CN115995818A - Power flow calculation method for multi-energy complementary alternating current-direct current hybrid power distribution network - Google Patents

Abstract

A power flow calculation method of a multi-energy complementary alternating current-direct current hybrid power distribution network comprises the following steps: s1, acquiring power lines of related equipment nodes, constructing a topological structure of a power distribution network, acquiring topological structure information, and establishing a loop-branch matrix; s2, dividing a power flow calculation module based on a topological structure of the power distribution network, and dividing the power flow calculation module into an alternating current sub-network module, a direct current sub-network module and a converter module; s3, setting a control mode of the direct current sub-network module, and setting initial values, positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module; s4, carrying out alternating iterative convergence judgment on the power flow calculation of the alternating current sub-network module and the direct current sub-network module to finish calculation; in the application, the power distribution network is divided in a modularized mode, so that the number of network matrixes of each part is reduced, alternating iterative computation is carried out on the alternating current sub-network module and the direct current sub-network module, and the computation iteration speed and flexibility are improved. Therefore, the invention has higher calculation efficiency and more accurate result.

Description

A Power Flow Calculation Method for Multi-energy Complementary AC-DC Hybrid Distribution Network

technical field

The invention relates to a power flow calculation method, which belongs to the technical field of active distribution networks, in particular to a power flow calculation method for a multi-energy complementary AC-DC hybrid distribution network.

Background technique

With the continuous development of power electronics technology, the AC-DC hybrid distribution network will be further developed. On the one hand, with the increasing proportion of distributed power sources, the power flow and operation control methods of AC and DC systems will undergo fundamental changes; to adversely affect. The power system is dominated by AC. When some DC transmission units are connected, the power flow calculation is still based on AC and supplemented by DC. When the proportion of DC transmission units continues to rise, the power flow of AC-DC hybrid distribution network Calculations must be performed concurrently in order to obtain good convergence characteristics. The convergence effect of the traditional AC-DC separation power flow calculation is not good; the unified calculation method that completely eliminates the DC variables, because the sensitivity information of the AC-DC connection is concealed, leads to a complex Jacobian matrix structure; when selecting the initial value of the iteration, there is a blind The unified power flow calculation method that permanently preserves the control angle of DC transmission specifies the reactive power of the DC side, and the calculation efficiency is low. To some extent, it also deviates from the purpose of power flow calculation, and the obtained results have certain deviations.

The information disclosed in this background section is only intended to increase the understanding of the general background of the application, and should not be considered as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

Contents of the invention

The purpose of the present invention is to overcome the defects and problems of low calculation efficiency and certain deviation in the results in the prior art, and provide a multi-energy complementary AC-DC hybrid power distribution with low calculation efficiency and relatively accurate results Network power flow calculation method.

In order to achieve the above objectives, the technical solution of the present invention is: a multi-energy complementary AC-DC hybrid distribution network power flow calculation method, the calculation method includes the following steps:

S1. Obtain the power lines of relevant equipment nodes, construct the topology structure of the distribution network, collect topology information, and establish a loop-branch matrix;

S2. Based on the topological structure of the distribution network, the power flow calculation module is divided into AC subnetwork module, DC subnetwork module and converter module;

S3. Set the control mode of the DC subnet module, and set the initial value, positive direction and convergence accuracy of the AC subnet module and the DC subnet module;

S4. Carry out alternate iterative convergence judgment for the power flow calculation of the AC subnetwork module and the DC subnetwork module, output the calculation results, and complete the calculation.

In the step S1, the step of establishing a loop-branch matrix includes:

S11. Obtain the power data information of nodes, loops and branches in the topology of the distribution network;

S12. Number the nodes and branches in the distribution network topology, and obtain the numbered distribution network topology;

S13. Based on the numbered distribution network topology, establish a standard vector group with the same number of circuits, determine the number of branches associated with each circuit, and obtain the power data of each branch;

S14. Based on the power data of each branch, assign a value to the standard vector corresponding to each circuit, thereby obtaining feature vector groups of different circuits, and construct a circuit-branch matrix according to different feature vector groups.

In the step S2, dividing the power flow calculation module means: taking the converter as the boundary, dividing the distribution network into modules, dividing it into an AC subnet module, a DC subnet module and a converter module.

In the step S3, the steps of setting the initial value, positive direction and convergence accuracy of the AC subnet module and the DC subnet module include:

S31. Collect the node types of the distribution network topology, and classify the node types according to the attributes of the nodes;

S32. According to the parameters of the AC subnet module and the DC subnet module, assign values to the node attributes of different categories to obtain initial values, and set the positive direction and convergence accuracy of the AC subnet module and the DC subnet module.

In the step S4, the step of performing alternate iterative convergence judgment of the AC subnetwork module and the DC subnetwork module power flow calculation includes:

S41. According to the established circuit-branch matrix, combined with the initial value and positive direction, calculate the unbalance amount , and ;in: , Respectively, the active and reactive power imbalances of the system nodes; is the active power imbalance of the system nodes under different control modes;

S42. According to the convergence accuracy, determine the unbalance amount , and Whether to converge;

If it converges, calculate the power flow of each branch and the operating parameters of the DC transmission unit until the power flow calculations of the AC subnetwork module and the DC subnetwork module converge, output the calculation results, and complete the power flow calculation;

If it does not converge, first preprocess the DC output unit, and establish the Jacobian matrix of the AC transmission system, and then add the micro-increment model of the DC transmission unit and the new constraint equation according to the control method, and solve and correct it. Each node voltage and direct current, and repeat step S42.

In the step S42, the steps of calculating the power flow of each branch are as follows:

S421. Perform the power flow calculation of the AC subnet module until the calculation converges;

S422. Carry out the power flow calculation of the converter module, obtain the power flow and loss of the converter, and check whether the converter exceeds the limit according to the power flow and loss of the converter. If the limit is exceeded, go to step S422; if not If the limit is exceeded, proceed to step S423;

S423. Carry out power flow calculation of the DC subnetwork module; if the calculation converges, it is determined that the power flow calculation is completed, and a result is output to complete the power flow calculation; if it cannot be converged, go to step S421 until the calculation converges.

In the step S42, the preprocessing refers to: use the following formula to make the expression of the node power balance equation unified, and the formula is as follows:

;

;

in: for injection node AC active power; for injection node AC reactive power; for injection node DC active power; for injection node DC reactive power; for node voltage; for node voltage; , nodes respectively , Connected conductance and susceptance; for node , The voltage phase difference; is the inherent loss of the converter;

Among them, the expression of the power flow equation of the DC subnetwork module is:

;

in: Active power injected into the DC side of the converter; Active power injected into the AC side; is the current flowing through the converter; is the equivalent resistance of the converter.

In the step S42, the equations of the micro-increment model and the constraint equation are as follows:

;

in: , , Respectively, the unbalanced amount of DC active power, AC active power and reactive power; is the AC voltage phase angle; is the DC active power; is a direct current; is the AC node voltage; , , , is the communication element in the Jacobian matrix; , is the DC element in the Jacobian matrix.

In the step S3, the control methods include the following: the first type: constant current on the rectifier side, constant voltage on the inverter side; the second type: constant current on the rectifier side, and constant arc extinguishing angle on the inverter side; the third type : Constant power on the rectifier side, constant voltage on the inverter side; fourth: constant power on the rectifier side, constant arc extinguishing angle on the inverter side; fifth: constant firing angle on the rectifier side, constant current on the inverter side.

In the step S12, numbering the nodes and branches in the distribution network topology refers to:

First, set the access point of the distribution network and the upper-level power grid as the head node, set its number to 0, and set the number of the branch associated with the head node to 1, then the numbers of other branches diverged from the branch numbered 1 Increment along the flow direction, the number of other nodes except the first node is consistent with the number of the branch pointing to the node, the number of the branch connected to the ground through the node is consistent with the number of the corresponding node connected to the ground, and it is numbered, Obtain the numbered distribution network topology.

Compared with prior art, the beneficial effect of the present invention is:

In the method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network in the present invention, the distribution network is modularized to reduce the number of network matrices in each part, and the AC subnet module and the DC subnet module are alternately iterated Calculation convergence judgment reduces the difficulty of power flow calculation for AC-DC hybrid distribution network, improves calculation speed, flexibility and algorithm convergence speed, and improves the accuracy of results to a certain extent. At the same time, this method can be applied to other distribution networks In network computing, it has certain universality. Therefore, the present invention not only has higher calculation efficiency, but also has more accurate results.

Description of drawings

Fig. 1 is a schematic flow chart of the present invention.

Fig. 2 is a node power flow model diagram of the AC/DC hybrid distribution network of the present invention.

Fig. 3 is a schematic flow chart of the power flow calculation of the present invention.

Fig. 4 is a topological structure diagram of the multi-energy complementary AC-DC hybrid distribution network of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to Figures 1-4, a method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network, the calculation method includes the following steps:

S1. Obtain the power lines of relevant equipment nodes, construct the topology structure of the distribution network, collect topology information, and establish a loop-branch matrix;

S2. Based on the topological structure of the distribution network, the power flow calculation module is divided into AC subnetwork module, DC subnetwork module and converter module;

S3. Set the control mode of the DC subnet module, and set the initial value, positive direction and convergence accuracy of the AC subnet module and the DC subnet module;

S4. Carry out alternate iterative convergence judgment for the power flow calculation of the AC subnetwork module and the DC subnetwork module, output the calculation results, and complete the calculation.

In the step S1, the step of establishing a loop-branch matrix includes:

S11. Obtain the power data information of nodes, loops and branches in the topology of the distribution network;

S12. Number the nodes and branches in the distribution network topology, and obtain the numbered distribution network topology;

S13. Based on the numbered distribution network topology, establish a standard vector group with the same number of circuits, determine the number of branches associated with each circuit, and obtain the power data of each branch;

S14. Based on the power data of each branch, assign a value to the standard vector corresponding to each circuit, thereby obtaining feature vector groups of different circuits, and construct a circuit-branch matrix according to different feature vector groups.

In the step S2, dividing the power flow calculation module means: taking the converter as the boundary, dividing the distribution network into modules, dividing it into an AC subnet module, a DC subnet module and a converter module.

In the step S3, the steps of setting the initial value, positive direction and convergence accuracy of the AC subnet module and the DC subnet module include:

S31. Collect the node types of the distribution network topology, and classify the node types according to the attributes of the nodes;

S32. According to the parameters of the AC subnet module and the DC subnet module, assign values to the node attributes of different categories to obtain initial values, and set the positive direction and convergence accuracy of the AC subnet module and the DC subnet module.

In the step S4, the step of performing alternate iterative convergence judgment of the AC subnetwork module and the DC subnetwork module power flow calculation includes:

S41. According to the established circuit-branch matrix, combined with the initial value and positive direction, calculate the unbalance amount , and ;in: , Respectively, the active and reactive power imbalances of the system nodes; is the active power imbalance of the system nodes under different control modes;

S42. According to the convergence accuracy, determine the unbalance amount , and Whether to converge;

If it converges, calculate the power flow of each branch and the operating parameters of the DC transmission unit until the power flow calculations of the AC subnetwork module and the DC subnetwork module converge, output the calculation results, and complete the power flow calculation;

If it does not converge, first preprocess the DC output unit, and establish the Jacobian matrix of the AC transmission system, and then add the micro-increment model of the DC transmission unit and the new constraint equation according to the control method, and solve and correct it. Each node voltage and direct current, and repeat step S42.

In the step S42, the steps of calculating the power flow of each branch are as follows:

S421. Perform the power flow calculation of the AC subnet module until the calculation converges;

S422. Carry out the power flow calculation of the converter module, obtain the power flow and loss of the converter, and check whether the converter exceeds the limit according to the power flow and loss of the converter. If the limit is exceeded, go to step S422; if not If the limit is exceeded, proceed to step S423;

S423. Carry out power flow calculation of the DC subnetwork module; if the calculation converges, it is determined that the power flow calculation is completed, and a result is output to complete the power flow calculation; if it cannot be converged, go to step S421 until the calculation converges.

In the step S42, the preprocessing refers to: use the following formula to make the expression of the node power balance equation unified, and the formula is as follows:

;

;

in: for injection node AC active power; for injection node AC reactive power; for injection node DC active power; for injection node DC reactive power; for node voltage; for node voltage; , nodes respectively , Connected conductance and susceptance; for node , The voltage phase difference; is the inherent loss of the converter;

Among them, the expression of the power flow equation of the DC subnetwork module is:

;

in: Active power injected into the DC side of the converter; Active power injected into the AC side; is the current flowing through the converter; is the equivalent resistance of the converter.

In the step S42, the equations of the micro-increment model and the constraint equation are as follows:

;

in: , , Respectively, the unbalanced amount of DC active power, AC active power and reactive power; is the AC voltage phase angle; is the DC active power; is a direct current;is the AC node voltage; , , , is the communication element in the Jacobian matrix; , is the DC element in the Jacobian matrix.

In the step S3, the control methods include the following: the first type: constant current on the rectifier side, constant voltage on the inverter side; the second type: constant current on the rectifier side, and constant arc extinguishing angle on the inverter side; the third type : Constant power on the rectifier side, constant voltage on the inverter side; fourth: constant power on the rectifier side, constant arc extinguishing angle on the inverter side; fifth: constant firing angle on the rectifier side, constant current on the inverter side.

In the step S12, numbering the nodes and branches in the distribution network topology refers to:

First, set the access point of the distribution network and the upper-level power grid as the head node, set its number to 0, and set the number of the branch associated with the head node to 1, then the numbers of other branches diverged from the branch numbered 1 Increment along the flow direction, the number of other nodes except the first node is consistent with the number of the branch pointing to the node, the number of the branch connected to the ground through the node is consistent with the number of the corresponding node connected to the ground, and it is numbered, Obtain the numbered distribution network topology.

Example 1:

Referring to Figures 1-4, a method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network, the calculation method includes the following steps:

S1. Obtain the power lines of relevant equipment nodes, construct the topology structure of the distribution network, collect topology information, and establish a loop-branch matrix;

Furthermore, constructing the topological structure of the distribution network refers to converting the actual preset circuit into a graphical form, describing the structure of the circuit with nodes, circuits, etc., and determining the required number of nodes, circuits, and branches. and the reference direction, the topological structure of the distribution network can be obtained;

Further, the steps of establishing the loop-branch matrix include the following:

S11. Obtain the power data information of nodes, loops and branches in the topology of the distribution network;

S12. Number the nodes and branches in the distribution network topology, and obtain the numbered distribution network topology;

Preferably, in the step S12, numbering the nodes and branches in the distribution network topology refers to:

First, set the access point of the distribution network and the upper-level power grid as the head node, set its number to 0, and set the number of the branch associated with the head node to 1, then the numbers of other branches diverged from the branch numbered 1 Increment along the flow direction, the number of other nodes except the first node is consistent with the number of the branch pointing to the node, the number of the branch connected to the ground through the node is consistent with the number of the corresponding node connected to the ground, and it is numbered, Obtain the topological structure of the numbered distribution network; the distribution network is usually a tree network structure. Taking N nodes in the distribution network as an example, the distribution network with N nodes has N-1=n independent circuits. According to the above, Numbering each node and branch of the distribution network with N nodes can obtain the topology structure of the numbered distribution network;

S13. Based on the numbered distribution network topology, establish a standard vector group with the same number of circuits, determine the number of branches associated with each circuit, and obtain the power data of each branch; the power data includes each The reactance, resistance and impedance of the branch circuit;

S14. Based on the power data of each branch, assign a value to the standard vector corresponding to each circuit, so as to obtain eigenvector groups of different circuits, and construct a circuit-branch matrix according to different eigenvector groups;

S2. Based on the topological structure of the distribution network, the power flow calculation module is divided into AC subnetwork module, DC subnetwork module and converter module;

Further, the division of power flow calculation modules refers to: taking the converter as the boundary, the distribution network is divided into modules, and divided into AC sub-network modules, DC sub-network modules and converter modules;

S3. Set the control mode of the DC subnet module, and set the initial value, positive direction and convergence accuracy of the AC subnet module and the DC subnet module;

Further, the control methods include the following: the first type: constant current on the rectifier side, constant voltage on the inverter side; the second type: constant current on the rectifier side, and constant arc extinguishing angle on the inverter side; Constant power, constant voltage on the inverter side; fourth: constant power on the rectifier side, constant arc extinguishing angle on the inverter side; fifth: constant firing angle on the rectifier side, constant current on the inverter side; choose any of them according to the actual situation during calculation one or any combination;

Further, the steps of setting the initial value, positive direction and convergence accuracy of the AC subnetwork module and the DC subnetwork module include:

S31. Collect the node types of the distribution network topology, and classify the node types according to the attributes of the nodes;

Preferably, the node types include PV nodes and PQ nodes, the node voltage and active power of PV nodes are constant values; the node active power and reactive power of PQ nodes are constant values;

S32. According to the parameters of the AC subnet module and the DC subnet module, assign values to the node attributes of different classifications, obtain initial values, and set the positive direction and convergence accuracy of the AC subnet module and the DC subnet module;

S4. Carry out alternate iterative convergence judgment for the power flow calculation of the AC subnetwork module and the DC subnetwork module, output the calculation results, and complete the calculation;

Further, the steps of performing alternate iterative convergence judgment of the AC subnetwork module and the DC subnetwork module power flow calculation include:

S41. According to the established circuit-branch matrix, combined with the initial value and positive direction, calculate the unbalance amount,and;in:,Respectively, the active and reactive power imbalances of the system nodes;is the active power imbalance of the system nodes under different control modes;

S42. According to the convergence accuracy, determine the unbalance amount,andWhether to converge;

If it converges, calculate the power flow of each branch and the operating parameters of the DC transmission unit until the power flow calculations of the AC subnetwork module and the DC subnetwork module converge, output the calculation results, and complete the power flow calculation;

If it does not converge, first preprocess the DC output unit, and establish the Jacobian matrix of the AC transmission system, and then add the micro-increment model of the DC transmission unit and the new constraint equation according to the control method, and solve and correct it. Each node voltage and DC current, and repeat step S42;

Further, in step S42, the steps of calculating the power flow of each branch are as follows:

S421. Perform the power flow calculation of the AC subnet module until the calculation converges;

Preferably, the converter module is regarded as a load in the calculation of the AC subnetwork module, and the absorbed power is positive, and it is assumed that there is no power loss between the DC subnetwork module and the converter module, and the initial value of the converter module is brought into the AC The subnet module performs power flow calculation;

S422. Carry out the power flow calculation of the converter module, obtain the power flow and loss of the converter, and check whether the converter exceeds the limit according to the power flow and loss of the converter. If the limit is exceeded, go to step S422; if not If the limit is exceeded, proceed to step S423;

Preferably, the power flow calculation of the converter module is performed using the VSC model, and the power input to the converter module by the AC subnetwork module is used as the initial value, and after calculating the DC side power and voltage of the converter module, it is checked for exceeding the limit, The operating constraint of the VSC limit-crossing check is expressed as the following formula:

;

;

in:,are the lower limit and upper limit of the VSC operating voltage;,Respectively, the upper and lower limits of VSC active output and reactive output;

S423. Perform the power flow calculation of the DC subnetwork module; if the calculation converges, it is determined that the power flow calculation is completed, and the result is output to complete the power flow calculation; if it cannot be converged, proceed to step S421 until the calculation converges;

Preferably, the output power obtained from the power flow calculation of the converter module is used as the input of the power flow calculation of the DC subnet module, and the input power is negative;

Preferably, in step S42, the following formula is preferably used for preprocessing, so that the expression of the node power balance equation is unified, and the formula is as follows:

;

;

in:for injection nodeAC active power;for injection nodeAC reactive power;for injection nodeDC active power;for injection nodeDC reactive power;for nodevoltage;for nodevoltage;,nodes respectively,Connected conductance and susceptance;for node,The voltage phase difference;is the inherent loss of the converter;

Among them, the expression of the power flow equation of the DC subnetwork module is:

;

in:Active power injected into the DC side of the converter;Active power injected into the AC side;is the current flowing through the converter;is the equivalent resistance of the converter;

Preferably, the incremental model and constraint equations in step S42 are preferably as follows:

;

in:,,Respectively, the unbalanced amount of DC active power, AC active power and reactive power;is the AC voltage phase angle;is the DC active power;is a direct current;is the AC node voltage;,,,is the communication element in the Jacobian matrix;,is the DC element in the Jacobian matrix.

The above descriptions are only preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments, but all equivalent modifications or changes made by those of ordinary skill in the art according to the disclosure of the present invention should be included within the scope of protection described in the claims.

Claims (10)

1. A method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network is characterized in that the calculation method comprises the following steps: S1. Obtain the power lines of relevant equipment nodes, construct the topology structure of the distribution network, collect topology information, and establish a loop-branch matrix; S2. Based on the topological structure of the distribution network, the power flow calculation module is divided into AC subnetwork module, DC subnetwork module and converter module; S3. Set the control mode of the DC subnet module, and set the initial value, positive direction and convergence accuracy of the AC subnet module and the DC subnet module; S4. Carry out alternate iterative convergence judgment for the power flow calculation of the AC subnetwork module and the DC subnetwork module, output the calculation results, and complete the calculation. 2. A method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network according to claim 1, characterized in that: In the step S1, the step of establishing a loop-branch matrix includes: S11. Obtain the power data information of nodes, loops and branches in the topology of the distribution network; S12. Number the nodes and branches in the distribution network topology, and obtain the numbered distribution network topology; S13. Based on the numbered distribution network topology, establish a standard vector group with the same number of circuits, determine the number of branches associated with each circuit, and obtain the power data of each branch; S14. Based on the power data of each branch, assign a value to the standard vector corresponding to each circuit, thereby obtaining feature vector groups of different circuits, and construct a circuit-branch matrix according to different feature vector groups. 3. A method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network according to claim 1, characterized in that: In the step S2, dividing the power flow calculation module means: taking the converter as the boundary, dividing the distribution network into modules, dividing it into an AC subnet module, a DC subnet module and a converter module. 4. A method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network according to claim 1, characterized in that: In the step S3, the steps of setting the initial value, positive direction and convergence accuracy of the AC subnet module and the DC subnet module include: S31. Collect the node types of the distribution network topology, and classify the node types according to the attributes of the nodes; S32. According to the parameters of the AC subnet module and the DC subnet module, assign values to the node attributes of different categories to obtain initial values, and set the positive direction and convergence accuracy of the AC subnet module and the DC subnet module. 5. A multi-energy complementary AC-DC hybrid distribution network power flow calculation method according to claim 1, characterized in that: In the step S4, the step of performing alternate iterative convergence judgment of the AC subnetwork module and the DC subnetwork module power flow calculation includes: S41. According to the established circuit-branch matrix, combined with the initial value and positive direction, calculate the unbalance amount , and ;in: , Respectively, the active and reactive power imbalances of the system nodes; is the active power imbalance of the system nodes under different control modes; S42. According to the convergence accuracy, determine the unbalance amount , and Whether to converge; If it converges, calculate the power flow of each branch and the operating parameters of the DC transmission unit until the power flow calculations of the AC subnetwork module and the DC subnetwork module converge, output the calculation results, and complete the power flow calculation; If it does not converge, first preprocess the DC output unit, and establish the Jacobian matrix of the AC transmission system, and then add the micro-increment model of the DC transmission unit and the new constraint equation according to the control method, and solve and correct it. Each node voltage and direct current, and repeat step S42. 6. A method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network according to claim 5, characterized in that: In the step S42, the steps of calculating the power flow of each branch are as follows: S421. Perform the power flow calculation of the AC subnet module until the calculation converges; S422. Carry out the power flow calculation of the converter module, obtain the power flow and loss of the converter, and check whether the converter exceeds the limit according to the power flow and loss of the converter. If the limit is exceeded, go to step S422; if not If the limit is exceeded, proceed to step S423; S423. Carry out power flow calculation of the DC subnetwork module; if the calculation converges, it is determined that the power flow calculation is completed, and the result is output to complete the power flow calculation; if it cannot be converged, go to step S421 until the calculation converges. 7. A multi-energy complementary AC-DC hybrid distribution network power flow calculation method according to claim 6, characterized in that: In the step S42, the preprocessing refers to: use the following formula to make the expression of the node power balance equation unified, and the formula is as follows: ; ; in: for injection node AC active power; for injection node AC reactive power; for injection node DC active power; for injection node DC reactive power; for node voltage; for node voltage; , nodes respectively , Connected conductance and susceptance; for node , The voltage phase difference; is the inherent loss of the converter; Among them, the expression of the power flow equation of the DC subnetwork module is: ; in: Active power injected into the DC side of the converter; Active power injected into the AC side; is the current flowing through the converter; is the equivalent resistance of the converter. 8. A multi-energy complementary AC-DC hybrid distribution network power flow calculation method according to claim 7, characterized in that: In the step S42, the equations of the micro-increment model and the constraint equation are as follows: ; in: , , Respectively, the unbalanced amount of DC active power, AC active power and reactive power; is the AC voltage phase angle; is the DC active power; is a direct current; is the AC node voltage; , , , is the communication element in the Jacobian matrix; , is the DC element in the Jacobian matrix. 9. A method for calculating the power flow of a multi-energy complementary AC-DC hybrid distribution network according to any one of claims 1-6, characterized in that: In the step S3, the control methods include the following: the first type: constant current on the rectifier side, constant voltage on the inverter side; the second type: constant current on the rectifier side, and constant arc extinguishing angle on the inverter side; the third type : Constant power on the rectifier side, constant voltage on the inverter side; fourth: constant power on the rectifier side, constant arc extinguishing angle on the inverter side; fifth: constant firing angle on the rectifier side, constant current on the inverter side. 10. A multi-energy complementary AC-DC hybrid distribution network power flow calculation method according to claim 2, characterized in that: In the step S12, numbering the nodes and branches in the distribution network topology refers to: First, set the access point of the distribution network and the upper-level power grid as the head node, set its number to 0, and set the number of the branch associated with the head node to 1, then the numbers of other branches diverged from the branch numbered 1 Increment along the direction of the flow, the number of other nodes except the first node is consistent with the number of the branch pointing to the node, the number of the branch connected to the ground through the node is consistent with the number of the corresponding node connected to the ground, and it is numbered, Obtain the numbered distribution network topology.

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