Three-phase imbalance treatment device

Abstract

The invention discloses a three-phase imbalance treatment device, and aims to solve the problem of three-phase imbalance in the operation process of a micro-grid so as to improve the operation stability of the micro-grid. The device comprises a plurality of intelligent treatment terminal modules, a cloud server module and a terminal computer module, the invention further comprises a distributed control method based on the device. According to the technical scheme, the method is characterized in that firstly, a micro-grid model of an application scene is built, user loads are divided according to attributes of detected user load nodes, then a fishing optimization algorithm is used for solving a multi-objective function, and optimal liberation in a Pareto solution set is obtained through calculation; and an optimal solution is obtained through a satisfaction function to provide a basis for a real-time strategy of three-phase imbalance treatment of the micro-grid. According to the method, the three-phase unbalance degree of the micro-grid user load is effectively reduced with the minimum load commutation frequency and reactive compensation amount, and the operation stability of the micro-grid is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrical engineering, and in particular to a three-phase unbalance treatment device. Background Art

[0002] As people's demand for intelligent equipment continues to increase, the impact of three-phase imbalance problems in microgrids is gradually increasing. In microgrids, most user loads are single-phase and nonlinear, and random changes will lead to three-phase imbalance problems, thereby affecting the power supply quality of the microgrid, increasing line losses, and reducing power supply reliability. Therefore, in the three-phase imbalance management of the microgrid, the user load is automatically adjusted by phase switching with the help of phase-changing switches, but in the past, only the overall three-phase imbalance management of the microgrid was considered, which would lead to a sudden change in the three-phase imbalance of a local node. In addition, combined with reactive power compensation, the overall and local three-phase imbalance management of the microgrid is accurately completed. Summary of the invention

[0003] In order to solve the three-phase imbalance problem existing in the operation of microgrid, a three-phase imbalance control device combining user load phase switching and reactive power compensation is provided.

[0004] The present invention proposes a three-phase unbalance management device, comprising a cloud server module, a terminal computer module and a plurality of intelligent management terminal modules;

[0005] The intelligent management terminal module is composed of a load phase-changing module, a reactive power compensation module, a detection module and a data transmission module. One end of the intelligent management terminal module is connected to the power demand end of the user load, and the other end is connected to the A, B and C three-phases of the microgrid;

[0006] The cloud server module serves as a data storage module of the three-phase unbalance management device, and the cloud server module is wirelessly connected to the intelligent management terminal module;

[0007] The terminal computer module serves as the core controller of the three-phase unbalanced management device. The network port of the terminal computer module is wiredly connected to the cloud server module, and the terminal computer module is wirelessly connected to the intelligent management terminal module.

[0008] The terminal computer module is used to establish a line model of the microgrid, divide the user loads in the model according to the positions of the user loads connected to phases A, B, and C according to the data of the microgrid operation detected by the intelligent management terminal module, and mark each user load as node 1, node 2, node 3, etc. according to the position, analyze the three-phase imbalance of each node of the current microgrid according to the data of the microgrid operation status detected by the intelligent management terminal module, and judge whether to perform user load phase switching operation or reactive power compensation operation; set the load phase switching times m to be the minimum, the three-phase imbalance degree δ% and δ% after load phase switchingi The objective function is to minimize the reactive power compensation Δψ and set constraints for the normal operation of the stable microgrid. After the terminal computer module calculates the most suitable action plan for the intelligent management terminal module, it sends an action instruction to the intelligent management terminal module and updates the latest connection status of all user loads.

[0009] The three-phase unbalance degree of each user load node in the function of the terminal computer module is:

[0010]

[0011] In the formula, I ai ,I bi and I ci are the current values ​​of the three phases A, B, and C of each user node i; I avgi For I ai ,I bi and I ci The average value of

[0012] The three-phase imbalance of the entire microgrid model in the function run by the terminal computer module is:

[0013]

[0014] Where α, β and η are the transformer nodes, all user load nodes and fitting function f in the microgrid model respectively. t The weight coefficient of , and α>β>η; f t is the microgrid model fitting function and can be a constant.

[0015] The objective function in the terminal computer module is:

[0016]

[0017] The constraint function in the function of terminal computer module operation is:

[0018]

[0019] Where U * is the voltage per unit value; I * is the per unit current value; I max* is the current overload value.

[0020] The satisfaction function M in the function of the terminal computer module is:

[0021]

[0022] Where: λ1, λ2, λ3 and λ4 are weight functions of the satisfaction function M, and λ1=λ4>λ2>λ3.

[0023] The terminal computer module is used to analyze the three-phase imbalance of each user load node, dynamically evaluate and determine whether the intelligent management terminal module needs to perform user load phase switching operation. If necessary, the fishing optimization algorithm is used to calculate the user load phase switching under the condition that the objective function and the constraint function are met. After the terminal computer module finds the optimal value, it is placed in the Pareto optimal solution set, and evaluated in the calculated Pareto optimal solution set according to the minimum priority of min{m} and min{δ%}, and sends instructions to the intelligent management terminal module to update the connection status of each user load, and the user load phase switching operation is completed.

[0024] The terminal computer module is used to dynamically evaluate and determine whether the intelligent management terminal module needs to perform reactive power compensation operation. If necessary, Newton's method is used to perform flow calculation and analysis on the operating status of each user load node, and a greedy algorithm with a step size of 0.2 is set for dynamic reactive power compensation. After each compensation, the flow calculation is called to analyze the estimated current value of the current node. When the difference between the estimated current value and the standard current value is less than 2%, the reactive power compensation operation ends.

[0025] The beneficial effects of the present invention are as follows: the present invention can detect the operating status of all user loads in the applied microgrid, analyze and evaluate the reliability and safety of the entire microgrid; and manage three-phase imbalance through distributed control, combining the two management modes of user load phase switching and reactive power compensation to accurately perform three-phase imbalance management operations with minimal damage to the power quality of the microgrid, thereby reducing the overall and local three-phase imbalance of the microgrid and improving the operating stability of the microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the prior art and the drawings required for use in the embodiments. The following drawings are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is the principle diagram of the present invention;

[0028] Figure 2 It is the installation schematic diagram of the present invention;

[0029] Figure 3 It is a control method flow chart of the three-phase unbalanced treatment device of the present invention;

[0030] Figure 4 This is a working diagram of the intelligent management terminal module of the present invention;

[0031] Figure 5 This is a test diagram before the three-phase imbalance control of the present invention;

[0032] Figure 6 This is a diagram showing the effect of the three-phase imbalance control according to the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the 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 creative work are within the scope of protection of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0035] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0036] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0037] In one embodiment provided by the present invention, Figure 1 and Figure 2 As shown, a three-phase unbalance management device is provided, comprising a cloud server module, a terminal computer module and a plurality of intelligent management terminal modules;

[0038] The intelligent management terminal module is composed of a load phase-changing module, a reactive power compensation module, a detection module and a data transmission module. One end of the intelligent management terminal module is connected to the power demand end of the user load, and the other end is connected to the A, B and C three-phases of the microgrid;

[0039] The cloud server module serves as a data storage module of the three-phase unbalance management device, and the cloud server module is wirelessly connected to the intelligent management terminal module;

[0040] The terminal computer module serves as the core controller of the three-phase unbalanced management device. The network port of the terminal computer module is wiredly connected to the cloud server module, and the terminal computer module is wirelessly connected to the intelligent management terminal module.

[0041] like Figure 3 As shown, the terminal computer module is used to establish a line model of the microgrid. According to the data of the microgrid operation detected by the intelligent management terminal module, the user load in the model is divided according to the position where the user load is connected to the A, B, and C phases, and each user load is marked as node 1, node 2, node 3, etc. according to the position. According to the data of the microgrid operation status detected by the intelligent management terminal module, the three-phase imbalance of each node of the current microgrid is analyzed to determine whether the user load phase change operation or reactive power compensation operation is performed; the load phase change times m are set to be the minimum, the three-phase imbalance after load phase change δ% and δ i The objective function is to minimize the reactive power compensation Δψ and set constraints for the normal operation of the stable microgrid. After the terminal computer module calculates the most suitable action plan for the intelligent management terminal module, it sends an action instruction to the intelligent management terminal module and updates the latest connection status of all user loads.

[0042] The three-phase unbalance degree of each user load node in the function of the terminal computer module is:

[0043]

[0044] In the formula, I ai ,I bi and I ci are the current values ​​of the three phases A, B, and C of each user node i; I avgi For I ai ,I bi and I ci The average value of

[0045] The three-phase imbalance of the entire microgrid model in the function run by the terminal computer module is:

[0046]

[0047] Where α, β and η are the transformer nodes, all user load nodes and fitting function f in the microgrid model respectively. t The weight coefficient of f t is the microgrid model fitting function and can be a constant.

[0048] The objective function in the terminal computer module is:

[0049]

[0050] The constraint function in the function of terminal computer module operation is:

[0051]

[0052] Where U * is the voltage per unit value; I * is the per unit current value; I max* is the current overload value.

[0053] The satisfaction function M in the function of the terminal computer module is:

[0054]

[0055] Where: λ1, λ2, λ3 and λ4 are weight functions of the satisfaction function M, and λ1=λ4>λ2>λ3.

[0056] like Figure 4 As shown, the terminal computer module is used to analyze the three-phase imbalance of each user load node, dynamically evaluate and determine whether the intelligent management terminal module needs to perform user load phase switching operation, and use the fishing optimization algorithm if necessary to calculate the user load phase switching under the condition of satisfying the objective function and constraint function. After the terminal computer module finds the optimal value, it is placed in the Pareto optimal solution set, and evaluated in the calculated Pareto optimal solution set according to the minimum priority of min{m} and min{δ%}, and sends instructions to the intelligent management terminal module to update the connection status of each user load, and the user load phase switching operation is completed.

[0057] The terminal computer module is used to dynamically evaluate and determine whether the intelligent management terminal module needs to perform reactive power compensation operation. If necessary, Newton's method is used to perform flow calculation and analysis on the operating status of each user load node, and a greedy algorithm with a step size of 0.2 is set for dynamic reactive power compensation. After each compensation, the flow calculation is called to analyze the estimated current value of the current node. When the difference between the estimated current value and the standard current value is less than 2%, the reactive power compensation operation ends.

[0058] In order to enable the terminal computer module to find a more suitable solution for three-phase imbalance management, the present invention introduces a fishing optimization algorithm to solve the multi-objective optimization problem. First, the community is initialized, the community position is initialized using a normal distribution, and the boundary of the community is defined according to the objective function: Fisher i,j,k,n =(b i -b j )*r+(b k -b n )*q, r and q are random numbers between (0, 1), b i , b j , b kand b n are the upper, lower, left and right boundaries of the population respectively; then the optimization process is carried out, first using a dynamic fishing rate (learning efficiency χ): Where P r is the number of current optimal solutions, MaxP r is the maximum number of estimated optimal solutions; when χ is less than the probability P, re-search; otherwise, perform independent search and comparison; then output the results and compare the obtained values. If P r ≤MaxP r The algorithm process ends, and the optimal solution is output to the Pareto optimal solution set; finally, the optimal applicable solution is selected, and the satisfaction function M is designed for each solution set calculated from the Pareto optimal solution set calculated by the algorithm with the objective function as a reference to evaluate the solution. When the satisfaction function M is the largest, it is sent to the intelligent governance terminal module as the best governance solution.

[0059] The following will be combined with the appended Figure 1 The present invention is further described in detail with reference to IEEE 33 nodes. The exemplary implementation scheme and description of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0060] Taking the community building microgrid as an example, the user load situation is simulated; when the intelligent management device detects the operating status of each user load node, it determines the load attributes of each node through waveform comparison and calculation deduction, and then sends the data to the cloud server module through wireless transmission to facilitate the terminal computer module to call; the terminal computer module calls the data in the cloud server module for analysis, evaluates the stability of the current operating status of the community building microgrid, evaluates and calculates the three-phase imbalance of each user load node and the three-phase imbalance of the entire microgrid; if it meets the needs of three-phase imbalance management, then the management method and plan for the current situation are determined; finally, the three-phase imbalance management of the community building microgrid is realized.

[0061] The model building and simulation of an embodiment provided by the present invention are carried out in the following steps:

[0062] S1. Input the line parameters of the community building microgrid and define the location and connection method of each user load node;

[0063] S2. Detect the operating data of each user load node and upload it to the control system program in the form of an Excel file to analyze and detect the power quality of the microgrid;

[0064] S3. Obtain the load conditions of each user load node, and calculate and evaluate the three-phase unbalanced governance solution through the improved fishing optimization algorithm proposed in the specification;

[0065] S4. By comparing the satisfaction function, a specific implementation method of three-phase unbalance management is obtained, and the instruction is sent to the intelligent management terminal module to make it take action;

[0066] S5. After the action is completed, repeat the operation of S2.

[0067] An embodiment provided by the present invention sets the location and line parameters of the user load node of the community building microgrid according to the following Table 1:

[0068] Table 1 Distribution line parameters

[0069]

[0070]

[0071] Running the three-phase unbalanced treatment device proposed in the present invention can obtain Figure 6 , compared with the three-phase unbalance degree of each user load node before the three-phase unbalance control device proposed by the present invention is run. Figure 5 As shown in the figure, by comparison, the power quality of the microgrid is improved and the three-phase imbalance of the microgrid is reduced.

[0072] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A three-phase unbalanced treatment device, characterized in that: It includes cloud server module, terminal computer module and multiple intelligent management terminal modules; The intelligent management terminal module is composed of a load phase-changing module, a reactive power compensation module, a detection module and a data transmission module. One end of the intelligent management terminal module is connected to the power demand end of the user load, and the other end is connected to the A, B and C three-phases of the microgrid; The cloud server module serves as a data storage module of the three-phase unbalance management device, and the cloud server module is wirelessly connected to the intelligent management terminal module; The terminal computer module serves as the core controller of the three-phase unbalanced management device. The network port of the terminal computer module is wiredly connected to the cloud server module, and the terminal computer module is wirelessly connected to the intelligent management terminal module.

2. A three-phase unbalanced treatment device according to claim 1, characterized in that: The terminal computer module is used to establish a line model of the microgrid, divide the user loads in the model according to the positions of the user loads connected to phases A, B, and C according to the data of the microgrid operation detected by the intelligent management terminal module, and mark each user load as node 1, node 2, node 3, etc. according to the position, analyze the three-phase imbalance of each node of the current microgrid according to the data of the microgrid operation status detected by the intelligent management terminal module, and judge whether to perform user load phase switching operation or reactive power compensation operation; set the load phase switching times m to be the minimum, the three-phase imbalance degree δ% and δ% after load phase switching i The objective function is to minimize the reactive power compensation Δψ and set constraints for the normal operation of the stable microgrid. After the terminal computer module calculates the most suitable action plan for the intelligent management terminal module, it sends an action instruction to the intelligent management terminal module and updates the latest connection status of all user loads.

3. A three-phase unbalanced treatment device according to claim 1, characterized in that: The three-phase unbalance degree of each user load node in the function of the terminal computer module is: In the formula, I ai ,I bi and I ci are the current values ​​of the three phases A, B, and C of each user node i; I avgi For I ai ,I bi and I ci The average value of .

4. A three-phase unbalanced treatment device according to claim 1, characterized in that: The three-phase imbalance of the entire microgrid model in the function run by the terminal computer module is: Where α, β and η are the transformer nodes, all user load nodes and fitting function f in the microgrid model respectively. t The weight coefficient of , and α>β>η; f t is the microgrid model fitting function and can be a constant.

5. A three-phase unbalanced treatment device according to claim 1, characterized in that: The objective function in the terminal computer module is:

6. A three-phase unbalanced treatment device according to claim 1, characterized in that: The constraint function in the function of terminal computer module operation is: Where U * is the voltage per unit value; I * is the per unit current value; I max* is the current overload value.

7. A three-phase unbalance treatment device according to claim 1, characterized in that: The satisfaction function M in the function of the terminal computer module is: Where: λ1, λ2, λ3 and λ4 are weight functions of the satisfaction function M, and λ1=λ4>λ2>λ3.

8. A three-phase unbalanced treatment device according to claim 1, characterized in that: The terminal computer module is used to analyze the three-phase imbalance of each user load node, dynamically evaluate and determine whether the intelligent management terminal module needs to perform user load phase switching operation. If necessary, the fishing optimization algorithm is used to calculate the user load phase switching under the condition that the objective function and the constraint function are met. After the terminal computer module finds the optimal value, it is placed in the Pareto optimal solution set, and evaluated in the calculated Pareto optimal solution set according to the minimum priority of min{m} and min{δ%}, and sends instructions to the intelligent management terminal module to update the connection status of each user load, and the user load phase switching operation is completed.

9. A three-phase unbalance treatment device according to claim 1, characterized in that: The terminal computer module is used to dynamically evaluate and determine whether the intelligent management terminal module needs to perform reactive power compensation operation. If necessary, Newton's method is used to perform flow calculation and analysis on the operating status of each user load node, and a greedy algorithm with a step size of 0.2 is set for dynamic reactive power compensation. After each compensation, the flow calculation is called to analyze the estimated current value of the current node. When the difference between the estimated current value and the standard current value is less than 2%, the reactive power compensation operation ends.

Images