CN116826786B - New energy power system weak point positioning method and system - Google Patents
New energy power system weak point positioning method and system Download PDFInfo
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Abstract
The invention provides a method and a system for locating weak points of a new energy power system, comprising the following steps: the method comprises the steps of adopting a new energy station impedance identification method driven by data and knowledge in a combined mode to acquire broadband impedance of a new energy station at a grid-connected point and broadband impedance of an alternating current power grid on line; adopting an impedance stability criterion to evaluate the stability of the system on line, and acquiring the phase margin and the potential oscillation frequency of the system; if the system phase margin is lower than the threshold value, calculating the real part of impedance of each new energy station at the potential oscillation frequency according to the broadband impedance identified on line; sequencing according to the magnitude of the real part of the impedance, wherein one or more new energy stations with the smallest real part of the impedance are weak points of the system; if the system phase margin is greater than the threshold, the rolling on-line assessment of the weak points of the system is repeated at intervals. The invention carries out real-time online evaluation on the stable state of the new energy power system; the weak point of the system is located before oscillation occurs to further eliminate the oscillation hidden trouble.
Description
Technical Field
The invention relates to the technical field of new energy power generation, in particular to a method and a system for locating weak points of a new energy power system.
Background
Under the severe situations of energy and environmental crisis, the construction of a novel power system mainly based on new energy has become an industry consensus. However, with the massive access of high-proportion new energy and high-proportion power electronic equipment, the problem of broadband oscillation of the novel power system is different from that of the traditional power system, and the novel power system provides challenges for the stable control of the power grid.
In order to reduce the impact of broadband oscillation on a new energy power system, research on an online risk assessment method of broadband oscillation is urgently needed, and online assessment of the system steady state and positioning of system oscillation weak points are necessary, and preventive measures are adopted in advance before oscillation occurs to improve the system stability and reduce the system oscillation risk. The existing research mainly aims at an oscillation tracing method adopted after the traditional power system or the new energy power system generates low-frequency or subsynchronous/supersynchronous oscillation, but the stability of the system before oscillation occurs is evaluated on line and weak points are positioned in a few documents, and particularly, effective means are not available in the aspect of positioning broadband oscillation weak points of the power system mainly based on new energy.
Therefore, the invention provides a method and a system for locating weak points of a new energy power system.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method and a system for locating weak points of a new energy power system.
According to a first aspect of the present invention, there is provided a new energy power system weak point positioning method, comprising:
The method comprises the steps of adopting a new energy station impedance identification method driven by data and knowledge in a combined mode to acquire broadband impedance of a new energy station at a grid-connected point and broadband impedance of an alternating current power grid on line;
Based on the broadband impedance, adopting an impedance stability criterion to evaluate the stability of the system on line, and acquiring the phase margin and the potential oscillation frequency of the system;
If the system phase margin is lower than a set threshold value, calculating an impedance real part of each new energy station at a potential oscillation frequency according to the broadband impedance identified on line; sequencing according to the magnitude of the real part of the impedance, wherein one or more new energy stations with the smallest real part of the impedance are weak points of the system;
And if the system phase margin is larger than the set threshold value, repeatedly performing rolling online evaluation on the weak points of the system according to the set interval time.
Preferably, the new energy power system includes: the system comprises a permanent magnet direct drive wind power plant, a doubly-fed wind power plant, a photovoltaic power station, a synchronous generator, a transmission line and an energy storage power station.
Preferably, the method for identifying impedance of a new energy station driven by combination of data and knowledge obtains broadband impedance of the new energy station at a grid-connected point and broadband impedance of an ac power grid on line, including:
Aiming at a new energy unit with random uncertainty input, a data driving method is adopted to establish a broadband impedance online identification model covering the whole steady-state operation condition; combining a physical structure model of the new energy station to construct a data-model fusion-driven new energy station broadband impedance online identification model; according to the network topology among the new energy stations, obtaining a broadband impedance online identification model of the new energy cluster through impedance network calculation;
Based on the broadband impedance online identification model of the new energy cluster, broadband impedance Z REx of each new energy station and broadband impedance Z RE of the new energy cluster are obtained according to the running state of each new energy unit and the voltage and current measurement data, and broadband impedance Z g of the alternating current power grid is obtained online.
Preferably, the step of evaluating the stability of the system on line based on the broadband impedance by adopting an impedance stability criterion to obtain a system phase margin and a potential oscillation frequency includes:
According to the broadband impedance Z RE of the new energy cluster at the grid-connected point and the broadband impedance Z g of the alternating current power grid, defining a system phase margin as follows:
Wherein: the symbol I refers to amplitude, the phase is referred to as < lambda > and PM refers to phase margin, and omega c refers to frequency corresponding to the intersection point of the frequency curves of the impedance Z g and Z RE;
Setting a threshold value of a system phase margin PM as theta th;
If the system phase margin PM is larger than the set threshold value theta th and the system stability margin is larger, the system is in a stable state;
if the system phase margin PM is smaller than the set threshold value θ th, the system stability margin is smaller, and there is a risk of instability, the intersection frequency ω c is referred to as the potential oscillation frequency.
Preferably, if the system phase margin is lower than a set threshold value θ th, calculating the real impedance part of each new energy station at the potential oscillation frequency ω c, and sorting according to the magnitude of the real impedance part, where one or several new energy stations with the smallest real impedance part are weak points of the system, including:
the broadband impedance ZREx(jω1)、ZREx(jω2)、…、ZREx(jωc)、…、ZREx(jωn)(x＝1,2,…n,x at the ports of each new energy station at different frequencies (omega 1 to omega n) is obtained separately to represent different new energy stations,
According to the potential oscillation frequency, obtaining impedance Z RE1(jωc)、ZRE2(jωc)、…ZREn(jωc at each new energy station port, and respectively extracting the real part R RE1(jωc)、RRE2(jωc)、…RREn(jωc of the impedance at each new energy station port);
sequencing according to the magnitude of the real parts of the impedance to obtain the smallest real part or parts of the impedance, wherein the corresponding new energy station is defined as a weak point of the system.
Preferably, the set interval time is 15 minutes.
Preferably, the threshold range of the system phase margin PM is 15 to 45 degrees.
According to a second aspect of the present invention, there is provided a weak point positioning system of a new energy power system, comprising:
The new energy station impedance identification module adopts a new energy station impedance identification method driven by data and knowledge in a combined mode, and obtains broadband impedance of the new energy station at a grid connection point and broadband impedance of an alternating current power grid on line;
the stability margin evaluation module is used for evaluating the stability of the system on line by utilizing an impedance stability criterion based on the broadband impedance, and acquiring the phase margin and the potential oscillation frequency of the system;
the weak point positioning module calculates the real part of impedance of each new energy station at the potential oscillation frequency according to the broadband impedance identified on line under the condition that the system phase margin is lower than a set threshold value; sequencing according to the magnitude of the real part of the impedance, wherein one or more new energy stations with the smallest real part of the impedance are weak points of the system;
And the timing module repeatedly starts the new energy station impedance identification module, the stability margin evaluation module and the weak point positioning module at intervals when the system phase margin is larger than a set threshold value, and performs rolling online evaluation on the weak point of the system.
According to a third aspect of the present invention, there is provided a terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor being operable to perform the method of locating points of weakness of the new energy power system or to run the system of locating points of weakness of the new energy power system when executing the program.
According to a fourth aspect of the present invention, there is provided a computer readable storage medium having stored thereon a computer program which when executed by a processor is operable to perform the new energy power system vulnerability localization method or to run the new energy power system vulnerability localization system.
By adopting the technical scheme, compared with the prior art, the embodiment of the invention has at least one of the following beneficial effects:
The method and the system for locating the weak points of the new energy power system can be used for carrying out real-time online evaluation on the stable state of the new energy power system;
According to the method and the system for locating the weak points of the new energy power system, provided by the embodiment of the invention, the weak points of the system are located before oscillation occurs, so that the hidden danger of oscillation is further eliminated. The method is suitable for a complex new energy power system and has the advantages of strong operability, high accuracy and the like.
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Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a flow chart of a method for locating weak points of a new energy station according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a weak point positioning system of a new energy station according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of a new energy station according to a preferred embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a new energy power system simplified into three small new energy stations according to a preferred embodiment of the present invention;
FIG. 5 is a bird diagram of the grid tie-in impedance and the AC grid impedance of the new energy station in a preferred embodiment of the present invention; (a) a graph reflecting impedance magnitude versus frequency; the graph (b) reflects the impedance phase and frequency relationship.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
As shown in fig. 1, the invention provides an embodiment, a new energy station weak point positioning method based on port time domain response, which specifically comprises the following steps:
S100, acquiring broadband impedance of the new energy station at a grid-connected point and broadband impedance of an alternating current power grid on line by adopting a new energy station impedance identification method driven by data and knowledge;
s200, broadband impedance is obtained based on the S100, the stability of the system is evaluated on line by utilizing an impedance stability criterion, and the phase margin and the potential oscillation frequency of the system are obtained;
S300, if the system phase margin in S200 is lower than a set threshold, calculating the real part of impedance of each new energy station at the potential oscillation frequency according to the broadband impedance identified on line; sequencing according to the magnitude of the real part of the impedance, wherein one or more new energy stations with the smallest real part of the impedance are weak points of the system;
s400, if the system phase margin in S200 is larger than the set threshold, repeating S100-S300 according to the set interval time, and performing rolling online evaluation on the weak points of the system.
The embodiment can carry out real-time online evaluation on the stable state of the new energy power system; in the embodiment, the weak point of the system is positioned before oscillation occurs, so that the hidden danger of the oscillation is eliminated.
In a preferred embodiment of the invention, the new energy station comprises a full-power permanent magnet direct-drive wind turbine, a double-fed wind turbine, a photovoltaic generator, a synchronous machine, a transmission line, an energy storage unit and the like.
In a preferred embodiment of the present invention, S100 is implemented, and a method for identifying impedance of a new energy station driven by combination of data and knowledge is adopted to obtain broadband impedance of the new energy station at a grid-connected point and broadband impedance of an ac power grid on line, and specifically includes the following steps:
S101, aiming at a new energy unit with random uncertainty input, a data driving method is adopted to establish a broadband impedance online identification model covering the whole steady-state operation condition;
s102, constructing a data-model fusion-driven new energy station broadband impedance online identification model by combining a physical structure model of the new energy station;
s103, further obtaining a broadband impedance online identification model of the new energy cluster through impedance network calculation according to the network topology among the new energy stations;
s104, based on the broadband impedance online identification model of the new energy station in S103, according to the running state of each new energy unit and the voltage and current measurement data, broadband impedance Z REx of each new energy station and broadband impedance ZRE of the new energy cluster are obtained, and broadband impedance Z g of the alternating current power grid is obtained online.
Further, for a detailed implementation of S100, see patent application number 202210991337.8.
In a preferred embodiment of the present invention, implementation S200, evaluating the stability of the system based on the impedance stability criterion, obtaining the phase margin and the potential oscillation frequency of the system, specifically includes the following steps:
s201, according to broadband impedance Z RE of the online acquired new energy cluster at the grid-connected point and broadband impedance Z g of the alternating current power grid, defining a system phase margin as follows:
wherein: the symbol I refers to amplitude, the phase, PM refers to phase margin, and omega c refers to the frequency corresponding to the intersection point of the frequency curves of the impedance Z g and Z RE.
S202, setting the threshold value of the system phase margin PM to be theta th, wherein the threshold value of PM is generally 15 to 45 degrees.
If the system phase margin PM is larger than the set threshold value theta th and the system stability margin is larger, the system is in a stable state;
If the system phase margin PM is smaller than the set threshold value θ th, the system stability margin is lower, and there is a risk of instability, the intersection frequency ω c is referred to as the potential oscillation frequency.
In this embodiment, step S200 evaluates the stability of the system based on the impedance stability criterion, acquires the phase margin and the potential oscillation frequency of the system, and after determining the potential oscillation frequency, performs step S300 to locate the weak station under the potential oscillation frequency.
In a preferred embodiment of the present invention, implementing S300, if the system phase margin is lower than a set threshold value θ th, calculating the real impedance of each new energy station at the potential oscillation frequency ω c, and sorting according to the magnitude of the real impedance, where one or several new energy stations with the smallest real impedance are weak points of the system, specifically including the following steps:
According to potential oscillation frequency, obtain impedance Z RE1(jωc)、ZRE2(jωc)、…ZREn(jωc at each new energy station port), extract real part R RE1(jωc)、RRE2(jωc)、…RREn(jωc of impedance at each new energy station port respectively, rank according to the magnitude of real part of impedance, obtain minimum real part of one or several impedances, corresponding new energy station is defined as weak point of system (real part of impedance represents resistance, at potential oscillation frequency, station with small resistance considers that its damping to oscillation is smaller, therefore considered weak point).
The embodiment locates weak points of the system before oscillation occurs to further eliminate the oscillation hidden trouble. The method is suitable for a complex new energy power system and has the advantages of strong operability, high accuracy and the like.
In a preferred embodiment of the invention, S400 is implemented, wherein if the system phase margin is greater than the set threshold, the above steps are continued for 15 minutes intervals, and the system weak points are evaluated online by scrolling.
The embodiment sets the weak point of the timing on-line evaluation system, can ensure that the weak point of the system is found in time, and avoids oscillation.
Referring to fig. 2, based on the same inventive concept, in other embodiments of the present invention, there is provided a weak point positioning system of a new energy station, comprising:
The new energy station impedance identification module adopts a new energy station impedance identification method driven by data and knowledge in a combined mode, and obtains broadband impedance of the new energy station at a grid connection point and broadband impedance of an alternating current power grid on line;
the stability margin evaluation module is used for evaluating the stability of the system on line by utilizing impedance stability criteria and acquiring the phase margin and the potential oscillation frequency of the system;
The weak point positioning module calculates the real part of impedance of each new energy station at the potential oscillation frequency according to the broadband impedance identified on line under the condition that the system phase margin is lower than a set threshold value; sequencing according to the magnitude of the real part of the impedance, wherein one or more new energy stations with the smallest real part of the impedance are weak points of the system;
and the timing module repeatedly starts the new energy station impedance identification module, the stability margin evaluation module and the weak point positioning module at intervals when the system phase margin is larger than a set threshold value, and performs rolling online evaluation on the weak point of the system.
The specific implementation techniques of the steps corresponding to the weak point positioning method of the new energy station in the foregoing embodiments may be referred to for each module/unit in the foregoing embodiments of the present invention, and will not be described herein again.
Based on the same inventive concept, in other embodiments of the present invention, a terminal is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor being operable to perform the above-described method or to run the above-described system when executing the program.
Optionally, a memory for storing a program; memory, which may include volatile memory (english) such as random-access memory (RAM), such as static random-access memory (SRAM), double data rate synchronous dynamic random-access memory (Double Data Rate Synchronous Dynamic Random Access Memory, DDR SDRAM), and the like; the memory may also include a non-volatile memory (English) such as a flash memory (English). The memory is used to store computer programs (e.g., application programs, functional modules, etc. that implement the methods described above), computer instructions, etc., which may be stored in one or more memories in a partitioned manner. And the above-described computer programs, computer instructions, data, etc. may be invoked by a processor.
A processor for executing the computer program stored in the memory to implement the steps in the method according to the above embodiment. Reference may be made in particular to the description of the embodiments of the method described above.
The processor and the memory may be separate structures or may be integrated structures that are integrated together. When the processor and the memory are separate structures, the memory and the processor may be connected by a bus coupling.
Based on the same inventive concept, in other embodiments of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, which program, when being executed by a processor, is operative to perform the method described above, or to run the system described above.
Among them, computer-readable media include computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. In addition, the ASIC may reside in a user device. The processor and the storage medium may reside as discrete components in a communication device.
It will be appreciated by those skilled in the art that 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 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.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
The technical solutions provided in the above embodiments of the present invention are described in further detail below in conjunction with a specific application example.
In the specific application example, the voltage of an alternating current power grid is 220kV/50Hz, the voltage of a port of a new energy station is 230kV/50Hz, the new energy stations are connected through a 230kV alternating current line, and the internal reactance of the alternating current power grid is composed of a pure inductor L g.
As shown in fig. 3, in this specific application example, the new energy power system includes a wind farm, a photovoltaic power station, a transmission line, a synchronous machine, a load, and the like.
As shown in fig. 4, in this specific application example, the new energy power system is simplified into three small new energy stations, in which the new energy station 3 has twice as many new energy stations 1 and 2.
As shown in fig. 5, the graph (a) in fig. 5 reflects the relationship between the impedance amplitude and the frequency, and the graph (b) in fig. 5 reflects the relationship between the impedance phase and the frequency. And identifying the impedance of the new energy station cluster at the grid connection point and the real-time impedance of the alternating current power grid, so that an impedance amplitude and phase curve of the new energy station at the grid connection point, shown by a black solid line, is obtained, and the black dotted line is the impedance amplitude and phase curve of the alternating current power grid.
According to broadband impedance Z RE of the new energy cluster at the grid-connected point and broadband impedance Z g of the alternating current power grid, defining a system phase margin as follows:
wherein: the symbol I refers to amplitude, the phase, PM refers to phase margin, and omega c refers to the frequency corresponding to the intersection point of the frequency curves of the impedance Z g and Z RE.
If the system phase margin PM is less than the set threshold value θ th, then the intersection frequency ω c is referred to as the potential oscillation frequency.
The phase threshold is set to 15 degrees, the frequency of the system at the intersection point is 293Hz, the phase margin is 9.5 degrees, and is lower than the set phase threshold, thus defining 293Hz as the potential oscillation frequency of the system. Then, the real part of the port impedance of each new energy station at the potential oscillation frequency is calculated, R 1＝R2＝1.22Ω,R3 =0.60deg.C, and it can be seen that the real part of the impedance of the new energy station 3 is the smallest, so that the new energy station 3 is a weak station of the system.
The broadband impedance based on online identification can realize online evaluation of broadband oscillation stability of the new energy power system, and accurately position weak points of the system before oscillation occurs, thereby laying a foundation for further eliminating hidden danger of oscillation.
Claims (8)
1. The utility model provides a new forms of energy electric power system weak point location method which characterized in that includes:
The method comprises the steps of adopting a new energy station impedance identification method driven by data and knowledge in a combined mode to acquire broadband impedance of a new energy station at a grid-connected point and broadband impedance of an alternating current power grid on line;
Based on the broadband impedance, adopting an impedance stability criterion to evaluate the stability of the system on line, and acquiring the phase margin and the potential oscillation frequency of the system;
If the system phase margin is lower than a set threshold value, calculating an impedance real part of each new energy station at a potential oscillation frequency according to the broadband impedance identified on line; sequencing according to the magnitude of the real part of the impedance, wherein one or more new energy stations with the smallest real part of the impedance are weak points of the system;
If the system phase margin is larger than the set threshold value, repeatedly performing rolling online evaluation on the weak points of the system according to the set interval time;
The method for identifying the impedance of the new energy station driven by the combination of data and knowledge obtains the broadband impedance of the new energy station at the grid-connected point and the broadband impedance of the alternating current power grid on line, and comprises the following steps:
Aiming at a new energy unit with random uncertainty input, a data driving method is adopted to establish a broadband impedance online identification model covering the whole steady-state operation condition; combining a physical structure model of the new energy station to construct a data-model fusion-driven new energy station broadband impedance online identification model; according to the network topology among the new energy stations, obtaining a broadband impedance online identification model of the new energy cluster through impedance network calculation;
Based on the broadband impedance online identification model of the new energy clusters, obtaining broadband impedance Z REx of each new energy station and broadband impedance Z RE of the new energy clusters according to the running state of each new energy unit and the voltage and current measurement data, and obtaining broadband impedance Z g of an alternating current power grid online;
Based on the broadband impedance, the stability of the system is evaluated on line by adopting an impedance stability criterion, and the phase margin and the potential oscillation frequency of the system are obtained, comprising the following steps:
According to the broadband impedance Z RE of the new energy cluster at the grid-connected point and the broadband impedance Z g of the alternating current power grid, defining a system phase margin as follows:
Wherein: sign symbol Finger amplitude value/>Referring to the phase, PM represents the phase margin, ω c represents the frequency corresponding to the intersection point of the impedance Z g and Z RE amplitude-frequency curves;
Setting a threshold value of a system phase margin PM as theta th;
If the system phase margin PM is larger than the set threshold value theta th and the system stability margin is larger, the system is in a stable state;
if the system phase margin PM is smaller than the set threshold value θ th, the system stability margin is smaller, and there is a risk of instability, the intersection frequency ω c is referred to as the potential oscillation frequency.
2. The method for locating weak points of a new energy power system according to claim 1, wherein the new energy power system comprises: the system comprises a permanent magnet direct drive wind power plant, a doubly-fed wind power plant, a photovoltaic power station, a synchronous generator, a transmission line and an energy storage power station.
3. The method for locating weak points of a new energy power system according to claim 1, wherein if the system phase margin is lower than a set threshold value θ th, calculating the real impedance of each new energy station at a potential oscillation frequency ω c, and sorting according to the magnitude of the real impedance, wherein one or several new energy stations with the smallest real impedance are weak points of the system, including:
Respectively obtaining broadband impedance ZREx（jω1）、ZREx（jω2）、…、ZREx（jωc）、…、ZREx（jωn）, of each new energy station at ports of different frequencies omega 1 to omega n, wherein x=1, 2, … n, x represents different new energy stations, obtaining impedance Z RE1（jωc）、ZRE2（jωc）、…ZREn（jωc of each new energy station port according to the potential oscillation frequency omega c), and respectively extracting real part R RE1（jωc）、RRE2（jωc）、…RREn（jωc of the impedance of each new energy station port;
sequencing according to the magnitude of the real parts of the impedance to obtain the smallest real part or parts of the impedance, wherein the corresponding new energy station is defined as a weak point of the system.
4. The method for locating weak points of a new energy power system according to claim 1, wherein the time interval is 15 minutes.
5. The method for locating weak points of a new energy power system according to claim 4, wherein the threshold range of the system phase margin PM is 15-45 degrees.
6. A weak point positioning system of a new energy power system is characterized by comprising:
The new energy station impedance identification module adopts a new energy station impedance identification method driven by data and knowledge in a combined mode, and obtains broadband impedance of the new energy station at a grid connection point and broadband impedance of an alternating current power grid on line;
the stability margin evaluation module is used for evaluating the stability of the system on line by utilizing an impedance stability criterion based on the broadband impedance, and acquiring the phase margin and the potential oscillation frequency of the system;
the weak point positioning module calculates the real part of impedance of each new energy station at the potential oscillation frequency according to the broadband impedance identified on line under the condition that the system phase margin is lower than a set threshold value; sequencing according to the magnitude of the real part of the impedance, wherein one or more new energy stations with the smallest real part of the impedance are weak points of the system;
The timing module repeatedly starts the new energy station impedance identification module, the stability margin evaluation module and the weak point positioning module at intervals when the system phase margin is larger than a set threshold value, and performs rolling online evaluation on the weak point of the system;
The method for identifying the impedance of the new energy station driven by the combination of data and knowledge obtains the broadband impedance of the new energy station at the grid-connected point and the broadband impedance of the alternating current power grid on line, and comprises the following steps:
Aiming at a new energy unit with random uncertainty input, a data driving method is adopted to establish a broadband impedance online identification model covering the whole steady-state operation condition; combining a physical structure model of the new energy station to construct a data-model fusion-driven new energy station broadband impedance online identification model; according to the network topology among the new energy stations, obtaining a broadband impedance online identification model of the new energy cluster through impedance network calculation;
Based on the broadband impedance online identification model of the new energy clusters, obtaining broadband impedance Z REx of each new energy station and broadband impedance Z RE of the new energy clusters according to the running state of each new energy unit and the voltage and current measurement data, and obtaining broadband impedance Z g of an alternating current power grid online;
Based on the broadband impedance, the stability of the system is evaluated on line by adopting an impedance stability criterion, and the phase margin and the potential oscillation frequency of the system are obtained, comprising the following steps:
According to the broadband impedance Z RE of the new energy cluster at the grid-connected point and the broadband impedance Z g of the alternating current power grid, defining a system phase margin as follows:
Wherein: sign symbol Finger amplitude value/>Referring to the phase, PM represents the phase margin, ω c represents the frequency corresponding to the intersection point of the impedance Z g and Z RE amplitude-frequency curves;
Setting a threshold value of a system phase margin PM as theta th;
If the system phase margin PM is larger than the set threshold value theta th and the system stability margin is larger, the system is in a stable state;
if the system phase margin PM is smaller than the set threshold value θ th, the system stability margin is smaller, and there is a risk of instability, the intersection frequency ω c is referred to as the potential oscillation frequency.
7. A terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor is operable to perform the method of any one of claims 1-5 or to run the system of claim 6 when the program is executed by the processor.
8. A computer readable storage medium having stored thereon a computer program, which when executed by a processor is operative to perform the method of any one of claims 1-5 or to run the system of claim 6.
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| CN112381671A (en) * | 2020-11-30 | 2021-02-19 | 华北电力科学研究院有限责任公司 | Broadband oscillation risk assessment method for new energy station grid-connected power system |
| CN115249980A (en) * | 2022-08-18 | 2022-10-28 | 上海交通大学 | New energy station impedance identification method and system driven by data and knowledge in combined mode |
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| CN112381671A (en) * | 2020-11-30 | 2021-02-19 | 华北电力科学研究院有限责任公司 | Broadband oscillation risk assessment method for new energy station grid-connected power system |
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