A broadband oscillation evaluation method, apparatus and equipment

Abstract

This invention discloses a broadband oscillation assessment method, apparatus, and device. By applying harmonic voltage and current sources, it calculates the node harmonic response values ​​at different harmonic orders, plots node harmonic response curves based on these values, and determines whether a node has a resonance risk based on the curves. This method does not rely on the accuracy of system modeling and does not require system disconnection or shutdown. Compared to pre-assessment methods, it is more accurate and more flexible than on-site protection assessment methods, solving the technical problems of poor accuracy and flexibility in existing broadband oscillation assessment methods.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a broadband oscillation assessment method, apparatus, and device. Background Technology

[0002] The oscillation mechanism can be divided into two categories. One is that the impedance of the converter decreases in the subsynchronous / supersynchronous frequency range, which leads to insufficient suppression of subsynchronous harmonics of the wind farm by the converter, and further triggers continuous oscillation. The other is that the converter exhibits negative resistance characteristics in the mid-to-high frequency range, which amplifies the harmonic voltage and current of the system by the converter, and further triggers divergent oscillation.

[0003] There are two existing methods for assessing broadband oscillations. One is the pre-assessment method, which uses impedance analysis or state variable methods to pre-analyze the resonance risk of the system based on the actual device under assessment, determining under what operating conditions the resonance risk will occur, and thus taking resonance suppression measures in advance. The main drawback of this method is its reliance on the accuracy of the target system modeling. If influencing factors are not fully considered or the relevant impedance modeling is inaccurate, the accuracy of the results will be seriously affected. In actual systems, it is often impossible to consider all factors, so the accuracy of this method is difficult to guarantee. The other method is the on-site protection assessment method, which focuses on the accident site. Based on the information collected on-site, it determines the occurrence of broadband oscillation risk and promptly cuts off the key parts affected by resonance to suppress resonance, or disconnects the entire system to avoid equipment damage caused by broadband resonance. However, this method mainly focuses on disconnecting or shutting down the system from a protection perspective and cannot provide timely warnings of resonance during system operation, resulting in poor flexibility. Therefore, how to solve the accuracy and flexibility problems of existing broadband oscillation assessment methods is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a broadband oscillation evaluation method, apparatus, and device to solve the technical problems of poor accuracy and lack of flexibility in existing broadband oscillation evaluation methods.

[0005] In view of this, the first aspect of the present invention provides a flexible DC passive grid islanding operation control method, comprising the following steps:

[0006] S1. Apply an nth harmonic voltage source to the AC bus at any node of the target system and record the amplitude U of the harmonic voltage source. n0 and phase Φ n0 Where n is not less than 0;

[0007] S2, Record the amplitude U of the harmonic voltage source. n0 and phase Φ n0Then, an nth harmonic current source is applied to the AC bus at the same node, and the amplitude I of the harmonic current source is recorded. n and phase Φ n Simultaneously record the amplitude U of the harmonic voltage source after applying the harmonic current source. n1 and phase Φ n1 ;

[0008] S3, based on the harmonic voltage source amplitude U n0 and phase Φ n0 Harmonic current source amplitude I n and phase φ n Harmonic voltage source amplitude U n1 and phase Φ n1 Calculate the nodal harmonic response values;

[0009] S4. Change the value of harmonic order n according to the preset step size setting rule, and repeat steps S1 to S3 to obtain the nodal harmonic response values ​​under different harmonic orders.

[0010] S5. Based on the node harmonic response values ​​for different harmonic orders, plot the node harmonic response curves. Determine whether the node has a resonance risk based on the node harmonic response curves. The judgment criteria are: for any point on the node harmonic response curve, if the preset resonance condition is not met, then the node has no resonance risk; otherwise, the node has a resonance risk. The preset condition is:

[0011]

[0012] Among them, Z n Z represents the nodal harmonic response value. t Let Ang be the short-circuit impedance of the node AC transformer, and Ang be the impedance angle.

[0013] Optionally, the formula for calculating the nodal harmonic response value is:

[0014]

[0015] Optionally, in step S4, the preset step size setting rule is as follows: when the harmonic order n is less than 2, the preset step size is 0.1, and when the harmonic order n is not less than 2, the preset step size is 1.

[0016] Optionally, after step S5, the method further includes:

[0017] S6 sequentially obtains the node harmonic response values ​​of all nodes in the target system, calculates the real part of the node harmonic response values, and considers the node with the largest absolute value among the impedances whose real part of the node harmonic response value is negative as the resonance risk sensitive point of the target system.

[0018] Optionally, in step S2, the amplitude of the applied nth harmonic current source is within the range of 0.5% to 1% of the operating current.

[0019] A second aspect of the present invention provides a broadband oscillation evaluation device, comprising the following modules:

[0020] The first measurement module is used to apply an nth harmonic voltage source to the AC bus at any node of the target system and record the amplitude U of the harmonic voltage source. n0 and phase Φ n0 Where n is not less than 0;

[0021] The second measurement module is used to record the amplitude U of the harmonic voltage source. n0 and phase Φ n0 Then, an nth harmonic current source is applied to the AC bus at the same node, and the amplitude I of the harmonic current source is recorded. n and phase Φ n Simultaneously record the amplitude U of the harmonic voltage source after applying the harmonic current source. n1 and phase Φ n1 ;

[0022] The harmonic response calculation module is used to calculate the harmonic response based on the harmonic voltage source amplitude U. n0 and phase Φ n0 Harmonic current source amplitude I n and phase φ n Harmonic voltage source amplitude U n1 and phase Φ n1 Calculate the nodal harmonic response values;

[0023] The repeat module is used to change the value of the harmonic order n according to the preset step size setting rules, and repeatedly execute the first measurement module, the second measurement module and the harmonic response calculation module to obtain the nodal harmonic response values ​​under different harmonic orders.

[0024] The resonance risk assessment module is used to plot node harmonic response curves based on the node harmonic response values ​​at different harmonic orders. It then determines whether a node has a resonance risk based on these curves. The judgment criterion is: for any point on the node harmonic response curve, if a preset resonance condition is not met, the node has no resonance risk; otherwise, the node has a resonance risk. The preset condition is:

[0025]

[0026] Among them, Z n Z represents the nodal harmonic response value. t Let Ang be the short-circuit impedance of the node AC transformer, and Ang be the impedance angle.

[0027] Optionally, the formula for calculating the nodal harmonic response value is:

[0028]

[0029] Optionally, in the repeating module, the preset step size setting rule is as follows: when the harmonic number n is less than 2, the preset step size is 0.1, and when the harmonic number n is not less than 2, the preset step size is 1.

[0030] Optionally, after the resonance risk assessment and judgment module, the following module may also be included:

[0031] The sensitive point identification module is used to sequentially obtain the node harmonic response values ​​of all nodes in the target system, calculate the real part of the node harmonic response values, and regard the node with the largest absolute value among the impedances whose real part of the node harmonic response value is negative as the resonant risk sensitive point of the target system.

[0032] Optionally, in the second measurement module, the amplitude of the applied nth harmonic current source is within the range of 0.5% to 1% of the operating current.

[0033] A third aspect of the present invention provides a wideband oscillation evaluation device, the device comprising a processor and a memory:

[0034] The memory is used to store program code and transmit the program code to the processor;

[0035] The processor is configured to execute any one of the broadband oscillation evaluation methods described in the first aspect according to the instructions in the program code.

[0036] As can be seen from the above technical solutions, the broadband oscillation evaluation method provided by the present invention has the following advantages:

[0037] The broadband oscillation assessment method provided by this invention calculates the node harmonic response values ​​under different harmonic orders by applying harmonic voltage and current sources, plots node harmonic response curves based on the node harmonic response values ​​under different harmonic orders, and determines whether there is a resonance risk at the node based on the node harmonic response curves. It does not depend on the accuracy of system modeling, nor does it require system disconnection or shutdown. Compared with pre-assessment methods, it has higher accuracy and is more flexible than on-site protection assessment methods, solving the technical problems of poor accuracy and lack of flexibility in existing broadband oscillation assessment methods.

[0038] Meanwhile, the broadband oscillation evaluation method provided by this invention determines the location of the resonance risk sensitive point by comparing the responses of multiple points in the system, which is beneficial for timely handling of resonance weak points in the system and improving system reliability. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic flowchart of a broadband oscillation evaluation method provided in an embodiment of the present invention;

[0041] Figure 2 This is another flowchart illustrating a broadband oscillation evaluation method provided in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of a broadband oscillation evaluation system provided in an embodiment of the present invention. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] For easier understanding, please refer to Figure 1 This invention provides an embodiment of a broadband oscillation evaluation method, comprising:

[0045] Step S1: Apply an nth harmonic voltage source to the AC bus at any node of the target system and record the amplitude U of the harmonic voltage source. n0 and phase Φ n0 , where n is not less than 0.

[0046] It should be noted that in this invention, an nth harmonic voltage source is applied to the AC bus of a certain node in the target system, and the amplitude U of the harmonic voltage source is recorded. n0 and phase Φ n0 n is the harmonic order, and its value is not less than 0.

[0047] Step S2: Record the amplitude U of the harmonic voltage source. n0 and phase Φ n0 Then, an nth harmonic current source is applied to the AC bus at the same node, and the amplitude I of the harmonic current source is recorded. n and phase Φ n Simultaneously record the amplitude U of the harmonic voltage source after applying the harmonic current source. n1and phase Φ n1 .

[0048] It should be noted that for a node where an nth harmonic voltage source has been applied in step 101, the amplitude U of the harmonic voltage source is recorded. n0 and phase Φ n0 Then, an nth harmonic current source is applied to the AC bus at the same node, and the amplitude I of the harmonic current source is recorded. n and phase Φ n Simultaneously record the amplitude U of the harmonic voltage source after applying the harmonic current source. n1 and phase Φ n1 The optimal amplitude of the applied nth harmonic current source is within the operating current range of 0.5%-1%.

[0049] Step S3: Based on the harmonic voltage source amplitude U n0 and phase Φ n0 Harmonic current source amplitude I n and phase φ n Harmonic voltage source amplitude U n1 and phase Φ n1 Calculate the harmonic response values ​​of the nodes.

[0050] It should be noted that, in this embodiment of the invention, the formula for calculating the nodal harmonic response value is as follows:

[0051]

[0052] Among them, Z n This represents the node harmonic response value.

[0053] Step S4: Change the value of the harmonic order n according to the preset step size setting rule, and repeat steps S1 to S3 to obtain the nodal harmonic response values ​​under different harmonic orders.

[0054] It should be noted that by changing the value of the harmonic order n according to the preset step size setting rule, and repeating steps S1 to S3, the nodal harmonic response values ​​under different harmonic orders are obtained. The preset step size setting rule is as follows: when the harmonic order n is less than 2, the preset step size is 0.1 or smaller than 0.1; when the harmonic order n is not less than 2, the preset step size is 1.

[0055] Step S5: Based on the node harmonic response values ​​for different harmonic orders, plot the node harmonic response curves. Determine whether the node has a resonance risk based on the node harmonic response curves. The judgment criteria are: for any point on the node harmonic response curve, if the preset resonance condition is not met, then the node has no resonance risk; otherwise, the node has a resonance risk. The preset condition is:

[0056]

[0057] Among them, Z n Z represents the nodal harmonic response value. t Let Ang be the short-circuit impedance of the node AC transformer, and Ang be the impedance angle.

[0058] It should be noted that after step 104, the nodal harmonic response values ​​for different harmonic orders can be obtained. These nodal harmonic response values ​​can then be plotted as curves to obtain the nodal harmonic response curves. The following steps determine whether the nodal harmonic response curves meet the following conditions:

[0059]

[0060] Among them, Z n Z represents the nodal harmonic response value. t Let Ang be the short-circuit impedance of the node AC transformer, and Ang be the impedance angle.

[0061] If the node harmonic response curve does not meet the conditions, then the node does not have a resonance risk; if the node harmonic response curve meets the conditions, then the node has a resonance risk.

[0062] The broadband oscillation assessment method provided by this invention calculates the node harmonic response values ​​under different harmonic orders by applying harmonic voltage and current sources, plots node harmonic response curves based on the node harmonic response values ​​under different harmonic orders, and determines whether there is a resonance risk at the node based on the node harmonic response curves. It does not depend on the accuracy of system modeling, nor does it require system disconnection or shutdown. Compared with pre-assessment methods, it has higher accuracy and is more flexible than on-site protection assessment methods, solving the technical problems of poor accuracy and lack of flexibility in existing broadband oscillation assessment methods.

[0063] In one embodiment, see Figure 2 After step S5, the following is also included:

[0064] Step S6: Sequentially obtain the node harmonic response values ​​of all nodes in the target system, calculate the real part of the node harmonic response values, and regard the node with the largest absolute value among the impedances whose real part of the node harmonic response value is negative as the resonance risk sensitive point of the target system.

[0065] It should be noted that, according to steps S1 to S2, the node harmonic response values ​​of all nodes in the target system can be obtained in sequence, the real part of the node harmonic response value of each node is calculated, and the node with the largest absolute value among the impedances whose real part of the node harmonic response value is negative is regarded as the resonance risk sensitive point of the target system.

[0066] The broadband oscillation evaluation method provided by this invention determines the location of resonance risk-sensitive points by comparing the responses of multiple points within the system, which is beneficial for timely handling of resonance weaknesses in the system and improving system reliability.

[0067] For easier understanding, please refer to Figure 3 This invention provides a broadband oscillation evaluation device, comprising the following modules:

[0068] The first measurement module is used to apply an nth harmonic voltage source to the AC bus at any node of the target system and record the amplitude U of the harmonic voltage source. n0 and phase Φ n0 Where n is not less than 0;

[0069] The second measurement module is used to record the amplitude U of the harmonic voltage source. n0 and phase Φ n0 Then, an nth harmonic current source is applied to the AC bus at the same node, and the amplitude I of the harmonic current source is recorded. n and phase Φ n Simultaneously record the amplitude U of the harmonic voltage source after applying the harmonic current source. n1 and phase Φ n1 ;

[0070] The harmonic response calculation module is used to calculate the harmonic response based on the harmonic voltage source amplitude U. n0 and phase Φ n0 Harmonic current source amplitude I n and phase φ n Harmonic voltage source amplitude U n1 and phase Φ n1 Calculate the nodal harmonic response values;

[0071] The repeat module is used to change the value of the harmonic order n according to the preset step size setting rules, and repeatedly execute the first measurement module, the second measurement module and the harmonic response calculation module to obtain the nodal harmonic response values ​​under different harmonic orders.

[0072] The resonance risk assessment module is used to plot node harmonic response curves based on the node harmonic response values ​​at different harmonic orders. It then determines whether a node has a resonance risk based on these curves. The judgment criterion is: for any point on the node harmonic response curve, if a preset resonance condition is not met, the node has no resonance risk; otherwise, the node has a resonance risk. The preset condition is:

[0073]

[0074] Among them, Z n Z represents the nodal harmonic response value. t Let Ang be the short-circuit impedance of the node AC transformer, and Ang be the impedance angle.

[0075] The formula for calculating the nodal harmonic response value is:

[0076]

[0077] The preset step size setting rule is as follows: when the harmonic order n is less than 2, the preset step size is 0.1; when the harmonic order n is not less than 2, the preset step size is 1.

[0078] Following the resonance risk assessment module, the following is also included:

[0079] The sensitive point identification module is used to sequentially obtain the node harmonic response values ​​of all nodes in the target system, calculate the real part of the node harmonic response values, and regard the node with the largest absolute value among the impedances whose real part of the node harmonic response value is negative as the resonant risk sensitive point of the target system.

[0080] In the second measurement module, the amplitude of the applied nth harmonic current source is within the range of 0.5% to 1% of the operating current.

[0081] This invention also provides an embodiment of a broadband oscillation evaluation device, the device including a processor and a memory:

[0082] The memory is used to store program code and transmit the program code to the processor;

[0083] The processor is used to execute the wideband oscillation evaluation method of the present invention according to the instructions in the program code.

[0084] The broadband oscillation evaluation device and equipment provided in this invention are used to execute the broadband oscillation evaluation method provided in this invention. Their principles and the technical effects achieved are the same as those of the broadband oscillation evaluation method provided in this invention, and will not be repeated here.

[0085] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband oscillation evaluation method, characterized by, Comprising the following steps: S1, applying an n-th harmonic voltage source on the AC bus of any node of the target system, recording the harmonic voltage source amplitude U n0 and phase Φ n0 wherein n is not less than 0; S2, record harmonic voltage source amplitude U n0 and phase Φ n0 After, the same node AC bus on the application of n harmonic current source, record harmonic current source amplitude I n and phase Φ n , while recording the harmonic voltage source amplitude U n1 and phase Φ n1 ; S3. Calculate the harmonic response value of the node according to the harmonic voltage source amplitude U n0 and phase Φ n0 , the harmonic current source amplitude I n and phase φ n , the harmonic voltage source amplitude U n1 and phase Φ n1 ; S4, set the value of the harmonic order n of the regular transformation according to a preset step length, repeat steps S1 to S3 to obtain the node harmonic response value under different harmonic orders; S5, draw a node harmonic response curve according to the node harmonic response value under different harmonic orders, and judge whether the node exists resonance risk according to the node harmonic response curve, the judgment basis is: for any point in the node harmonic response curve, if the preset vibration condition is not met, the node does not exist resonance risk, otherwise, the node exists resonance risk, and the preset condition is: wherein Z n is the node harmonic response value, Z t is the short circuit impedance of the node AC transformer, and Ang is the impedance angle.

2. The broadband oscillation evaluation method according to claim 1, characterized in that, The calculation formula of the node harmonic response value is:

3. The broadband oscillation evaluation method according to claim 1, characterized in that, In step S4, the preset step length setting rule is: when the harmonic order n is less than 2, the preset step length is 0.1, and when the harmonic order n is not less than 2, the preset step length is 1.

4. The broadband oscillation evaluation method according to claim 1, characterized by, After step S5, further comprising: S6, obtain the node harmonic response value of all nodes of the target system in turn, calculate the real part of the node harmonic response value, and regard the node with the largest absolute value in the impedance with the negative real part of the node harmonic response value as the resonance risk sensitive point of the target system.

5. The broadband oscillation evaluation method according to claim 4, characterized in that, In step S2, the amplitude of the n-th harmonic current source applied is in the range of 0.5% to 1% of the operating current.

6. A broadband oscillation evaluation device, characterized by Comprising the following modules: a first measuring module for applying an n-th harmonic voltage source on an AC bus of any node of the target system, recording the harmonic voltage source amplitude U n0 and phase Φ n0 wherein n is not less than 0; Second measurement module for recording the harmonic voltage source amplitude U n0 and phase Φ n0 After, the same node AC bus on the application of n harmonic current source, record the harmonic current source amplitude I n and phase Φ n , while recording the harmonic voltage source amplitude U n1 and phase Φ n1 after the application of harmonic current source; a harmonic response calculation module for calculating a node harmonic response value from a harmonic voltage source amplitude U n0 and phase Φ n0 , a harmonic current source amplitude I n and phase φ n , a harmonic voltage source amplitude U n1 and phase Φ n1 ​ A repeating module for setting the value of the harmonic order n according to a preset step length, repeating the execution of the first measuring module, the second measuring module and the harmonic response calculating module to obtain the node harmonic response value under different harmonic orders; A resonance risk evaluation and judgment module for drawing a node harmonic response curve according to the node harmonic response value under different harmonic orders, and judging whether the node exists resonance risk according to the node harmonic response curve, the judgment basis is: for any point in the node harmonic response curve, if the preset vibration condition is not met, the node does not exist resonance risk, otherwise, the node exists resonance risk, and the preset condition is: where Z n is the node harmonic response value, Z t is the short circuit impedance of the node AC transformer, and Ang is the impedance angle.

7. The broadband oscillation evaluation device according to claim 6, characterized in that The calculation formula of the node harmonic response value is:

8. The broadband oscillation evaluation device according to claim 6, characterized in that In the repeating module, the preset step length setting rule is: when the harmonic order n is less than 2, the preset step length is 0.1, and when the harmonic order n is not less than 2, the preset step length is 1.

9. The broadband oscillation evaluation device according to claim 6, characterized in that After the resonance risk evaluation and judgment module, further comprising: A sensitive point identification module for obtaining the node harmonic response value of all nodes of the target system in turn, calculating the real part of the node harmonic response value, and regarding the node with the largest absolute value in the impedance with the negative real part of the node harmonic response value as the resonance risk sensitive point of the target system.

10. A broadband oscillation evaluation device, characterized by The device comprises a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the instructions in the program code to perform the broadband oscillation evaluation method according to any one of claims 1-5.

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