Impedance shaping based method for damping wide frequency oscillations in high penetration wind power integrated system

Abstract

The present application relates to the technical field of power system stability control, and particularly relates to a high-proportion wind power access system wide-frequency oscillation suppression method based on impedance shaping. The content comprises: constructing a frequency domain output impedance matrix, extracting a dominant wide-frequency oscillation coupling mode frequency band, introducing a mode suppression driven impedance shaping compensation mechanism, constructing a mode suppression driving quantity based on the mode direction in the dominant wide-frequency oscillation coupling mode, and performing local impedance shaping on the output impedance; based on the mode suppression driving quantity, quantifying the mode interference sensitivity between wind power converters, and introducing an impedance shaping gain correction mechanism based on the mode interference sensitivity, to correct the target output impedance after local shaping. The problems that the shaping process cannot effectively adjust dynamically according to the equipment capacity of the wind power converter and the frequency risk, resulting in no difference shaping and excessive compensation, and the problems that the interference coupling between the wind power converters cannot be effectively suppressed, resulting in excessive oscillation or suppression are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system stability control, and in particular to a wideband oscillation suppression method for a high-proportion wind power access system based on impedance shaping. BACKGROUND

[0002] With the rapid development of renewable energy, a large amount of new energy such as wind power is connected to the power grid, which changes the impedance structure of the system, and the stability support capability of the traditional synchronous generator inertia gradually weakens, especially in the region with high proportion of wind power grid connection. The wind farm is connected to the power grid through a power electronic converter, which changes the equivalent impedance characteristics of the system, and easily excites wideband oscillation in the medium and high frequency band, affecting the system stability and power quality.

[0003] In order to ensure the stability and efficient operation of the wind power access system, the output impedance shaping of the wind power converter is the key to improve the system performance. In the prior art, the wind power converter optimizes its output characteristics through modal analysis and impedance shaping method. Although these methods can improve the stability of the system to some extent, there are often the following problems: (1) no difference shaping and overcompensation: in the shaping process, the device capacity and frequency risk of each wind power converter are not effectively adjusted dynamically, resulting in no difference shaping and overcompensation, affecting the overall stability of the system; (2) interference coupling problem: the interference coupling between wind power converters cannot be effectively suppressed, which may cause unreasonable modal interference amplification, excessive oscillation or suppression, and affect the frequency response of the system.

[0004] Therefore, in view of the above problems, it is urgent to provide a wideband oscillation suppression method for a high-proportion wind power access system based on impedance shaping. SUMMARY

[0005] The present application provides a wideband oscillation suppression method for a high-proportion wind power access system based on impedance shaping, which solves the problems that in the shaping process, the device capacity and frequency risk of each wind power converter are not effectively adjusted dynamically, resulting in no difference shaping and overcompensation, affecting the overall stability of the system; the interference coupling between wind power converters cannot be effectively suppressed, which may cause unreasonable modal interference amplification, excessive oscillation or suppression, and affect the frequency response of the system.

[0006] The wideband oscillation suppression method for a high-proportion wind power access system based on impedance shaping of the present application comprises the following steps:

[0007] S1. Collect the output impedance at each frequency sampling point, and construct a frequency domain output impedance matrix; based on the frequency domain output impedance matrix, extract the dominant broadband oscillation coupling modal frequency band, and obtain the modal direction and modal contribution degree of the dominant broadband oscillation coupling modal; introduce the impedance shaping compensation mechanism of modal suppression driving, based on the modal direction in the dominant broadband oscillation coupling modal, construct the modal suppression driving quantity, and locally shape the output impedance to obtain the target output impedance after local shaping;

[0008] S2. Based on the modal suppression driving quantity, quantify the modal interference sensitivity between the wind power converters, and introduce the impedance shaping gain correction mechanism based on the modal interference sensitivity to correct the locally shaped target output impedance to obtain the final output impedance after global shaping.

[0009] Preferably, the S1 specifically comprises:

[0010] By singular value decomposition method, singular value decomposition is performed on the frequency domain output impedance matrix, the maximum singular value is selected, and normalization processing is performed to construct a normalized maximum singular value sequence.

[0011] Preferably, the S1 specifically comprises:

[0012] Based on the normalized maximum singular value sequence, the dominant broadband oscillation coupling modal frequency band is extracted in combination with a preset threshold; based on the frequency sampling points covered in the dominant broadband oscillation coupling modal frequency band, a frequency sampling point sub-set is constructed, the dominant broadband oscillation coupling modal direction under the frequency sampling point is extracted, and the modal contribution degree is obtained.

[0013] Preferably, the S1 specifically comprises:

[0014] In the implementation process of the impedance shaping compensation mechanism of modal suppression driving, based on the dominant broadband oscillation coupling modal direction, the modal contribution degree normalization factor is calculated, the frequency risk weight is combined, and the controller shaping ability factor is introduced to construct the modal suppression driving quantity; the frequency risk weight is calculated based on the maximum singular value.

[0015] Preferably, the S1 specifically comprises:

[0016] The modal suppression driving quantity is applied to the modal contribution degree to locally shape the output impedance in the frequency domain output impedance matrix to obtain the target output impedance after local shaping.

[0017] Preferably, the S2 specifically comprises:

[0018] In the implementation process of the impedance shaping gain correction mechanism based on the modal interference sensitivity, based on the modal contribution degree, the modal interference influence coefficient between the shaping behaviors of different wind power converters is quantified, and the modal interference sensitivity is obtained in combination with the modal suppression driving quantity.

[0019] Preferably, S2 specifically includes:

[0020] In the implementation process of the impedance shaping gain correction mechanism based on modal interference sensitivity, the modal interference sensitivity is summed and averaged to calculate the shaping gain correction factor.

[0021] Preferably, S2 specifically includes:

[0022] In the implementation process of the impedance shaping gain correction mechanism based on modal interference sensitivity, based on the shaping gain correction factor, the modal suppression driving amount and the modal contribution degree, the impedance shaping adjustment amount is obtained; based on the impedance shaping adjustment amount, the locally shaped target output impedance is corrected to obtain the final output impedance after global shaping.

[0023] The beneficial effects of the technical solutions of the present application are:

[0024] 1. The present application proposes a modal suppression driven impedance shaping compensation mechanism, which can accurately guide the shaping direction to align the dominant wideband oscillation coupling mode, and can also adjust the shaping strength according to the wind power converter device capacity and the frequency sampling point risk level, effectively avoiding the problems of non-difference shaping and overcompensation, and realizing local shaping.

[0025] 2. The present application proposes an impedance shaping gain correction mechanism based on modal interference sensitivity, which not only considers the modal response capability of each wind power converter, but also considers the modal interference sensitivity between wind power converters, reduces unreasonable interference coupling, avoids the risk of excessive oscillation or excessive suppression, and ensures the safe and stable operation of high proportion wind power integrated system. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flowchart of the high proportion wind power integrated system wideband oscillation suppression method based on impedance shaping according to the present application. DETAILED DESCRIPTION

[0027] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0029] The application provides an impedance shaping-based wide-frequency oscillation suppression method for a high-proportion wind power access system.

[0030] With reference to the accompanying drawings Figure 1 , the application provides an impedance shaping-based wide-frequency oscillation suppression method flowchart, which comprises the following steps:

[0031] S1. Collect output impedance at each frequency sampling point and construct a frequency-domain output impedance matrix; based on the frequency-domain output impedance matrix, extract a dominant wide-frequency oscillation coupling mode frequency band and obtain a mode direction and a mode contribution degree of the dominant wide-frequency oscillation coupling mode; introduce a mode suppression driven impedance shaping compensation mechanism, construct a mode suppression driving quantity based on the mode direction in the dominant wide-frequency oscillation coupling mode, and perform local impedance shaping on the output impedance to obtain a target output impedance after local impedance shaping;

[0032] The wind power access system is composed of wind power converters, and the output impedance of each wind power converter at a frequency is expressed as a function , wherein represents the index of the wind power converter, ; in order to represent the coupling relationship of the wind power converters in the entire wind power access system in a frequency band , an equal interval is selected to form a frequency set , wherein the frequency band may be set according to the frequency sampling points corresponding to the historical output impedance in the existing wind power converter database, and represent the lower limit and the upper limit of the frequency band, respectively, represents the index of the frequency sampling point, ; at each frequency sampling point , a frequency-domain output impedance matrix of the wind power access system level is constructed, the diagonal element of the frequency-domain output impedance matrix is the output impedance of the first wind power converter at the frequency sampling point , and the non-diagonal element is the coupling impedance between the first wind power converter and the first wind power converter at the frequency sampling point .

[0033] Furthermore, based on the frequency domain output impedance matrix, the dominant broadband oscillation coupling mode frequency band is determined: using existing singular value decomposition methods, the frequency domain output impedance matrix is ​​analyzed. Perform singular value decomposition and select the largest singular value. And sample the maximum singular value by frequency point The values ​​are sorted from smallest to largest to generate the frequency response curve with the largest singular value. The frequency sampling points are then calculated. Maximum singular value at The ratio of the maximum value of the largest singular value among all frequency sampling points to the maximum value of the largest singular value yields the normalized maximum singular value sequence. Based on the normalized maximum singular value sequence, a threshold is set using the existing mean deviation method. Frequency sampling points in the normalized maximum singular value sequence that are greater than the threshold are aggregated according to their frequency sampling point values ​​to identify one or more sets of continuous frequency sampling point intervals. The closed interval between the minimum and maximum frequency sampling points in each set is taken as the dominant broadband oscillation coupling mode frequency band. Subsequently, the frequency sampling points covered within the dominant broadband oscillation coupling mode frequency band are collected to form a frequency sampling point subset. ,in, This indicates the index of the frequency sampling point within the frequency band of the dominant broadband oscillation coupling mode. , This represents the number of frequency sampling points within the dominant broadband oscillation coupling mode band, and represents a subset of frequency sampling points. Each frequency sampling point The corresponding maximum singular value The corresponding left singular vector As frequency sampling point The dominant broadband oscillatory coupled mode direction at the location, where each left singular vector component Indicates at frequency sampling point In the dominant broadband oscillation coupled mode at the location of the first Modal contribution of the typhoon power converter, the It is a complex value, where the amplitude represents the modal contribution modulus and the phase angle reflects the response phase.

[0034] After extracting the frequency band of the dominant broadband oscillation coupling mode of the wind power grid and the mode direction and mode contribution of each wind power converter in the dominant broadband oscillation coupling mode, the impedance local shaping stage is entered: a mode suppression driven impedance shaping compensation mechanism is proposed. Based on the dominant broadband oscillation coupling mode direction, a mode suppression driving quantity is constructed, consisting of a mode contribution normalization factor, a controller shaping capability factor, and a frequency risk weight. The mode suppression driving quantity is applied to the mode contribution in a multiplicative structure, thereby achieving directional weakening of the output impedance in the dominant broadband oscillation coupling mode direction, and obtaining the target output impedance after local shaping, as shown in the following formula:

[0035] ,

[0036] in, For the first time after local plastic surgery Typhoon power converter at frequency sampling point The target output impedance at that point is the target output impedance under ideal conditions; For the first Typhoon power converter at frequency sampling point Output impedance at the point; For the first Typhoon power converter at frequency sampling point The modal suppression driving force at a given point is obtained by multiplying the modal contribution normalization factor, the controller shaping capability factor, and the frequency risk weight; , indicating the first Typhoon power converter at frequency sampling point Modal contribution normalization factor at the location, where Indicates the first Typhoon power converter at frequency sampling point The modal contribution of the dominant broadband oscillation coupling mode at a given location can indicate the direction of shaping. The amplitude represents the modal contribution modulus. , indicating the first The controller shaping capability factor of the typhoon power converter is obtained through the existing wind power converter database; , where is the frequency risk weight, representing the frequency sampling point The relative risk level of the frequency in the dominant broadband oscillation coupling mode is determined by the frequency risk weight. The larger the frequency risk weight, the greater the risk of the frequency sampling point, and the more the shaping intensity should be increased. For frequency sampling points At that point, the maximum singular value of the frequency domain output impedance matrix; It is a subset of frequency sampling points within the dominant broadband oscillation coupling mode frequency band.

[0037] The above formula proposes a mode suppression-driven impedance shaping compensation mechanism, which can accurately guide the shaping direction to align with the dominant broadband oscillation coupling mode. It can also adjust the shaping intensity according to the wind power converter equipment capacity and the risk level of the frequency sampling point, effectively avoiding the problems of indiscriminate shaping and overcompensation, and realizing local shaping.

[0038] S2. Based on the modal suppression driving quantity, the modal interference sensitivity between wind power converters is quantified, and an impedance shaping gain correction mechanism based on the modal interference sensitivity is introduced to correct the target output impedance after local shaping, so as to obtain the final output impedance after global shaping.

[0039] Further, in order to realize the global coordinated impedance shaping of the wind power converter in the wind power integrated system, a gain correction mechanism of the impedance shaping based on the modal disturbance sensitivity is proposed. The gain correction factor of the impedance shaping of the wind power converter at the frequency sampling point is obtained by calculating the modal disturbance influence coefficient of the wind power converter on the wind power converter, combining the modal suppression driving amount of the wind power converter, obtaining the global modal disturbance sensitivity average value by summing and averaging the modal disturbance sensitivity, and finally obtaining the gain correction factor of the impedance shaping of the wind power converter at the frequency sampling point by the mode of The shaping behavior of the wind power converter influences the modal disturbance of the wind power converter The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance sensitivity of the wind power converter is obtained by summing and averaging the modal disturbance sensitivity of the wind power converter The global modal disturbance sensitivity average value is obtained by summing and averaging the modal disturbance sensitivity of the wind power converter The gain correction factor of the impedance shaping of the wind power converter at the frequency sampling point The gain correction factor of the impedance shaping of the wind power converter at the frequency sampling point

[0040] ,

[0041] Wherein, The gain correction factor of the impedance shaping of the wind power converter at the frequency sampling point The number of wind power converters The number of wind power converters other than the wind power converter The number of wind power converters The number of wind power converters other than the wind power converter The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point If the value of the modal disturbance influence coefficient is positive, it indicates that the shaping behavior of the wind power converter is consistent with the dominant wide-frequency oscillation coupling modal direction of the wind power converter, and there is a coupling enhancement effect between them, which will increase the global wide-frequency oscillation response of the wind power integrated system, and therefore coordinated impedance shaping is needed If the value of the modal disturbance influence coefficient is negative, it indicates that the shaping behavior of the wind power converter is opposite to the dominant wide-frequency oscillation coupling modal direction of the wind power converter, and there is an interference suppression effect between them, which will reduce the global wide-frequency oscillation response of the wind power integrated system The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal disturbance influence coefficient of the wind power converter on the wind power converter can reflect the influence degree of the shaping behavior of the wind power converter on the dominant wide-frequency oscillation coupling modal direction of the wind power converter at the frequency sampling point The modal contribution degree of the wind power converter at the frequency sampling point in the direction of the dominant broadband oscillation coupling modal, denotes conjugate transpose; denotes the The modal contribution degree of the wind power converter at the frequency sampling point in the direction of the dominant broadband oscillation coupling modal; denotes the The modal interference sensitivity of the wind power converter to the The modal interference sensitivity of the wind power converter; denotes the The modal suppression driving amount of the wind power converter at the frequency sampling point .

[0042] The above formula proposes an impedance shaping gain correction mechanism based on modal interference sensitivity, which not only considers the modal response capability of each wind power converter, but also considers the modal interference sensitivity between wind power converters, can reduce unreasonable interference coupling, avoid the risk of excessive oscillation or excessive suppression, and ensure the safe and stable operation of the high proportion of wind power access system.

[0043] Finally, by multiplying the shaping gain correction factor of the The modal suppression driving amount of the wind power converter at the frequency sampling point , the impedance shaping adjustment amount is obtained, and based on the impedance shaping adjustment amount, the locally shaped target output impedance is corrected to obtain the final output impedance after global shaping, and the formula is as follows:

[0044] ,

[0045] wherein, is the final output impedance of the The wind power converter at the frequency sampling point ; is the target output impedance of the The wind power converter at the frequency sampling point after local shaping, which is the target output impedance under ideal state; denotes the The impedance shaping adjustment amount of the wind power converter at the frequency sampling point ; is the shaping gain correction factor of the The wind power converter at the frequency sampling point ; is the modal suppression driving amount of the The wind power converter at the frequency sampling point ; denotes the The frequency sampling point of the typhoon power converter is coupled with the modal direction of the wide frequency oscillation. The modal contribution degree in the modal direction of the wide frequency oscillation at the frequency sampling point.

[0046] In summary, the method for suppressing wide frequency oscillation of high proportion wind power access system based on impedance shaping is completed.

[0047] The sequence of the embodiments of the application is only for description, and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are also possible or can be advantageous.

[0048] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other. Each embodiment mainly explains the difference from other embodiments.

[0049] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features. The modification or replacement does not change the essence of the corresponding technical solutions, and should be included in the protection scope of the present application.

Claims

1. A method for suppressing wideband oscillation in a high-penetration wind power integrated system based on impedance shaping, characterized in that, The method comprises the following steps: S1. Collecting the output impedance at each frequency sampling point and constructing a frequency domain output impedance matrix; performing singular value decomposition on the frequency domain output impedance matrix by a singular value decomposition method, selecting the maximum singular value, and performing normalization processing to construct a normalized maximum singular value sequence; Based on the normalized maximum singular value sequence, a preset threshold is combined to extract a dominant broadband oscillation coupling modal frequency band; Based on the frequency sampling points covered by the dominant broadband oscillation coupling modal frequency band, a frequency sampling point subset is constructed, the dominant broadband oscillation coupling modal direction under the frequency sampling points is extracted, and the modal contribution degree is obtained; an impedance shaping compensation mechanism driven by modal suppression is introduced, the modal contribution degree normalization factor is calculated based on the modal direction in the dominant broadband oscillation coupling modal, the frequency risk weight is combined, and the controller shaping ability factor is introduced to construct the modal suppression driving amount, and the output impedance is locally shaped to obtain the target output impedance after local shaping. The frequency risk weight is calculated based on the maximum singular value; S2. Based on the modal suppression driving amount, the modal interference sensitivity between wind power converters is quantified, and an impedance shaping gain correction mechanism based on the modal interference sensitivity is introduced to correct the locally shaped target output impedance to obtain the final output impedance after global shaping.

2. The impedance shaping based high renewable penetration power system wideband oscillation suppression method of claim 1, wherein, The S1 specifically comprises: The modal suppression driving amount is applied to the modal contribution degree to locally shape the output impedance in the frequency domain output impedance matrix to obtain the target output impedance after local shaping.

3. The impedance shaping based high renewable penetration power system wideband oscillation suppression method of claim 1, wherein, The S2 specifically comprises: In the implementation process of the impedance shaping gain correction mechanism based on the modal interference sensitivity, the modal interference influence coefficient between the shaping behaviors of different wind power converters is quantified based on the modal contribution degree, and the modal interference sensitivity is obtained in combination with the modal suppression driving amount.

4. The impedance shaping based high renewable penetration power system wideband oscillation suppression method of claim 3, wherein, The S2 specifically comprises: In the implementation process of the impedance shaping gain correction mechanism based on the modal interference sensitivity, the shaping gain correction factor is calculated by summing and averaging the modal interference sensitivity.

5. The impedance shaping based high renewable penetration power system wideband oscillation damping method according to claim 4, wherein, The S2 specifically comprises: In the implementation process of the impedance shaping gain correction mechanism based on the modal interference sensitivity, the impedance shaping adjustment amount is obtained based on the shaping gain correction factor, the modal suppression driving amount and the modal contribution degree; the locally shaped target output impedance is corrected based on the impedance shaping adjustment amount to obtain the final output impedance after global shaping.

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