Optimal site selection method and device for resonance suppression device of power electronic power system

Abstract

The invention provides an optimal site selection method and device for a resonance suppression device of a power electronic power system, and the method comprises the steps: constructing a node impedance matrix model of a to-be-researched system, and determining the self-impedance values and mutual impedance values of n nodes of the system; m nodes with harmonic peaks in the system and corresponding resonant frequencies are screened out; establishing a suppression device access influence model, and when the active resonance suppression device accesses a node i with equivalent impedance, updating a node impedance matrix based on a branch addition method, and generating an updated node self-impedance value; defining a resonance suppression effectiveness criterion: for the kth resonance mode, when and only when the self-impedance variation of the node mk at the frequency fk is greater than a set threshold value, judging that the kth resonance mode is effective suppression; and selecting the node which meets the resonance suppression effectiveness criterion and the constraint condition that the sum of the self-impedance variations of the node is maximum as the optimal site. According to the invention, the access of the resonance suppression device in the system planning construction stage can be guided, and the economy and effectiveness of resonance suppression are improved.

Description

Technical Field

[0001] The present invention relates to the field of electrical engineering technology, and in particular to a method for optimizing the addressing of a power electronic power system resonance suppression device. Background Art

[0002] With the advancement of the "dual carbon" strategy, various devices containing power electronic converters, such as wind power, photovoltaics, electric vehicles, and uninterruptible power supplies, are becoming increasingly popular. "Power electronics" has become a typical feature of the current power system. However, the LC, LCL, and other types of filters at the ports of these power electronic devices, as well as other passive filters in the system, all have obvious resonant characteristics. The interaction between power electronic devices and between devices and the AC power grid will make the power system resonance problem more complicated. For example, multiple resonant points may exist simultaneously in the system. When the harmonic disturbance in the power system, especially the distribution network, is close to any of these resonant frequencies, it may cause harmonic amplification, affecting the safe and stable operation of the power system. Therefore, resonance suppression research is very important.

[0003] Active dampers are a widely used device for resonance suppression. As a low-power, high-switching-frequency converter, they have little impact on the system's operating state and are less restricted in their application scenarios. Currently, in terms of resonance suppression, the usual practice is to connect them directly in parallel to the resonant node. This approach can effectively suppress a single resonance problem in the system, but when there are multiple resonance points in the system at the same time (which will inevitably happen when the proportion of power electronic converters increases), the aforementioned approach will not be able to effectively suppress the resonance problems of other resonance points. If a suppression device is installed at each resonance point, the economic investment will be too large and the cost-effectiveness will be low. A reasonable approach is to optimize the position of the suppression device in the system so that it can maximize the suppression effect on the resonant modes of each resonance point at the same time, achieving the highest overall cost-effectiveness.

[0004] To address this issue, there is currently no suitable and effective method to determine the optimal deployment location of the suppression device in the system. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a site selection optimization method for a resonance suppression device in a power electronic power system, which guides the design and site selection of the resonance suppression device through a simple calculation method.

[0006] A method for optimizing the location of a resonance suppression device in a power electronic power system comprises the following steps:

[0007] Construct a node impedance matrix model of the system to be studied and determine the self-impedance values ​​of n nodes in the system and mutual impedance Where i, j∈[1,n], f is the frequency variable, represents the self-impedance of node i at frequency f, represents the mutual impedance between node i and node j at frequency f;

[0008] Identify the set of resonant modes to be suppressed and select m nodes {m1,...,m m} and its corresponding resonant frequencies {f1,...,f m}, forming the resonant mode characteristic parameter set {(m k ,f k )|k=1,...,m};

[0009] Establish the influence model of the suppression device access. When the active resonance suppression device is connected with equal impedance When node i is connected, the node impedance matrix is ​​updated based on the branch addition method to generate the updated node self-impedance value Z f ;

[0010] Define the resonance suppression effectiveness criterion: for the kth resonance mode, if and only if node m k At frequency f k When the change in self-impedance at the position is greater than the set threshold, it is determined to be effectively suppressed;

[0011] Perform global scanning optimization, calculate the sum of the node self-impedance changes when the source resonance suppression device is connected to n nodes in turn, and select the node that meets the resonance suppression effectiveness criterion and has the largest sum of the node self-impedance changes as the optimal location.

[0012] Furthermore, the updated node self-impedance value is generated, where the self-impedance of node i becomes The self-impedance of the other nodes becomes

[0013] Furthermore, the resonance suppression effectiveness criterion is: Where ε is the threshold.

[0014] Furthermore, the constraint condition for satisfying the resonance suppression effectiveness criterion and maximizing the sum of node self-impedance changes is:

[0015]

[0016] Furthermore, it also includes: substituting the self-impedance of node i and the self-impedance of other nodes into the constraint conditions to solve the equivalent impedance Z of the resonance suppression device under the threshold value. m The value range of Ω ok When designing suppression strategies and parameters, it is only necessary to check the impedance of the suppression device port to ensure that it meets the value range Ω ok , that is, it is believed that the suppression strategy and parameters can achieve the resonance suppression goal.

[0017] A device for optimizing addressing of a power electronic power system resonance suppression device, comprising:

[0018] The node impedance matrix model building module of the system to be studied is used to determine the self-impedance values ​​of n nodes in the system and mutual impedance Where i, j∈[1,n], f is the frequency variable, represents the self-impedance of node i at frequency f, represents the mutual impedance between node i and node j at frequency f;

[0019] The module for identifying the set of resonant modes to be suppressed is used to screen out m nodes {m1,...,m m} and its corresponding resonant frequencies {f1,...,f m}, forming the resonant mode characteristic parameter set {(m k ,f k )|k=1,...,m};

[0020] The suppression device is connected to the impact model establishment module, which is used when the active resonance suppression device is connected with equal impedance When node i is connected, the node impedance matrix is ​​updated based on the branch addition method to generate the updated node self-impedance value Z f ;

[0021] The resonance suppression validity criterion definition module is used to define the kth resonance mode if and only if the node m k At frequency f k When the change in self-impedance at the position is greater than the set threshold, it is determined to be effectively suppressed;

[0022] The optimal addressing module is used to perform global scanning optimization, sequentially calculate the sum of the node self-impedance changes when the source resonance suppression device is connected to n nodes, and select the node that meets the resonance suppression effectiveness criterion and has the largest sum of the node self-impedance changes as the optimal addressing. Furthermore, the updated node self-impedance value is generated, where the self-impedance of node i will become The self-impedance of the other nodes becomes

[0023]

[0024] Furthermore, the resonance suppression effectiveness criterion is: Where ε is the threshold.

[0025] Furthermore, the constraint condition for satisfying the resonance suppression effectiveness criterion and maximizing the sum of node self-impedance changes is:

[0026]

[0027] Furthermore, it also includes:

[0028] The control strategy and parameter design module is used to substitute the self-impedance of node i and the self-impedance of other nodes into the constraint conditions to solve the equivalent impedance Z of the resonance suppression device under the threshold. m The value range of Ω ok When designing suppression strategies and parameters, it is only necessary to check the impedance of the suppression device port to ensure that it meets the value range Ω ok , that is, it is believed that the suppression strategy and parameters can achieve the resonance suppression goal.

[0029] The present invention provides a method for selecting the optimal installation location of a resonance suppression device when dealing with multi-modal resonance problems in a power electronic power system. This method can guide the connection of the resonance suppression device during the system planning and construction phase, thereby improving the economy and effectiveness of resonance suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flowchart of a method for optimally selecting a power electronic power system resonance suppression device according to an embodiment of the present invention.

[0031] Figure 2 It is a structural diagram of a simple calculation example system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0033] by Figure 2 The following simplified example system illustrates the implementation of the present method. This example system contains three power electronic converters connected to nodes 2, 3, and 4, respectively. After parallel connection, they are centrally connected to grid node 1. Calculations indicate that this system has two resonant modes to be controlled, with frequencies f1 and f2, corresponding to node 2 and node 4, respectively.

[0034] In order to determine the optimal installation position of the active resonance suppression device, according to the method proposed by the present invention, the specific implementation steps are as follows (see Figure 1 ):

[0035] (1) Based on the mathematical model of each component, the frequency-impedance model of each component is established, and then the original node impedance matrix Z0 of the system is generated according to the system topology;

[0036] (2) Assume that the resonance suppression device is connected to the first node. Based on the branch addition method, regenerate the node impedance matrix Z of the system after the suppression device is connected.

[0037] (3) Check whether the self-impedance change at node 2 and node 4 is greater than the set threshold (in the per-unit value system, the threshold is usually set to 0.5~1), that is, judge and whether it is established;

[0038] (4) If the judgment condition in step (3) is met, the sum of the squares of the changes in the self-impedance amplitudes of the two nodes at their respective corresponding frequencies is further calculated, that is, After saving the value, go to step (5); if not, go directly to step (5);

[0039] (5) Determine whether the resonance suppression device has traversed all nodes of the system. If not, increment the node number to which the resonance suppression device is connected by 1 and repeat the process from step (2) to step (4). If all nodes have been traversed, proceed to step (6).

[0040] (6) Compare the values ​​of L1 to L4 and find the maximum value. The subscript is the optimal location where the resonance suppression device should be deployed.

[0041] In the above example, after calculation, it can be found that the resonance suppression device installed at nodes 1, 2, and 4 can all meet the constraints in step (3), that is, it has a suppressive effect on the two resonant modes in the system, while installing it at node 3 cannot achieve this effect. At the same time, at different installation positions, the relationship between the changes in the self-impedance amplitude of the two resonant nodes is L4>L1>L2, indicating that installing it at node 4 has the best comprehensive suppression effect on the two resonant modes.

[0042] An embodiment of the present invention further provides a device for optimizing the addressing of a power electronic power system resonance suppression device corresponding to the above method, including:

[0043] The node impedance matrix model building module of the system to be studied is used to determine the self-impedance values ​​of n nodes in the system and mutual impedance Where i, j∈[1,n], f is the frequency variable, represents the self-impedance of node i at frequency f, represents the mutual impedance between node i and node j at frequency f;

[0044] The module for identifying the set of resonant modes to be suppressed is used to screen out m nodes {m1,...,m m} and its corresponding resonant frequencies {f1,...,f m}, forming the resonant mode characteristic parameter set {(m k ,f k )|k=1,...,m};

[0045] The suppression device is connected to the impact model establishment module, which is used when the active resonance suppression device is connected with equal impedance When node i is connected, the node impedance matrix is ​​updated based on the branch addition method to generate the updated node self-impedance value Z f ;

[0046] The resonance suppression validity criterion definition module is used to define the kth resonance mode if and only if the node m k At frequency f k When the change in self-impedance at the position is greater than the set threshold, it is determined to be effectively suppressed;

[0047] The optimal location module is used to perform global scanning optimization, calculate the sum of the node self-impedance changes when the source resonance suppression device is connected to n nodes, and select the node that meets the resonance suppression effectiveness criterion and has the largest sum of the node self-impedance changes as the optimal location.

[0048] It should be noted that although the above example is a simple system, the ideas and technical solutions of the present invention can still be promoted and applied to the resonance suppression design of power systems with a larger number of nodes, more complex equipment types and topological structures, providing a new solution for power electronic power systems to achieve high-quality power supply for the entire network.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for optimally selecting a power electronic power system resonance suppression device, characterized in that: The steps include: Construct a node impedance matrix model of the system to be studied and determine the self-impedance values ​​of n nodes in the system and mutual impedance Where i, j∈[1,n], f is the frequency variable, represents the self-impedance of node i at frequency f, represents the mutual impedance between node i and node j at frequency f; Identify the set of resonant modes to be suppressed and select m nodes {m1,...,m m } and its corresponding resonant frequencies {f1,...,f m }, forming the resonant mode characteristic parameter set {(m k ,f k )|k=1,...,m}; Establish the influence model of the suppression device access. When the active resonance suppression device is connected with equal impedance When node i is connected, the node impedance matrix is ​​updated based on the branch addition method to generate the updated node self-impedance value Z f ; Define the resonance suppression effectiveness criterion: for the kth resonance mode, if and only if node m k At frequency f k When the change in self-impedance at the position is greater than the set threshold, it is determined to be effectively suppressed; Perform global scanning optimization, calculate the sum of the node self-impedance changes when the source resonance suppression device is connected to n nodes in turn, and select the node that meets the resonance suppression effectiveness criterion and has the largest sum of the node self-impedance changes as the optimal location.

2. The method for optimizing the addressing of a power electronic power system resonance suppression device according to claim 1, wherein: The updated node self-impedance value is generated, where the self-impedance of node i becomes The self-impedance of the other nodes becomes 3. The method for optimizing the addressing of a power electronic power system resonance suppression device according to claim 2, wherein: The resonance suppression effectiveness criterion is: Where ε is the threshold.

4. The method for optimizing the addressing of a power electronic power system resonance suppression device according to claim 3, wherein: The constraint condition for satisfying the resonance suppression effectiveness criterion and maximizing the sum of node self-impedance changes is:

5. The method for optimizing the addressing of a power electronic power system resonance suppression device according to claim 4, wherein: Also includes: Substitute the self-impedance of node i and the self-impedance of other nodes into the constraint conditions to solve the equivalent impedance Z of the resonance suppression device under the threshold. m The value range of Ω ok When designing suppression strategies and parameters, it is only necessary to check the impedance of the suppression device port to ensure that it meets the value range Ω ok , that is, it is believed that the suppression strategy and parameters can achieve the resonance suppression goal.

6. A device for optimizing the addressing of a power electronic power system resonance suppression device, characterized in that: include: The node impedance matrix model building module of the system to be studied is used to determine the self-impedance values ​​of n nodes in the system and mutual impedance Where i, j∈[1,n], f is the frequency variable, represents the self-impedance of node i at frequency f, represents the mutual impedance between node i and node j at frequency f; The module for identifying the set of resonant modes to be suppressed is used to screen out m nodes {m1,...,m m } and its corresponding resonant frequencies {f1,...,f m }, forming the resonant mode characteristic parameter set {(m k ,f k )|k=1,...,m}; The suppression device is connected to the impact model establishment module, which is used when the active resonance suppression device is connected with equal impedance When node i is connected, the node impedance matrix is ​​updated based on the branch addition method to generate the updated node self-impedance value Z f ; The resonance suppression validity criterion definition module is used to define the kth resonance mode if and only if the node m k At frequency f k When the change in self-impedance at the position is greater than the set threshold, it is determined to be effectively suppressed; The optimal location module is used to perform global scanning optimization, calculate the sum of the node self-impedance changes when the source resonance suppression device is connected to n nodes, and select the node that meets the resonance suppression effectiveness criterion and has the largest sum of the node self-impedance changes as the optimal location.

7. The optimal addressing device for a power electronic power system resonance suppression device according to claim 6, characterized in that: The updated node self-impedance value is generated, where the self-impedance of node i becomes The self-impedance of the other nodes becomes 8. The optimal addressing device for a power electronic power system resonance suppression device according to claim 7, characterized in that: The resonance suppression effectiveness criterion is: Where ε is the threshold.

9. The optimal addressing device for a power electronic power system resonance suppression device according to claim 8, characterized in that: The constraint condition for satisfying the resonance suppression effectiveness criterion and maximizing the sum of node self-impedance changes is:

10. The optimal addressing device for a power electronic power system resonance suppression device according to claim 9, characterized in that: Also includes: The control strategy and parameter design module is used to substitute the self-impedance of node i and the self-impedance of other nodes into the constraint conditions to solve the equivalent impedance Z of the resonance suppression device under the threshold. m The value range of Ω ok When designing suppression strategies and parameters, it is only necessary to check the impedance of the suppression device port to ensure that it meets the value range Ω ok , that is, it is believed that the suppression strategy and parameters can achieve the resonance suppression goal.

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