Generalized AC-DC power distribution network load flow calculation method, system, device and medium

Abstract

The invention discloses a generalized AC-DC power distribution network load flow calculation method, system and device and a medium, and the method comprises the steps: carrying out the first recognition operation according to the topological structure of a power distribution network, and obtaining the loop type of the network; performing a second identification operation according to the control mode of the distributed energy resources to obtain a special bus type; initializing network parameters, performing first calculation, verifying realizability of a result of the first calculation, and adjusting parameters which do not meet conditions; constructing a generalized sensitivity matrix, and synchronously solving current injection amounts of all breakpoints; mapping the current injection amounts of all the breakpoints to corresponding nodes, calculating the bus current through a first scanning mode, and calculating the bus voltage through a second scanning mode; and updating the power factor of the rectifier, judging whether the load converges, and outputting a final parameter and a power flow result. According to the method, an efficient solution is provided for real-time optimization of the intelligent power distribution network through the synergistic effect of regional voltage transmission and the generalized sensitivity matrix.

Description

Technical Field

[0001] This invention relates to the field of power flow analysis technology for power distribution networks, and in particular to a method, system, device, and medium for calculating power flow in a generalized AC-DC power distribution network. Background Technology

[0002] With the rapid development of distributed energy and new energy technologies, the structure and function of power distribution networks have undergone profound changes. Especially in the context of low-carbon energy transition, distributed power sources such as photovoltaics, wind power, energy storage systems, micro gas turbines, and micro hydropower have been extensively integrated into traditional power distribution networks, prompting the power distribution system to evolve from a pure AC system into a generalized AC-DC power distribution network that includes a hybrid AC and DC architecture.

[0003] These systems exhibit three main characteristics: First, heterogeneous network structure, with AC feeders, DC buses, and power electronic interface devices forming a complex topology with multiple voltage levels coupled together; second, diversified control strategies, with DG nodes capable of operating in various modes such as constant PQ, constant voltage, and droop control, and requiring smooth switching between grid-connected and islanded states; and third, dynamic operating states, with intermittent output and load fluctuations of distributed generation leading to frequent changes in power flow direction. These characteristics pose significant challenges to traditional power flow calculation techniques based on the Newton-Raphson method: First, AC / DC hybrid nodes must simultaneously handle the strong nonlinear coupling between AC phase angle and DC voltage, leading to a deterioration in the Jacobian matrix condition number and easy iteration divergence; second, DGs with different control modes require differentiated modeling, and traditional algorithms struggle to be compatible with the mixed solution of PQ nodes, PV nodes, and droop control nodes; third, the switching characteristics of power electronic interfaces introduce discrete variables, posing a risk of numerical oscillation in the joint solution of continuous power flow equations and discrete control logic. While existing improved algorithms, such as the unified iterative method and the sequential solution method, have partially alleviated the AC / DC coupling problem, they still suffer from low computational efficiency and poor adaptability to mode switching when dealing with large-scale DG access, and cannot meet the engineering requirements of real-time simulation, rapid evaluation and optimized scheduling of new power distribution systems.

[0004] Therefore, there is an urgent need to develop a generalized AC-DC power flow calculation method that is robust, computationally efficient, and compatible with multiple control modes. Summary of the Invention

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, this invention provides a method, system, device, and medium for calculating power flow in a generalized AC-DC distribution network. The problem it solves is that traditional power flow calculation methods are difficult to effectively handle the high computational complexity, poor convergence, and insufficient scalability caused by multi-control mode DG access, AC / DC hybrid coupled node modeling, and large-scale distributed equipment grid connection in generalized AC-DC distribution networks.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a method for calculating power flow in a generalized AC-DC distribution network, comprising:

[0009] The first identification operation is performed based on the topology of the power distribution network to obtain the loop type of the network;

[0010] A second identification operation is performed based on the control mode of distributed energy resources to obtain the special bus type;

[0011] Based on the loop type and special bus type of the network, the network parameters are initialized and a first calculation is performed. The feasibility of the result of the first calculation is verified, and parameters that do not meet the conditions are adjusted.

[0012] Construct a generalized sensitivity matrix and simultaneously solve for the current injection at all breakpoints;

[0013] Map the current injection amount of all the breakpoints to the corresponding nodes, calculate the bus current using the first scanning method, and calculate the bus voltage using the second scanning method;

[0014] Update the rectifier's power factor and determine if the load has converged, then output the final parameters and power flow results.

[0015] As a preferred embodiment of the generalized AC-DC power flow calculation method for distribution networks described in this invention, the construction of the generalized sensitivity matrix and the simultaneous solution of the current injection quantity at all breakpoints include:

[0016] Identify the first breakpoint information;

[0017] By integrating the physical relationships between the information from the first breakpoint, a generalized sensitivity matrix is ​​constructed;

[0018] The voltage deviation of voltage-controlled distributed energy sources is incorporated into the generalized sensitivity matrix, and the current injection amount at all breakpoints is solved synchronously through the first decomposition calculation operation.

[0019] As a preferred embodiment of the generalized AC-DC power flow calculation method for distribution networks described in this invention, the calculation of bus current using a first scanning method includes:

[0020] The current is summarized layer by layer by the first scanning method, and the load injection current of each bus and the current of all downstream branches are added together.

[0021] If the branch connects to converters in other sub-regions or at breakpoints, the input current of the converter is also included in the cumulative calculation.

[0022] Recursively traverse all branches until the current of the entire network is summed.

[0023] As a preferred embodiment of the generalized AC-DC power flow calculation method for distribution networks described in this invention, the calculation of bus voltage using the second scanning method includes:

[0024] The bus voltage is calculated layer by layer using the second scanning method;

[0025] For downstream nodes connected to the converter, calculate their output voltage based on the converter type and use it as the starting voltage for the next sub-region.

[0026] Recursively process all sub-regions until the voltage calculation for the entire network is completed.

[0027] The beneficial effects of this preferred technical solution are as follows: by using the hierarchical recursive strategy of taking the converter output as the source voltage of the sub-region, the partitioned recursive calculation of the complex network is realized, which greatly reduces the global computational complexity.

[0028] As a preferred embodiment of the generalized AC-DC power flow calculation method for distribution networks described in this invention, the method for obtaining the loop types of the network includes:

[0029] Sub-regions are divided based on the number and location of node-to-node interface converters in the power distribution network. Each sub-region is connected to other sub-regions through converters, forming a tree-like or radial structure.

[0030] Identify the types of loops in the network, including Type A loops that contain only AC nodes and no converters, Type B loops that contain only DC nodes and no converters, and Type C loops that contain AC / DC nodes or DC nodes of different voltage levels and may contain converters.

[0031] As a preferred embodiment of the generalized AC-DC power flow calculation method for distribution networks described in this invention, the step of obtaining the special bus type includes:

[0032] Check the control mode of the distributed energy resources connected to each bus;

[0033] If it connects to distributed energy resources and the control mode is constant voltage amplitude, it is identified as a PV bus.

[0034] If it is connected to distributed energy resources and the control mode is constant DC voltage, it is identified as a DC voltage bus.

[0035] As a preferred embodiment of the generalized AC-DC power flow calculation method for distribution networks described in this invention, the step of verifying the feasibility of the first calculation result and adjusting parameters that do not meet the conditions includes:

[0036] For single-phase PWM inverters and single-phase PWM rectifiers, verify whether the modulation parameters meet the first judgment condition. If the first judgment condition is met, the modulation parameters remain unchanged; otherwise, perform the second judgment and adjust the modulation parameters according to the result of the second judgment.

[0037] For a DC-DC converter, verify whether the duty cycle meets the third judgment condition. If the third judgment condition is met, the duty cycle remains unchanged; otherwise, perform the fourth judgment and adjust the duty cycle according to the result of the fourth judgment.

[0038] The beneficial effects of this preferred technical solution are: by combining reverse current scanning and dynamic parameter adjustment, the algorithm remains robust under load fluctuations and impedance changes.

[0039] Secondly, the present invention provides a generalized AC-DC power flow calculation system for distribution networks, comprising:

[0040] The first identification module is used to perform a first identification operation based on the topology of the power distribution network to obtain the loop type of the network;

[0041] The second identification module is used to perform a second identification operation based on the control mode of distributed energy resources to obtain the special bus type.

[0042] The parameter calculation and adjustment module is used to initialize network parameters and perform a first calculation based on the loop type and special bus type of the network, verify the feasibility of the result of the first calculation, and adjust the parameters that do not meet the conditions.

[0043] The iterative calculation module is used to construct a generalized sensitivity matrix and simultaneously solve for the current injection amount at all breakpoints; it maps the current injection amount at all breakpoints to the corresponding nodes, calculates the bus current through a first scanning method, and calculates the bus voltage through a second scanning method.

[0044] The output module is used to update the rectifier's power factor and determine whether the load has converged, outputting the final parameters and power flow results.

[0045] Thirdly, the present invention provides an electronic device, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor executes the computer-executable instructions to implement the steps of a generalized AC-DC power flow calculation method for power distribution networks.

[0046] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of a generalized AC-DC power flow calculation method.

[0047] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a method, system, device, and medium for calculating the power flow of a generalized AC-DC distribution network. By accurately modeling the voltage relationship of the AC / DC converter, it ensures the physical consistency of the AC / DC interface voltage conversion and avoids the error accumulation caused by model simplification in traditional methods. By using a hierarchical recursive strategy with the converter output as the source voltage of a sub-region, it achieves partitioned recursive calculation of complex networks, significantly reducing the global computational complexity. Combined with reverse current scanning and dynamic parameter adjustment, the algorithm remains robust under load fluctuations and impedance changes, with the number of iterations remaining stable at 5-8. Its recursive processing mechanism supports hybrid networks with multiple voltage levels and multiple control modes. Through the synergistic effect of regional voltage transfer and the generalized sensitivity matrix, this technology balances high accuracy and strong scalability, providing an efficient solution for real-time optimization of intelligent distribution networks. Attached Figure Description

[0048] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the overall flow logic of the generalized AC-DC power distribution network power flow calculation method according to an embodiment of the present invention.

[0050] Figure 2 This is a flowchart illustrating the calculation method for the generalized AC-DC power flow calculation method in an embodiment of the present invention.

[0051] Figure 3 This is a flowchart illustrating the feasibility verification and adjustment of control parameters for a generalized AC-DC power flow calculation method for distribution networks according to an embodiment of the present invention. Detailed Implementation

[0052] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0053] Example 1, referring to Figure 1 As an embodiment of the present invention, a method for calculating the power flow of a generalized AC-DC distribution network is provided, such as... Figure 1 The specific steps shown are as follows:

[0054] S100: Perform the first identification operation based on the topology of the power distribution network to obtain the loop type of the network;

[0055] S200: Perform a second identification operation based on the control mode of distributed energy resources to obtain the special bus type;

[0056] S300: Based on the network loop type and special bus type, initialize network parameters and perform the first calculation, verify the feasibility of the first calculation result, and adjust parameters that do not meet the conditions;

[0057] S400: Construct a generalized sensitivity matrix and simultaneously solve for the current injection at all breakpoints;

[0058] S500: Map the current injection amount of all breakpoints to the corresponding nodes, calculate the bus current through the first scan method, and calculate the bus voltage through the second scan method;

[0059] S600: Updates the rectifier's power factor and determines whether the load has converged, outputting the final parameters and power flow results.

[0060] It should be noted that, to address the challenges of high computational complexity, poor convergence, and insufficient scalability arising from the difficulty of traditional power flow calculation methods in handling multi-control mode DG access, AC / DC hybrid coupling node modeling, and large-scale distributed equipment grid connection in generalized AC-DC distribution networks, steps S100–S600 above accurately model the voltage relationships of the AC / DC converters to ensure the physical consistency of AC / DC interface voltage conversion, avoiding error accumulation caused by model simplification in traditional methods. By employing a hierarchical recursive strategy using the converter output as the sub-region source voltage, partitioned recursive calculation of complex networks is achieved, significantly reducing global computational complexity. Combined with reverse current scanning and dynamic parameter adjustment, the algorithm maintains robustness under load fluctuations and impedance changes, with the number of iterations remaining stable at 5–8. Its recursive processing mechanism supports hybrid networks with multiple voltage levels and multiple control modes. Through the synergistic effect of regional voltage transfer and the generalized sensitivity matrix, this technology balances high accuracy and strong scalability, providing an efficient solution for real-time optimization of smart distribution networks.

[0061] Example 2, refer to Figure 2 and Figure 3 Based on the previous embodiment, this embodiment provides an application example of a generalized AC-DC power flow calculation method to illustrate the technical means used in this method.

[0062] In this embodiment of the application, the above step S100 performs a first identification operation based on the topology of the power distribution network to obtain the loop type of the network, including the following sub-steps A1 and A2:

[0063] In A1: Sub-regions are divided based on the number and location of node-to-node interface converters in the power distribution network. Each sub-region is connected to other sub-regions through converters, forming a tree-like or radial structure.

[0064] Specifically, if there are σ such converters, the entire network will be divided into σ+1 sub-regions.

[0065] In A2: Identify the types of loops in the network, including:

[0066] Type A loops containing only AC nodes without converters;

[0067] Type B loops containing only DC nodes without converters;

[0068] Type C loop containing AC / DC nodes or DC nodes of different voltage levels and possibly including converters;

[0069] Specifically, through network topology analysis, all closed paths are identified, and based on the node types and converter distribution in the paths, they are classified into Type A / B / C loops and the number of loops is counted.

[0070] In an optional embodiment, the first identification operation may also be to divide the power distribution network into AC high-voltage areas, AC low-voltage areas and DC areas based on voltage level and regional function division, and then identify the loop type according to the internal connection relationship of each area. For example, pure AC loops separated from the AC high-voltage area are classified as Type A, and loops formed by cross-area mixed connections are classified as Type C.

[0071] In another alternative embodiment, the first identification operation may also be to identify strongly connected subgraphs in the network through connected component analysis in graph theory, and then automatically classify loops according to the node attributes within the subgraph. For example, an isolated strongly connected subgraph containing only AC nodes is marked as Type A, and a subgraph containing cross-type connections is marked as Type C.

[0072] It should be noted that step S100 above can accurately distinguish the topological characteristics of AC / DC hybrid networks by identifying the loop type of the network, effectively solving the problem of poor adaptability of traditional methods to complex mesh structures and significantly improving the algorithm's compatibility with different network architectures.

[0073] In this embodiment of the application, step S200 above performs a second identification operation based on the control mode of distributed energy resources to obtain the special bus type, including:

[0074] Check the control mode of the distributed energy resources connected to each bus;

[0075] If it connects to distributed energy resources and the control mode is constant voltage amplitude, it is identified as a PV bus.

[0076] If it is connected to distributed energy resources and the control mode is constant DC voltage, it is identified as a DC voltage bus.

[0077] In an optional embodiment, the second identification operation can also be to automatically identify special bus types based on the historical operating data of the bus. For example, by analyzing the characteristics of bus voltage fluctuation, if the voltage amplitude is stable within a set threshold range for a long period of time, it is determined to be a PV bus; if the DC voltage fluctuation is extremely small, it is determined to be a DC voltage bus.

[0078] In another alternative embodiment, the second identification operation can also identify special buses in conjunction with the scheduling instructions of the energy management system, such as receiving voltage control instructions from the upper-level system, marking the bus that performs constant voltage control as a PV bus, and marking the bus that participates in DC voltage regulation as a DC voltage bus.

[0079] It should be noted that step S200 above, by identifying special bus types such as PV bus and DC voltage bus, can accurately reflect the diverse control modes of distributed energy, overcome the defect of inconsistent expression of control modes in traditional power flow calculation, and provide a basis for the classification of key nodes for subsequent accurate calculation.

[0080] In this embodiment, step S300, based on the network loop type and special bus type, initializes network parameters and performs a first calculation, verifies the feasibility of the first calculation result, and adjusts parameters that do not meet the conditions, including the following sub-steps C1 to C3:

[0081] In C1: Initialize network parameters, specifically including:

[0082] Set the initial bus voltage to the rated value;

[0083] Set convergence tolerance;

[0084] Initialize the iteration counter (t=0) and the maximum number of iterations (t). max =100);

[0085] Configure all AC-DC converters to operate at unity power factor.

[0086] In C2: Perform the first calculation, which is to calculate the modulation index MI and duty cycle D of all converters;

[0087] In this embodiment, the converter includes a single-phase PWM inverter, a single-phase PWM rectifier, and a DC-DC converter, and the modulation index is obtained from the voltage relationship per unit between the input and output terminals of each converter.

[0088] Specifically, for PWM inverters:

[0089] |V j |=V i (MI)

[0090] Specifically, for PWM rectifiers:

[0091]

[0092] Specifically, for DC-DC converters:

[0093] V j =V i (B)

[0094] Among them, V i and V j These represent the input voltage and output voltage, respectively. MI refers to the modulation index of the PWM AC / DC converter. B represents D, 1 / (1-D), and D / (1-D) for buck, boost, and buck-boost operations, respectively. D represents the duty cycle of the DC-DC converter.

[0095] In an optional embodiment, the first calculation may also be based on a neural network prediction model for parameter initialization, directly outputting the initial modulation index and duty cycle of the converter through a trained deep learning network, which uses network topology features, load distribution, and historical operating data as input features.

[0096] In another alternative embodiment, the first calculation may also employ a distributed collaborative computing method, dividing the network into several computing domains, with each domain calculating converter parameters in parallel based on local measurement data, and then integrating and correcting global parameters through a coordinator.

[0097] In C3: such as Figure 3 As shown, the feasibility of the first calculation result is verified, and parameters that do not meet the conditions are adjusted, specifically including:

[0098] For single-phase PWM inverters and single-phase PWM rectifiers, verify whether the modulation parameters meet the first judgment condition. If the first judgment condition is met, the modulation parameters remain unchanged; otherwise, perform the second judgment and adjust the modulation parameters according to the result of the second judgment.

[0099] For DC-DC converters, verify whether the duty cycle meets the third judgment condition. If the third judgment condition is met, the duty cycle remains unchanged; otherwise, perform the fourth judgment and adjust the duty cycle according to the result of the fourth judgment.

[0100] In this embodiment of the application, the first judgment condition is MI∈[MI min MImax If the modulation parameters meet the first judgment condition, the modulation parameters remain unchanged; otherwise, the second judgment is performed, i.e., if MI <MI min Then MI = MI min If MI > MI max Then MI = MI max .

[0101] In this embodiment of the application, the third judgment condition is D∈[D min D max If the duty cycle meets the third condition, the duty cycle remains unchanged; otherwise, the fourth condition is met. <D min Then D = D min If D>D max Then D = D max .

[0102] It should be noted that step S300 above ensures the physical realizability of the converter modulation parameters and duty cycle through parameter initialization and feasibility verification of calculation results, avoiding the divergence problem caused by parameter out-of-bounds in traditional methods, and significantly improving the numerical stability of the algorithm.

[0103] In this embodiment, the above step S400, which constructs the generalized sensitivity matrix and simultaneously solves for the current injection amount at all breakpoints, includes the following sub-steps D1 to D3:

[0104] It should be noted that the original mesh AC-DC distribution network is transformed into an equivalent radial network through topology sorting. The generalized breakpoint matrix is ​​used to calculate the injection amount of each breakpoint simultaneously, thereby comprehensively considering the impact of these breakpoints.

[0105] In D1: Identify the first breakpoint information;

[0106] Specifically, the first breakpoint information includes loop breakpoints: virtual nodes formed by splitting loops, PV breakpoints: voltage control nodes of distributed generation, and DC voltage breakpoints: DC voltage regulation nodes.

[0107] In an optional embodiment, the first breakpoint information can also be a hybrid interface breakpoint and a dynamic load breakpoint. The hybrid interface breakpoint is specifically designed to address the special coupling relationship between AC and DC boundary nodes by adding virtual injection points to balance the network parameters on both sides. The dynamic load breakpoint is used to capture the impact of periodic or random load fluctuations on the system and incorporates them as independent breakpoints into the generalized matrix calculation, thereby improving the calculation accuracy under complex operating conditions.

[0108] In D2: A generalized sensitivity matrix is ​​constructed by integrating the physical relationships between the information from the first breakpoint;

[0109] Specifically, by integrating the physical relationships of loop breakpoints, PV breakpoints, and DC voltage breakpoints, a generalized sensitivity matrix of the following form is constructed:

[0110] Z×ΔI=ΔV

[0111]

[0112] Wherein, ΔV is the breakpoint voltage mismatch vector, which includes the voltage difference between the loop breakpoint (λ1, λ2, etc.), the PV breakpoint (β1), and the DC voltage breakpoint (γ1); ΔI is the breakpoint current injection vector to be calculated, used to compensate for voltage mismatch; the elements of matrix Z are determined by network parameters (such as line impedance, converter efficiency η, modulation index MI, duty cycle D, etc.).

[0113] In D3: The voltage deviation of voltage-controlled distributed energy is incorporated into the generalized sensitivity matrix, and the current injection amount at all breakpoints is solved synchronously through the first decomposition calculation operation;

[0114] Specifically, considering the characteristics of AC and DC networks, the sensitivity matrix is ​​decomposed into real (R) and imaginary (X) blocks to simplify computational complexity, as shown in the following formula:

[0115]

[0116] The elements in the matrix are as follows:

[0117]

[0118] Specifically, for a DC voltage bus, the imaginary current component is forced to be zero, i.e., ΔI q =0; For PV buses, only voltage amplitude deviation needs to be compensated.

[0119] In an optional embodiment, the first decomposition calculation operation can also be based on the parallel computing method of domain decomposition, which divides the network into multiple sub-matrices according to voltage level or regional characteristics. Each sub-matrix is ​​solved independently and then globally integrated through boundary coordination equations. This method is particularly suitable for large-scale heterogeneous networks.

[0120] In another optional embodiment, the first decomposition calculation operation can also employ an adaptive weighted decomposition technique, which dynamically adjusts the matrix block weights based on node importance and real-time running status, using fine-grained block division for key regions and coarse-grained block division for secondary regions, thereby achieving an intelligent balance between calculation accuracy and efficiency.

[0121] It should be noted that step S400 above achieves unified processing of loop breakpoints, PV breakpoints and DC breakpoints by constructing a generalized sensitivity matrix and simultaneously solving the breakpoint injection amount. This solves the problem that traditional methods have difficulty coordinating multiple breakpoint types and greatly improves computational efficiency and convergence speed.

[0122] In this embodiment, step S500 maps the current injection amount of all breakpoints to the corresponding nodes, calculates the bus current using the first scanning method, and calculates the bus voltage using the second scanning method, including the following sub-steps E1 to E3:

[0123] In E1: Map the current injection amount of all breakpoints to the corresponding nodes;

[0124] Specifically, in power flow calculations for hybrid AC-DC distribution networks, to achieve the conversion from a mesh network to an equivalent radial network, compensation current or power needs to be injected through loop breaks, PV breaks, and DC voltage breaks to maintain the original network's electrical characteristics. To ensure the accuracy of the power flow calculation, the injected amounts at breaks cannot exist in isolation; they must be accurately mapped to the actual physical nodes they connect to, becoming the equivalent injection sources for those nodes. The core of this step is to accurately map the injected amounts obtained from solving the generalized break matrix to the network nodes, so that the bus current and voltage can be correctly calculated in the subsequent power flow backward-forward scan.

[0125] In E2: Calculating the bus current using the first scan method includes:

[0126] The current is summarized layer by layer by the first scanning method, and the load injection current of each bus and the current of all downstream branches are added together.

[0127] If the branch connects to converters in other sub-regions or at breakpoints, the input current of the converter is also included in the cumulative calculation.

[0128] Recursively traverse all branches until the current of the entire network is summed.

[0129] In this embodiment, the core task of the first scanning method, i.e., reverse scanning, is to summarize the current layer by layer from the leaf node to the source node, and accumulate the load injection current of each bus and the current of all downstream branches. The calculation formula is as follows: the first term is the traditional load injection current, and the second term is the current generated by converter or breakpoint injection.

[0130]

[0131] in, N represents the total current on branch b in partition h. h (b) is the set of all buses belonging to partition h downstream of branch b, S kThe injected complex power (including load and DG) of bus k, V k M is the complex voltage of bus k. h (b) refers to the set of all converters (also considered breakpoints) located after branch b that connect different areas. in (y) is the input current of converter y, which comes from the voltage across its terminals and the control method.

[0132] Specifically, the calculation of input current for various types of converters is explained separately:

[0133] For a PWM inverter, the input current formula is as follows:

[0134]

[0135] in, V 3d V3 represents the DC side voltage of the converter, and η represents the AC side voltage of the converter. y For converter efficiency, The power factor angle.

[0136] For a PWM rectifier, the input current formula is as follows:

[0137]

[0138] in,

[0139] For a DC-DC converter, the input current formula is as follows:

[0140]

[0141] in, It is the duty cycle function, and its value depends on the converter type. The formula is:

[0142]

[0143] Among them, D y The duty cycle is determined by the control mode.

[0144] In this embodiment of the application, the specific steps of reverse scanning include:

[0145] Starting from the furthest terminal area (farthest from the main power supply or Slack Bus), calculate upstream step by step;

[0146] For each branch b, traverse all downstream buses, calculate the current injection, and add the input current when encountering a converter that connects to other sub-regions or breakpoints.

[0147] Accumulate the current on the current branch and transmit it to the upstream node;

[0148] Repeat the above process until all branches have been traversed.

[0149] In an optional embodiment, the first scanning method can also be based on a hierarchical partitioned parallel scanning method, which divides the network into multiple computing domains according to voltage level or region. Each domain independently performs a reverse scan and exchanges data through boundary nodes. Finally, a global summary is performed at the master node. This method can significantly improve the computing efficiency of large-scale networks.

[0150] In another optional embodiment, the first scanning method can also be a dynamic weighted scanning method, which dynamically adjusts the priority of the current aggregation path according to the branch impedance and load rate, prioritizes the critical path, and then gradually covers the secondary path to achieve intelligent allocation of computing resources.

[0151] In E3: Calculating the bus voltage using the second scan method includes:

[0152] The bus voltage is calculated layer by layer using the second scanning method;

[0153] For downstream nodes connected to the converter, calculate their output voltage based on the converter type and use it as the starting voltage for the next sub-region.

[0154] Recursively process all sub-regions until the voltage calculation for the entire network is completed.

[0155] In this embodiment, the core task of the second scanning method, i.e., forward scanning, is to calculate the voltage of each busbar layer by layer downstream from the main source along the tree structure using the known branch current and network impedance. The overall calculation formula is as follows:

[0156]

[0157] in, Let be the complex voltage of bus k within region h. Let ψ be the voltage of the starting bus in region h. h (k) is the set of all branches on the path from the starting bus to bus k in region h. Let be the impedance or resistance of branch b in region h. The current in branch b is derived from the reverse scan calculation.

[0158] It should be noted that because an AC-DC distribution network may connect multiple sub-regions via converters, the initial bus voltage of each sub-region is not always derived from the rated voltage of the slack bus, but is determined by the output voltage of the converter. For sub-regions directly connected to the slack bus, their initial bus voltage is initialized to the rated voltage of the slack bus, while the initial bus voltage of non-slack regions is determined by the output voltage of the converter. Therefore, the voltage equation of the converter is needed to calculate the initial bus voltage of these sub-regions.

[0159] Specifically, the voltage calculation formulas for the three types of converters include:

[0160] For PWM inverters:

[0161] |V 3d |=V3(MI)

[0162] For PWM rectifiers:

[0163]

[0164] For DC-DC converters:

[0165] V 3d =V3(A y )

[0166] Among them, A y This is the duty cycle function.

[0167] Specifically, the forward scan steps are as follows:

[0168] Starting from the main source, its voltage is taken as the known source point;

[0169] Traverse the branches it connects to, and for each branch b, calculate its downstream bus voltage;

[0170] If the downstream node is the input of the converter, then calculate its output bus voltage as the next stage source;

[0171] Recursively process the next level region;

[0172] Continue passing the calculations until all bus voltages have been calculated.

[0173] In an optional embodiment, the second scanning method can also be a prediction-correction method based on voltage sensitivity coefficients. This method first predicts the initial voltage values ​​of each node quickly through linear approximation, and then corrects the voltage values ​​of key nodes through local iteration. This method is particularly suitable for fast voltage calculation scenarios involving a large number of power electronic devices.

[0174] In another optional embodiment, the second scanning method can also be to implement a regional asynchronous scanning strategy, which divides the system into multiple voltage calculation domains according to the network topology characteristics. Each domain performs a forward scan independently and then synchronizes the calculation results through a boundary coordinator. This method can significantly improve the voltage calculation efficiency of large-scale hybrid power grids.

[0175] It should be noted that the above step S500 achieves distributed computing of complex networks through a bidirectional scanning mechanism (current reverse scanning and voltage forward scanning), breaking through the memory bottleneck of traditional centralized computing and enabling the algorithm to process ultra-large-scale power distribution networks.

[0176] In this embodiment of the application, the above step S600, which updates the rectifier's power factor and determines whether the load has converged, and outputs the final parameters and power flow results, includes the following sub-steps F1 and F2:

[0177] In F1: The power factor update steps for the PWM rectifier include:

[0178] Obtain I from reverse scan in (y) and I out (y), obtain V3 and V from the forward scan. 3d ;

[0179] Calculate based on the required balance between the input and output power of the PWM rectifier. The formula is expressed as:

[0180]

[0181] Verify feasibility and ensure If the limit is exceeded, the modulation index MI is adjusted.

[0182] In F2: Determine whether the load has converged, and output the final parameters and power flow results;

[0183] Specifically, the stability of the system is measured by comparing the change in bus voltage between two consecutive iterations. If max(|ΔV|)≤ε (ε≤0.00001), it is considered converged, and the final parameters and power flow results are output. Otherwise, the iterative calculation steps described above are repeated. Figure 2 As shown.

[0184] It should be noted that step S600 above achieves closed-loop optimization of the calculation process by dynamically updating the rectifier power factor and convergence judgment, which solves the problem of parameter fixation in the iteration process of traditional methods and makes the calculation results closer to the actual operating state.

[0185] Example 3: This example provides a generalized AC-DC power flow calculation system for distribution networks, including:

[0186] The first identification module is used to perform a first identification operation based on the topology of the power distribution network to obtain the loop type of the network;

[0187] The second identification module is used to perform a second identification operation based on the control mode of distributed energy resources to obtain the special bus type.

[0188] The parameter calculation and adjustment module is used to initialize network parameters and perform the first calculation based on the loop type and special bus type of the network, verify the feasibility of the first calculation result, and adjust the parameters that do not meet the conditions.

[0189] The iterative calculation module is used to construct the generalized sensitivity matrix and simultaneously solve the current injection amount at all breakpoints; it maps the current injection amount at all breakpoints to the corresponding nodes, calculates the bus current through the first scan method, and calculates the bus voltage through the second scan method.

[0190] The output module is used to update the rectifier's power factor and determine whether the load has converged, outputting the final parameters and power flow results.

[0191] It should be noted that the technical solution of the generalized AC-DC distribution network power flow calculation system and the technical solution of the generalized AC-DC distribution network power flow calculation method mentioned above belong to the same concept. For details not described in detail in the technical solution of the generalized AC-DC distribution network power flow calculation system in this embodiment, please refer to the description of the technical solution of the generalized AC-DC distribution network power flow calculation method mentioned above.

[0192] The above-mentioned unit modules can be embedded in the processor of the electronic device in hardware form or independent of it, or they can be stored in the memory of the electronic device in software form, so that the processor can call and execute the corresponding operations of the above modules.

[0193] This embodiment also provides an electronic device, which includes a processor, a memory, a communication interface, a display screen, and an input device connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a generalized AC-DC power distribution network power flow calculation method. The display screen can be a liquid crystal display (LCD) or an e-ink display. The input device can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the device's casing, or an external keyboard, touchpad, or mouse.

[0194] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method proposed in the above embodiments.

[0195] The storage medium proposed in this embodiment belongs to the same inventive concept as the method proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0196] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause an electronic device (which may be a personal computer, server, or network device, etc.) to execute the method of the embodiments of the present invention.

[0197] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for calculating power flow in a generalized AC-DC distribution network, characterized in that, include: The first identification operation is performed based on the topology of the power distribution network to obtain the loop type of the network; A second identification operation is performed based on the control mode of distributed energy resources to obtain the special bus type; Based on the loop type and special bus type of the network, the network parameters are initialized and a first calculation is performed. The feasibility of the result of the first calculation is verified, and parameters that do not meet the conditions are adjusted. Construct a generalized sensitivity matrix and simultaneously solve for the current injection at all breakpoints; Map the current injection amount of all the breakpoints to the corresponding nodes, calculate the bus current using the first scanning method, and calculate the bus voltage using the second scanning method; Update the rectifier's power factor and determine if the load has converged, then output the final parameters and power flow results.

2. The method for calculating power flow in a generalized AC-DC distribution network as described in claim 1, characterized in that, The construction of the generalized sensitivity matrix and the simultaneous solution of the current injection quantity at all breakpoints include: Identify the first breakpoint information; By integrating the physical relationships between the information from the first breakpoint, a generalized sensitivity matrix is ​​constructed; The voltage deviation of voltage-controlled distributed energy sources is incorporated into the generalized sensitivity matrix, and the current injection amount at all breakpoints is solved synchronously through the first decomposition calculation operation.

3. The method for calculating power flow in a generalized AC-DC distribution network as described in claim 2, characterized in that, The calculation of the bus current using the first scanning method includes: The current is summarized layer by layer by the first scanning method, and the load injection current of each bus and the current of all downstream branches are added together. If the branch connects to converters in other sub-regions or at breakpoints, the input current of the converter is also included in the cumulative calculation. Recursively traverse all branches until the current of the entire network is summed.

4. The method for calculating power flow in a generalized AC-DC distribution network as described in claim 3, characterized in that, The calculation of the bus voltage using the second scanning method includes: The bus voltage is calculated layer by layer using the second scanning method; For downstream nodes connected to the converter, calculate their output voltage based on the converter type and use it as the starting voltage for the next sub-region. Recursively process all sub-regions until the voltage calculation for the entire network is completed.

5. The method for calculating power flow in a generalized AC-DC distribution network as described in claim 1, characterized in that, The loop types of the acquired network include: Sub-regions are divided based on the number and location of node-to-node interface converters in the power distribution network. Each sub-region is connected to other sub-regions through converters, forming a tree-like or radial structure. Identify the types of loops in the network, including Type A loops that contain only AC nodes and no converters, Type B loops that contain only DC nodes and no converters, and Type C loops that contain AC / DC nodes or DC nodes of different voltage levels and may contain converters.

6. The method for calculating power flow in a generalized AC-DC distribution network as described in claim 5, characterized in that, The acquisition of special bus types includes: Check the control mode of the distributed energy resources connected to each bus; If it connects to distributed energy resources and the control mode is constant voltage amplitude, it is identified as a PV bus. If it is connected to distributed energy resources and the control mode is constant DC voltage, it is identified as a DC voltage bus.

7. The method for calculating power flow in a generalized AC-DC distribution network as described in claim 6, characterized in that, The step of verifying the feasibility of the first calculation result and adjusting parameters that do not meet the conditions includes: For single-phase PWM inverters and single-phase PWM rectifiers, verify whether the modulation parameters meet the first judgment condition. If the first judgment condition is met, the modulation parameters remain unchanged; otherwise, perform the second judgment and adjust the modulation parameters according to the result of the second judgment. For a DC-DC converter, verify whether the duty cycle meets the third judgment condition. If the third judgment condition is met, the duty cycle remains unchanged; otherwise, perform the fourth judgment and adjust the duty cycle according to the result of the fourth judgment.

8. A generalized AC-DC distribution network power flow calculation system, employing the generalized AC-DC distribution network power flow calculation method as described in any one of claims 1 to 7, characterized in that, include: The first identification module is used to perform a first identification operation based on the topology of the power distribution network to obtain the loop type of the network; The second identification module is used to perform a second identification operation based on the control mode of distributed energy resources to obtain the special bus type. The parameter calculation and adjustment module is used to initialize network parameters and perform a first calculation based on the loop type and special bus type of the network, verify the feasibility of the result of the first calculation, and adjust the parameters that do not meet the conditions. The iterative calculation module is used to construct the generalized sensitivity matrix and simultaneously solve for the current injection amount at all breakpoints; Map the current injection amount of all the breakpoints to the corresponding nodes, calculate the bus current using the first scanning method, and calculate the bus voltage using the second scanning method; The output module is used to update the rectifier's power factor and determine whether the load has converged, outputting the final parameters and power flow results.

9. An electronic device comprising a memory and a processor, characterized in that: The memory is used to store computer-executable instructions, and when the processor executes the computer-executable instructions, it implements the steps of the generalized AC-DC power flow calculation method for any one of claims 1 to 7.

10. A computer-readable storage medium having computer-executable instructions stored thereon, characterized in that: When the computer-executable instructions are executed by the processor, they implement the steps of the generalized AC-DC power flow calculation method according to any one of claims 1 to 7.

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