CN111291464A - Dynamic equivalence method and device for power system - Google Patents
Dynamic equivalence method and device for power system Download PDFInfo
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- CN111291464A CN111291464A CN201811494498.6A CN201811494498A CN111291464A CN 111291464 A CN111291464 A CN 111291464A CN 201811494498 A CN201811494498 A CN 201811494498A CN 111291464 A CN111291464 A CN 111291464A
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Abstract
The invention relates to a dynamic equivalence method and a device for an electric power system, comprising the following steps: step 1: applying disturbance to a research area in a power system through simulation to obtain a first dynamic response of the research area; step 2: partitioning areas outside the research area in the power system by using a clustering algorithm, and performing equivalence on generator nodes in the partitions to obtain an equivalent power system; and step 3: applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area; and 4, step 4: according to the distortion rate between the first dynamic response and the second dynamic response, the transfer function of the equivalent generator node of the subarea outside the research area in the power system is output.
Description
Technical Field
The invention relates to the field of dynamic analysis of power systems, in particular to a dynamic equivalence method and device for a power system.
Background
In the planning design and actual operation of the power system, a large amount of transient process simulation calculation is needed to ensure the reliability of power transmission so as to estimate the stability of the system after disturbance. With the rapid development of 'west-east power transmission' and 'large-area interconnection' projects, the scale of modern power grids is continuously enlarged. How to rapidly and accurately analyze such a huge and complex nonlinear time-varying system and give correct countermeasures in time becomes a focus of increasing attention of people. In order to improve the economy and reliability of power transmission, modern power systems tend to be interconnected in regions more and more, so that the calculation amount of digital simulation is greatly increased. In fact, according to the current theoretical level and technical conditions, there are many difficulties in performing complete real-time online analysis on a large power system, and people generally only pay attention to their local areas, but do appropriate simplification and order reduction processing on external systems which are in weak contact with research systems. It is therefore necessary to make dynamic equivalence to large power systems. In dynamic equivalence, a complete system is divided into a research system and an external system, and the dynamic equivalence is mainly performed on the research system, so that the external system can be simplified under the condition of ensuring that the dynamic influence of the external system on the research system is not distorted.
Commonly used dynamic equivalence methods include a homodyne equivalence method, a mode equivalence method and an estimation equivalence method. The coherent equivalence method is high in physical transparency, suitable for nonlinear calculation and large-disturbance working conditions of a system, and capable of being directly used for transient analysis. The generator rotor homodyne equivalence method is the most basic one and is mainly used for transient stability analysis, a research system before and after equivalence is required to have an approximate rotor rocking curve under large disturbance, and elements in an equivalence system are required to be actual power system elements so as to be directly analyzed by a transient stability program. It includes relevant cluster identification, network simplification and relevant cluster parameter aggregation 3 parts. The parameter aggregation of related clusters is to construct 1 equivalent generator and its regulating system, so that it can well simulate the comprehensive dynamic response of all generators and their regulating systems in one related cluster in the transient stability simulation process.
The homodyne equivalence method is theoretically rigorous, but has the following disadvantages: the aggregation algorithm is complex and the equivalence time is long for large systems. The operation experience of a calculator is excessively relied on, the obtained equivalent model needs to be determined by factors such as disturbance places, disturbance types and the like, the workload is large, and an optimal equivalent scheme is difficult to make for complex disturbance conditions.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to retain the influence of an external system on the dynamic behavior of a research system, effectively simplify the system and improve the analysis speed on the premise of ensuring the requirement of engineering analysis precision.
The purpose of the invention is realized by adopting the following technical scheme:
in a power system dynamic equivalence method, the improvement comprising:
step 1: applying disturbance to a research area in a power system through simulation to obtain a first dynamic response of the research area;
step 2: partitioning areas outside the research area in the power system by using a clustering algorithm, and performing equivalence on generator nodes in the partitions to obtain an equivalent power system;
and step 3: applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area;
and 4, step 4: and outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system according to the distortion rate between the first dynamic response and the second dynamic response.
Preferably, step 1 is preceded by: the study region is selected in a cluster tree system of a power system.
Further, a cluster tree system of the power system is established according to electromechanical distances among generator nodes in the power system;
wherein the electromechanical distance between the generator node i and the node j is determined according to the following formula:
in the above formula,. DELTA.omegaijIs the angular velocity difference between node i and node j; delta is the power angle difference of the node i and the node j; eiIs the voltage of node i, EjThe voltage at node j, G (i, j) is the difference between the conductances at node i and node j, B (i, j) is the difference between the susceptances at node i and node j, and T is 1/50.
Preferably, the step 2 includes:
clustering generator nodes in the external system by using a k-means algorithm to obtain a clustering result;
and obtaining the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center in the clustering result, and taking the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center as the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system.
Preferably, the step 4 includes:
and if the distortion rate between the first dynamic response and the second dynamic response is smaller than a preset threshold value, outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system.
In a power system dynamic equivalence device, the improvement comprising:
the first simulation module is used for applying disturbance to a research area in the power system through simulation to obtain a first dynamic response of the research area;
the equivalence module is used for partitioning regions outside the research region in the power system by using a clustering algorithm, and carrying out equivalence on generator nodes in the partitions to obtain an equivalent power system;
the second simulation module is used for applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area;
and the judging module is used for outputting the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system according to the distortion rate between the first dynamic response and the second dynamic response.
Preferably, the system further comprises: a selection module to select the region of interest in a clustering tree system of an electrical power system.
Further, a cluster tree system of the power system is established according to electromechanical distances among generator nodes in the power system;
wherein the electromechanical distance between the generator node i and the node j is determined according to the following formula:
in the above formula,. DELTA.omegaijIs the angular velocity difference between node i and node j; delta is the power angle difference of the node i and the node j; eiIs the voltage of node i, EjIs the voltage of node j, G (i, j)B (i, j) is the difference between the susceptances of node i and node j, and T is 1/50.
Preferably, the equivalence module is configured to:
clustering generator nodes in the external system by using a k-means algorithm to obtain a clustering result;
and obtaining the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center in the clustering result, and taking the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center as the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system.
Preferably, the judging module is configured to:
and if the distortion rate between the first dynamic response and the second dynamic response is smaller than a preset threshold value, outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system.
Compared with the closest prior art, the invention has the following beneficial effects:
the technical scheme provided by the invention comprises the following steps of 1: applying disturbance to a research area in a power system through simulation to obtain a first dynamic response of the research area; step 2: partitioning areas outside the research area in the power system by using a clustering algorithm, and performing equivalence on generator nodes in the partitions to obtain an equivalent power system; and step 3: applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area; and 4, step 4: according to the technical scheme, a transfer function of equivalent generator nodes of partitions outside a research area in the power system is output according to the distortion rate between the first dynamic response and the second dynamic response, a dynamic equivalence method of the power system is realized based on a simulation platform, mechanical and electrical distances between generators are used as quantitative indexes for measuring the coupling strength of each unit, the system is further subdivided into a plurality of weakly coupled subsystems by adopting a clustering method, and parameters are aggregated one by one. And performing digital-analog hybrid simulation in a simulation platform, and verifying the dynamic equivalence method.
Drawings
FIG. 1 is a flow chart of a power system dynamic equivalence method;
FIG. 2 is a schematic diagram of a power system dynamic equivalent device.
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a dynamic equivalence method for a power system, which comprises the following steps of:
step 1: applying disturbance to a research area in a power system through simulation to obtain a first dynamic response of the research area;
step 2: partitioning areas outside the research area in the power system by using a clustering algorithm, and performing equivalence on generator nodes in the partitions to obtain an equivalent power system;
and step 3: applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area;
and 4, step 4: and outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system according to the distortion rate between the first dynamic response and the second dynamic response.
The simulation process of the step 1 and the step 3 can be carried out through a semi-physical real-time simulation platform based on RT-LAB;
before the step 1, the method comprises the following steps: the study region is selected in a cluster tree system of a power system.
The clustering tree system of the power system is established according to electromechanical distances among generator nodes in the power system;
the electromechanical distance between generator node i and node j is determined as follows:
in the above formula,. DELTA.omegaijIs the angular velocity difference between node i and node j; delta is the power angle difference of the node i and the node j; eiIs the voltage of node i, EjThe voltage at node j, G (i, j) is the difference between the conductances at node i and node j, B (i, j) is the difference between the susceptances at node i and node j, and T is 1/50.
In the embodiment provided by the invention, the research area can be selected according to the electromechanical distance between the generator node i and the node j, and the node is selected firstly, then the electromechanical distance between the node and other nodes is taken as the selection basis, and the node with the electromechanical distance between the node and other nodes smaller than the preset value is selected as the generator node contained in the research area;
specifically, in the step 1, a power simulation system is built through a semi-physical real-time simulation platform based on RT-LAB, a disturbance application place is selected in a research system, a disturbance type is determined, and dynamic responses under various typical disturbance actions are obtained through simulation;
the step 2 includes:
clustering generator nodes in the external system by using a k-means algorithm to obtain a clustering result;
and obtaining the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center in the clustering result, and taking the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center as the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system.
Furthermore, because the dynamic equivalence of the regional generator nodes belongs to the prior art, the method is not limited to adding the transfer functions of the excitation system models of the generator nodes in the clustering center in the clustering result as the transfer functions of the equivalent generator nodes of the corresponding partitions of the clustering center;
the step 4 comprises the following steps:
and if the distortion rate between the first dynamic response and the second dynamic response is smaller than a preset threshold value, outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system.
The invention also relates to a dynamic equivalent device of a power system, as shown in fig. 2, the device comprises:
the first simulation module is used for applying disturbance to a research area in the power system through simulation to obtain a first dynamic response of the research area;
the equivalence module is used for partitioning regions outside the research region in the power system by using a clustering algorithm, and carrying out equivalence on generator nodes in the partitions to obtain an equivalent power system;
the second simulation module is used for applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area;
and the judging module is used for outputting the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system according to the distortion rate between the first dynamic response and the second dynamic response.
Preferably, the system further comprises: a selection module to select the region of interest in a clustering tree system of an electrical power system.
Further, a cluster tree system of the power system is established according to electromechanical distances among generator nodes in the power system;
wherein the electromechanical distance between the generator node i and the node j is determined according to the following formula:
in the above formula,. DELTA.omegaijIs the angular velocity difference between node i and node j; delta is the power angle difference of the node i and the node j; eiIs the voltage of node i, EjIs the voltage at node j, G (i, j) is the difference between the conductances at node i and node j, B (i, j) is the difference between the susceptances at node i and node j, and T is 1/50。
Preferably, the equivalence module is configured to:
clustering generator nodes in the external system by using a k-means algorithm to obtain a clustering result;
and obtaining the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center in the clustering result, and taking the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center as the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system.
Preferably, the judging module is configured to:
and if the distortion rate between the first dynamic response and the second dynamic response is smaller than a preset threshold value, outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A power system dynamic equivalence method, the method comprising:
step 1: applying disturbance to a research area in a power system through simulation to obtain a first dynamic response of the research area;
step 2: partitioning areas outside the research area in the power system by using a clustering algorithm, and performing equivalence on generator nodes in the partitions to obtain an equivalent power system;
and step 3: applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area;
and 4, step 4: and outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system according to the distortion rate between the first dynamic response and the second dynamic response.
2. The method of claim 1, wherein step 1 is preceded by: the study region is selected in a cluster tree system of a power system.
3. The method of claim 2, wherein the clustering tree system of the power system is established based on electromechanical distances between generator nodes in the power system;
wherein the electromechanical distance between the generator node i and the node j is determined according to the following formula:
in the above formula,. DELTA.omegaijIs the angular velocity difference between node i and node j; delta is the power angle difference of the node i and the node j; eiIs the voltage of node i, EjThe voltage at node j, G (i, j) is the difference between the conductances at node i and node j, B (i, j) is the difference between the susceptances at node i and node j, and T is 1/50.
4. The method of claim 1, wherein step 2, comprises:
clustering generator nodes in the external system by using a k-means algorithm to obtain a clustering result;
and obtaining the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center in the clustering result, and taking the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center as the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system.
5. The method of claim 1, wherein step 4 comprises:
and if the distortion rate between the first dynamic response and the second dynamic response is smaller than a preset threshold value, outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system.
6. A power system dynamic equivalence device, the device comprising:
the first simulation module is used for applying disturbance to a research area in the power system through simulation to obtain a first dynamic response of the research area;
the equivalence module is used for partitioning regions outside the research region in the power system by using a clustering algorithm, and carrying out equivalence on generator nodes in the partitions to obtain an equivalent power system;
the second simulation module is used for applying disturbance to a research area in the equivalent power system through simulation to obtain a second dynamic response of the research area;
and the judging module is used for outputting the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system according to the distortion rate between the first dynamic response and the second dynamic response.
7. The apparatus of claim 6, wherein the system further comprises: a selection module to select the region of interest in a clustering tree system of an electrical power system.
8. The apparatus of claim 7, wherein the clustering tree system of the power system is established based on electromechanical distances between generator nodes in the power system;
wherein the electromechanical distance between the generator node i and the node j is determined according to the following formula:
in the above formula,. DELTA.omegaijIs the angular velocity difference between node i and node j; delta is the power angle difference of the node i and the node j; eiIs the voltage of node i, EjIs the voltage at node j, G (i, j) is the difference between the conductances at node i and node j, and B (i, j) is node i and node jj, T-1/50.
9. The apparatus of claim 6, wherein the equivalence module is to:
clustering generator nodes in the external system by using a k-means algorithm to obtain a clustering result;
and obtaining the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center in the clustering result, and taking the sum of the transfer functions of the excitation system models of the generator nodes in the clustering center as the transfer function of the equivalent generator nodes of the subareas outside the research area in the power system.
10. The apparatus of claim 6, wherein the determination module is to:
and if the distortion rate between the first dynamic response and the second dynamic response is smaller than a preset threshold value, outputting the transfer function of the equivalent generator node of the subarea outside the research area in the power system.
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