A distribution network power flow calculation method and system based on DistFlow linear power flow

Abstract

The present invention belongs to the technical field of power distribution network flow analysis of electric power system, and provides a distribution network flow calculation method and system based on DistFlow linear flow. The method includes: deriving a DistFlow linear flow model; according to the topological structure of the distribution network system, starting from the last node of the radial line, deriving the active flow expression and reactive flow expression of each branch according to the DistFlow linear flow expression; according to the active flow expression and reactive flow expression of each branch, respectively obtaining the active power generation load transfer factor matrix and the reactive power generation load transfer factor matrix; according to the active power generation load transfer factor matrix and the reactive power generation load transfer factor matrix, respectively obtaining the calculation formula of the branch active flow and the calculation formula of the branch reactive flow; according to the active power generation load transfer factor matrix, the reactive power generation load transfer factor matrix and the node net power, according to the voltage amplitude expression, determining the calculation formula of the voltage amplitude of each node.

Description

Technical Field

[0001] The present invention belongs to the technical field of power distribution network flow analysis in an electric power system, and in particular relates to a distribution network flow calculation method and system based on DistFlow linear flow. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Power flow analysis is of great significance to the operation and control of modern power systems. In terms of system safety, power flow analysis is used to prevent transmission line overload and system power imbalance. Transmission line overload will cause transmission line shutdown, and power imbalance will cause frequency and voltage instability. Both of these situations may cause large-scale power outages, causing huge economic losses and affecting people's lives. Based on the rapid solution of power flow under certain conditions, through power dispatching control and generator control, line overload and power imbalance problems can be avoided in a short time to ensure system safety.

[0004] Since the mid-20th century, many classic algorithms have been proposed to solve power flow, such as Gauss-Seidel algorithm, Newton-Raphson algorithm, fast decoupling algorithm, etc. Among them, the Newton-Raphson algorithm can obtain the most accurate results and has been applied to normal operation analysis in practice. However, since the calculation and iteration process of the Jacobian matrix takes a relatively long time, this method is slow for modern power system security analysis. Based on some assumptions about the network and operating status, the fast decoupling algorithm can simplify the calculation. However, although the algorithm has a limited number of iterations, the running time is still long. In order to further speed up the power flow calculation, some new algorithms based on the Newton-Raphson algorithm and the fast decoupling algorithm have been proposed. However, since the algorithm still needs to be iterated, the calculation time cannot be significantly reduced.

[0005] In order to significantly reduce the time of power flow calculation, some linear estimation methods that do not require iteration have emerged. For example, the Newton-Raphson algorithm and the distribution factor based on the Jacobian matrix are used to calculate the power flow, but this method depends on the real-time operating status of the system. Compared with this algorithm, the generation load transfer factor model only depends on the network topology. The application of the generation load transfer factor can calculate the power flow in a short time without iteration, and is used for active power balance control and frequency stability control. The premise of applying this generation load transfer factor is to assume that the resistance in the system is much smaller than the reactance. However, this assumption does not hold true in the distribution network. Therefore, the traditional generation load transfer factor based on DC power flow is not applicable to the distribution network.

[0006] With the increasing penetration of renewable energy, its volatility and randomness have brought huge negative impacts on the distribution network. The power flow optimization and voltage control in the distribution network are particularly important. Summary of the invention

[0007] In order to solve the technical problem of how to quickly solve the active power flow, reactive power flow and voltage of the distribution network and combine them with the optimized operation of the distribution network, the present invention provides a distribution network power flow calculation method and system based on DistFlow linear power flow, which can quickly solve the active power flow and reactive power flow, as well as the voltage amplitude of the distribution network.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A first aspect of the present invention provides a distribution network power flow calculation method based on DistFlow linear power flow.

[0010] A distribution network power flow calculation method based on DistFlow linear power flow, comprising:

[0011] Determine the topological structure of the distribution network system, select a point on the radial line as the reference node, specify the positive direction of the power flow, recursively deduce the net active power, net reactive power and voltage amplitude of each branch, and obtain the DistFlow linear power flow expression and voltage amplitude expression;

[0012] According to the topological structure of the distribution network system, starting from the last node of the radial line, the active power flow expression and reactive power flow expression of each branch are derived based on the DistFlow linear power flow expression;

[0013] According to the active power flow expression of each branch, the active power generation load transfer factor matrix is ​​obtained;

[0014] According to the reactive power flow expression of each branch, the reactive power generation load transfer factor matrix is ​​obtained;

[0015] According to the active power generation load transfer factor matrix, the calculation formula of the branch active power flow is determined to obtain the active power of all branches;

[0016] According to the reactive power generation load transfer factor matrix, the calculation formula of branch reactive power flow is determined to obtain the reactive power of all branches;

[0017] According to the active power generation load transfer factor matrix, the reactive power generation load transfer factor matrix and the node net power, according to the voltage amplitude expression, the calculation formula of the voltage amplitude of each node is determined to obtain the voltage amplitude of all nodes.

[0018] Furthermore, after obtaining the calculation formula of the branch active power flow and the calculation formula of the branch reactive power flow, the method further includes constructing branch power flow constraint conditions according to the calculation formula of the branch active power flow and the calculation formula of the branch reactive power flow.

[0019] Furthermore, after obtaining the branch power flow constraint condition, the method further includes processing the branch power flow constraint condition according to a linearization processing method and converting the branch power flow constraint condition into a linear constraint condition.

[0020] Furthermore, after obtaining the calculation formula for the voltage amplitude of each node, the method further includes obtaining upper and lower limit constraints of the voltage amplitude of each node according to the calculation formula for the voltage amplitude of each node.

[0021] Furthermore, before selecting a point of the radial line as a reference node, the method also includes modeling the topological structure of the distribution network system and converting the graphic information into data information.

[0022] Furthermore, the assumptions of the DistFlow linear power flow are: the three-phase balance of the distribution network, the network loss is 0, and the node voltage phase angle is 0.

[0023] Furthermore, the active power flow expression of each branch is expressed only by the branch active power flow of the known expression;

[0024] Furthermore, the reactive power flow expression of each branch is expressed only by the branch reactive power flow of the known expression;

[0025] Furthermore, the calculation formula of the branch active power flow only includes the active generation load transfer factor and the node net active power;

[0026] Furthermore, the calculation formula of branch reactive power flow only includes reactive generation load transfer factor and node net reactive power;

[0027] Further, the active power generation load transfer factor matrix and the reactive power generation load transfer factor matrix are the same.

[0028] A second aspect of the present invention provides a distribution network power flow calculation system based on DistFlow linear power flow.

[0029] A distribution network power flow calculation system based on DistFlow linear power flow, comprising:

[0030] A construction and recursion module is configured to: determine the topological structure of the distribution network system, select a point of the radial line as a reference node, specify the positive direction of the power flow, recursively deduce the net active power, net reactive power and voltage amplitude of each branch, and obtain the DistFlow linear power flow expression and voltage amplitude expression;

[0031] The power flow calculation module is configured to: derive the active power flow expression and reactive power flow expression of each branch according to the DistFlow linear power flow expression, starting from the last node of the radial line according to the topology of the distribution network system;

[0032] A first transfer factor building module is configured to: obtain an active power generation load transfer factor matrix according to an active power flow expression of each branch;

[0033] A second transfer factor building module is configured to: obtain a reactive power generation load transfer factor matrix according to a reactive power flow expression of each branch;

[0034] An active power calculation module is configured to: determine a calculation formula for branch active power flow according to an active power generation load transfer factor matrix, and obtain active power of all branches;

[0035] A reactive power calculation module is configured to: determine a calculation formula for branch reactive power flow according to a reactive power generation load transfer factor matrix, and obtain reactive power of all branches;

[0036] The voltage amplitude calculation module is configured to: determine the calculation formula of the voltage amplitude of each node according to the active power generation load transfer factor matrix, the reactive power generation load transfer factor matrix and the node net power, and obtain the voltage amplitude of all nodes according to the voltage amplitude expression.

[0037] A third aspect of the present invention provides a computer-readable storage medium.

[0038] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps in the distribution network power flow calculation method based on DistFlow linear power flow as described in the first aspect above.

[0039] A fourth aspect of the present invention provides a computer device.

[0040] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps in the distribution network flow calculation method based on DistFlow linear flow as described in the first aspect above are implemented.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention takes into account the actual characteristics of the distribution network and is suitable for power flow optimization, safety analysis and voltage control according to the voltage amplitude and reactive power of the distribution network.

[0043] The invention is different from the existing power generation load transfer factor based on DC power flow, and the proposed power generation load transfer factor is particularly used in the distribution network.

[0044] The power generation load transfer factor proposed in the present invention does not require iteration and can be used to quickly solve the active power flow and reactive power flow of the distribution network, and has the same accuracy as the DistFlow linear power flow model.

[0045] The present invention completes the analytical expression of branch active power flow, branch reactive power flow and voltage amplitude, and can further constrain the upper and lower limits thereof, and can be conveniently embedded in the distribution network optimization operation model without increasing the complexity of the model.

[0046] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0048] Figure 1 It is a flow chart of a distribution network power flow calculation method based on DistFlow linear power flow shown in the first embodiment of the present invention;

[0049] Figure 2 is a flow chart of a distribution network power flow calculation system based on DistFlow linear power flow shown in the second embodiment of the present invention;

[0050] Figure 3 It is a schematic diagram of a radial distribution network shown in the first embodiment of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0052] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0053] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0054] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the methods and systems according to various embodiments of the present disclosure. It should be noted that each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the module, program segment, or a part of a code may include one or more executable instructions for implementing the logical functions specified in each embodiment. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the flowchart and / or block diagram, and the combination of boxes in the flowchart and / or block diagram can be implemented using a dedicated hardware-based system that performs a specified function or operation, or can be implemented using a combination of dedicated hardware and computer instructions.

[0055] Embodiment 1

[0056] like Figure 1 As shown, this embodiment provides a distribution network power flow calculation method based on DistFlow linear power flow. This embodiment uses the method applied to a server as an example for illustration. It can be understood that the method can also be applied to a terminal, and can also be applied to a terminal, a server, and a system, and is implemented through the interaction between the terminal and the server. The server can be an independent physical server, or a server cluster or a distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network servers, cloud communications, middleware services, domain name services, security services CDN, and big data and artificial intelligence platforms. The terminal can be a smart phone, a tablet computer, a laptop computer, a desktop computer, a smart speaker, a smart watch, etc., but is not limited to this. The terminal and the server can be directly or indirectly connected via wired or wireless communication, which is not limited in this application. In this embodiment, the method includes the following steps:

[0057] S101: Deriving the DistFlow Linear Power Flow Model

[0058] In step S101, the derivation of the DistFlow linear power flow model is divided into four steps.

[0059] The distribution network system mentioned needs to be explained as follows: Figure 1 As shown in Figure 1, the DistFlow linear power flow model is based on a radial distribution network and assumes that the distribution network is three-phase balanced. It should be noted that this power flow model is the same as the traditional AC power flow model, both of which are complete descriptions of the characteristics of the power system and are physically equivalent.

[0060] Specifically, the four steps of derivation of the DistFlow linear power flow model are as follows.

[0061] The first step is to select a reference node for the radial circuit. The voltage amplitude of the reference node is a constant. Then the apparent power and voltage of the end node of the first branch satisfy the following equation:

[0062]

[0063]

[0064] Where S1 represents the net apparent power of node 1; S0, S*0 represent the net apparent power of node 0 and its conjugate; represents the apparent power loss of branch 0-1; V, θ represent the voltage amplitude and phase angle at the node respectively, I represents the current, and z1 represents the impedance on line (0)(1).

[0065] In the second step, repeat the above recursive process for each branch and obtain the following formula:

[0066]

[0067] Where P i(i+1) ,Q i(i+1) Respectively represent the net active power and net reactive power on branch i-(i+1); Represents the square of the voltage amplitude at node i+1.

[0068] In the third step, based on the second step, ignoring the branch power flow loss, the branch power flow becomes the following formula:

[0069]

[0070] Step 4: Based on the third step, assuming that (Vi-V0)2≈0, we get Vi2≈V02+2V0(Vi-V0), which is combined with formula (4) to finally get the linear voltage amplitude calculation formula as follows:

[0071] V i+1 =V i -(r i(i+1) P i(i+1) +x i(i+1) Q i(i+1) ) / V0 (5)

[0072] S102: Based on the DistFlow linear power flow model, a new model of generation load transfer factor applicable to the distribution network is derived.

[0073] In step S102, the derivation of the new model of power generation load transfer factor is divided into four steps.

[0074] Specifically, the four steps of deriving the new model of power generation load transfer factor are as follows.

[0075] The first step, such as Figure 3 As shown, the positive direction of the flow is first specified.

[0076] The second step is to obtain the active power flow and reactive power flow expressions of each branch through recursion based on the system topology and formula (4). It should be noted that in this expression, the branch active power flow and branch reactive power flow are only expressed by the net power at the node (that is, the power emitted by the power source minus the power absorbed by the load) and written in matrix form. As shown in the following formula, it can be seen that the power flow of a branch is equal to the sum of the power injected by all nodes powered by it.

[0077]

[0078]

[0079] Wherein, the element in the mth row and kth column of the matrix represents the generation load transfer factor of node k to branch m.

[0080] The third step is to obtain the general form of the branch active and reactive power flow calculation formula based on the power generation load transfer factor and the node net power, as shown in the following formula:

[0081]

[0082] In the formula, It is important to note that since the active power flow and reactive power flow have the same positive direction, the active and reactive power flow transfer factors are the same. If the power flow of branch ij flows into node k, then otherwise,

[0083] The fourth step is to obtain the general expression of the voltage amplitude calculation formula according to formula (5):

[0084]

[0085] It should be noted that, unlike formula (5), in formula (9), only the reference node voltage amplitude, generation load transfer factor, and node net power need to be known to calculate the voltage amplitude of each node.

[0086] According to equations (8)-(9), the branch power flow constraints and voltage amplitude upper and lower limit constraints are obtained, as shown in the following equations:

[0087]

[0088]

[0089] In the formula, represents the maximum capacity of branch ij; They represent the upper and lower limits of the voltage amplitude at node k respectively.

[0090] S103: According to the linearization processing method, the nonlinear part (10) in the model is processed and converted into a linear model.

[0091]

[0092] In the formula,

[0093] This embodiment constructs a new model of power generation load transfer factor based on DistFlow linear power flow applicable to distribution network, rigorously derives the power generation load transfer factor, and rigorously analyzes the branch power flow and node voltage amplitude. In addition, the nonlinear branch power flow constraint is converted into a linear constraint, which improves the efficiency and reliability of problem solving.

[0094] The new model of power generation load transfer factor, branch flow constraints and voltage amplitude constraints constructed in this embodiment are linear and do not require iteration. They can be directly applied to the fast calculation of distribution network flow, safety analysis, voltage control, and other aspects, as well as the distribution network optimization operation model.

[0095] Embodiment 2

[0096] This embodiment provides a distribution network power flow calculation system based on DistFlow linear power flow.

[0097] like Figure 2 As shown, a distribution network power flow calculation system based on DistFlow linear power flow includes:

[0098] A construction and recursion module is configured to: determine the topological structure of the distribution network system, select a point of the radial line as a reference node, specify the positive direction of the power flow, recursively deduce the net active power, net reactive power and voltage amplitude of each branch, and obtain the DistFlow linear power flow expression and voltage amplitude expression;

[0099] The power flow calculation module is configured to: derive the active power flow expression and reactive power flow expression of each branch according to the DistFlow linear power flow expression, starting from the last node of the radial line according to the topology of the distribution network system;

[0100] A first transfer factor building module is configured to: obtain an active power generation load transfer factor matrix according to an active power flow expression of each branch;

[0101] A second transfer factor building module is configured to: obtain a reactive power generation load transfer factor matrix according to a reactive power flow expression of each branch;

[0102] An active power calculation module is configured to: determine a calculation formula for branch active power flow according to an active power generation load transfer factor matrix, and obtain active power of all branches;

[0103] A reactive power calculation module is configured to: determine a calculation formula for branch reactive power flow according to a reactive power generation load transfer factor matrix, and obtain reactive power of all branches;

[0104] The voltage amplitude calculation module is configured to: determine the calculation formula of the voltage amplitude of each node according to the active power generation load transfer factor matrix, the reactive power generation load transfer factor matrix and the node net power, and obtain the voltage amplitude of all nodes according to the voltage amplitude expression.

[0105] As one or more implementation modes, it also includes: a first constraint module, which is configured to: construct a branch flow constraint condition according to a calculation formula for branch active power flow and a calculation formula for branch reactive power flow.

[0106] As one or more implementation modes, it also includes: a linearization processing module, which is configured to: process the branch power flow constraint conditions according to the linearization processing method and convert them into linear constraint conditions.

[0107] As one or more implementation modes, it further includes: a second constraint module, which is configured to: obtain upper and lower limit constraints of the voltage amplitude of each node according to the calculation formula of the voltage amplitude of each node.

[0108] It should be noted that the above-mentioned construction and recursion module, power flow calculation module, first transfer factor construction module, second transfer factor construction module, active power calculation module, reactive power calculation module, voltage amplitude calculation module, first constraint module, linearization processing module and second constraint module are the same as the examples and application scenarios implemented by the steps in Embodiment 1, but are not limited to the contents disclosed in Embodiment 1. It should be noted that the above-mentioned modules as part of the system can be executed in a computer system such as a set of computer executable instructions.

[0109] Embodiment 3

[0110] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps in the distribution network power flow calculation method based on DistFlow linear power flow as described in the first embodiment above are implemented.

[0111] Embodiment 4

[0112] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps in the distribution network flow calculation method based on DistFlow linear flow as described in the first embodiment are implemented.

[0113] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program code.

[0114] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0115] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0116] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0117] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A distribution network power flow calculation method based on DistFlow linear power flow, characterized in that: include: Determine the topological structure of the distribution network system, select a point on the radial line as the reference node, specify the positive direction of the power flow, recursively deduce the net active power, net reactive power and voltage amplitude of each branch, and obtain the DistFlow linear power flow expression and voltage amplitude expression; According to the topological structure of the distribution network system, starting from the last node of the radial line, the active power flow expression and reactive power flow expression of each branch are derived based on the DistFlow linear power flow expression; According to the active power flow expression of each branch, the active power generation load transfer factor matrix is ​​obtained; According to the reactive power flow expression of each branch, the reactive power generation load transfer factor matrix is ​​obtained; According to the active power generation load transfer factor matrix, the calculation formula of the branch active power flow is determined to obtain the active power of all branches; According to the reactive power generation load transfer factor matrix, the calculation formula of branch reactive power flow is determined to obtain the reactive power of all branches; According to the active power generation load transfer factor matrix, the reactive power generation load transfer factor matrix and the node net power, according to the voltage amplitude expression, the calculation formula of the voltage amplitude of each node is determined to obtain the voltage amplitude of all nodes.

2. The distribution network power flow calculation method based on DistFlow linear power flow according to claim 1 is characterized in that: After obtaining the calculation formula of the branch active power flow and the calculation formula of the branch reactive power flow, the method further includes constructing branch power flow constraint conditions according to the calculation formula of the branch active power flow and the calculation formula of the branch reactive power flow.

3. The distribution network power flow calculation method based on DistFlow linear power flow according to claim 2 is characterized in that: After obtaining the branch power flow constraint conditions, the method further includes processing the branch power flow constraint conditions according to a linearization processing method and converting them into linear constraint conditions.

4. The distribution network power flow calculation method based on DistFlow linear power flow according to claim 1 is characterized in that: After obtaining the calculation formula of the voltage amplitude of each node, the method further includes obtaining the upper and lower limit constraints of the voltage amplitude of each node according to the calculation formula of the voltage amplitude of each node.

5. The distribution network power flow calculation method based on DistFlow linear power flow according to claim 1 is characterized in that: Before selecting a point of the radial line as a reference node, the method also includes modeling the topological structure of the distribution network system and converting the graphic information into data information.

6. The distribution network power flow calculation method based on DistFlow linear power flow according to claim 1 is characterized in that: The assumptions of the DistFlow linear power flow are: the three-phase balance of the distribution network, the network loss is 0, and the node voltage phase angle is 0.

7. The distribution network power flow calculation method based on DistFlow linear power flow according to claim 1 is characterized in that: The active power flow expression of each branch is expressed only by the branch active power flow of known expression; Or, the reactive power flow expression of each branch is expressed only by the branch reactive power flow of known expression; Or, the calculation formula of branch active power flow only includes active generation load transfer factor and node net active power; Or, the calculation formula of branch reactive power flow only includes reactive generation load transfer factor and node net reactive power; Alternatively, the active generation load transfer factor matrix and the reactive generation load transfer factor matrix are the same.

8. A distribution network power flow calculation system based on DistFlow linear power flow, characterized in that: include: A construction and recursion module is configured to: determine the topological structure of the distribution network system, select a point of the radial line as a reference node, specify the positive direction of the power flow, recursively deduce the net active power, net reactive power and voltage amplitude of each branch, and obtain the DistFlow linear power flow expression and voltage amplitude expression; The power flow calculation module is configured to: derive the active power flow expression and reactive power flow expression of each branch according to the DistFlow linear power flow expression, starting from the last node of the radial line according to the topology of the distribution network system; A first transfer factor building module is configured to: obtain an active power generation load transfer factor matrix according to an active power flow expression of each branch; A second transfer factor building module is configured to: obtain a reactive power generation load transfer factor matrix according to a reactive power flow expression of each branch; An active power calculation module is configured to: determine a calculation formula for branch active power flow according to an active power generation load transfer factor matrix, and obtain active power of all branches; A reactive power calculation module is configured to: determine a calculation formula for branch reactive power flow according to a reactive power generation load transfer factor matrix, and obtain reactive power of all branches; The voltage amplitude calculation module is configured to: determine the calculation formula of the voltage amplitude of each node according to the active power generation load transfer factor matrix, the reactive power generation load transfer factor matrix and the node net power, and obtain the voltage amplitude of all nodes according to the voltage amplitude expression.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps in the distribution network power flow calculation method based on DistFlow linear power flow as described in any one of claims 1 to 7 are implemented.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the distribution network power flow calculation method based on DistFlow linear power flow as described in any one of claims 1-7 are implemented.

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