4 belongs to a system critical line, and the line 2-4 belongs to a system non-critical line. The effect of the two-wire admittance change from 5 to 20 on the value of the generalized short-circuit ratio, i.e. the stability of the system glitch, is observed, as shown in fig. 4. It can be seen that the change in admittance values of lines 3-4 compared to lines 2-4 has a more significant effect on the generalized short-circuit ratio values, which is consistent with the results shown in table 4.
Correspondingly, the dominant characteristic root of the system changes during the process of changing the admittance of the line 3-4 and the line 2-4 from 5 to 20 as shown in fig. 5. As can be seen from fig. 5, the change in admittance values of lines 3-4 compared to lines 2-4 has a more significant effect on the damping ratio values, which is consistent with the results shown in table 4 and fig. 4.
Assuming that the lines 3-4 and the lines 2-4 are double circuit lines, and one circuit line is disconnected due to the fault of the lines, the small interference stability condition of the system when the two lines are respectively disconnected with one circuit line is analyzed. If the line 3-4 is disconnected with a return line, the line admittance is changed from 10.417 to 5.209, the generalized short-circuit ratio is changed from 5.656 to 4.041, the critical value of the stable operation of the system cannot be met, and hidden danger is buried for the stable operation of the system; if line 2-4 breaks a loop, the line admittance changes from 15.625 to 7.812, the generalized short-circuit ratio changes from 5.656 to 5.405, but still meets the system steady operation threshold of 4.40. It can be seen that the switching-off of the critical line 3-4 has a greater impact on the small interference stability of the system than the switching-off of the non-critical line 2-4, and therefore, important attention should be paid.
The correctness of this conclusion is verified by time domain simulation below. If the system is disturbed when the node 5 is t =0.1s during line maintenance, the voltage of the alternating current power grid drops by 10%, and recovers after 0.1s, and the system voltage waveform is observed, as shown in fig. 6. It can be seen from the figure that the system cannot be kept stable under small disturbance when the critical line 3-4 is disconnected from a return line, but the system can still be kept stable under small disturbance after the non-critical line 2-4 is disconnected from a return line, which means that attention should be paid to the critical line for preventing the small disturbance instability caused by line faults.
According to the verification embodiment of the invention, based on the generalized short-circuit ratio index of the power electronic multi-feed-in power system, the key line of the new energy unit under the large-scale grid-connected condition is obtained from the angle of small interference stability, accurate guidance can be provided for planning and operation of the new energy power station, comprehensiveness of planning and design consideration of the power system is facilitated, the problem of small interference stability can be effectively reduced in practical engineering application, and the remarkable technical effect is achieved.
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 flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations 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.
Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, and such modifications and equivalents are within the scope of the claims of the present invention as hereinafter claimed.
Claims (2)
1. A method for identifying a key line of a power electronic multi-feed-in power system is characterized by comprising the following steps:
step 1, calculating to obtain an extended admittance matrix based on impedance parameters and a grid structure of a power electronic multi-feed-in power system; obtaining generalized short-circuit ratio of the power electronic multi-feed-in power system through eigenvalue decomposition;
step 2, calculating the sensitivity of the generalized short-circuit ratio of the power electronic multi-feed-in power system to each network line admittance;
step 3, finishing the identification of the key circuit of the power electronic multi-feed-in power system based on the sequencing of the sensitivity obtained in the step 2;
in step 1, the step of calculating an extended admittance matrix based on the impedance parameters and the grid structure of the power electronic multi-feed-in power system specifically includes:
capacity diagonal matrix S formed by rated capacity of each feed-in point power electronic equipment B (ii) a Obtaining an equivalent admittance matrix B from the impedance parameters and the topological structure of the alternating current power grid of the power electronic multi-feed-in power system initial Obtaining a reduced order node admittance matrix B through a Schur complement operation;
extended admittance matrix J eq The expression of (a) is as follows,
in step 1, the step of obtaining the generalized short-circuit ratio of the power electronic multi-feed-in power system through eigenvalue decomposition specifically includes:
obtaining a minimum eigenvalue of the extended admittance matrix; the minimum characteristic value is a generalized short-circuit ratio gSCR of the power electronic multi-feed power system, and the expression is,
gSCR＝minλ(J eq )，
in the formula, λ (J) eq ) To expand the admittance matrix J eq A characteristic value of (d);
the step 2 specifically comprises the following steps:
judging node classification at two ends of each network line; wherein the classifying includes: power electronic device nodes, passive nodes and infinite nodes;
calculating the sensitivity of the generalized short circuit ratio gSCR relative to each network line admittance according to different node classifications; wherein, the first and the second end of the pipe are connected with each other,
both nodes are power electronic equipment nodes, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
denotes the ith 1 An n x 1 dimensional matrix with 1 element and 0 elements,
i th of phi 1 N is the number of nodes of the power electronic equipment, i 1 ，j 1 Representing two power electronics nodes in the system, b i1j1 Is a node i 1 、j 1 Line admittance in between;
wherein psi and phi are respectively the extended admittance matrix J eq Left and right eigenvectors corresponding to eigenvalues gSCR,
one node is a power electronic device node and the other node is an infinite node, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
wherein, the first and the second end of the pipe are connected with each other,
denotes the ith 2 N x 1 dimension with 1 element and 0 elementsThe matrix is a matrix of a plurality of matrices,
i of phi 2 Each element, n is the number of nodes of the power electronic equipment, i 2 As power electronics nodes, j 2 Being an infinite node, b i2j2 Is a node i 2 、j 2 Line admittance therebetween;
both nodes are passive nodes, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
represents the (i) th 3 -n) m x 1 dimensional matrices with elements 1 and the remaining elements 0, m being the number of passive nodes,
denotes the (j) th 3 N) m x 1 dimensional matrices with 1 elements and 0 remaining elements, i 3 ，j 3 Are all passive nodes, n is the number of nodes of the power electronic equipment, b i3j3 Is a node i 3 、j 3 Line admittance between, ρ i3 Is B' ac I th of (1) 3 Element of ρ j3 Is B' ac J (d) of 3 An element;
one node is a passive node and the other node is an infinite node, the sensitivity of the generalized short-circuit ratio to the line admittance is,
in the formula (I), the compound is shown in the specification,
represents the (i) th 4 -n) m x 1 dimensional matrices with elements 1 and the remaining elements 0, m being the number of passive nodes, n being the number of power electronics nodes, i 4 Is a passive node, j 4 As a power electronics node, b i4j4 Is a node i 4 、j 4 Line admittance between, p i4 Is B' ac I th of (1) 4 Element of ρ j4 Is B' ac J (d) of 4 An element;
one node is a power electronic device node and the other node is a passive node, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
denotes the ith 5 An n x 1 dimensional matrix with 1 element and 0 elements,
i of phi 5 Each element, n being the number of power electronics nodes,
denotes the (j) th 5 N) m x 1 dimensional matrix with 1 elements and 0 remaining elements, m being the number of passive nodes, i 5 As power electronics nodes, j 5 Being a passive node, b i5j5 Is a node i 5 、j 5 Admittance of the connection line, p j5 Is B' ac J (d) of 5 And (4) each element.
2. A power electronic multi-feed power system key line identification system, comprising:
the generalized short-circuit ratio acquisition module is used for calculating to obtain an extended admittance matrix based on impedance parameters and a grid structure of the power electronic multi-feed-in power system; obtaining generalized short-circuit ratio of the power electronic multi-feed-in power system through eigenvalue decomposition;
the sensitivity acquisition module is used for calculating the sensitivity of the generalized short-circuit ratio of the power electronic multi-feed power system to each network line admittance;
the identification module is used for finishing identification of the key lines of the power electronic multi-feed power system based on the obtained sensitivity sequence;
in the generalized short-circuit ratio obtaining module, the step of calculating to obtain the extended admittance matrix based on the impedance parameters and the grid structure of the power electronic multi-feed-in power system specifically includes:
capacity diagonal matrix S formed by rated capacity of each feed-in point power electronic equipment B (ii) a Obtaining an equivalent admittance matrix B from the impedance parameters and the topological structure of the alternating current power grid of the power electronic multi-feed-in power system initial Obtaining a reduced order node admittance matrix B through a Schuler's complement operation;
extended admittance matrix J eq The expression of (a) is as follows,
in the generalized short-circuit ratio obtaining module, the step of obtaining the generalized short-circuit ratio of the power electronic multi-feed-in power system through eigenvalue decomposition specifically includes:
obtaining a minimum eigenvalue of the extended admittance matrix; the minimum characteristic value is a generalized short-circuit ratio gSCR of the power electronic multi-feed power system, and the expression is,
gSCR＝minλ(J eq )，
in the formula, λ (J) eq ) To expand the admittance matrix J eq The characteristic value of (a);
in the sensitivity acquisition module, judging the classification of nodes at two ends of each network line; wherein the classifying includes: power electronic device nodes, passive nodes and infinite nodes;
calculating the sensitivity of the generalized short circuit ratio gSCR relative to each network line admittance according to different node classifications; wherein, the first and the second end of the pipe are connected with each other,
both nodes are power electronic equipment nodes, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
denotes the ith 1 An n × 1-dimensional matrix in which each element is 1 and the remaining elements are 0,
i th of phi 1 N is the number of nodes of the power electronic equipment, i 1 ，j 1 Representing two power electronics nodes in the system, b i1j1 Is a node i 1 、j 1 Line admittance therebetween;
wherein psi and phi are respectively the extended admittance matrix J eq Left and right eigenvectors corresponding to eigenvalues gSCR,
one node is a power electronic equipment node and the other node is an infinite node, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
wherein the content of the first and second substances,
denotes the ith 2 An n x 1 dimensional matrix with 1 element and 0 elements,
i th of phi 2 N is the number of nodes of the power electronic equipment, i 2 As power electronics nodes, j 2 As an infinite node, b i2j2 Is a node i 2 、j 2 Line admittance in between;
both nodes are passive nodes, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
represents the (i) th 3 -n) m x 1 dimensional matrices with elements 1 and the remaining elements 0, m being the number of passive nodes,
denotes the (j) th 3 N) m x 1 dimensional matrices with 1 elements and 0 remaining elements, i 3 ，j 3 Are all passive nodes, n is the number of nodes of the power electronic equipment, b i3j3 Is a node i 3 、j 3 Line admittance between, ρ i3 Is B' ac Ith of (2) 3 Element of ρ j3 Is B' ac J (d) of 3 An element;
one node is a passive node and the other node is an infinite node, the sensitivity of the generalized short-circuit ratio to the line admittance is,
in the formula (I), the compound is shown in the specification,
represents the (i) th 4 -n) m x 1 dimensional matrices with elements 1 and the remaining elements 0, m being the number of passive nodes, n being the number of power electronics nodes, i 4 Is a passive node, j 4 As power electronics nodes, b i4j4 Is a node i 4 、j 4 Line admittance between, p i4 Is B' ac Ith of (2) 4 Element of ρ j4 Is B' ac J (d) of 4 An element;
one node is a power electronic device node and the other node is a passive node, the sensitivity of the generalized short-circuit ratio gSCR to the line admittance is,
in the formula (I), the compound is shown in the specification,
denotes the ith 5 An n × 1-dimensional matrix in which each element is 1 and the remaining elements are 0,
i of phi 5 Each element, n being the number of power electronics nodes,
denotes the (j) th 5 N) m x 1 dimensional matrix with 1 elements and 0 remaining elements, m being the number of passive nodes, i 5 As power electronics nodes, j 5 Being a passive node, b i5j5 Is a node i 5 、j 5 Admittance of the connection line, p j5 Is B' ac J (d) of 5 And (4) each element.
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