Dynamic voltage restorer and parallel distributed power supply voltage compensation method and device

Abstract

The present invention discloses a method and device for voltage compensation of a dynamic voltage restorer and a parallel distributed power supply, including establishing an upper-layer dynamic voltage restorer output optimization model and a lower-layer distributed power supply optimization model to form a double-layer optimization model, wherein the upper-layer dynamic voltage restorer minimum output power is targeted to control the voltage and phase of the dynamic voltage restorer compensation; the lower-layer distributed power supply optimization model is targeted to minimize the network loss of the distribution network, and controls the output of the parallel distributed power supply in different partitions of the distribution network, and minimizes the network loss of the distribution network under the premise of meeting the minimum power operation of the dynamic voltage restorer and the safety of the distribution network, and can provide guidance for the operation of the distribution network. At the same time, the cross-direction multiplier method is used for distributed solution to reduce the communication pressure and the controller processing pressure; the acceleration algorithm is used for the convergence of the cross-direction multiplier method algorithm to improve the convergence speed and enhance the real-time performance of the control.

Description

Technical Field

[0001] The present application relates to the field of new energy distribution network control technology, and in particular to a dynamic voltage restorer and a parallel distributed power supply voltage compensation method and device. Background Art

[0002] There are two major issues that need to be addressed in order to solve the problem of voltage exceeding the limit in the distribution network: (1) what equipment to use for treatment and (2) what method to use for coordinating the equipment.

[0003] In response to problem (1), existing research methods use parallel voltage regulation equipment for regulation, such as distributed renewable energy such as wind power and photovoltaic power, and various reactive compensation equipment, such as static synchronous compensators. Through the reactive capacity of the renewable energy inverter or through coordinated control of multiple parallel devices, the line voltage drop can be compensated to achieve voltage over-limit management of the distribution network. However, the voltage management of parallel devices is achieved through compensation current. When the voltage over-limit management is performed on the remote node under the high line impedance of the long line distribution network, the compensation current will cause the network loss to increase, reducing the economic efficiency of the system operation.

[0004] Series voltage management equipment can be operated in coordination with parallel equipment to achieve voltage over-limit management while ensuring the economic operation of the system. Series voltage management equipment includes dynamic voltage restorers and on-load tap changers. The literature proposes a method for coordinated control of on-load tap changers and parallel distributed power sources. However, the action time of on-load tap changers is longer than that of fully controlled power electronic devices. Voltage compensation of the power grid through on-load tap changers is still a long-term optimization problem, which is difficult to meet the requirements of rapid recovery from voltage over-limit. The dynamic voltage restorer uses fully controlled devices to control the voltage, which has the advantages of being more direct and faster, and has more prominent advantages in voltage over-limit management.

[0005] Regarding problem (2), the commissioning of the dynamic voltage restorer will affect the voltage and current distribution in the power grid, and then change the optimal output operating point of the parallel distributed power generation in the power grid. No research has yet provided coordinated control of distributed power generation and dynamic voltage restorer. Summary of the invention

[0006] In order to solve the above problems, an embodiment of the present invention provides a dynamic voltage restorer and a parallel distributed power supply voltage compensation method and device to achieve the best overall operating effect.

[0007] According to a first aspect of an embodiment of the present application, a dynamic voltage restorer and a parallel distributed power supply voltage compensation method are provided, including:

[0008] Establish an upper-level dynamic voltage restorer output optimization model with the output voltage and power of the dynamic voltage restorer as optimization variables and the purpose of maintaining the voltage at the installation location of the dynamic voltage restorer;

[0009] Establish a lower-level distributed power optimization model with the output power of each distributed power source in the distribution network as the optimization variable and the purpose of minimizing the network loss in the distribution network;

[0010] The upper-layer dynamic voltage restorer output optimization model is solved based on semi-positive definite relaxation programming, the external load characteristics of the node are changed according to the solution results, and the information is transmitted to the lower layer; the lower layer solves the distributed power optimization model based on second-order cone programming and accelerated cross-direction multiplier method, updates the voltage of the node where the dynamic voltage restorer is located, and transmits it to the upper layer for further optimization; until the node voltage deviation controlled by the upper and lower layers meets the requirements, the optimized distributed power output and the compensation voltage of the dynamic voltage restorer are obtained respectively;

[0011] The distributed power source and the dynamic voltage restorer are controlled respectively based on the optimized distributed power source output and the compensation voltage of the dynamic voltage restorer.

[0012] According to a second aspect of an embodiment of the present application, a dynamic voltage restorer and a parallel distributed power supply voltage compensation device are provided, including:

[0013] The first model building module is used to establish an upper-level dynamic voltage restorer output optimization model with the output voltage and power of the dynamic voltage restorer as optimization variables and the purpose of maintaining the voltage at the installation location of the dynamic voltage restorer;

[0014] The second model building module is used to establish a lower-layer distributed power optimization model with the output power of each distributed power source in the distribution network as the optimization variable and the purpose of minimizing the network loss in the distribution network;

[0015] A model solving module is used to solve the upper-layer dynamic voltage restorer output optimization model based on semi-positive definite relaxation programming, change the external load characteristics of the node according to the solution result, and transmit the information to the lower layer; the lower layer solves the distributed power optimization model based on second-order cone programming and accelerated cross-direction multiplier method, updates the voltage of the node where the dynamic voltage restorer is located, and transmits it to the upper layer for further optimization; until the node voltage deviation controlled by the upper and lower layers meets the requirements, the optimized distributed power output and the compensation voltage of the dynamic voltage restorer are obtained respectively;

[0016] The control module is used to control the distributed power source and the dynamic voltage restorer respectively based on the optimized distributed power source output and the compensation voltage of the dynamic voltage restorer.

[0017] The technical solution provided by the embodiments of the present application may have the following beneficial effects:

[0018] It can be seen from the above embodiments that the upper-layer dynamic voltage restorer output optimization model and the lower-layer distributed power supply optimization model of the present application form a double-layer optimization model, and then a solution method is used to solve the model. Under the premise of satisfying the minimum power operation of the dynamic voltage restorer and the safety of the distribution network, the distribution network loss is minimized, which can provide guidance for the operation of the distribution network.

[0019] The cross-direction multiplier method is used for distributed solution to reduce the communication pressure and controller processing pressure; the acceleration algorithm is used for the convergence of the cross-direction multiplier method algorithm to improve the convergence speed and enhance the real-time performance of the control.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0022] Figure 1 The present invention is a flow chart showing a dynamic voltage restorer and a parallel distributed power supply voltage compensation method according to an exemplary embodiment.

[0023] Figure 2 The figure is a schematic diagram of branch power flow of a radial distribution network according to an exemplary embodiment.

[0024] Figure 3 The figure is a schematic diagram of data exchange between upper and lower layers of a double-layer model according to an exemplary embodiment.

[0025] Figure 4 The example IEEE 33-node network and its partitions are shown according to an exemplary embodiment.

[0026] Figure 5 is a normalized curve showing different load changes over 24 hours according to an exemplary embodiment.

[0027] Figure 6 is a normalized curve of different lighting conditions for 24 hours according to an exemplary embodiment.

[0028] Figure 7 FIG. 4 is a diagram showing network loss of an IEEE 33 system under different load and illumination conditions according to an exemplary embodiment.

[0029] Figure 8The invention is a block diagram showing a dynamic voltage restorer and a parallel distributed power supply voltage compensation device according to an exemplary embodiment. DETAILED DESCRIPTION

[0030] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0031] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0032] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0033] Figure 1 is a flow chart showing a method for voltage compensation of a dynamic voltage restorer and a parallel distributed power supply according to an exemplary embodiment. Figure 1 As shown, the method may include the following steps:

[0034] S1: Establish an upper-level dynamic voltage restorer output optimization model with the output voltage and power of the dynamic voltage restorer as optimization variables and the purpose of maintaining the voltage at the installation location of the dynamic voltage restorer;

[0035] Specifically, when the dynamic voltage restorer uses energy storage elements as energy, it should use the minimum energy compensation method as much as possible when providing voltage support.

[0036] (1)

[0037] Where: P dvr , P L , P s , P lossThey are the active power consumed by the dynamic voltage restorer, the active power required by the load, the active power output from the grid side and the active power loss on the line.

[0038] Expressing (1) in terms of current, we have

[0039] (2)

[0040] Where: R is the real part of the line impedance; I L is the line current.

[0041] At the same time, in order to ensure that the load side voltage after compensation does not exceed the limit, the line current needs to meet

[0042] (3)

[0043] Where: U Lmin , U Lmax , S L They are the minimum voltage, maximum voltage, and apparent power of the load allowed at the installation location of the dynamic voltage restorer.

[0044] After the dynamic voltage restorer compensates the load side voltage, it changes the original line current and reflects this change in the node information in the form of node load. The node load change is

[0045] (4)

[0046] Where: is the apparent power of this node to other nodes in the distribution network; P dvr , P L They are respectively the active power consumed by the dynamic voltage restorer and the active power required by the load; Q dvr , Q L They are the reactive power consumed by the dynamic voltage restorer and the reactive power required by the load; U g is the grid-side voltage; X is the imaginary part of the line impedance.

[0047] This is a non-convex constraint condition, so it constitutes a non-convex quadratic constrained quadratic programming problem, denoted as

[0048] (5)

[0049] Where: A0 is a 2×2 real symmetric positive definite matrix, one of A1 and A2 is a negative definite matrix, b0 and c0 are constants.

[0050] Through this step, the dynamic voltage restorer output optimization model is established, and the solution of the optimization model can be used as the output of the dynamic voltage restorer. At the same time, the node load change provides a hub for building the connection between the dynamic voltage restorer and the distributed power layer.

[0051] S2: Establish a lower-level distributed power optimization model with the output power of each distributed power source in the distribution network as the optimization variable and the purpose of minimizing the network loss in the distribution network;

[0052] Specifically, the objective function of the lower distributed power optimization model is:

[0053] (6)

[0054] Where: P loss is the total network loss of the total distribution network, i j is the current in the line connecting child node j and its parent node, r j is the resistance value of the line connecting child node j and its parent node.

[0055] The constraints of the radial distribution network include the power flow constraints of the distribution network and the upper and lower limit constraints of the state quantity. Each line variable is marked through the sub-node, such as Figure 2 The corresponding constraints are:

[0056] (7)

[0057] Where: V j is the voltage of the jth node; i kj , Z k are the current from parent node j to child node k and the impedance of the line; r k 、x k represents the line resistance and inductance of the line flowing to child node k; k:j→k represents all child nodes with j as the parent node; P k , Q k represents the active power and reactive power flowing into child node k; , denote the active load and reactive load of node j respectively; and They represent the active output and reactive output of the distributed power source connected to node j; V1 is the root node voltage; V set is the root node voltage setting value; ε is the allowable deviation of the node voltage; and They are respectively the upper limit of active power output and reactive power output of distributed power sources; N is the number of nodes.

[0058] Through this step, a distributed power optimization model is established, and the solution of the optimization model can be used as the output of the distributed power. At the same time, the voltage at the installation location of the dynamic voltage restorer is considered in the model and can be fed back to the upper layer.

[0059] S3: Solve the upper-layer dynamic voltage restorer output optimization model based on semi-positive definite relaxation programming, change the external load characteristics of the node according to the solution results, and pass the information to the lower layer; the lower layer solves the distributed power optimization model based on second-order cone programming and accelerated cross-direction multiplier method, updates the voltage of the node where the dynamic voltage restorer is located, and passes it to the upper layer for further optimization; until the node voltage deviation controlled by the upper and lower layers meets the requirements, the optimized distributed power output and the compensation voltage of the dynamic voltage restorer are obtained respectively;

[0060] Based on the node load information provided by equation (3) and the distribution network information obtained by equation (7), the voltage compensation of the dynamic voltage restorer and the compensation capacity of the distributed generation can be linked to each other through the distribution network flow to achieve coordinated compensation when the distribution network voltage drops. The data flow is as follows: Figure 3 As shown. In the collaborative process, the optimized control of the distributed power source always updates the voltage of the node where the dynamic voltage restorer is located, thereby changing the compensation voltage of the dynamic voltage restorer. The change of the compensation voltage of the dynamic voltage restorer causes the external load characteristics of the node to change, requiring the distributed power source to further optimize the control. Finally, when the voltage deviation of the nodes controlled by both parties meets the requirements, the optimized distributed power output and the compensation voltage of the dynamic voltage restorer are obtained.

[0061] The method of solving the lower-layer distributed power optimization model based on second-order cone programming and accelerated cross multiplication method includes the following sub-steps:

[0062] A1: Transform the lower distributed generation optimization model into a second-order cone form;

[0063] Specifically, the dynamic voltage restorer output optimization model can be convexified by using semi-positive definite programming relaxation, (5) is equivalent to:

[0064] (8)

[0065] Ignoring the rank condition, equation (8) is a solvable form of the optimizer. Therefore, the optimization solution of the non-convex problem can be obtained by solving this semi-positive definite programming problem, that is, the active current and reactive current at the optimal output of the dynamic voltage restorer, and the output voltage and corresponding output power of the dynamic voltage restorer can be calculated based on this.

[0066] The branch power flow equation (7) in the distributed power optimization model is relaxed by the second-order cone. By eliminating the phase angle of current and voltage, the power equality constraint is converted into the form of second-order cone programming (SOCP). According to the structure of the radial distribution network, it can be convexified as follows:

[0067] (9)

[0068] Where: U j = , I j = , represent the square of node voltage and current respectively.

[0069] A2: transform the lower distributed power optimization model transformed into the second-order cone form into a distributed form;

[0070] Specifically, the distribution network is decomposed into regions, and the optimization model is further transformed into a distributed form:

[0071] (10)

[0072] Where: f i (x i ) is the objective function of the sub-problem in region i; R is the number of regions divided by the distribution network; h i (x i ), g i (x i ) are the equality constraints and inequality constraints corresponding to the subproblems respectively; the variable x i represents all state variables in region i, including the power, voltage, line current and distributed power output of each node; region j represents the adjacent region connected to region i through a branch. M,C,i is x i Part of X M,C,j is the boundary variable of another region j. R is the number of regions decomposed.

[0073] A3: Solve the lower-level distributed power optimization model through the accelerated cross multiplication method.

[0074] Specifically, the augmented Lagrangian function of the distributed model after the optimization model transformation is:

[0075] (11)

[0076] Where: A and λ B are the dual vectors of the boundary information of region A and region B respectively; ρ is the penalty term coefficient. The update method of the variables in the region at this time is:

[0077] (12)

[0078] Where: t is the number of iterations; X M,C,A With X M,C,B Follow x A With x B Update, XtB and XtA are the boundary information of region B and region A at the tth iteration respectively.

[0079] Then the dual vector is updated as follows:

[0080] (13)

[0081] The cross multiplication method is further accelerated, and equation (13) is updated as follows:

[0082] (14)

[0083] Among them, there are

[0084] (15)

[0085] In the formula, σ t is the acceleration factor at the tth iteration.

[0086] Through this step, the upper-level semi-positive definite programming solution and the lower-level second-order cone programming and accelerated cross multiplier method solution are realized. Under the premise of meeting the minimum power operation of the dynamic voltage restorer and the safety of the distribution network, the distribution network loss is minimized, which can provide guidance for the operation of the distribution network. The cross-direction multiplier method is used for distributed solution to reduce the communication pressure and controller processing pressure; the acceleration algorithm is used for the convergence of the cross-direction multiplier method algorithm to improve the convergence speed and enhance the real-time performance of the control.

[0087] S4: Based on the optimized distributed power output and the compensation voltage of the dynamic voltage restorer, the distributed power source and the dynamic voltage restorer are controlled respectively.

[0088] The solution of the above two-layer model can be used as the operating parameters of the dynamic voltage restorer and distributed power supply.

[0089] like Figure 4 The IEEE 33-node network shown in the figure has three areas. Nodes 3, 12, 15, 16, and 25 are equipped with controllable distributed active power sources with a maximum output power of 350 kW. Nodes 3, 12, 16, 23, 27, and 30 are equipped with distributed reactive power sources with a maximum power of 350 kvar. Nodes 18, 20, 27, and 28 are equipped with photovoltaic power sources with a maximum power of 150 kW. The dynamic voltage restorer is connected to nodes 17 and 32, and the load size at node 32 is twice the initial value. In the IEEE 33 system, considering different load conditions and different light conditions in 24 hours, the load size is calculated as follows: Figure 5 and Figure 6 The normalized change curve shown in the figure is changed, and the double-layer optimization control is performed at 24 time points to obtain the network loss of the IEEE 33 system under different loads and light conditions. Figure 7As shown in the figure: Under different load conditions, the two-layer optimization method can achieve optimal control of the system at each control time point, effectively reducing the network loss of the distribution network system and raising the terminal node voltage.

[0090] Corresponding to the aforementioned embodiments of the dynamic voltage restorer and the parallel distributed power supply voltage compensation method, the present application also provides embodiments of the dynamic voltage restorer and the parallel distributed power supply voltage compensation device.

[0091] Figure 8 1 is a block diagram of a dynamic voltage restorer and a parallel distributed power supply voltage compensation device according to an exemplary embodiment. Figure 8 , the device comprises:

[0092] The first model building module 1 is used to establish an upper-level dynamic voltage restorer output optimization model with the output voltage and power of the dynamic voltage restorer as optimization variables and the purpose of maintaining the voltage at the installation location of the dynamic voltage restorer;

[0093] The second model building module 2 is used to establish a lower-layer distributed power optimization model with the output power of each distributed power source in the distribution network as the optimization variable and the purpose of minimizing the network loss in the distribution network;

[0094] Model solving module 3 is used to solve the upper-layer dynamic voltage restorer output optimization model based on semi-positive definite relaxation programming, change the external load characteristics of the node according to the solution result, and transmit the information to the lower layer; the lower layer solves the distributed power optimization model based on second-order cone programming and accelerated cross-direction multiplier method, updates the voltage of the node where the dynamic voltage restorer is located, and transmits it to the upper layer for further optimization; until the node voltage deviation controlled by the upper and lower layers meets the requirements, the optimized distributed power output and the compensation voltage of the dynamic voltage restorer are obtained respectively;

[0095] The control module 4 is used to control the distributed power source and the dynamic voltage restorer respectively based on the optimized distributed power source output and the compensation voltage of the dynamic voltage restorer.

[0096] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0097] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0098] Correspondingly, the present application also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the dynamic voltage restorer and parallel distributed power supply voltage compensation method as described above.

[0099] Correspondingly, the present application also provides a computer-readable storage medium on which computer instructions are stored. When the instructions are executed by a processor, the dynamic voltage restorer and the parallel distributed power supply voltage compensation method as described above are implemented.

[0100] Those skilled in the art will readily appreciate other embodiments of the present application after considering the description and practicing the contents disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The description and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0101] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A dynamic voltage restorer and a parallel distributed power supply voltage compensation method, characterized in that: include: Establish an upper-level dynamic voltage restorer output optimization model with the output voltage and power of the dynamic voltage restorer as optimization variables and the purpose of maintaining the voltage at the installation location of the dynamic voltage restorer; Establish a lower-level distributed power optimization model with the output power of each distributed power source in the distribution network as the optimization variable and the purpose of minimizing the network loss in the distribution network; Solving the output optimization model of the upper-layer dynamic voltage restorer based on semi-positive definite relaxation programming, changing the external load characteristics of the node according to the solution result, and transmitting the information to the lower layer; The lower layer solves the distributed power optimization model based on second-order cone programming and accelerated cross-direction multiplier method, updates the voltage of the node where the dynamic voltage restorer is located, and transmits it to the upper layer for further optimization; until the node voltage deviation controlled by the upper and lower layers reaches the requirement, the optimized distributed power output and the compensation voltage of the dynamic voltage restorer are obtained respectively; The distributed power source and the dynamic voltage restorer are controlled respectively based on the optimized distributed power source output and the compensation voltage of the dynamic voltage restorer.

2. The method according to claim 1, characterized in that: The objective function of the upper layer dynamic voltage restorer output optimization model is: minP dvr =P L -P s +P loss ; Where: P dvr , P L , P s , P loss They are the active power consumed by the dynamic voltage restorer, the active power required by the load, the active power output from the grid side and the active power loss on the line.

3. The method according to claim 1, characterized in that: The constraints of the upper layer dynamic voltage restorer output optimization model are: Where: U Lmin , U Lmax , S L ,I L They are the minimum voltage, maximum voltage, load apparent power and load current allowed at the installation location of the dynamic voltage restorer.

4. The method according to claim 1, characterized in that: The objective function of the lower distributed power optimization model is the total network loss of the distribution network.

5. A dynamic voltage restorer and a parallel distributed power supply voltage compensation method as claimed in claim 1, characterized in that: The constraints of the lower distributed power optimization model are: Where: V j is the voltage of the jth node; Z k is the impedance of the line from parent node j to child node k; r k 、x k represents the line resistance and inductance of the line flowing to child node k; k:j→k represents all child nodes with j as the parent node; P k , Q k represents the active power and reactive power flowing into child node k; denote the active load and reactive load of node j respectively; and They represent the active output and reactive output of the distributed power source connected to node j; V1 is the root node voltage; V set is the root node voltage setting value; ε is the allowable deviation of the node voltage; and They are respectively the upper limit of active power output and reactive power output of distributed power sources; N is the number of nodes.

6. The method according to claim 1, characterized in that: The method of solving the lower distributed power optimization model based on second-order cone programming and accelerated cross multiplication method includes: A1: Transform the lower distributed generation optimization model into a second-order cone form; A2: transform the lower distributed power optimization model transformed into the second-order cone form into a distributed form; A3: Solve the lower-level distributed power optimization model through the accelerated cross multiplication method.

7. The method according to claim 6, characterized in that The lower distributed power optimization model is transformed into a second-order cone form as follows: Where: U j is the square of the voltage at the jth node; I j is the square of the current flowing into the kth child node; r k 、x k represents the line resistance and inductance of the line flowing to child node k; k:j→k represents all child nodes with j as the parent node; P k , Q k represents the active power and reactive power flowing into child node k; denote the active load and reactive load of node j respectively; and Respectively represent the active output and reactive output of the distributed power source connected to node j; V set is the root node voltage setting value; ε is the allowable deviation of the node voltage; and They are respectively the upper limit of active power output and reactive power output of distributed power sources; N is the number of nodes.

8. The method according to claim 6, characterized in that The lower distributed power optimization model transformed into the second-order cone form is transformed into a distributed form, as follows: Decomposing the distribution network area, the optimization problem in distributed form can be expressed as: Where: f i (x i ) is the objective function of the sub-problem in region i; R is the number of regions divided by the distribution network; h i (x i ), g i (x i ) are the equality constraints and inequality constraints corresponding to the subproblems respectively; the variable x i Represents all state variables in region i, including the power and voltage of each node, the line current in the region, and the output of distributed generation; Region j represents an adjacent region connected to region i through a branch; X M,C,i is x i Part of X M,C,j is the boundary variable of another region j; R is the number of decomposed regions.

9. The method according to claim 6, characterized in that The lower distributed power optimization model is solved by the accelerated cross multiplication method, as follows: The augmented Lagrangian function L of the distributed model is: Where: variable x i Represents all state variables in region i, including the power and voltage of each node, the line current in the region, and the output of distributed generation; Region j represents an adjacent region connected to region i through a branch; X M,C,i is x i Part of X M,C,j is the boundary variable of another region j; A and λ B are the dual vectors of the boundary information of region A and region B respectively; ρ is the penalty term coefficient. The update method of the variables in the region at this time is: Where: t is the number of iterations; X M,C,A With X M,C,B Follow x A With x B renew, and They are the boundary information of area B and area A at the tth iteration; Then the dual vector is updated as follows: The accelerated cross multiplication method is embodied in: in, In the formula, σ t is the acceleration factor at the tth iteration.

10. A dynamic voltage restorer and a parallel type distributed power supply voltage compensation device, characterized in that: include: The first model building module is used to establish an upper-level dynamic voltage restorer output optimization model with the output voltage and power of the dynamic voltage restorer as optimization variables and the purpose of maintaining the voltage at the installation location of the dynamic voltage restorer; The second model building module is used to establish a lower-layer distributed power optimization model with the output power of each distributed power source in the distribution network as the optimization variable and the purpose of minimizing the network loss in the distribution network; A model solving module, used for solving the output optimization model of the upper-layer dynamic voltage restorer based on semi-positive definite relaxation programming, changing the external load characteristics of the node according to the solution result, and transmitting the information to the lower layer; The lower layer solves the distributed power optimization model based on second-order cone programming and accelerated cross-direction multiplier method, updates the voltage of the node where the dynamic voltage restorer is located, and transmits it to the upper layer for further optimization; until the node voltage deviation controlled by the upper and lower layers reaches the requirement, the optimized distributed power output and the compensation voltage of the dynamic voltage restorer are obtained respectively; The control module is used to control the distributed power source and the dynamic voltage restorer respectively based on the optimized distributed power source output and the compensation voltage of the dynamic voltage restorer.

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