A three-phase imbalance treatment device

Abstract

The application discloses a kind of three-phase unbalance treatment devices, to solve the three-phase unbalance problem existing in the process of microgrid operation, to improve the operation stability of microgrid.The device includes: multiple intelligent management terminal module, cloud server module and terminal computer module;The application also includes distributed control method based on the device;The technical scheme of its is: first, build the microgrid model of application scene, according to the attribute of detection user load node to divide user load, then use fish optimization algorithm to solve multi-objective function, calculate the optimal solution in Pareto solution set, then through satisfaction function, the optimal solution is the real-time strategy of microgrid three-phase unbalance management provides basis.The application effectively reduces the three-phase unbalance degree of microgrid user load with the least load commutation frequency and reactive power compensation amount, improves the operation stability of microgrid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical engineering, and in particular to a three-phase imbalance treatment device. BACKGROUND

[0002] With the increasing demand for intelligent devices, the influence of three-phase imbalance in microgrids is gradually increasing. In microgrids, user loads are mostly single-phase and nonlinear, and random changes will cause three-phase imbalance, affecting the power supply quality of microgrids, increasing line losses, and reducing power supply reliability. Therefore, in the treatment of three-phase imbalance in microgrids, the automatic adjustment of user load commutation by means of phase change switches is used, but the previous treatment only considered the overall three-phase imbalance of the microgrid, which would cause the sudden change of the three-phase imbalance of a local node. In addition, combined with reactive power compensation, the overall and local three-phase imbalance of the microgrid is accurately treated. SUMMARY

[0003] In order to solve the problem of three-phase imbalance in the operation of microgrids, a three-phase imbalance treatment device is provided, which combines user load commutation and reactive power compensation.

[0004] The three-phase imbalance treatment device provided by the present application comprises a cloud server module, a terminal computer module, and a plurality of intelligent treatment terminal modules.

[0005] The intelligent treatment terminal module is composed of a load commutation module, a reactive power compensation module, a detection module, and a data transmission module. One end of the intelligent treatment 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-phase of the microgrid.

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

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

[0008] The terminal computer module is used to establish a line model of the microgrid, divide the user load in the model according to the position of the user load connected to the A, B, and C phases, 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 state detected by the intelligent treatment terminal module, and determine whether to perform user load commutation or reactive power compensation. The minimum number of load commutations m, the three-phase imbalance δ% after load commutation, and the three-phase imbalance δ% of the microgrid are set.i The minimum reactive compensation amount Δψmin is the objective function, and a constraint condition for stabilizing normal operation of the micro-grid is added. After the terminal computer module calculates the most suitable action scheme of the intelligent management terminal module, the action instruction is sent to the intelligent management terminal module, and the latest connection state of all user loads is updated.

[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 A, B and C three-phase of each user node i; I avgi is the average value of I ai , I bi and I ci .

[0012] The three-phase unbalance degree of the entire micro-grid model in the function of the terminal computer module is:

[0013]

[0014] In the formula, α, β and η are the weight coefficients of the transformer node, all user load nodes and the fitting function f t in the micro-grid model respectively, and α>β>η; f t is the fitting function of the micro-grid model, which can be a constant.

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

[0016]

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

[0018]

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

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

[0021]

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

[0023] The terminal computer module is used for analyzing the three-phase unbalance degree of each user load node, dynamically evaluating whether the intelligent management terminal module needs to perform user load phase conversion operation, and if so, using the fish optimization algorithm to perform user load phase conversion calculation under the condition of meeting the target function and constraint function, and placing the optimal value found by the terminal computer module in the Pareto optimal solution set, evaluating in the calculated Pareto optimal solution set according to the minimum priority of min{m} and min{delta%}, and sending an instruction to the intelligent management terminal module to update the connection of each user load, and ending the user load phase conversion operation.

[0024] The terminal computer module is used for dynamically evaluating whether the intelligent management terminal module needs to perform reactive power compensation operation, and if so, using the Newton method to perform power flow calculation and analysis on the running state of each user load node, setting the step length of the greedy algorithm dynamic reactive power compensation to 0.2, calling the power flow calculation to analyze the estimated current value of the current node after each compensation, and ending the reactive power compensation operation when the difference between the estimated current value and the standard current value is less than 2%.

[0025] The present application has the following advantages: the present application can detect the running state of all user loads in the applied micro-grid, analyze and evaluate the reliability and safety of the entire micro-grid, and perform three-phase imbalance management through distributed control, accurately perform three-phase imbalance management operation with minimum damage to the power quality of the micro-grid by combining user load phase conversion and reactive power compensation management modes, thereby reducing the three-phase imbalance degree of the entire and local micro-grid and improving the operation stability of the micro-grid. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings needed to be used in the prior art and embodiments, and the following drawings are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the premise of not paying creative labor.

[0027] Figure 1 It is a schematic diagram of the present application;

[0028] Figure 2 It is a schematic diagram of the present application;

[0029] Figure 3 It is a control mode flow chart of the three-phase imbalance management device of the present application;

[0030] Figure 4 It is a working flow chart of the intelligent management terminal module of the present application;

[0031] Figure 5 It is a test chart before three-phase imbalance management of the present application;

[0032] Figure 6 Effect diagram after three-phase imbalance treatment of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the 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, in the following embodiments, "connected" between the objects connected should be understood as "electrically connected", "communicatively connected" and the like if there is transmission of electrical signals or data between the objects connected.

[0036] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It should also be understood that the term "comprising" or "including" or "having" and the like, specifies the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0037] In one embodiment provided by the present application, as shown in Figure 1 and Figure 2 A three-phase imbalance treatment device is provided, comprising a cloud server module, a terminal computer module and a plurality of intelligent treatment terminal modules;

[0038] The intelligent treatment terminal module is composed of a load commutation module, a reactive power compensation module, a detection module and a data transmission module. One end of the intelligent treatment 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-phase of the microgrid;

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

[0040] The terminal computer module is a core controller of the three-phase imbalance treatment device, and the network port end of the terminal computer module is wired connected with the cloud server module, and the terminal computer module is wirelessly connected with the intelligent treatment terminal module.

[0041] As shown in Figure 3 , the terminal computer module is used to establish a line model of the micro-grid, divides the user loads in the model according to the positions of the user loads connected to the A, B and C phases according to the data of the micro-grid operation detected by the intelligent treatment terminal module, and marks each user load as node 1, node 2, node 3, etc. according to the positions, analyzes the three-phase imbalance degrees of each node of the current micro-grid according to the data of the micro-grid operation state detected by the intelligent treatment terminal module, and judges to perform a user load commutation operation or a reactive power compensation operation; sets the minimum number of load commutation times m, the minimum three-phase imbalance degree δ% after load commutation and the minimum reactive power compensation amount Δψ as the objective function, and adds a constraint condition for stabilizing the normal operation of the micro-grid, and after the terminal computer module calculates the most suitable action scheme of the intelligent treatment terminal module, sends an action instruction to the intelligent treatment terminal module, and updates the latest connection state of all user loads. i

[0042] The three-phase imbalance 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 A, B and C three-phase of each user node i; I avgi is the average value of I ai , I bi and I ci .

[0045] The three-phase imbalance degree of the entire micro-grid model in the function of the terminal computer module is:

[0046]

[0047] In the formula, α, β and η are the weight coefficients of the transformer node, all user load nodes and the fitting function f t in the micro-grid model respectively, and α>β>η; f t is the fitting function of the micro-grid model, which can be a constant.

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

[0049] ​

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

[0051]

[0052] In the formula, U * is a voltage unit; I * is a current unit; I max* is a current overload value.

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

[0054]

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

[0056] As Figure 4 shown, the terminal computer module is used for analyzing the three-phase unbalance degree of each user load node, dynamically evaluating and judging whether the intelligent management terminal module needs to perform user load phase conversion operation, and if so, using the fishing optimization algorithm to perform user load phase conversion calculation under the condition of meeting the target function and the constraint function. The terminal computer module finds the optimal value and places it in a Pareto optimal solution set. The evaluation is performed in the calculated Pareto optimal solution set according to the minimum priority of min{m} and min{δ%}, and an instruction is sent to the intelligent management terminal module to update the connection of each user load. The user load phase conversion operation is completed.

[0057] The terminal computer module is used for dynamically evaluating and judging whether the intelligent management terminal module needs to perform reactive power compensation operation, and if so, using the Newton method to perform power flow calculation and analysis on the running state of each user load node, setting the step length of the greedy algorithm dynamic reactive power compensation to 0.2, calling the power flow calculation to analyze the estimated current value of the current node after each compensation, and when the difference between the estimated current value and the standard current value is less than 2%, the reactive power compensation operation is completed.

[0058] In order to enable the function of the terminal computer module to find a more suitable three-phase unbalance management scheme, the fishing optimization algorithm is introduced to solve the multi-objective optimization problem. First, the colony is initialized, the colony position is initialized using normal distribution, and the boundary of the colony is defined according to the target function: Fisher i,j,k,n = (b i -b j )*r + (b k -b n )*q, r and q are random numbers between 0 and 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 of all, the dynamic fishing rate (learning efficiency χ) is adopted: where P r is the current optimal solution quantity, MaxP r is the estimated maximum number of optimal solutions; when χ is less than the probability P, re-search is carried out; otherwise, independent search and comparison are carried out; then the result output is carried out, the values obtained are compared, if P r ≤MaxP r the algorithm flow ends, and the optimal solution is output to the Pareto optimal solution set; finally, the optimal applicable solution is selected, each set of solutions calculated in the Pareto optimal solution set calculated by the algorithm is evaluated as a reference design satisfaction function M of the target function, and when the satisfaction function M is maximum, it is regarded as the best governance scheme and is sent to the intelligent governance terminal module.

[0059] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, will be described in detail. Figure 1 and IEEE 33 nodes, the illustrative embodiment of the application and the description thereof are only used to explain the application, and do not limit the application.

[0060] Taking the cell building micro-grid as an example, the user load condition is simulated; after the intelligent governance device detects the running state of each user load node, the load properties of each node are judged through waveform comparison and calculation deduction, and the data is sent to the cloud server module through wireless transmission, so that the terminal computer module can call; the terminal computer module calls the data in the cloud server module for analysis, evaluates the stability of the current cell building micro-grid running state, evaluates and calculates the three-phase imbalance of each user load node and the three-phase imbalance of the entire micro-grid; if it meets the demand of three-phase imbalance governance, the current situation governance mode and scheme are judged; finally, the three-phase imbalance governance of the cell building micro-grid is realized.

[0061] An embodiment provided by the application is modeled and simulated, and the steps are as follows:

[0062] S1, input the line parameters of the cell building micro-grid, and define the positions and connection modes of each user load node;

[0063] S2, detect the running data of each user load node, which is uploaded to the control system program in the form of an Excel file, and the micro-grid power quality is analyzed and detected;

[0064] S3, obtain the load condition of each user load node, and calculate and evaluate the three-phase imbalance governance scheme through the improved fishing optimization algorithm proposed in the specification;

[0065] S4, through the comparison of the satisfaction function, the specific implementation method of the three-phase imbalance treatment is obtained, and instructions are sent to the intelligent treatment terminal module to make it act;

[0066] S5, after the action is completed, the operation of S2 is performed again.

[0067] One embodiment of the present application sets the position and line parameters of the user load nodes of the cell building micro-grid according to the following table 1:

[0068] Table 1 distribution line parameter table

[0069]

[0070]

[0071] The three-phase imbalance treatment device proposed in the present application can obtain Figure 6 The three-phase imbalance degree of each user load node before the three-phase imbalance treatment device proposed in the present application is not run is as shown in Figure 5 The comparison shows that the power quality of the micro-grid is improved, and the three-phase imbalance degree of the micro-grid is reduced.

[0072] The above describes one embodiment of the present application in detail, but the content described is only the preferred embodiment of the present application, and cannot be considered as limiting the implementation range of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the patent coverage range of the present application.

Claims

1. A three-phase imbalance control device, characterized in that: Includes cloud server module, terminal computer module and multiple intelligent management terminal modules; The intelligent management terminal module consists of a load phase change 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 phases of the microgrid; The cloud server module serves as a data storage module for 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 unbalance management device. The network port of the terminal computer module is connected to the cloud server module by wire, and the terminal computer module is connected to the intelligent management terminal module by wireless. The terminal computer module is used to establish a line model of the microgrid, divide the user loads in the model according to the position of the user load 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. 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 to be performed; set the load phase change times Minimum, three-phase imbalance after load commutation and Minimum and reactive compensation The minimum objective function is set, and the constraints for the normal operation of the stable microgrid are added. 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. The three-phase unbalance degree of each user load node in the function of the terminal computer module is: Where, 、 and are the current values ​​of phases A, B, and C of each user node i; for 、 and The average value of The three-phase imbalance of the entire microgrid model in the function run by the terminal computer module is: Where, 、 and They are transformer nodes, all user load nodes and fitting functions in the microgrid model. The weight coefficient of ; is the microgrid model fitting function, which is a constant; The satisfaction function M of the terminal computer module is: Where: 、 、 and is the weight function of the satisfaction function M, and .

2. A three-phase unbalance control device according to claim 1, characterized in that: The objective function of the terminal computer module is: 。 3. The three-phase imbalance control device according to claim 1, characterized in that: The constraint function in the terminal computer module operation is: Where, is the per-unit voltage value; is the per-unit value of the current; is the current overload value.

4. The three-phase imbalance control 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, and if necessary, use the fishing optimization algorithm to calculate the user load phase switching under the conditions of meeting 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 and The minimum priority is evaluated in the calculated Pareto optimal solution set, and an instruction is sent to the intelligent management terminal module to update the connection status of each user load, and the user load switching operation is completed.

5. The three-phase imbalance control 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 compensation operation. If necessary, the Newton 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 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 compensation operation is completed.

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