A method for protecting power grid by partitioned cooperative control of UPFC and adjustable generator

Abstract

This invention discloses a grid protection method based on zoned collaborative control of UPFC and adjustable generators. This method supplements existing relay protection systems by using a distributed approach to control UPFC and adjustable generators to adjust the power flow injected into the grid to cope with power flow fluctuations caused by faults. Installing UPFC in different zones and using distributed control eliminates the need for a centralized control center, improving system robustness while protecting regional privacy. Zones only need to exchange boundary information to achieve optimized protection. A zoned protection algorithm based on UPFC and adjustable generators is designed to effectively solve the single control problem of UPFC devices. The practical problem is transformed into an optimization problem, which is then decomposed into sub-optimization problems. Global optimality is achieved by solving these sub-optimization problems, minimizing the power flow deviation of the lines to achieve the protection objective.

Description

Technical Field

[0001] This invention relates to the field of power grid safety technology, and in particular to a power grid protection method for a zoned collaborative control UPFC and an adjustable generator. Background Technology

[0002] Although the development of smart grids has improved the reliability of power systems, the frequent occurrence of large-scale power outages still causes inconvenience to production and daily life, resulting in huge economic losses. This means that relying solely on existing protection systems may not be enough to prevent power outages, thus necessitating the development of new methods to enhance the security performance of the power grid based on existing protection systems.

[0003] Traditional power grid protection strategies are mostly based on relay protection systems. When a fault occurs, relays closer to the fault point operate, thus preventing cascading accidents. However, relay protection systems are prone to malfunction, and there are numerous real-world cases of relay malfunctions leading to cascading accidents. With the development of power electronics, Flexible AC Transmission Systems (FACTS) are increasingly being used in power grid control and protection. Unified Power Flow Controllers (UPFCs), as a new generation of FACTS devices, have the functions of controlling power flow and stabilizing voltage. In practical cases, UPFCs have been used in the power grids of Suzhou, Nanjing, and Shanghai in Jiangsu Province. However, these applications only focus on the protection and support role of a single UPFC station for the local power grid, limiting the impact to the local area. Existing control strategies focus on the control of a single UPFC project and have not actually studied the protective effect of the synergy between UPFC projects in these three locations on the Jiangsu-Shanghai power grid. Therefore, researching the synergistic effect of multiple UPFC devices on the support of the regional power grid is an urgent gap to be filled.

[0004] Therefore, the narrow scope of application and limited protection of existing technologies, as well as the single control strategy of UPFC devices, are technical problems that urgently need to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing technology has a narrow scope of application, limited scope of protection, and a single control strategy for UPFC devices.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a grid protection method for partitioned collaborative control of UPFC and adjustable generators, which specifically includes the following steps:

[0007] Based on the partitioned power grid, an objective function for the optimization problem is established.

[0008] Establish multiple constraints;

[0009] Based on the objective function and the constraints, the optimization problem is transformed into an optimization problem model;

[0010] The optimization problem model of any sub-region A in the partitioned power grid is solved based on the distributed alternating direction multiplier method and using a standard commercial solver;

[0011] Multiple iteration stopping criteria are set. When any one of the stopping criteria is met, the iteration stops and the solution result for sub-region A is obtained.

[0012] Based on the solution results for sub-region A, obtain the power flow required by the boundary bus of sub-region A. Adjust the power flow injected into the bus on the sub-region A side using UPFC to eliminate the fault. Share the adjusted boundary information of the sub-region A side with the neighboring sub-region B, and determine whether the fault has been completely eliminated.

[0013] If the fault is completely eliminated, it is only necessary to adjust the power flow injected into the boundary bus on the sub-region B side of the UPFC to eliminate the power flow change on the common transmission line. Sub-region B no longer needs to solve the optimization problem, and the fault can be resolved.

[0014] If the fault still exists, sub-region B solves its optimization problem based on the boundary information shared by its neighboring sub-region A, shares the solution results of sub-region B with the remaining neighboring sub-regions, and continues to determine whether the neighboring sub-regions need to solve their sub-optimization problems until the fault is completely eliminated.

[0015] Furthermore, the power grid includes M bus nodes and N transmission lines. Represents the set of bus nodes. Represents a set of transmission lines; letters Indicates a bus node. Indicates connecting busbar section and Transmission lines; uppercase letters , , It is the identifier of the sub-region; Subregion bus nodes in This represents the boundary bus node in the sub-region. Subregion The boundary generatrix; similarly This represents a common transmission line between different sub-regions. Indicates connecting sub-regions and subregions The common transmission line; no distinction is made between UPFC and adjustable generator in the power grid, and both are uniformly replaced by the UPFC identifier.

[0016] Furthermore, based on the partitioned power grid, the objective function for the optimization problem is established as follows:

[0017]

[0018] In the formula for The column vector represents the actual active and reactive power transmitted by the transmission line. For the desired line flow.

[0019] Furthermore, the establishment of multiple constraints includes: power flow balance constraints for bus nodes;

[0020] For bus nodes without UPFC equipment installed The power flow balance constraint can be expressed as:

[0021]

[0022] In the formula , bus nodes The active and reactive power injected into the power grid. bus nodes Injected active and reactive power, , bus nodes Active load and reactive load; This refers to the set of boundary busbars connected to the transmission lines where UPFCs are installed;

[0023] If the bus node For the nodes at both ends of the transmission line where the UPFC device is installed, the power flow balance constraints are as follows:

[0024]

[0025] In the formula , Inject bus nodes into UPFC equipment Active power and reactive power;

[0026] It also includes the power flow balance of the line, whose linearized expression is:

[0027]

[0028] In the formula These are the bus nodes at both ends of the transmission line where the UPFC equipment is installed. Transmission lines The transmitted active and reactive power, bus nodes The square of the voltage amplitude and the square of the voltage amplitude difference. These are the line conductance and susceptance, respectively. bus node The voltage angle difference.

[0029] Furthermore, the establishment of multiple constraints includes: system-integrated generator operation constraints, the expression of which is as follows:

[0030]

[0031] In the formula This indicates the bus node of the primary generator in the system. bus nodes The active and reactive power injected into the network, bus node The upper and lower bounds of the active power injected into the network. bus node Upper and lower bounds of reactive power injected into the network.

[0032] Furthermore, the establishment of various constraints includes: safe operation constraints, the expression of which is as follows:

[0033]

[0034] These are adjustable parameters, set according to network operating conditions. These are the desired bus nodes. The square of the voltage value, For transmission lines The expected values ​​of active and reactive power transmitted are generally set to the values ​​under normal operating conditions.

[0035] Furthermore, the establishment of various constraints includes: UPFC constraints, the expression of which is as follows:

[0036]

[0037] in These represent the active and reactive power injected into the grid by the UPFC equipment, respectively. This refers to the upper and lower bounds of the active power injected into the power grid. These are the upper and lower bounds of the reactive power injected into the power grid.

[0038] Furthermore, based on the objective function and each of the constraints, the optimization problem is transformed into an optimization problem model, the specific expression of which is as follows:

[0039]

[0040] make The objective function of the above optimization problem is: Expandable to Its matrix form is:

[0041]

[0042] here and To and All associated equality and inequality constraints, and Define all constraints associated with UPFC; The set of all decision and constraint variables allows the optimization problem model to be transformed into a standard optimization problem model:

[0043]

[0044] here For decision variables and The set of relevant constraints.

[0045] Furthermore, the solution of the optimization problem model for any sub-region A in the partitioned power grid based on the distributed alternating direction multiplier method and using a standard commercial solver includes:

[0046] For the partitioned power grid, the optimization problem model for any sub-region A can be written as:

[0047]

[0048] Let A represent the decision variables shared by neighboring regions and region A, and its corresponding Lagrange function be:

[0049]

[0050] In the formula Is and constraint Related scaling dual variables, , yes dual variables, As the penalty factor; using the distributed alternating direction multiplier method to solve the optimization problem of subregion A, the iterative dynamics can be obtained:

[0051]

[0052] After obtaining the optimization problem of subregion A and its iterative formula for solving the problem, a standard commercial solver is used to solve the problem. The iteration stops when any stopping criterion is met, and the solution result is obtained.

[0053] Furthermore, the setting of various stopping rules includes:

[0054] Stopping Criterion 1: Boundary Residuals Once the accuracy requirements are met, the simulation stops.

[0055] Stopping Criterion 2: The number of simulation steps reaches the preset value. The simulation stopped.

[0056] Stopping Criterion 3: Objective Function Value The simulation stops when the value stabilizes; here, it is defined that the value is continuous. A state of no change is considered stable.

[0057] The technical solution provided by this invention has the following beneficial effects:

[0058] 1. This invention proposes a zoned distributed power grid protection method based on UPFC and adjustable generators. The proposed protection method is a supplement to the existing relay protection system. By controlling UPFC and adjustable generators in a distributed manner, the power flow injected into the power grid is adjusted to cope with power flow fluctuations caused by faults. UPFCs are installed in different areas and controlled in a distributed manner. This not only eliminates the centralized control center and improves the robustness of the system, but also protects the privacy of the areas. Only the boundary information needs to be exchanged between areas to achieve the purpose of optimized protection.

[0059] 2. A zoned protection algorithm based on UPFC and adjustable generators was designed, effectively solving the single control problem of UPFC equipment. The practical problem is transformed into an optimization problem, which is then decomposed into sub-optimization problems. Global optimum is achieved by solving these sub-optimization problems, and protection is achieved by minimizing the power flow deviation of the line. Attached Figure Description

[0060] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0061] Figure 1 This is a flowchart illustrating the overall process of a grid protection method for a partitioned collaborative control UPFC and adjustable generator according to the present invention.

[0062] Figure 2 This is a schematic diagram of the region division of the IEEE-24 node system 2 in an embodiment of the present invention;

[0063] Figure 3 This is a schematic diagram illustrating the collaborative protection between the three sub-regions in an embodiment of the present invention;

[0064] Figure 4 The objective function in this embodiment of the invention and boundary residuals The trajectory, where (a) the objective function The trajectory, (b) boundary residual The trajectory;

[0065] Figure 5 This refers to the active power injected by the UPFC at the boundary bus of regions A and B in this embodiment of the invention, where (a) corresponds to region A and (b) corresponds to region B.

[0066] Figure 6 This refers to the reactive power injected by the UPFC at the boundary bus of regions A and B in this embodiment of the invention, where (a) corresponds to region A and (b) corresponds to region B.

[0067] Figure 7 The values ​​of the bus node voltage before and after the fault in this embodiment of the invention;

[0068] Figure 8 This is a schematic diagram of the structure of an electronic device according to the present invention. Detailed Implementation

[0069] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0070] This invention provides a power grid protection method for zoned collaborative control UPFC and adjustable generators, comprising the following steps:

[0071] S1: Based on the partitioned power grid, establish the objective function for the optimization problem;

[0072] S2: Establish multiple constraints;

[0073] S3: Based on the objective function and the constraints, the optimization problem is transformed into an optimization problem model;

[0074] S4: Solve the optimization problem model of any sub-region A in the partitioned power grid based on the distributed alternating direction multiplier method and using a standard commercial solver;

[0075] S5: Set multiple iteration stopping criteria. When any one of the stopping criteria is met, the iteration stops and the solution result of sub-region A is obtained.

[0076] S6: Based on the solution results for sub-region A, obtain the power flow required by the boundary bus of sub-region A. Adjust the power flow injected into the bus on the sub-region A side through UPFC to eliminate the fault. Share the adjusted boundary information of the sub-region A side with the neighboring sub-region B, and determine whether the fault has been completely eliminated.

[0077] S7: If the fault is completely eliminated, it is only necessary to adjust the power flow injected into the boundary bus of the UPFC on the B side of the sub-region to eliminate the power flow change on the common transmission line. The sub-region B no longer needs to solve the optimization problem, and the fault can be resolved.

[0078] S8: If the fault still exists, sub-region B solves the optimization problem of sub-region B based on the boundary information shared by neighboring sub-region A, shares the solution result of sub-region B with the other neighboring sub-regions, and continues to determine whether the neighboring sub-regions need to solve the sub-optimization problem of that region, until the fault is completely eliminated.

[0079] Specifically, the implementation of this invention is based on a partitioned power grid. For large-scale power grids, they can be first divided into regions. Taking the IEEE 24-bus system as an example, the partitioned regions are as follows: Figure 2 As shown. For a power network with M bus nodes and N transmission lines, the following can be used: Represents the set of bus nodes. Represents a set of transmission lines. (Letters) Indicates a bus node. Indicates connecting busbar section and Transmission lines. (Uppercase letters) , , It is the identifier of a sub-region. Without loss of generality, Subregion bus nodes in This represents the boundary bus node in the sub-region. Subregion The boundary generatrix. Similarly... This represents a common transmission line between different sub-regions. Indicates connecting sub-regions and subregions The common transmission line. Furthermore, this invention does not distinguish between UPFC and adjustable generators, merging them during modeling and uniformly replacing both with the UPFC identifier. The following optimization problem is first proposed:

[0080] The objective function of the optimization problem is as follows:

[0081] (1.1)

[0082] In the formula for The column vector represents the actual active and reactive power transmitted by the transmission line. This represents the desired line power flow. It is generally set to the value under normal operating conditions.

[0083] In addition, the following constraints need to be considered: power flow balance constraints, system-integrated generator operation constraints, safe operation constraints, and UPFC constraints.

[0084] The power flow balance constraints are divided into power flow balance constraints for bus nodes and power flow balance constraints for lines; for bus nodes without UPFC equipment... The power flow balance constraint can be expressed as:

[0085] (1.2)

[0086] In the formula , bus nodes The active and reactive power injected into the power grid. bus nodes Injected active and reactive power, , bus nodes Active load and reactive load; This refers to the set of boundary busbars connected to the transmission lines where UPFCs are installed;

[0087] If the bus node For the nodes at both ends of the transmission line where the UPFC device is installed, the power flow balance constraints are as follows:

[0088] (1.3)

[0089] In the formula These are the bus nodes at both ends of the transmission line where the UPFC equipment is installed. , Inject bus nodes into UPFC equipment Active power and reactive power;

[0090] The power flow balance constraint of the line is expressed as follows:

[0091] (1.4)

[0092] In the formula Transmission lines The transmitted active and reactive power, bus nodes The square of the voltage amplitude and the square of the voltage amplitude difference. These are the line conductance and susceptance, respectively. bus node The voltage angle difference.

[0093] The system has built-in generator operation constraints, the expressions of which are as follows:

[0094] (1.5)

[0095] In the formula This indicates the bus node of the primary generator in the system. bus nodes The active and reactive power injected into the network, bus node The upper and lower bounds of the active power injected into the network. bus node Upper and lower bounds of reactive power injected into the network.

[0096] The safe operation constraint is expressed as follows:

[0097] (1.6)

[0098] These are adjustable parameters, set according to network operating conditions. For example, according to national power industry standards, the following can be adopted: , These are the desired bus nodes. The square of the voltage value, For transmission lines The expected values ​​of active and reactive power transmitted are generally set to the values ​​under normal operating conditions.

[0099] UPFC constraints are expressed as follows:

[0100] (1.7)

[0101] in These represent the active and reactive power injected into the grid by the UPFC equipment, respectively. This refers to the upper and lower bounds of the active power injected into the power grid. The upper and lower bounds of reactive power injected into the grid are defined by the UPFC. The reactive and active power injected into the grid are finite.

[0102] Based on the above objective function and constraints, the optimization problem is transformed into an optimization problem model, the specific expression of which is as follows:

[0103] (1.8)

[0104] make The objective function of the above optimization problem is: Expandable to Its matrix form is:

[0105] (1.9)

[0106] here and To and All associated equality and inequality constraints, and Define all constraints associated with UPFC. This includes the entire set of decision and constraint variables. The optimization problem model can be transformed into a standard optimization problem model:

[0107] (1.10)

[0108] here For decision variables and The relevant constraints constitute a set. Then, the optimization problem model (1.10) is decomposed and solved.

[0109] For the partitioned power grid, without loss of generality, taking any sub-region as an example... For example, its optimization problem model can be written as:

[0110] (1.11)

[0111] like Figure 3 As shown, with Figure 3 Taking three sub-regions as an example, if a fault occurs in sub-region A, the central controller of sub-region A solves the sub-optimization problem of region A, then determines the power flow required for the boundary bus of sub-region A. It adjusts the power flow injected into the bus on the sub-region A side via the UPFC to eliminate the fault, and then shares the adjusted boundary information of sub-region A with neighboring region B. If the fault is completely eliminated, only the power flow injected into the boundary bus on the sub-region B side by the UPFC needs to be adjusted to eliminate the power flow change on the common transmission line. Sub-region B no longer needs to solve the optimization problem, and the fault is resolved. If the fault still exists, sub-region B solves the sub-optimization problem based on the boundary information shared by neighboring sub-region A, shares the result with neighboring sub-regions, and determines whether neighboring sub-regions need to solve the sub-optimization problem for that sub-region. The boundary information between sub-regions should be shared by the central controllers of both sub-regions and kept consistent. The optimization problem model for subregion A becomes:

[0112] (1.12)

[0113] This represents the decision variables shared by the neighboring regions and region A, and its corresponding Lagrangian function is:

[0114] (1.13)

[0115] In the formula Is and constraint Related scaling dual variables, , yes dual variables, Let be the penalty factor. Solving the optimization problem (1.12) using the Distributed Alternating Direction Multiplier Method (ADMM) yields the iterative dynamics:

[0116] (1.14)

[0117] After obtaining the optimization problem of subregion A and its iterative formula for solving the problem, a standard commercial solver is used to solve the problem. The iteration stops when any stopping criterion is met, and the solution result is obtained.

[0118] The stopping rules include:

[0119] Stopping Criterion 1: Boundary Residuals Once the accuracy requirements are met, the simulation stops.

[0120] Stopping Criterion 2: The number of simulation steps reaches the preset value. The simulation stopped.

[0121] Stopping Criterion 3: Objective Function Value The simulation stops when the value stabilizes; here, it is defined that the value is continuous. A state of no change is considered stable.

[0122] by Figure 2 The simulation of the 2-zone IEEE 24 bus node system shown is performed, with UPFC installed only on the common transmission line. Simulation parameter settings: the upper and lower bounds of the line power flow are set to normal values. This means The upper and lower bounds of the active and reactive power injected into the grid by UPFC are set as follows: pu and pu, penalty factor Boundary residuals and simulation step size The fault settings are shown in Table 1:

[0123] Table 1 Fault Settings

[0124]

[0125] Simulation results are as follows Figures 4-7 As shown, Figure 4 The objective function in this embodiment of the invention and boundary residuals The trajectory, where (a) the objective function The trajectory, (b) boundary residual The trajectory. According to Figure 4 It can be seen that after the fault occurs, as the iteration proceeds, the objective function... Gradual convergence demonstrates the effectiveness of the proposed zoned UPFC control. Furthermore, the active and reactive power injected into the grid by UPFC are as follows: Figure 5 and Figure 6 As shown, Figure 5 This refers to the active power injected by the UPFC at the boundary bus of regions A and B in this embodiment of the invention, where (a) corresponds to region A and (b) corresponds to region B. Figure 6 This refers to the reactive power injected by the UPFC at the boundary bus of regions A and B in this embodiment of the invention, where (a) corresponds to region A and (b) corresponds to region B. Figure 7 The bus node voltage values ​​before and after the fault in this embodiment of the invention; according to Figure 7 It can be seen that the voltage of the power grid nodes remained within a safe range before and after the fault.

[0126] like Figure 8The diagram illustrates the physical structure of an electronic device, which may include a processor 610, a communication interface 620, a memory 630, and a communication bus 640. The processor 610, communication interface 620, and memory 630 communicate with each other via the communication bus 640. The processor 610 can call logical instructions in the memory 630 to execute the steps of the aforementioned grid protection method for partitioned cooperative control UPFC and adjustable generators. Specifically, this includes: establishing an objective function for the optimization problem based on the partitioned grid; establishing multiple constraints; transforming the optimization problem into an optimization problem model based on the objective function and the constraints; solving the optimization problem model for any sub-region A in the partitioned grid using the distributed alternating direction multiplier method and a standard commercial solver; setting multiple iteration stopping criteria, stopping the iteration when any criterion is met, and obtaining the solution result for sub-region A; and obtaining the required boundary bus length for sub-region A based on the solution result for sub-region A. To eliminate the fault, the UPFC adjusts the power flow injected into the bus on the side of sub-region A. The adjusted boundary information of sub-region A is shared with neighboring sub-region B, and it is determined whether the fault has been completely eliminated. If the fault has been completely eliminated, only the power flow injected into the boundary bus on the side of sub-region B by the UPFC needs to be adjusted to eliminate the power flow change on the common transmission line. Sub-region B no longer needs to solve the optimization problem, and the fault can be resolved. If the fault still exists, sub-region B solves its optimization problem based on the boundary information shared by neighboring sub-region A, shares the solution results of sub-region B with the other neighboring sub-regions, and continues to determine whether neighboring sub-regions need to solve their sub-optimization problems until the fault is completely eliminated.

[0127] Furthermore, the logical instructions in the aforementioned memory 630 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0128] In another aspect, embodiments of the present invention also provide a storage medium storing a computer program. When executed by a processor, this computer program implements the steps of the aforementioned grid protection method for partitioned cooperative control (UPFC) and adjustable generators. Specifically, it includes: establishing an objective function for an optimization problem based on the partitioned grid; establishing multiple constraints; transforming the optimization problem into an optimization problem model based on the objective function and the constraints; solving the optimization problem model for any sub-region A in the partitioned grid using the distributed alternating direction multiplier method and a standard commercial solver; setting multiple iteration stopping criteria, stopping the iteration when any one criterion is met, and obtaining the solution result for sub-region A; and obtaining the solution result for sub-region A based on the solution result for sub-region A. The power flow required by the boundary bus of sub-region A is adjusted by UPFC to eliminate the fault in the bus injected into sub-region A. The adjusted boundary information of sub-region A is shared with neighboring sub-region B, and it is determined whether the fault has been completely eliminated. If the fault has been completely eliminated, it is only necessary to adjust the power flow injected into the boundary bus of sub-region B by UPFC to eliminate the power flow change on the common transmission line. Sub-region B no longer needs to solve the optimization problem, and the fault can be resolved. If the fault still exists, sub-region B solves its optimization problem based on the boundary information shared by neighboring sub-region A, shares the solution result of sub-region B with the other neighboring sub-regions, and continues to determine whether neighboring sub-regions need to solve their sub-optimization problems until the fault is completely eliminated.

[0129] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0130] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the unit claims listing several devices, several of these devices may be embodied by the same hardware item. The use of the terms first, second, and third, etc., does not indicate any order and can be interpreted as identifiers.

[0131] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for protection of power grid by zonal coordinated control of UPFC and adjustable generator, characterized in that, Includes the following steps: Based on the partitioned power grid, an objective function for the optimization problem is established. Establish multiple constraints; Based on the objective function and the constraints, the optimization problem is transformed into an optimization problem model; The optimization problem model of any sub-region A in the partitioned power grid is solved based on the distributed alternating direction multiplier method and using a standard commercial solver; Multiple iteration stopping criteria are set. When any one of the stopping criteria is met, the iteration stops and the solution result for sub-region A is obtained. Based on the solution results for sub-region A, obtain the power flow required by the boundary bus of sub-region A. Adjust the power flow injected into the bus on the sub-region A side using UPFC to eliminate the fault. Share the adjusted boundary information of the sub-region A side with the neighboring sub-region B, and determine whether the fault has been completely eliminated. If the fault is completely eliminated, it is only necessary to adjust the power flow injected into the boundary bus on the sub-region B side of the UPFC to eliminate the power flow change on the common transmission line. Sub-region B no longer needs to solve the optimization problem, and the fault can be resolved. If the fault still exists, sub-region B solves the optimization problem of sub-region B based on the boundary information shared by its neighboring sub-region A, shares the solution result of sub-region B with the other neighboring sub-regions, and continues to determine whether the neighboring sub-regions need to solve the sub-optimization problem of their region until the fault is completely eliminated. The solution of the optimization problem model for any sub-region A in the partitioned power grid based on the distributed alternating direction multiplier method and using a standard commercial solver includes: For the partitioned power grid, the optimization problem model for any sub-region A is written as: denotes the decision variable shared by the neighbor region and the A region, and its corresponding Lagrangian function is: In the formula Is and constraint Related scaling dual variables, , yes dual variables, As the penalty factor; using the distributed alternating direction multiplier method to solve the optimization problem of subregion A, the iterative dynamics can be obtained: After obtaining the optimization problem of subregion A and its iterative formula for solving the problem, a standard commercial solver is used to solve the problem. The iteration stops when any stopping criterion is met, and the solution result is obtained.

2. The method of claim 1, wherein the UPFC and the adjustable generator are controlled in coordination by the method. The power grid includes M Each bus node N One transmission line, Represents the set of bus nodes. Represents a set of transmission lines; letters Indicates a bus node. Indicates connecting busbar section and Transmission lines; uppercase letters , , It is the identifier of the sub-region; Subregion bus nodes in This represents the boundary bus node in the sub-region. Subregion The boundary generatrix; similarly This represents a common transmission line between different sub-regions. Indicates connecting sub-regions and subregions The common transmission line; no distinction is made between UPFC and adjustable generator in the power grid, and both are uniformly replaced by the UPFC identifier.

3. The method of claim 1, wherein the UPFC and the adjustable generator are controlled in coordination by the method. Based on the partitioned power grid, the objective function for the optimization problem is established as follows: wherein is P and Q are the active and reactive power, respectively, injected into the grid by the converter, is the desired line flow.

4. The method of claim 1, wherein the UPFC and the adjustable generator are controlled in coordination by the method. The establishment of various constraints includes: power flow balance constraints of bus nodes; For the bus nodes without UPFC devices The power flow balance constraint is expressed as: In the formula , bus nodes The active and reactive power injected into the power grid. bus nodes Injected active and reactive power, , bus nodes Active load and reactive load; This refers to the set of boundary busbars connected to the transmission lines where UPFCs are installed. Indicates a bus node; If the bus node For the nodes at both ends of the transmission line where the UPFC device is installed, the power flow balance constraints are as follows: In the formula These are the bus nodes at both ends of the transmission line where the UPFC equipment is installed. , Inject bus nodes into UPFC equipment Active power and reactive power; It also includes power flow balance constraints for the line, whose linearized expression is: In the formula Transmission lines The transmitted active and reactive power, bus nodes The square of the voltage amplitude and the square of the voltage amplitude difference. These are the line conductance and susceptance, respectively. bus node The voltage angle difference.

5. The grid protection method for partitioned collaborative control UPFC and adjustable generators according to claim 1, characterized in that, The established multiple constraints include: system-integrated generator operation constraints, the expression of which is as follows: In the formula This indicates the bus node of the primary generator in the system. bus nodes The active and reactive power injected into the network, bus node The upper and lower bounds of the active power injected into the network. bus node Upper and lower bounds of reactive power injected into the network.

6. The grid protection method for partitioned collaborative control UPFC and adjustable generators according to claim 1, characterized in that, The establishment of various constraints includes: safe operation constraints, the expression of which is as follows: These are adjustable parameters, set according to network operating conditions. These are the desired bus nodes. The square of the voltage value, For transmission lines The expected values ​​of transmitted active and reactive power are generally set to the values ​​under normal operating conditions. bus node The square of the voltage amplitude.

7. The grid protection method for partitioned collaborative control UPFC and adjustable generators according to claim 1, characterized in that, The established constraints include: UPFC constraints, the expression of which is as follows: in These represent the active and reactive power injected into the grid by the UPFC equipment, respectively. This refers to the upper and lower bounds of the active power injected into the power grid. These are the upper and lower bounds of the reactive power injected into the power grid.

8. The grid protection method for partitioned collaborative control UPFC and adjustable generators according to claim 3, characterized in that, Based on the objective function and the constraints, the optimization problem is transformed into an optimization problem model, the specific expression of which is as follows: Let The objective function of the optimization problem above is which expands to in matrix form: here and To and All associated equality and inequality constraints, and Define all constraints associated with UPFC; The set containing all decision and constraint variables transforms the optimization problem model into a standard optimization problem model: Here is a set of constraints related to the decision variables x and y.

9. The grid protection method for partitioned collaborative control UPFC and adjustable generators according to claim 1, characterized in that, The setting of multiple iteration stopping criteria includes: Stopping Criterion 1: Boundary Residuals Once the accuracy requirements are met, the simulation stops. Stop criterion 2: the simulation step number reaches a preset value , the simulation is stopped; Stopping criterion 3: objective function value Tends to stabilize, simulation stops, here the value is prescribed continuously Step does not change, i.e. stable.

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