CN117833276A - Broadband oscillation risk identification and suppression method and system for flexible direct current transmission system - Google Patents
Broadband oscillation risk identification and suppression method and system for flexible direct current transmission system Download PDFInfo
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Abstract
The invention relates to the technical field of electrical engineering, and provides a method and a system for identifying and inhibiting broadband oscillation risk of a flexible direct current transmission system, wherein the method comprises the following steps: determining broadband oscillation basic characteristics of a flexible direct current transmission system; scanning an equivalent system of the alternating current system by using a scanning impedance method to obtain an impedance characteristic matrix of corresponding oscillation frequency; constructing a flexible direct current transmission system broadband oscillation risk identification similarity model, and acquiring cosine similarity of the flexible direct current transmission system to be tested in an operation mode; determining the risk type of the flexible direct current transmission system according to the cosine similarity; and selecting corresponding oscillating risk operation measures according to the risk types to inhibit the risk. According to the invention, the high, medium and low frequency harmonic oscillation of the flexible direct current transmission system is comprehensively considered, the oscillation risk in the complex and changeable operation mode of the flexible direct current can be flexibly identified, corresponding measures are configured according to the existing risk, and the support is better provided for broadband oscillation suppression and stability improvement in actual engineering.
Description
Technical Field
The invention relates to the technical field of electrical engineering, in particular to a method and a system for identifying and inhibiting broadband oscillation risk of a flexible direct current transmission system.
Background
In recent decades, the flexible direct current (MMC-HVDC) power transmission technology has the advantages of no reactive power compensation, no commutation failure, independent adjustment of active power and reactive power and the like, is widely applied to the aspects of power grid island power transmission and the like, and is put into operation in a large amount of practical engineering worldwide. However, with the continuous increase of the scale of the flexible direct current transmission system and the power electronic devices, the broadband oscillation phenomenon frequently occurs, which forms a great threat to the safe and stable operation of the power grid. For example, a flexible direct current transmission line in south Australia of Guangdong in the process of gradually increasing the output of a wind farm observes oscillation phenomenon with the frequency of about 30 Hz; when the wind farm is sent out by flexible direct current, the Germany North sea generates oscillation of 250-350 Hz, and the oscillation current reaches more than 40% of the fundamental wave current; when a soft direct current converter station at one end of the Ruxi direct current engineering is connected into an alternating current power grid through a weak current network, high-frequency oscillation of about 1.2kHz occurs, system shutdown and the like are caused, and the stability of a power system is challenged by broadband oscillation.
Aiming at the oscillation problem brought by a flexible direct current power transmission system, the prior art is limited in the aspects of high-frequency oscillation generated by coupling of a flexible direct current converter station body and an alternating current system and the principle of medium-frequency and low-frequency oscillation generated by grid-connected power electronic equipment of flexible direct current and new energy. However, how to ensure safe and stable operation of the flexible dc power transmission system, how to effectively identify the oscillation risk existing in the current operation mode, and how to eliminate the oscillation risk by matching with corresponding suppression measures in advance are not paid attention to and solved in the prior art.
Disclosure of Invention
The invention aims to solve at least one technical problem in the background art and provides a method and a system for identifying and inhibiting broadband oscillation risk of a flexible direct current transmission system.
In order to achieve the above objective, the present invention provides a method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system, comprising:
determining broadband oscillation basic characteristics of a flexible direct current transmission system;
scanning an equivalent system of the alternating current system by using a scanning impedance method to obtain an impedance characteristic matrix of corresponding oscillation frequency;
constructing a flexible direct current transmission system broadband oscillation risk identification similarity model, and acquiring cosine similarity of the flexible direct current transmission system to be tested in an operation mode;
determining the risk type of the flexible direct current transmission system according to the cosine similarity;
and selecting corresponding oscillating risk operation measures according to the risk types to inhibit risks.
According to one aspect of the present invention, the broadband oscillation basic characteristic of the flexible direct current transmission system includes: oscillation type and corresponding oscillation frequency interval.
According to one aspect of the present invention, the scanning an equivalent system of an ac system by using a scanning impedance method to obtain an impedance characteristic matrix of a corresponding oscillation frequency includes:
determining a scan interval Δt and a scan interval f min ，f max ]The direct current is laterally opened, and a voltage with the amplitude v and the resonance frequency f is applied to the public connection point of the flexible direct current and the alternating current systemExcitation amplitude is I frequency f i Is>The two are divided to obtain the impedance of the corresponding oscillation frequency>
Wherein,for flexible direct current transmission system, the reference oscillation frequency is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the impedance matrix of the corresponding oscillation frequency is finally obtained as follows:
wherein f min Is the minimum value of oscillation frequency, f max For the maximum oscillation frequency, N is the total number of lines connected to the common point.
According to one scheme of the invention, the method for constructing the flexible direct current transmission system broadband oscillation risk identification similarity model is characterized in that the cosine similarity of the flexible direct current transmission system to be tested in the operation mode is as follows:
obtaining an impedance matrix of corresponding oscillation frequency of the flexible direct current transmission system to be tested in the operation mode by utilizing the scanning impedance:
wherein,the oscillation frequency of the flexible direct current transmission system to be tested is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the construction of the flexible direct current transmission system broadband oscillation risk cosine similarity model is as follows:
according to an aspect of the present invention, the determining the risk type of the flexible dc power transmission system according to the cosine similarity includes:
according to the acquired different oscillation frequencies f i Judging whether the similarity exceeds a similarity threshold value of the oscillation risk of the flexible direct current transmission system or not according to the cosine similarity, if so, meeting the similarity threshold value of the oscillation risk of the flexible direct current transmission systemDescription->And->The cosine value included angle between the two included angles tends to be 0, which indicates that the more similar the two included angles are, the risk of broadband oscillation of the flexible direct current transmission system is judged, and the next step is carried out, wherein +_in is carried out>Is a threshold value of similarity; if->Judging that the flexible direct current transmission system does not have broadband oscillation risk;
and determining the type of broadband oscillation risk of the flexible direct current transmission system according to the corresponding oscillation frequency meeting the cosine similarity condition.
According to one aspect of the present invention, the similarity threshold value is within a range of [ -1,1].
According to an aspect of the present invention, the selecting a corresponding oscillating risk operation measure according to the risk type to suppress risk includes:
if the flexible direct current transmission system has a low-frequency oscillation risk, the flexible direct current transmission system is restrained by reducing the PLL damping measure;
if the intermediate frequency oscillation risk exists in the flexible direct current transmission system, the intermediate frequency oscillation risk is restrained through the measures of the current loop additional damping controller:
wherein k is III_add For desired damping in mid-band section III, ω III_add1 、ω III_add2 To add damping controller operating band, H III_add The method comprises the steps that a damping transfer function is expected for a middle frequency band III, and s represents a complex frequency domain;
if the flexible direct current transmission system has high-frequency oscillation risk, the intermediate-frequency oscillation risk is restrained through the measures of the active damping controller:
wherein k is IV For high band IV desired damping omega IV1 、ω IV2 An active damping controller frequency operating band; omega IV1 ＝2π×f IV1 ，ω IV2 ＝2π×f IV2 ，f IV1 、f IV2 The upper frequency limit and the lower frequency limit of the active damping controller are respectively H IV For the high band IV band desired damping transfer function, s represents the complex frequency domain.
In order to achieve the above objective, the present invention further provides a system for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system, including:
the characteristic determining module is used for determining the broadband oscillation basic characteristic of the flexible direct current transmission system;
the impedance characteristic matrix acquisition module is used for scanning the equivalent system of the alternating current system by using a scanning impedance method to acquire an impedance characteristic matrix of corresponding oscillation frequency;
the similarity acquisition module is used for constructing a broadband oscillation risk identification similarity model of the flexible direct current transmission system and acquiring cosine similarity of the flexible direct current transmission system to be tested in an operation mode;
the risk type determining module is used for determining the risk type of the flexible direct current transmission system according to the cosine similarity;
and the risk suppression module is used for selecting corresponding oscillation risk operation measures according to the risk type to suppress risks.
In order to achieve the above objective, the present invention further provides an electronic device, which includes a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program when executed by the processor implements the method for identifying and suppressing risk of broadband oscillation of a flexible direct current transmission system as described above.
In order to achieve the above object, the present invention further provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor, implements the method for identifying and suppressing risk of broadband oscillation of a flexible direct current transmission system as described above.
According to the scheme of the invention, the broadband oscillation basic characteristic of the flexible direct current transmission system is determined. And scanning the equivalent system of the alternating current system by using a scanning impedance method to obtain an impedance characteristic matrix of the corresponding oscillation frequency. And acquiring cosine similarity of the corresponding flexible direct current transmission system in the operation mode by constructing a flexible direct current transmission system broadband oscillation risk identification similarity model. And determining the risk type of the flexible direct current transmission system according to the cosine similarity of the risk identification similarity model, and selecting corresponding oscillation risk operation measures according to the risk type of the flexible direct current transmission system. According to the invention, the high, medium and low frequency harmonic oscillation of the flexible direct current transmission system is comprehensively considered, the oscillation risk in the complex and changeable operation mode of the flexible direct current can be flexibly identified, corresponding measures are configured according to the existing risk, and the support is better provided for broadband oscillation suppression and stability improvement in actual engineering.
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Fig. 1 schematically illustrates a flowchart of a method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system according to an embodiment of the present invention;
fig. 2 schematically illustrates a flowchart of a method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system according to an embodiment of the present invention.
Detailed Description
The present disclosure will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are merely to enable those of ordinary skill in the art to better understand and thus practice the teachings of the present invention and do not imply any limitation on the scope of the invention.
As used herein, the term "comprising" and variants thereof are to be interpreted as meaning "including but not limited to" open-ended terms. The term "based on" is to be interpreted as "based at least in part on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment.
Fig. 1 schematically illustrates a flowchart of a method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system according to the present invention; fig. 2 schematically illustrates a flowchart of a method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system according to an embodiment of the present invention. As shown in fig. 1 and 2, in the present embodiment, the method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system includes:
determining broadband oscillation basic characteristics of a flexible direct current transmission system;
scanning an equivalent system of the alternating current system by using a scanning impedance method to obtain an impedance characteristic matrix of corresponding oscillation frequency;
constructing a flexible direct current transmission system broadband oscillation risk identification similarity model, and acquiring cosine similarity of the flexible direct current transmission system to be tested in an operation mode;
determining the risk type of the flexible direct current transmission system according to the cosine similarity;
and selecting corresponding oscillating risk operation measures according to the risk types to inhibit the risk.
According to one embodiment of the invention, the broadband oscillation basic characteristics of the flexible direct current transmission system comprise: oscillation type and corresponding oscillation frequency interval. The method specifically comprises the following steps: the high frequency, intermediate frequency and low frequency oscillation types and corresponding oscillation frequency intervals, [10, 300) Hz is low frequency; [300, 1000) Hz is an intermediate frequency; 1000Hz and above.
According to one embodiment of the present invention, scanning an equivalent system of an ac system by using a scan impedance method to obtain an impedance characteristic matrix of a corresponding oscillation frequency includes:
scan interval Δt=5 Hz and scan interval [10, 25 ] are determined00]The direct current is laterally opened, and a voltage with the amplitude v and the resonance frequency f is applied to the public connection point of the flexible direct current and the alternating current systemExcitation amplitude is I frequency f i Is (1) the current of the (a)The two are divided to obtain the impedance of the corresponding oscillation frequency>
Wherein,for flexible direct current transmission system, the reference oscillation frequency is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the impedance matrix of the corresponding oscillation frequency is finally obtained as follows:
wherein f min Is the minimum value of oscillation frequency, f max For the maximum oscillation frequency, N is the total number of lines connected to the common point.
According to one embodiment of the invention, a flexible direct current transmission system broadband oscillation risk identification similarity model is constructed, and the cosine similarity of the flexible direct current transmission system to be tested in the operation mode is obtained as follows:
obtaining an impedance matrix of corresponding oscillation frequency of the flexible direct current transmission system to be tested in the operation mode by utilizing the scanning impedance:
wherein,the oscillation frequency of the flexible direct current transmission system to be tested is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the construction of the flexible direct current transmission system broadband oscillation risk cosine similarity model is as follows:
according to one embodiment of the present invention, determining a risk type of the flexible dc power transmission system according to the cosine similarity includes:
according to the acquired different oscillation frequencies f i Judging whether the similarity exceeds a similarity threshold value of the oscillation risk of the flexible direct current transmission system or not according to the cosine similarity, if so, meeting the similarity threshold value of the oscillation risk of the flexible direct current transmission systemDescription->And->The cosine value included angle between the two included angles tends to be 0, which indicates that the more similar the two included angles are, the risk of broadband oscillation of the flexible direct current transmission system is judged, and the next step is carried out, wherein +_in is carried out>Is a threshold value of similarity; if->Judging that the flexible direct current transmission system does not have broadband oscillation risk;
and determining the type of broadband oscillation risk of the flexible direct current transmission system according to the corresponding oscillation frequency meeting the cosine similarity condition.
According to one embodiment of the invention, the oscillation risk similarity threshold value of the flexible direct current transmission system can be determined according to the working experience of power grid operators and the safe and stable operation principle, and in the embodiment, the value range of the similarity threshold value is [ -1,1].
According to one embodiment of the present invention, selecting a corresponding oscillating risk operation measure according to a risk type to suppress a risk includes:
if the flexible direct current transmission system has a low-frequency oscillation risk, the flexible direct current transmission system is restrained by reducing the PLL damping measure;
if the intermediate frequency oscillation risk exists in the flexible direct current transmission system, the intermediate frequency oscillation risk is restrained through the measures of the current loop additional damping controller:
wherein k is III_add For desired damping in mid-band section III, ω III_add1 、ω III_add2 To add damping controller operating band, H III_add The method comprises the steps that a damping transfer function is expected for a middle frequency band III, and s represents a complex frequency domain;
if the flexible direct current transmission system has high-frequency oscillation risk, the intermediate-frequency oscillation risk is restrained through the measures of the active damping controller:
wherein k is IV For high band IV desired damping omega IV1 、ω IV2 An active damping controller frequency operating band; omega IV1 ＝2π×f IV1 ，ω IV2 ＝2π×f IV2 ，f IV1 、f IV2 The upper frequency limit and the lower frequency limit of the active damping controller are respectively H IV For the high band IV band desired damping transfer function, s represents the complex frequency domain.
According to the scheme, the broadband oscillation basic characteristic of the flexible direct current transmission system is determined. And scanning the equivalent system of the alternating current system by using a scanning impedance method to obtain an impedance characteristic matrix of the corresponding oscillation frequency. And acquiring cosine similarity of the corresponding flexible direct current transmission system in the operation mode by constructing a flexible direct current transmission system broadband oscillation risk identification similarity model. And determining the risk type of the flexible direct current transmission system according to the cosine similarity of the risk identification similarity model, and selecting corresponding oscillation risk operation measures according to the risk type of the flexible direct current transmission system. According to the invention, the high, medium and low frequency harmonic oscillation of the flexible direct current transmission system is comprehensively considered, the oscillation risk in the complex and changeable operation mode of the flexible direct current can be flexibly identified, corresponding measures are configured according to the existing risk, and the support is better provided for broadband oscillation suppression and stability improvement in actual engineering.
Further, in order to achieve the above object, the present invention further provides a system for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system, including:
the characteristic determining module is used for determining the broadband oscillation basic characteristic of the flexible direct current transmission system;
the impedance characteristic matrix acquisition module is used for scanning the equivalent system of the alternating current system by using a scanning impedance method to acquire an impedance characteristic matrix of corresponding oscillation frequency;
the similarity acquisition module is used for constructing a broadband oscillation risk identification similarity model of the flexible direct current transmission system and acquiring cosine similarity of the flexible direct current transmission system to be tested in an operation mode;
the risk type determining module is used for determining the risk type of the flexible direct current transmission system according to the cosine similarity;
and the risk suppression module is used for selecting corresponding oscillation risk operation measures according to the risk type to suppress the risk.
According to one embodiment of the invention, the broadband oscillation basic characteristics of the flexible direct current transmission system comprise: oscillation type and corresponding oscillation frequency interval. The method specifically comprises the following steps: the high frequency, intermediate frequency and low frequency oscillation types and corresponding oscillation frequency intervals, [10, 300) Hz is low frequency; [300, 1000) Hz is an intermediate frequency; 1000Hz and above.
According to one embodiment of the present invention, scanning an equivalent system of an ac system by using a scan impedance method to obtain an impedance characteristic matrix of a corresponding oscillation frequency includes:
determining a scan interval Δt=5 Hz and a scan interval [10, 2500 ]]The direct current is laterally opened, and a voltage with the amplitude v and the resonance frequency f is applied to the public connection point of the flexible direct current and the alternating current systemExcitation amplitude is I frequency f i Is (1) the current of the (a)The two are divided to obtain the impedance of the corresponding oscillation frequency>
Wherein,for flexible direct current transmission system, the reference oscillation frequency is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the impedance matrix of the corresponding oscillation frequency is finally obtained as follows:
wherein f min Is the minimum value of oscillation frequency, f max For the maximum oscillation frequency, N is the total number of lines connected to the common point.
According to one embodiment of the invention, a flexible direct current transmission system broadband oscillation risk identification similarity model is constructed, and the cosine similarity of the flexible direct current transmission system to be tested in the operation mode is obtained as follows:
obtaining an impedance matrix of corresponding oscillation frequency of the flexible direct current transmission system to be tested in the operation mode by utilizing the scanning impedance:
wherein,the oscillation frequency of the flexible direct current transmission system to be tested is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the construction of the flexible direct current transmission system broadband oscillation risk cosine similarity model is as follows:
according to one embodiment of the present invention, determining a risk type of the flexible dc power transmission system according to the cosine similarity includes:
according to the acquired different oscillation frequencies f i Judging whether the similarity exceeds a similarity threshold value of the oscillation risk of the flexible direct current transmission system or not according to the cosine similarity, if so, meeting the similarity threshold value of the oscillation risk of the flexible direct current transmission systemDescription->And->The cosine value included angle between the two included angles tends to be 0, which indicates that the more similar the two included angles are, the risk of broadband oscillation of the flexible direct current transmission system is judged, and the next step is carried out, wherein +_in is carried out>Is a threshold value of similarity; if->Judging that the flexible direct current transmission system does not have broadband oscillation risk;
and determining the type of broadband oscillation risk of the flexible direct current transmission system according to the corresponding oscillation frequency meeting the cosine similarity condition.
According to one embodiment of the invention, the oscillation risk similarity threshold value of the flexible direct current transmission system can be determined according to the working experience of power grid operators and the safe and stable operation principle, and in the embodiment, the value range of the similarity threshold value is [ -1,1].
According to one embodiment of the present invention, selecting a corresponding oscillating risk operation measure according to a risk type to suppress a risk includes:
if the flexible direct current transmission system has a low-frequency oscillation risk, the flexible direct current transmission system is restrained by reducing the PLL damping measure;
if the intermediate frequency oscillation risk exists in the flexible direct current transmission system, the intermediate frequency oscillation risk is restrained through the measures of the current loop additional damping controller:
wherein k is III_add For desired damping in mid-band section III, ω III_add1 、ω dIII_add2 To add damping controller operating band, H III_add The method comprises the steps that a damping transfer function is expected for a middle frequency band III, and s represents a complex frequency domain;
if the flexible direct current transmission system has high-frequency oscillation risk, the intermediate-frequency oscillation risk is restrained through the measures of the active damping controller:
wherein k is IV For high band IV desired damping omega IV1 、ω IV2 An active damping controller frequency operating band; omega IV1 ＝2π×f IV1 ，ω IV2 ＝2π×f IV2 ，f IV1 、f IV2 The upper frequency limit and the lower frequency limit of the active damping controller are respectively H IV For the high band IV band desired damping transfer function, s represents the complex frequency domain.
According to the scheme, the broadband oscillation basic characteristic of the flexible direct current transmission system is determined. And scanning the equivalent system of the alternating current system by using a scanning impedance method to obtain an impedance characteristic matrix of the corresponding oscillation frequency. And acquiring cosine similarity of the corresponding flexible direct current transmission system in the operation mode by constructing a flexible direct current transmission system broadband oscillation risk identification similarity model. And determining the risk type of the flexible direct current transmission system according to the cosine similarity of the risk identification similarity model, and selecting corresponding oscillation risk operation measures according to the risk type of the flexible direct current transmission system. According to the invention, the high, medium and low frequency harmonic oscillation of the flexible direct current transmission system is comprehensively considered, the oscillation risk in the complex and changeable operation mode of the flexible direct current can be flexibly identified, corresponding measures are configured according to the existing risk, and the support is better provided for broadband oscillation suppression and stability improvement in actual engineering.
In order to achieve the above objective, the present invention further provides an electronic device, which includes a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program when executed by the processor implements the method for identifying and suppressing broadband oscillation risk of the flexible dc power transmission system as described above.
In order to achieve the above objective, the present invention further provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor, implements the method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system as described above.
Those of ordinary skill in the art will appreciate that the modules and algorithm steps described in connection with the embodiments disclosed herein can be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the apparatus and device described above may refer to corresponding procedures in the foregoing method embodiments, which are not described herein again.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, and for example, the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or modules, which may be in electrical, mechanical, or other forms.
The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules, i.e., may be located in one place, or may be distributed over a plurality of network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment of the invention.
In addition, each functional module in the embodiment of the present invention may be integrated in one processing module, or each module may exist alone physically, or two or more modules may be integrated in one module.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method for energy saving signal transmission/reception of the various embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk, etc.
The foregoing description is only of the preferred embodiments of the present application and is presented as a description of the principles of the technology being utilized. It will be appreciated by persons skilled in the art that the scope of the invention referred to in this application is not limited to the specific combinations of features described above, but it is intended to cover other embodiments in which any combination of features described above or equivalents thereof is possible without departing from the spirit of the invention. Such as the above-described features and technical features having similar functions (but not limited to) disclosed in the present application are replaced with each other.
It should be understood that, the sequence numbers of the steps in the summary and the embodiments of the present invention do not necessarily mean the order of execution, and the execution order of the processes should be determined by the functions and the internal logic, and should not be construed as limiting the implementation process of the embodiments of the present invention.
Claims (10)
1. The method for identifying and inhibiting the broadband oscillation risk of the flexible direct current transmission system is characterized by comprising the following steps of:
determining broadband oscillation basic characteristics of a flexible direct current transmission system;
scanning an equivalent system of the alternating current system by using a scanning impedance method to obtain an impedance characteristic matrix of corresponding oscillation frequency;
constructing a flexible direct current transmission system broadband oscillation risk identification similarity model, and acquiring cosine similarity of the flexible direct current transmission system to be tested in an operation mode;
determining the risk type of the flexible direct current transmission system according to the cosine similarity;
and selecting corresponding oscillating risk operation measures according to the risk types to inhibit risks.
2. The method for identifying and suppressing risk of broadband oscillation of a flexible direct current transmission system according to claim 1, wherein the basic characteristics of broadband oscillation of the flexible direct current transmission system include: oscillation type and corresponding oscillation frequency interval.
3. The method for identifying and suppressing broadband oscillation risk of a flexible direct current transmission system according to claim 1, wherein the scanning the equivalent system of the alternating current system by using the scanning impedance method to obtain the impedance characteristic matrix of the corresponding oscillation frequency comprises the following steps:
determining a scan interval Δt and a scan interval f min ，f max ]The direct current is laterally opened, and a voltage with the amplitude v and the resonance frequency f is applied to the public connection point of the flexible direct current and the alternating current systemExcitation amplitude is I frequency f i Is>The two are divided to obtain the impedance of the corresponding oscillation frequency>
Wherein,for flexible direct current transmission system, the reference oscillation frequency is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the impedance matrix of the corresponding oscillation frequency is finally obtained as follows:
wherein f min Is the minimum value of oscillation frequency, f max For maximum oscillation frequency, N is common toTotal number of lines connected by points.
4. The method for identifying and suppressing wideband oscillation risk of a flexible direct current transmission system according to claim 3, wherein the step of constructing a model for identifying similarity of wideband oscillation risk of the flexible direct current transmission system, and the step of obtaining cosine similarity of the flexible direct current transmission system to be tested in the operation mode is as follows:
obtaining an impedance matrix of corresponding oscillation frequency of the flexible direct current transmission system to be tested in the operation mode by utilizing the scanning impedance:
wherein,the oscillation frequency of the flexible direct current transmission system to be tested is f i Under the operating condition, the common connection point is connected with the j branch circuit to form equivalent impedance;
the construction of the flexible direct current transmission system broadband oscillation risk cosine similarity model is as follows:
5. the method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system according to claim 4, wherein determining the risk type of the flexible dc power transmission system according to the cosine similarity includes:
according to the acquired different oscillation frequencies f i Judging whether the similarity exceeds a similarity threshold value of the oscillation risk of the flexible direct current transmission system or not according to the cosine similarity, if so, meeting the similarity threshold value of the oscillation risk of the flexible direct current transmission systemDescription->And->The cosine value included angle between the two included angles tends to 0, which shows that the more similar the two included angles are, the risk of broadband oscillation of the flexible direct current transmission system is judged, and the next step is carried out, whereinIs a threshold value of similarity; if->Judging that the flexible direct current transmission system does not have broadband oscillation risk;
and determining the type of broadband oscillation risk of the flexible direct current transmission system according to the corresponding oscillation frequency meeting the cosine similarity condition.
6. The method for identifying and suppressing risk of broadband oscillation in a flexible dc power transmission system according to claim 5, wherein the similarity threshold is in a range of [ -1,1].
7. The method for identifying and suppressing risk of broadband oscillation of a flexible dc power transmission system according to claim 1, wherein the selecting a corresponding risk operation measure for suppressing risk according to the risk type includes:
if the flexible direct current transmission system has a low-frequency oscillation risk, the flexible direct current transmission system is restrained by reducing the PLL damping measure;
if the intermediate frequency oscillation risk exists in the flexible direct current transmission system, the intermediate frequency oscillation risk is restrained through the measures of the current loop additional damping controller:
wherein k is III_add For desired damping in mid-band section III, ω III_add1 、ω III_add2 To add damping controller operating band, H III_add The method comprises the steps that a damping transfer function is expected for a middle frequency band III, and s represents a complex frequency domain;
if the flexible direct current transmission system has high-frequency oscillation risk, the intermediate-frequency oscillation risk is restrained through the measures of the active damping controller:
wherein k is IV For high band IV desired damping omega IV 1 、ω IV 2 An active damping controller frequency operating band; omega IV1 ＝2π×f IV1 ，ω IV 2 ＝2π×f IV 2 ，f IV1 、f IV2 The upper frequency limit and the lower frequency limit of the active damping controller are respectively H IV For the high band IV band desired damping transfer function, s represents the complex frequency domain.
8. The utility model provides a flexible direct current transmission system broadband oscillation risk discernment and suppression system which characterized in that includes:
the characteristic determining module is used for determining the broadband oscillation basic characteristic of the flexible direct current transmission system;
the impedance characteristic matrix acquisition module is used for scanning the equivalent system of the alternating current system by using a scanning impedance method to acquire an impedance characteristic matrix of corresponding oscillation frequency;
the similarity acquisition module is used for constructing a broadband oscillation risk identification similarity model of the flexible direct current transmission system and acquiring cosine similarity of the flexible direct current transmission system to be tested in an operation mode;
the risk type determining module is used for determining the risk type of the flexible direct current transmission system according to the cosine similarity;
and the risk suppression module is used for selecting corresponding oscillation risk operation measures according to the risk type to suppress risks.
9. An electronic device comprising a processor, a memory, and a computer program stored on the memory and executable on the processor, the computer program when executed by the processor implementing the flexible direct current transmission system broadband oscillation risk identification and suppression method according to any one of claims 1 to 7.
10. A computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, and when the computer program is executed by a processor, the method for identifying and suppressing broadband oscillation risk of the flexible direct current power transmission system according to any one of claims 1 to 7 is realized.
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