Direct current magnetic bias calculation method based on power grid topology dynamic modeling

Abstract

The invention discloses a DC magnetic bias calculation method based on power grid topology dynamic modeling, and belongs to the technical field of power DC magnetic bias, and the method comprises the steps: S1, obtaining power grid topology structure information based on the operation information of a transformer substation, and constructing a power grid topology model based on the power grid topology structure information; s2, acquiring a power grid topology change type based on the change form of the power grid topology structure information, and constructing a dynamic power grid topology model based on the power grid topology change type and the power grid topology model; and S3, judging a power grid topology change type based on the power grid operation information obtained in real time, further obtaining a judgment result, and obtaining a direct current magnetic bias current based on the judgment result and the dynamic power grid topology model. The problem of difficulty in dynamically adapting to accurate calculation of direct-current magnetic bias under different working conditions is solved, and the safety and stability of a power system are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of electric direct current magnetic biasing technology, in particular to a direct current magnetic biasing calculation method based on dynamic modeling of power grid topology. Background Art

[0002] With the widespread application of new energy, distributed new energy is connected to the grid on a large scale, resulting in changes in the grid topology. The change in the grid topology will produce DC bias, which will affect the safety and stability of the power system. The existing technology mainly eliminates the influence of DC bias by regulating the power of the substation. For example, a multi-substation coordinated control method for dealing with reactive power shortage caused by DC bias is disclosed in Patent No. CN107947187A, which includes the following steps: S1, judging whether any converter station in the DC landing dense area has entered the single pole operation state, if so, executing S2, if not, executing S3; S2, using the WAMS system to coordinately control the reactive power of each substation in the DC landing dense area by a delay method, until any converter station in the DC landing dense area exits the single pole operation state, exits the coordinated control of the WAMS system, and executes S3; S3, using the local reactive power regulation control system of each substation in the DC landing dense area to coordinately control the reactive power of the corresponding substation. Although the above scheme accelerates the voltage stabilization process of each substation after the occurrence of DC bias magnetization, and improves the safe and stable operation level of the multi-substation power system in the DC dense landing area, the above scheme does not specifically consider the impact of different operating conditions on DC bias magnetization, and it is difficult to accurately calculate the DC bias magnetization under different operating conditions. Therefore, it is difficult to ensure the safety and stability of the power system. Summary of the invention

[0003] In view of the problem that the prior art is difficult to dynamically adapt to the accurate calculation of DC bias magnetism under different working conditions, the present invention provides a DC bias magnetism calculation method based on dynamic modeling of power grid topology, and comprehensively obtains the power grid topology change type through the dynamic nature of the change form of the power grid topology structure information. Furthermore, a dynamic power grid topology model is constructed according to the comprehensively obtained power grid topology change type, and then according to the judgment result of the power grid topology change type, the dynamic power grid topology model can be dynamically adjusted as the working conditions change, and the DC bias magnetism under the corresponding working conditions is accurately calculated according to the dynamic power grid topology model obtained by the dynamic adjustment, thereby meeting the accurate calculation requirements of DC bias magnetism under different working conditions, solving the problem that the prior art is difficult to dynamically adapt to the accurate calculation of DC bias magnetism under different working conditions, and significantly improving the safety and stability of the power system.

[0004] In order to solve the above technical problems, the present invention provides a DC bias magnetic calculation method based on power grid topology dynamic modeling, comprising the following steps: S1: Obtaining grid topology information based on substation operation information, and building a grid topology model based on the grid topology information; S2: obtaining a grid topology change type based on the change form of the grid topology structure information, and constructing a dynamic grid topology model based on the grid topology change type and the grid topology model; S3: Based on the real-time acquired grid operation information, determine the type of grid topology change, and then obtain a determination result, and obtain a DC bias current based on the determination result and a dynamic grid topology model.

[0005] After adopting the above technical solution, the present invention has the following advantages: By obtaining the operation information of the substation, the topology of the power grid can be accurately obtained, which lays the foundation for the construction of the dynamic power grid topology model, thereby improving the accuracy of the dynamic power grid topology model; The grid topology change type is comprehensively obtained through the dynamics of the change form of the grid topology structure information. Furthermore, a dynamic grid topology model is constructed according to the comprehensively obtained grid topology change type. Then, according to the judgment result of the grid topology change type, the dynamic grid topology model can be dynamically adjusted as the working conditions change. The DC bias magnetization under the corresponding working conditions is accurately calculated according to the dynamic grid topology model obtained by the dynamic adjustment, thereby meeting the accurate calculation requirements of the DC bias magnetization under different working conditions and significantly improving the safety and stability of the power system. The problem of accurate calculation of DC bias magnetization that is difficult to dynamically adapt to different working conditions is solved.

[0006] Preferably, the S1 comprises: S11: pre-processing the substation operation information, and obtaining key operation information from the operation information based on the influencing factors of the power grid topology; S12: Analyze the characteristics of the key operation information, combine the key operation information with the same characteristics to obtain the power grid topology information, and determine whether there is abnormal key operation information in the power grid topology information. If there is and the number is greater than a preset number, execute S11; if not, execute S13; if there is and the number is less than or equal to the preset number, correct the abnormal key operation information in the power grid topology information based on the historical operation information of the substation, and execute S13; S13: Constructing a power grid topology model based on the power grid topology structure information. Considering that there is information in the operation information of the substation that does not contribute to the construction of the power grid topology model, extracting key operation information from it helps to improve the calculation efficiency. Considering that there may be key operation information in the power grid topology structure information that has an impact on the construction of the power grid topology model and is abnormal, it is necessary to make a judgment to eliminate the operation of the key operation information that has an impact on the construction of the power grid topology model and is abnormal, thereby improving the accuracy of the power grid topology model.

[0007] Preferably, in S2, the types of grid topology changes include changes in the number of substations, changes in transformer grounding methods, and changes in the incorporation of distributed power sources into the grid.

[0008] Preferably, in S2, constructing a dynamic power grid topology model based on the power grid topology change type and the power grid topology model includes: According to the change in the number of substations, the dimensions of the matrix and the vector in the power grid topology model and the values ​​of the elements in the matrix and the vector are updated, thereby obtaining a first dynamic power grid topology model; The values ​​of the elements in the matrix and the vector in the power grid topology model are updated according to the change of the transformer grounding mode, thereby obtaining a second dynamic power grid topology model; The values ​​of the elements in the vector in the power grid topology model are updated according to the changes in the integration of distributed power sources into the power grid, thereby obtaining a third dynamic power grid topology model. The first dynamic power grid topology model, the second dynamic power grid topology model and the third dynamic power grid topology model constitute the dynamic power grid topology model.

[0009] Considering that when the number of substations changes, the dimensions of matrices and vectors in the power grid topology model will be affected by the number of substations, and the values ​​of the elements in the matrices and vectors will also change accordingly. Therefore, the dimensions of the matrices and vectors and the values ​​of the elements in the matrices and vectors in the power grid topology model are updated according to the change in the number of substations; considering that when the transformer grounding method changes, the values ​​of the elements in the matrices and vectors in the power grid topology model will change accordingly, so the values ​​of the elements in the matrices and vectors in the power grid topology model are updated according to the change in the transformer grounding method; considering that when the distributed power sources are connected to the power grid, the values ​​of the elements in the vectors in the power grid topology model will change accordingly, so the values ​​of the elements in the vectors in the power grid topology model are updated according to the change in the distributed power sources connected to the power grid; by updating the power grid topology model according to the type of power grid topology change, it can be ensured that the dynamic power grid topology model finally obtained is always consistent with the actual operating state of the power grid, which helps to improve the accuracy of the dynamic power grid topology model, thereby improving the accuracy of the obtained DC bias current, and enhancing the adaptability of the dynamic power grid topology model. By updating the dimensions and element values ​​of matrices and vectors to reflect the power grid topology change, the reconstruction of the entire dynamic power grid topology model can be avoided, which helps to reduce the amount of calculation and improve the calculation efficiency.

[0010] Preferably, updating the dimensions of matrices and vectors and the values ​​of elements in the matrices and vectors in the power grid topology model according to the change in the number of substations to obtain the first dynamic power grid topology model includes: The dimensions of the matrix and the vector in the power grid topology model are updated according to the difference in the total number of substations before and after the change in the number of substations, thereby obtaining an initial first dynamic power grid topology model; When the number of substations increases, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are updated based on the circuit parameters of the connection lines of the added substations; when the number of substations decreases, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are updated based on the circuit parameters of the connection lines of the decreased substations; When the number of substations increases, the values ​​of the elements in the first vector in the initial first dynamic power grid topology model are obtained based on the conductance column vectors of the added substations, thereby obtaining the process first dynamic power grid topology model; when the number of substations decreases, the values ​​of the elements in the first vector in the initial first dynamic power grid topology model are obtained based on the conductance column vectors of the decreased substations, thereby obtaining the process first dynamic power grid topology model; The second vector in the first dynamic power grid topology model is obtained based on the matrix in the first dynamic power grid topology model and the first vector in the first dynamic power grid topology model. The matrix in the first dynamic power grid topology model, the first vector in the first dynamic power grid topology model and the second vector in the first dynamic power grid topology model constitute the first dynamic power grid topology model. By considering the increase and decrease in the number of substations, the first dynamic power grid topology model can more flexibly respond to changes in the power grid structure, while further enhancing the adaptability of the first dynamic power grid topology model and further improving the accuracy of the obtained DC bias current.

[0011] Preferably, updating the values ​​of elements in the matrix and the vector in the power grid topology model according to the change of the transformer grounding mode to obtain the second dynamic power grid topology model includes: When the transformer grounding grid is connected in series with a resistor, the value of the element in the first vector in the vector is obtained based on the conductance column vector and the resistance value of the substation affected by the resistor, thereby obtaining an initial second dynamic power grid topology model; when the transformer is not grounded, the value of the element in the first vector is set to a preset value, thereby obtaining an initial second dynamic power grid topology model; Obtaining values ​​of elements in a matrix in the initial second dynamic power grid topology model based on values ​​of elements in a first vector in the initial second dynamic power grid topology model, thereby obtaining a process second dynamic power grid topology model; The second vector in the second dynamic grid topology model is obtained based on the first vector in the second dynamic grid topology model, and the matrix in the second dynamic grid topology model, the first vector in the second dynamic grid topology model and the second vector in the second dynamic grid topology model constitute the second dynamic grid topology model. By considering the series resistance and the ungrounded situation in the transformer grounding mode change, the second dynamic grid topology model can more flexibly respond to the change of the grid structure, while further enhancing the adaptability of the second dynamic grid topology model, and further improving the accuracy of the obtained DC bias current.

[0012] Preferably, updating the values ​​of elements in the vector in the power grid topology model according to the change of the distributed power source being connected to the power grid, thereby obtaining the third dynamic power grid topology model comprises: Acquire the injection current of the distributed power source connected to the power grid based on the type of the distributed power source connected to the power grid; The voltage distribution of the substation is obtained based on the injection current of the distributed generation and the injection current of the substation, and the value of the element in the second vector in the vector is updated based on the voltage distribution, so as to obtain the third dynamic power grid topology model of the process; The matrix in the third dynamic grid topology model, the first vector in the third dynamic grid topology model and the second vector in the third dynamic grid topology model constitute the third dynamic grid topology model. By considering the type of distributed power sources connected to the grid and obtaining the corresponding third dynamic grid topology model, the third dynamic grid topology model can more flexibly respond to changes in the grid structure. While further enhancing the adaptability of the third dynamic grid topology model, the accuracy of the obtained DC bias current is further improved.

[0013] Preferably, the obtaining of the voltage distribution of the substation based on the injection current of the distributed power source and the injection current of the substation includes: U i+1 =U i +Z i+1 (I i+1 +I dgs ), where U i is the voltage of substation i, U i+1 is the voltage of substation i+1, Z i+1 is the impedance of the i+1 branch, I i+1 is the injected current of substation i+1, I dgs is the injected current of the distributed power supply.

[0014] Preferably, the second vector in the third dynamic power grid topology model of the process is P=G -1 gV+ZI, where P is the second vector, G is the matrix in the power grid topology model, g is the first vector in the third dynamic power grid topology model of the process, V is the column vector of the surface potential distribution of the substation, Z is the impedance on the branch, and I is the injected current of the distributed power source.

[0015] Preferably, in S3, the DC bias current is obtained based on the judgment result and the dynamic grid topology model, including: if it is judged that the number of substations has changed, the DC bias current is obtained based on the first dynamic grid topology model; if it is judged that the transformer grounding method has changed, the DC bias current is obtained based on the second dynamic grid topology model; if it is judged that the distributed power source is connected to the grid, the DC bias current is obtained based on the third dynamic grid topology model. By selecting a dynamic grid topology model that matches the type of grid topology change for calculation, the adaptability of the dynamic grid topology model is further enhanced, and the accuracy of the DC bias current obtained is further improved.

[0016] Beneficial effects of this program: By obtaining the operation information of the substation, the topology of the power grid can be accurately obtained, which lays the foundation for the construction of the dynamic power grid topology model, thereby improving the accuracy of the dynamic power grid topology model; The grid topology change type is comprehensively obtained through the dynamics of the change form of the grid topology structure information. Furthermore, a dynamic grid topology model is constructed according to the comprehensively obtained grid topology change type. Then, according to the judgment result of the grid topology change type, the dynamic grid topology model can be dynamically adjusted as the working conditions change. The DC bias magnetization under the corresponding working conditions is accurately calculated according to the dynamic grid topology model obtained by the dynamic adjustment, thereby meeting the accurate calculation requirements of the DC bias magnetization under different working conditions and significantly improving the safety and stability of the power system. By further refining each type of grid topology change, the adaptability of the dynamic grid topology model is further enhanced, and the accuracy of the obtained DC bias current is further improved; The problem of accurate calculation of DC bias magnetization that is difficult to dynamically adapt to different working conditions is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. Also, the same reference symbols are used throughout the drawings to represent the same parts.

[0018] Figure 1 It is a flow chart of the DC bias magnetic calculation method based on the dynamic modeling of power grid topology of the present invention; DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations (or steps) as sequential processes, many of the operations (or steps) therein can be implemented in parallel, concurrently, or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the drawings; the process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0021] Embodiment 1: like Figure 1 As shown, the DC bias magnetic calculation method based on the dynamic modeling of the power grid topology includes the following steps: S1: Obtain grid topology information based on the operation information of the substation, and build a grid topology model based on the grid topology information.

[0022] The S1 includes: S11: pre-processing the substation operation information, and obtaining key operation information from the operation information based on the influencing factors of the power grid topology; S12: Analyze the characteristics of the key operation information, combine the key operation information with the same characteristics to obtain the power grid topology information, and determine whether there is abnormal key operation information in the power grid topology information. If there is and the number is greater than a preset number, execute S11; if not, execute S13; if there is and the number is less than or equal to the preset number, correct the abnormal key operation information in the power grid topology information based on the historical operation information of the substation, and execute S13; S13: Construct a power grid topology model based on the power grid topology structure information.

[0023] In this embodiment, a sensor network, a supervisory control and data acquisition system (SCADA) or a remote terminal unit (RTU) and other devices are used to obtain the operation information of the substation. The operation information of the substation includes the substation transformer, the grounding grid, the line connection between the substation nodes and its line resistance, the distributed power supply and the load power of the access substation node, the node voltage and the impedance of each branch. The operation information of the substation is preprocessed by cleaning, denoising, missing value, and abnormal value detection to ensure the accuracy and reliability of the data. According to the needs of the power grid topology model construction, key operation information is extracted from the preprocessed data, such as the substation node voltage, power, equipment resistance line connection, etc. Extracting key operation information from the operation information of the substation helps to improve the calculation efficiency.

[0024] The resistance of multiple transformers, transmission lines, and grounding grids in the substation node is equivalent, and the key operation information is analyzed by multi-feature using data analysis technology. The power grid topology model is constructed based on the analysis results. The power grid topology model includes the matrix in the power grid topology model. G is the matrix in the power grid topology model, i.e., the substation node admittance matrix, n is the number of substations, a ij Indicates the line connection status of the substation node, a ij =1 means that substation node i and substation node j are connected by a line, a ij =0 means that there is no line connection between substation node i and substation node j. The value calculation formula of the elements in the matrix is ​​as follows: R i is the equivalent resistance of transformer winding in substation i, Rd i is the equivalent resistance of the transformer grounding grid of substation i, Rx ij is the equivalent resistance of the transmission line between the substation transformer and the j transformer, G ii is the conductance of substation i, and its value is the sum of the conductances of all branches connected to substation i; G ij is the mutual conductance between substation i and substation j, and its value is the sum of the branch conductances connecting substation i and substation j and the negative number; The first vector in the power grid topology model, i.e., the substation conductance column vector, is Where g is the substation conductance column vector, g i It represents the sum of equivalent conductance of transformer i and grounding grid of substation; The second vector in the power grid topology model is the substation node voltage column vector U = [U 1 , ..., U n ], where U is the substation node voltage column vector, U i is the voltage of node i in substation.

[0025] S2: Obtain the type of grid topology change based on the change form of the grid topology structure information, and build a dynamic grid topology model based on the grid topology change type and the grid topology model.

[0026] In S2, the types of grid topology changes include changes in the number of substations, changes in transformer grounding methods, and changes in the integration of distributed power sources into the grid.

[0027] In S2, the construction of a dynamic power grid topology model based on the power grid topology change type and the power grid topology model includes: updating the dimensions of matrices and vectors in the power grid topology model and the values ​​of elements in the matrices and vectors according to the change in the number of substations, thereby obtaining a first dynamic power grid topology model; The values ​​of the elements in the matrix and the vector in the power grid topology model are updated according to the change of the transformer grounding mode, thereby obtaining a second dynamic power grid topology model; The values ​​of the elements in the vector in the power grid topology model are updated according to the changes in the integration of distributed power sources into the power grid, thereby obtaining a third dynamic power grid topology model. The first dynamic power grid topology model, the second dynamic power grid topology model and the third dynamic power grid topology model constitute the dynamic power grid topology model.

[0028] The updating of the dimensions of matrices and vectors and the values ​​of the elements in the matrices and vectors in the power grid topology model according to the change in the number of substations, thereby obtaining the first dynamic power grid topology model includes: The dimensions of the matrix and the vector in the power grid topology model are updated according to the difference in the total number of substations before and after the change in the number of substations, thereby obtaining an initial first dynamic power grid topology model; When the number of substations increases, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are updated based on the circuit parameters of the connection lines of the added substations; when the number of substations decreases, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are updated based on the circuit parameters of the connection lines of the decreased substations; When the number of substations increases, the values ​​of the elements in the first vector in the initial first dynamic power grid topology model are obtained based on the conductance column vectors of the added substations, thereby obtaining the process first dynamic power grid topology model; when the number of substations decreases, the values ​​of the elements in the first vector in the initial first dynamic power grid topology model are obtained based on the conductance column vectors of the decreased substations, thereby obtaining the process first dynamic power grid topology model; Based on the matrix in the first dynamic power grid topology model of the process and the first vector in the first dynamic power grid topology model of the process, the second vector in the first dynamic power grid topology model of the process is obtained. The matrix in the first dynamic power grid topology model of the process, the first vector in the first dynamic power grid topology model of the process and the second vector in the first dynamic power grid topology model of the process constitute the first dynamic power grid topology model.

[0029] The updating of the values ​​of the elements in the matrix and the vector in the power grid topology model according to the change of the transformer grounding mode, thereby obtaining the second dynamic power grid topology model includes: When the transformer grounding grid is connected in series with a resistor, the value of the element in the first vector in the vector is obtained based on the conductance column vector and the resistance value of the substation affected by the resistor, thereby obtaining an initial second dynamic power grid topology model; when the transformer is not grounded, the value of the element in the first vector is set to a preset value, thereby obtaining an initial second dynamic power grid topology model; Obtaining values ​​of elements in a matrix in the initial second dynamic power grid topology model based on values ​​of elements in a first vector in the initial second dynamic power grid topology model, thereby obtaining a process second dynamic power grid topology model; Based on the first vector in the second dynamic power grid topology model of the process, the second vector in the second dynamic power grid topology model of the process is obtained. The matrix in the second dynamic power grid topology model of the process, the first vector in the second dynamic power grid topology model of the process and the second vector in the second dynamic power grid topology model of the process constitute the second dynamic power grid topology model.

[0030] The updating of the values ​​of the elements in the vector in the power grid topology model according to the change of the distributed power generation being connected to the power grid, thereby obtaining the third dynamic power grid topology model includes: Acquire the injection current of the distributed power source connected to the power grid based on the type of the distributed power source connected to the power grid; The voltage distribution of the substation is obtained based on the injection current of the distributed generation and the injection current of the substation, and the value of the element in the second vector in the vector is updated based on the voltage distribution, so as to obtain the third dynamic power grid topology model of the process; The matrix in the process third dynamic power grid topology model, the first vector in the process third dynamic power grid topology model and the second vector in the process third dynamic power grid topology model constitute the third dynamic power grid topology model.

[0031] The method of obtaining the voltage distribution of the substation based on the injection current of the distributed power source and the injection current of the substation includes: U i+1 =U i +Z i+1 (I i+1 +I dgs ), where U i is the voltage of substation i, U i+1 is the voltage of substation i+1, Z i+1 is the impedance of the i+1 branch, I i+1 is the injected current of substation i+1, I dgs is the injected current of the distributed power supply.

[0032] The second vector in the third dynamic power grid topology model of the process is P=G -1 gV+ZI, where P is the second vector, G is the matrix in the power grid topology model, g is the first vector in the third dynamic power grid topology model of the process, V is the column vector of the surface potential distribution of the substation, Z is the impedance on the branch, and I is the injected current of the distributed power source.

[0033] In this embodiment, when the number of substations increases, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are obtained based on the circuit parameters of the connection lines of the added substations as follows: Among them, G ij is the mutual conductance between substation i and substation j in the initial first dynamic power grid topology model, n is the number of substations in the power grid topology model, m is the number of added substation nodes, R ij G is the equivalent resistance of the line connected to the added substation node. ii is the added self-conductance of the substation i node, g i is the equivalent conductance sum of the transformer i and the grounding grid of the substation in the initial first dynamic power grid topology model, 1≤i, j≤n+m; when the number of substations decreases, that is, when the substation is shut down for maintenance, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are obtained based on the circuit parameters of the connecting lines of the reduced substations as follows: Among them, G is the matrix in the initial first dynamic power grid topology model, G ij is the mutual conductance between substation i and substation j in the initial first dynamic power grid topology model, n is the number of substations in the power grid topology model, m is the number of reduced substation nodes, r ij G is the equivalent resistance of the line connected to the reduced substation node. ii is the reduced self-conductance of the substation node i, g i is the equivalent conductance sum of the transformer i and the grounding grid of the substation in the initial first dynamic power grid topology model, 1≤i, j≤nm; When the number of substations increases, the value of the element in the first vector in the initial first dynamic power grid topology model is obtained based on the conductance column vector of the added substation as follows: g = g n +g m , where g is the transformer conductance column vector in the initial first dynamic power grid topology model, g n is the transformer conductance column vector in the power grid topology model, g m is the increased transformer conductance column vector; when the number of substations decreases, the values ​​of the elements in the first vector in the initial first dynamic power grid topology model are obtained based on the conductance column vectors of the reduced substations as follows: g=g n -gm , where g is the transformer conductance column vector in the initial first dynamic power grid topology model, g n is the transformer conductance column vector in the power grid topology model, g m is the reduced transformer conductance column vector; based on the matrix in the first dynamic power grid topology model of the process and the first vector in the first dynamic power grid topology model of the process, the second vector in the first dynamic power grid topology model of the process is obtained as follows: U=G -1 gV,U is the voltage column vector of the substation node in the first dynamic power grid topology model of the process, and V is the surface point position column vector of the substation node in the first dynamic power grid topology model of the process.

[0034] By considering the increase and decrease in the number of substations, the first dynamic grid topology model can respond to changes in the grid structure more flexibly, while further enhancing the adaptability of the first dynamic grid topology model and further improving the accuracy of the obtained DC bias current.

[0035] When the transformer grounding grid is connected in series with a resistor, the values ​​of the elements in the first vector in the vector are obtained based on the conductance column vector of the substation affected by the resistor and the resistance value. The resistance value is set to 3. g i is the conductance column vector of the substation affected by the resistance. When the transformer is not grounded, the value of the element in the first vector is set to 0; The specific method for obtaining the values ​​of the elements in the matrix in the initial second dynamic power grid topology model based on the values ​​of the elements in the first vector in the initial second dynamic power grid topology model is as follows: ii =∑ j G ij -G ii +g i ; The second vector in the second dynamic power grid topology model is obtained based on the first vector in the second dynamic power grid topology model as follows: U=G -1 g V , U is the voltage column vector of the substation node in the second dynamic grid topology model of the process, and V is the surface point column vector of the substation node in the second dynamic grid topology model of the process. By considering the series resistance and the ungrounded situation in the change of transformer grounding mode, the second dynamic grid topology model can respond to the changes of the grid structure more flexibly, while further enhancing the adaptability of the second dynamic grid topology model, and further improving the accuracy of the obtained DC bias current.

[0036] The injection current of the distributed power source connected to the grid is obtained based on the type of the distributed power source connected to the grid as follows: If the distributed power source is wind power generation, it is a PQ constant node. At this time, the calculation formula for the injection current of the distributed power source is: Where P and Q are the active and reactive powers of the distributed power source, e and f are the real and imaginary parts of the distributed power source voltage respectively; When the distributed power source is photovoltaic power generation, it is a PV constant node. At this time, the calculation formula for the distributed power source injection current is: Where Z ii is the node impedance, V i is the node voltage vector; The calculation formula of substation node injection current is: Among them, I i Inject current into common node i; S i is the injected power corresponding to node i, V i is the injected power voltage corresponding to node i.

[0037] By considering the type of distributed power sources connected to the power grid and obtaining the corresponding third dynamic power grid topology model, the third dynamic power grid topology model can more flexibly respond to changes in the power grid structure. While further enhancing the adaptability of the third dynamic power grid topology model, the accuracy of the obtained DC bias current is further improved.

[0038] S3: Based on the real-time acquired grid operation information, determine the type of grid topology change, and then obtain a determination result, and obtain a DC bias current based on the determination result and a dynamic grid topology model.

[0039] In S3, obtaining the DC bias current based on the judgment result and the dynamic power grid topology model includes: If it is judged that the number of substations has changed, the DC bias current is obtained based on the first dynamic grid topology model. If it is judged that the transformer grounding method has changed, the DC bias current is obtained based on the second dynamic grid topology model. If it is judged that the distributed power source is connected to the grid, the DC bias current is obtained based on the third dynamic grid topology model.

[0040] In this embodiment, the DC bias current calculation formula is: I = (UV) g, where I is the DC bias current, U = G -1 By selecting a dynamic grid topology model that matches the type of grid topology change for calculation, the adaptability of the dynamic grid topology model is further enhanced, and the accuracy of the obtained DC bias current is further improved.

[0041] The specific implementation described above is a preferred implementation of the DC bias magnetic calculation method based on dynamic modeling of power grid topology of the present invention, and is not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to this specific implementation. All equivalent changes made in accordance with the shape and structure of the present invention are within the protection scope of the present invention.

Claims

1. A DC bias magnetic calculation method based on dynamic modeling of power grid topology, characterized in that: The following steps are involved: S1: Obtaining grid topology information based on substation operation information, and building a grid topology model based on the grid topology information; S2: obtaining a grid topology change type based on the change form of the grid topology structure information, and constructing a dynamic grid topology model based on the grid topology change type and the grid topology model; S3: Based on the real-time acquired grid operation information, determine the type of grid topology change, and then obtain a determination result, and obtain a DC bias current based on the determination result and a dynamic grid topology model.

2. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 1 is characterized in that: The S1 includes: S11: pre-processing the substation operation information, and obtaining key operation information from the operation information based on the influencing factors of the power grid topology; S12: Analyze the characteristics of the key operation information, combine the key operation information with the same characteristics to obtain the power grid topology information, and determine whether there is abnormal key operation information in the power grid topology information. If there is and the number is greater than a preset number, execute S11; if not, execute S13; if there is and the number is less than or equal to the preset number, correct the abnormal key operation information in the power grid topology information based on the historical operation information of the substation, and execute S13; S13: Construct a power grid topology model based on the power grid topology structure information.

3. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 1 is characterized in that: In S2, the types of grid topology changes include changes in the number of substations, changes in transformer grounding methods, and changes in the integration of distributed power sources into the grid.

4. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 3 is characterized in that: In S2, the construction of a dynamic power grid topology model based on the power grid topology change type and the power grid topology model includes: According to the change in the number of substations, the dimensions of the matrix and the vector in the power grid topology model and the values ​​of the elements in the matrix and the vector are updated, thereby obtaining a first dynamic power grid topology model; The values ​​of the elements in the matrix and the vector in the power grid topology model are updated according to the change of the transformer grounding mode, thereby obtaining a second dynamic power grid topology model; The values ​​of the elements in the vector in the power grid topology model are updated according to the changes in the integration of distributed power sources into the power grid, thereby obtaining a third dynamic power grid topology model. The first dynamic power grid topology model, the second dynamic power grid topology model and the third dynamic power grid topology model constitute the dynamic power grid topology model.

5. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 4 is characterized in that: The updating of the dimensions of matrices and vectors and the values ​​of the elements in the matrices and vectors in the power grid topology model according to the change in the number of substations, thereby obtaining the first dynamic power grid topology model includes: The dimensions of the matrix and the vector in the power grid topology model are updated according to the difference in the total number of substations before and after the change in the number of substations, thereby obtaining an initial first dynamic power grid topology model; When the number of substations increases, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are updated based on the circuit parameters of the connection lines of the added substations; when the number of substations decreases, the values ​​of the elements in the matrix in the initial first dynamic power grid topology model are updated based on the circuit parameters of the connection lines of the decreased substations; When the number of substations increases, the values ​​of the elements in the first vector in the initial first dynamic power grid topology model are obtained based on the conductance column vectors of the added substations, thereby obtaining the process first dynamic power grid topology model; when the number of substations decreases, the values ​​of the elements in the first vector in the initial first dynamic power grid topology model are obtained based on the conductance column vectors of the decreased substations, thereby obtaining the process first dynamic power grid topology model; Based on the matrix in the first dynamic power grid topology model of the process and the first vector in the first dynamic power grid topology model of the process, the second vector in the first dynamic power grid topology model of the process is obtained. The matrix in the first dynamic power grid topology model of the process, the first vector in the first dynamic power grid topology model of the process and the second vector in the first dynamic power grid topology model of the process constitute the first dynamic power grid topology model.

6. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 4 is characterized in that: The updating of the values ​​of the elements in the matrix and the vector in the power grid topology model according to the change of the transformer grounding mode, thereby obtaining the second dynamic power grid topology model includes: When the transformer grounding grid is connected in series with a resistor, the value of the element in the first vector in the vector is obtained based on the conductance column vector and the resistance value of the substation affected by the resistor, thereby obtaining an initial second dynamic power grid topology model; when the transformer is not grounded, the value of the element in the first vector is set to a preset value, thereby obtaining an initial second dynamic power grid topology model; Obtaining values ​​of elements in a matrix in the initial second dynamic power grid topology model based on values ​​of elements in a first vector in the initial second dynamic power grid topology model, thereby obtaining a process second dynamic power grid topology model; Based on the first vector in the second dynamic power grid topology model of the process, the second vector in the second dynamic power grid topology model of the process is obtained. The matrix in the second dynamic power grid topology model of the process, the first vector in the second dynamic power grid topology model of the process and the second vector in the second dynamic power grid topology model of the process constitute the second dynamic power grid topology model.

7. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 4 is characterized in that: The updating of the values ​​of the elements in the vector in the power grid topology model according to the change of the distributed power generation being connected to the power grid, thereby obtaining the third dynamic power grid topology model includes: Acquire the injection current of the distributed power source connected to the power grid based on the type of the distributed power source connected to the power grid; The voltage distribution of the substation is obtained based on the injection current of the distributed generation and the injection current of the substation, and the value of the element in the second vector in the vector is updated based on the voltage distribution, so as to obtain the third dynamic power grid topology model of the process; The matrix in the process third dynamic power grid topology model, the first vector in the process third dynamic power grid topology model and the second vector in the process third dynamic power grid topology model constitute the third dynamic power grid topology model.

8. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 7 is characterized in that: The method of obtaining the voltage distribution of the substation based on the injection current of the distributed power source and the injection current of the substation includes: U i+1 =U i +Z i+1 (I i+1 +I dgs ), where U i is the voltage of substation i, U i+1 is the voltage of substation i+1, Z i+1 is the impedance of the i+1 branch, I i+1 is the injected current of substation i+1, I dgs is the injected current of the distributed power supply.

9. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 7 is characterized in that: The second vector in the third dynamic power grid topology model of the process is P=G -1 gV+ZI, where P is the second vector, G is the matrix in the power grid topology model, g is the first vector in the third dynamic power grid topology model of the process, V is the column vector of the surface potential distribution of the substation, Z is the impedance on the branch, and I is the injected current of the distributed power source.

10. The DC bias magnetic calculation method based on power grid topology dynamic modeling according to claim 4 is characterized in that: In S3, obtaining the DC bias current based on the judgment result and the dynamic power grid topology model includes: If it is judged that the number of substations has changed, the DC bias current is obtained based on the first dynamic grid topology model. If it is judged that the transformer grounding method has changed, the DC bias current is obtained based on the second dynamic grid topology model. If it is judged that the distributed power source is connected to the grid, the DC bias current is obtained based on the third dynamic grid topology model.

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