Power distribution network cluster voltage control method and control system suitable for risk prevention and control, computer equipment and storage medium

Abstract

The invention discloses a power distribution network cluster voltage control method suitable for risk prevention and control, and the method comprises the steps: setting an objective function of a cluster voltage control model, and enabling the objective function to minimize node voltage deviation and system loss; a dominant node selection method of the cluster voltage control model is established, and the dominant node selection method is to select nodes capable of representing node voltage levels in a cluster based on observability and controllability indexes; establishing constraint conditions of the cluster voltage control model, wherein the constraint conditions comprise a power distribution network flow constraint, a distributed photovoltaic power generation output constraint, a voltage amplitude constraint and a branch power constraint; and constructing the cluster voltage control model based on the objective function and the constraint condition of the cluster voltage control model. According to the method, the problems of power grid node voltage rise, line tail end voltage exceeding, large coordination difficulty between controllable equipment, poor regional integration capability and the like caused by mass distributed photovoltaic access of the current power distribution network can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system voltage control, and in particular to a distribution network cluster voltage control method, control system, computer equipment and storage medium suitable for risk prevention and control. Background Art

[0002] With a large number of distributed photovoltaics connected to the distribution network, problems such as increased voltage at some nodes of the distribution network and excessive voltage at the end of the line have emerged. In addition, the current voltage control strategies of the distribution network mostly adopt centralized control strategies or simple on-site consumption, which makes coordination between controllable devices difficult and has poor regional integration capabilities.

[0003] Therefore, a cluster voltage control method is needed to deal with problems such as increased voltage at distribution network nodes, excessive voltage at the end of the line, difficulty in coordination between controllable devices, and poor regional integration capabilities. Summary of the invention

[0004] In view of the above existing problems, the present invention is proposed. Therefore, the present invention provides a distribution network cluster voltage control method suitable for risk prevention and control, which solves the current problems of increased voltage at distribution network nodes, excessive voltage at the end of the line, difficulty in coordination between controllable devices, and poor regional integration capabilities.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a distribution network cluster voltage control method suitable for risk prevention and control, comprising:

[0007] Setting an objective function of a cluster voltage control model, wherein the objective function is to minimize node voltage deviation and system loss;

[0008] A method for selecting a dominant node in a control model using cluster voltage, wherein the method for selecting the dominant node is performed based on observability and controllability indicators;

[0009] Establishing constraints of the cluster voltage control model, wherein the constraints include establishing distribution network flow constraints, distributed photovoltaic power generation output constraints, voltage amplitude constraints and branch power constraints;

[0010] Based on the objective function and constraints of the cluster voltage control model, a cluster voltage control model is constructed. The dominant node selection method based on observability and controllability indicators is adopted. The voltage level of each cluster is monitored through the dominant node, and the distributed photovoltaic active / reactive output connected to the dominant node is used to regulate the system voltage. The control variable is the adjustable resource output power of each cluster dominant node.

[0011] As a preferred solution of a distribution network cluster voltage control method suitable for risk prevention and control described in the present invention, the objective function is to minimize the node voltage deviation and system loss, which is expressed as:

[0012]

[0013] In the formula, α 1 ,α 2 represents the weight coefficient in the objective function, and the present invention sets its value to 0.8 and 0.2 respectively; U i,t represents the voltage amplitude of the dominant node i at time t; U pu is the voltage reference value, m and n represent the number of dominant nodes and total nodes respectively; G ij is the line impedance between nodes i and j; θ ij,t is the phase angle difference between nodes i and j at time t.

[0014] As a preferred solution of the distribution network cluster voltage control method suitable for risk prevention and control described in the present invention, the observability and controllability indicators are expressed as:

[0015] Observability index: According to the voltage level of the dominant node in the cluster, the voltage fluctuation of other nodes in the cluster can be judged. Based on the active and reactive voltage sensitivity of each node, the observability index O is defined. k as follows:

[0016]

[0017] Observability Index k It can reflect the comprehensive sensitivity of the voltage of the dominant node m in cluster k to the voltages of the other nodes in the cluster.

[0018] Controllability index: When a voltage problem occurs in the cluster, the voltage level of the entire cluster can be controlled by adjusting the active / reactive output of the dominant node. Define the controllability index M k as follows:

[0019]

[0020] In the formula, the controllability index M k It can reflect the impact of the active and reactive power changes of the dominant node m in cluster k on the voltage of other nodes in the cluster;

[0021] According to formula (2)-formula (3), the selection basis of the dominant node in cluster k is defined as shown in formula (4):

[0022] ω=max{ζ o ·O k +ζ m ·M k} (4)

[0023] In the formula, ζ o and m Respectively represent the weight coefficients of observability and controllability, ζ o +ζ m =1.

[0024] As a preferred solution of a distribution network cluster voltage control method suitable for risk prevention and control described in the present invention, wherein: the distribution network flow constraint specifically includes:

[0025]

[0026] Where P i,t , Q i,t They represent the active power and reactive power injected into node i at time t respectively; G ij , B ij are the line impedance and admittance between nodes i and j respectively; θ ij,t is the phase angle difference between nodes i and j at time t; are the active and reactive power of the load at node i at time t respectively; are the active and reactive power of distributed photovoltaic power station i at time t respectively.

[0027] As a preferred solution of a distribution network cluster voltage control method suitable for risk prevention and control described in the present invention, wherein: the distributed photovoltaic power generation output constraint specifically includes:

[0028]

[0029] η i ≥η min (8)

[0030] In the formula, is the capacity of distributed photovoltaic at node i; T is the scheduling period, which is 24h; ηi is the photovoltaic utilization rate of node i during period T; is the theoretical output of distributed photovoltaic power generation at node i at time t (output before power curtailment); η min is the photovoltaic utilization rate limit.

[0031] It should be noted that although both active and reactive power can be adjusted to achieve voltage control, considering the different costs, reactive resources in the cluster should be used first when adjusting the voltage of the distribution network. The present invention gives priority to using the reactive adjustable capacity of distributed photovoltaics, and after the reactive adjustment capacity is exhausted, the distributed photovoltaics are abandoned.

[0032] As a preferred solution of a distribution network cluster voltage control method suitable for risk prevention and control described in the present invention, the voltage amplitude constraint specifically includes:

[0033] U max ≤U i,t ≤U min (9)

[0034] Where U max , U min Respectively represent the upper and lower limits of the node voltage amplitude. According to the provisions of GB / T 40427-2021, the node voltage constraint range is set to 0.93U N ~1.07U N , where U N is the rated voltage (the per-unit value is 1).

[0035] As a preferred solution of a distribution network cluster voltage control method suitable for risk prevention and control described in the present invention, wherein: branch power constraints specifically include:

[0036]

[0037] In the formula, Respectively represent the upper and lower limits of branch power.

[0038] In a second aspect, the present invention provides a distribution network cluster voltage control system suitable for risk prevention and control, which includes:

[0039] The objective function building module of the cluster voltage control model is used to obtain the objective function of minimizing the node voltage deviation and system loss;

[0040] A module for establishing a dominant node selection method of a cluster voltage control model is used to select a node that can represent the voltage level of nodes in the cluster. The dominant node selection method is based on observability and controllability indicators.

[0041] The constraint condition establishment module of the cluster voltage control model is used to establish distribution network flow constraints, distributed photovoltaic power generation output constraints, voltage amplitude constraints, and branch power constraints;

[0042] The cluster voltage control model establishment module is used to establish the cluster voltage control model. It adopts the dominant node selection method based on observability and controllability indicators, monitors the voltage level of each cluster through the dominant node, and regulates the system voltage based on the distributed photovoltaic active / reactive output connected to the dominant node. The control variable is the adjustable resource output power of each cluster dominant node.

[0043] As a preferred solution of a distribution network cluster voltage control system suitable for risk prevention and control described in the present invention, the constraint condition establishment module of the cluster voltage control model is based on a 50-node example, and the advantages of the cluster voltage regulation method are verified through comparative experiments with no active voltage regulation and centralized voltage regulation.

[0044] In a third aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, it implements any step of the above-mentioned distribution network cluster voltage control method suitable for risk prevention and control.

[0045] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the above-mentioned distribution network cluster voltage control method suitable for risk prevention and control is implemented.

[0046] Beneficial effects of the present invention: The present invention constructs a distribution network cluster voltage control model with the goal of minimizing node voltage deviation and system loss, and considers distribution network flow constraints, distributed photovoltaic power generation output constraints, voltage amplitude constraints, and branch power constraints, and finally determines the cluster voltage control scheme based on typical scenarios. It can solve the current distribution network problems such as increased grid node voltage, excessive line end voltage, difficulty in coordination between controllable devices, and poor regional integration capabilities caused by the large-scale access of distributed photovoltaics. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0048] Figure 1 A schematic diagram of a 50-node distribution network cluster voltage control calculation example of a distribution network cluster voltage control method suitable for risk prevention and control according to an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of the voltage status of the original distribution network nodes of a distribution network cluster voltage control method suitable for risk prevention and control according to an embodiment of the present invention;

[0050] Figure 3 A schematic diagram of a distribution network cluster voltage control method for distribution network cluster voltage control suitable for risk prevention and control according to an embodiment of the present invention;

[0051] Figure 4 A schematic diagram showing a comparison of voltage control effects of a centralized method of a distribution network cluster voltage control method suitable for risk prevention and control according to an embodiment of the present invention;

[0052] Figure 5A schematic diagram showing a comparison of reactive power regulation quantities of a centralized method of a distribution network cluster voltage control method suitable for risk prevention and control according to an embodiment of the present invention;

[0053] Figure 6 A schematic diagram of reactive power call amount of a centralized voltage regulation method of a distribution network cluster voltage control method suitable for risk prevention and control according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0056] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0057] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0058] At the same time, in the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0059] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] Example 1

[0061] Reference Figure 1 , is an embodiment of the present invention, and provides a distribution network cluster voltage control method suitable for risk prevention and control, comprising:

[0062] S1: Set the objective function of the cluster voltage control model, which is to minimize node voltage deviation and system loss;

[0063] Furthermore, the objective function is to minimize the node voltage deviation and system loss:

[0064]

[0065] In the formula, α 1 ,α 2 represents the weight coefficient in the objective function, and the present invention sets its value to 0.8 and 0.2 respectively; U i,t represents the voltage amplitude of the dominant node i at time t; U pu is the voltage reference value, m and n represent the number of dominant nodes and total nodes respectively; G ij is the line impedance between nodes i and j; θ ij,t is the phase angle difference between nodes i and j at time t.

[0066] Furthermore, the leading node selection method includes:

[0067] The dominant node refers to the node that can represent the voltage level of the nodes in the cluster. When a voltage problem occurs in the cluster, the voltage level of the entire cluster can be controlled by adjusting the active and reactive output of the dominant node. Therefore, the dominant node must have certain observability, controllability and flexible adjustment capabilities. Nodes with distributed photovoltaics have higher flexible adjustment capabilities and importance, and are more suitable as dominant nodes for cluster control.

[0068] The traditional method of determining the dominant node using sensitivity information focuses more on the electrical connection between the dominant node and other nodes in the cluster, and does not conduct in-depth research on the power regulation capability of the dominant node itself. In this regard, the present invention determines the cluster dominant node through the two dimensions of observability and controllability, thereby improving the observability and regulation potential of the system.

[0069] Furthermore, observability indicators include:

[0070] According to the voltage level of the dominant node in the cluster, the voltage fluctuation of other nodes in the cluster can be judged. Based on the active and reactive voltage sensitivity of each node, the observability index O is defined. k as follows:

[0071]

[0072] Observability Index k It can reflect the comprehensive sensitivity of the voltage of the dominant node m in cluster k to the voltages of the other nodes in the cluster.

[0073] Furthermore, controllability indicators include:

[0074] When a voltage problem occurs in the cluster, the voltage level of the entire cluster can be controlled by adjusting the active / reactive output of the dominant node. Define the controllability index M k as follows:

[0075]

[0076] In the formula, the controllability index M k It can reflect the impact of the active and reactive power changes of the dominant node m in cluster k on the voltage of other nodes in the cluster.

[0077] According to formula (2)-formula (3), the selection basis of the dominant node in cluster k is defined as shown in formula (4):

[0078] ω=max{ζ o ·O k +ζ m ·M k} (4)

[0079] In the formula, ζ o and m Respectively represent the weight coefficients of observability and controllability, ζ o +ζ m =1.

[0080] S2: Establish the constraints of the cluster voltage control model, including distribution network flow constraints, distributed photovoltaic power generation output constraints, voltage amplitude constraints, and branch power constraints;

[0081] Furthermore, the power flow constraints of the distribution network are established, including:

[0082]

[0083] Where P i,t , Q i,tThey represent the active power and reactive power injected into node i at time t respectively; G ij , B ij are the line impedance and admittance between nodes i and j respectively; θ ij,t is the phase angle difference between nodes i and j at time t; are the active and reactive power of the load at node i at time t respectively; are the active and reactive power of distributed photovoltaic power station i at time t respectively.

[0084] Furthermore, the output constraints of distributed photovoltaic power generation are established, including:

[0085]

[0086] η i ≥η min (11)

[0087] In the formula, is the capacity of distributed photovoltaic at node i; T is the scheduling period, which is 24h; η i is the photovoltaic utilization rate of node i in period T; is the theoretical output of distributed photovoltaic power generation at node i at time t (output before power curtailment); η min is the photovoltaic utilization rate limit.

[0088] It should be noted that although both active and reactive power can be adjusted to achieve voltage control, considering the different costs, reactive resources in the cluster should be used first when adjusting the voltage of the distribution network. The present invention gives priority to using the reactive adjustable capacity of distributed photovoltaics, and after the reactive adjustment capacity is exhausted, the distributed photovoltaics are abandoned.

[0089] Furthermore, voltage amplitude constraints are established, including:

[0090] U max ≤U i,t ≤U min (12)

[0091] Where U max , U min Respectively represent the upper and lower limits of the node voltage amplitude. According to the provisions of GB / T 40427-2021, the node voltage constraint range is set to 0.93U N ~1.07U N , where U N is the rated voltage (the per unit value is 1).

[0092] Furthermore, branch power constraints are established, including:

[0093]

[0094] In the formula, Respectively represent the upper and lower limits of branch power.

[0095] S3: Based on the objective function and constraints of the cluster voltage control model, a cluster voltage control model is constructed.

[0096] After defining the objective function and constraints, the distribution network cluster voltage control model suitable for risk prevention and control is constructed as follows:

[0097]

[0098] st(5)-(13)

[0099] Furthermore, this embodiment also provides a distribution network cluster voltage control system suitable for risk prevention and control, including:

[0100] The objective function building module of the cluster voltage control model is used to obtain the objective function of minimizing the node voltage deviation and system loss;

[0101] A module for establishing a leading node selection method of a cluster voltage control model is used to select nodes that can represent the voltage level of nodes in the cluster;

[0102] The constraint condition establishment module of the cluster voltage control model is used to establish distribution network flow constraints, distributed photovoltaic power generation output constraints, voltage amplitude constraints, and branch power constraints;

[0103] The cluster voltage control model building module is used to build a cluster voltage control model.

[0104] This embodiment also provides a computer device, which is suitable for the distribution network cluster voltage control method for risk prevention and control, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the distribution network cluster voltage control method suitable for risk prevention and control as proposed in the above embodiment.

[0105] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0106] This embodiment further provides a storage medium on which a computer program is stored. When the program is executed by a processor, the distribution network cluster voltage control method suitable for risk prevention and control proposed in the above embodiment is implemented.

[0107] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0108] Example 2

[0109] Reference Figure 1-5 And Table 1-2 is an embodiment of the present invention, which provides a distribution network cluster voltage control method suitable for risk prevention and control. In order to verify its beneficial effects, the beneficial effects are explained by comparing data.

[0110] The main steps are:

[0111] Input the topology data of the voltage control example of a 50-node distribution network cluster.

[0112] Input cluster data, distributed photovoltaic node number, and distributed photovoltaic installed capacity.

[0113] Call the dominant node selection method to obtain the dominant node selection result.

[0114] Input the dominant node selection result and call the distribution network cluster voltage control model suitable for risk prevention and control to obtain the cluster voltage control result.

[0115] Specifically, Figure 1, the 50-node distribution network cluster voltage control example shown is used as the simulation system. This distribution network system contains 50 nodes and 49 branches, which is a typical radial distribution network system. In order to verify the effectiveness of the cluster voltage control method of the present invention, the present invention lists the location and capacity information of the distributed power source based on the example topology structure and the distributed photovoltaic access ledger, as shown in Table 1.

[0116] Table 1 Capacity and location of distributed power generation in distribution network system

[0117]

[0118] In the example of the present invention, the voltage level is 10kV, and the installation positions of the distributed power supply nodes are nodes 11, 13, 14, 15, 17, 18, 19, 20, 28, 29, 30, 31, 32, 33, 35, 41, and 46. The present invention adopts an empirical method to determine the number of partitions, that is, for a set containing n points, the number of partitions can be set to Therefore, we set the number of clusters to 5.

[0119] The dominant node selection method is called to obtain the dominant node selection result, as shown in Table 2.

[0120] Table 2. Results of leading node selection

[0121]

[0122] In order to demonstrate the effectiveness of the cluster voltage control effect of the present invention, Figure 2 This is the voltage situation before the intervention of active voltage regulation equipment. From the node point of view, after node 35, due to the large installed capacity of distributed photovoltaics and the distributed photovoltaics located at the end of the long feeder, the voltage over-limit is more serious, and 20% of the nodes in the system have experienced the problem of voltage over-limit; from the time point of view, the voltage over-limit occurs from 9h to 14h. During this period, the distributed photovoltaics are at the peak of output, resulting in a more serious voltage over-limit situation.

[0123] According to calculation, Figure 2 Without active voltage regulation, the system voltage deviation is 18.54pu (based on the balance node voltage of 1.0pu), and the maximum deviation of node 46 at 13:00 is 0.1021pu. The cluster leading node of the present invention is used to regulate the distribution network voltage. The regulated system voltage for 24 hours a day is as follows: Figure 3As shown in the figure, it can be seen that the system controls the voltage within the limit range during the whole day. Under this control mode, the total voltage deviation of the system is 14.63pu, which is 21.09% lower than the original voltage deviation. The maximum deviation of the whole day is also at 13:46 node, which is only 0.0591pu, which is 42.12% lower than the maximum node voltage deviation in the original system. It can be seen that the optimization method proposed in the present invention has a good voltage regulation effect.

[0124] In order to compare the voltage conditions of each node before and after the control strategy of the present invention, the typical time of noon photovoltaic power generation, 13h, is selected as an example for single section analysis. Figure 4 It can be seen that the voltage over-limit problem mainly occurs in cluster 1. The dominant node 41 of cluster 1 determined by the method of the present invention can effectively represent the node voltage level within the cluster during this period, thus realizing the observability of the voltage over-limit problem within the cluster. Figure 4 It can be seen from the node voltage after the control strategy of the present invention that the voltage level of the entire cluster can be effectively controlled by adjusting the power of the dominant node 41. This further proves the effectiveness of the dominant node selection and cluster voltage control scheme proposed by the present invention.

[0125] In order to verify the scientific effectiveness of the distribution network cluster voltage control model suitable for risk prevention and control in the present invention, the method of the present invention is compared with the centralized voltage control method (centralized voltage regulation through the adjustable capacity of all distributed photovoltaics) under the same simulation environment.

[0126] First of all, from the perspective of voltage control effect, Figure 5 This is the result of the voltage distribution throughout the day under the centralized control strategy. As can be seen from the figure, the centralized voltage regulation effect is better than the partitioned distributed control scheme of the present invention. While solving the problem of voltage exceeding the upper limit, it reduces the overall voltage fluctuation of the system. Under the centralized control strategy, the total voltage deviation of the system is 8.04pu, which is 56.63% lower than the original voltage deviation and 35.54% higher than the control effect of the method of the present invention.

[0127] Secondly, from the perspective of reactive power call, the reactive power call of the centralized voltage regulation method is as follows: Figure 6 As shown, the total regulation amount for the whole day is 1.53 MVar, which is an increase of 123.27% compared with 0.68 MVar of the method of the present invention, indicating that the centralized voltage control method increases the flow of reactive power.

[0128] Then, from the perspective of photovoltaic utilization, we analyze Figure 6 The photovoltaic power curtailment of the centralized voltage regulation method and the method of the present invention is that the photovoltaic power curtailment of the centralized voltage regulation method is 6.46MWh, which is 5.11MWh more than that of the method of the present invention, and the utilization rate is 26 percentage points lower than that of the method of the present invention.

[0129] Finally, from the perspective of control and computational complexity, the method of the present invention and the centralized voltage regulation method have obvious differences in the dimension of the control variables. The former uses the number of clusters as a reference, while the latter uses the total number of access points of distributed photovoltaics. The computational complexity is positively correlated with the dimension of the variable to be determined. The number of iterations of the centralized voltage regulation strategy for the entire period is 2717 times, while the number of iterations of the cluster voltage control method of the present invention is 740 times, indicating that the calculation of the centralized control and computational strategy is more complex.

[0130] In summary, centralized voltage control is better than the method proposed in the present invention, under the premise of also solving the problem of voltage exceeding the upper limit. However, centralized control and calculation complexity are very high, making it difficult to apply in large-scale systems; and centralized methods require a larger reactive capacity of distributed photovoltaics, which greatly increases the abandoned light, and is not conducive to the grid connection and absorption of distributed photovoltaics. Therefore, the present invention is suitable for a distribution network cluster voltage control method for risk prevention and control, and is more advantageous in dealing with voltage problems caused by the access of large-scale distributed photovoltaics.

[0131] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A distribution network cluster voltage control method suitable for risk prevention and control, characterized in that: include: Setting an objective function of a cluster voltage control model, wherein the objective function is to minimize node voltage deviation and system loss; A method for selecting a dominant node in a control model using cluster voltage, wherein the method for selecting the dominant node is performed based on observability and controllability indicators; Establishing constraints for the cluster voltage control model, wherein the constraints include establishing distribution network flow constraints, distributed photovoltaic power generation output constraints, voltage amplitude constraints, and branch power constraints; Based on the objective function and constraints of the cluster voltage control model, a cluster voltage control model is constructed. The dominant node selection method based on observability and controllability indicators is adopted. The voltage level of each cluster is monitored through the dominant node, and the distributed photovoltaic active / reactive output connected to the dominant node is used to regulate the system voltage. The control variable is the adjustable resource output power of each cluster dominant node.

2. The distribution network cluster voltage control method suitable for risk prevention and control according to claim 1, characterized in that: The objective function is to minimize the node voltage deviation and system loss, which is expressed as: Wherein, α1, α2 represent weight coefficients in the objective function, and the present invention sets their values ​​to 0.8 and 0.2 respectively; U i,t represents the voltage amplitude of the dominant node i at time t; U pu is the voltage reference value, m and n represent the number of dominant nodes and total nodes respectively; G ij is the line impedance between nodes i and j; θ ij,t is the phase angle difference between nodes i and j at time t.

3. The distribution network cluster voltage control method suitable for risk prevention and control according to claim 1, characterized in that: The observability and controllability indicators are expressed as: Observability index: According to the voltage level of the dominant node in the cluster, the voltage fluctuation of other nodes in the cluster can be judged. Based on the active and reactive voltage sensitivity of each node, the observability index O is defined. k as follows: Observability Index k It can reflect the comprehensive sensitivity of the voltage of the dominant node m in cluster k to the voltages of the other nodes in the cluster; Controllability index: When a voltage problem occurs in the cluster, the voltage level of the entire cluster can be controlled by adjusting the active / reactive output of the dominant node. Define the controllability index M k as follows: In the formula, the controllability index M k It can reflect the impact of the active and reactive power changes of the dominant node m in cluster k on the voltage of other nodes in the cluster; According to formula (2)-formula (3), the selection basis of the dominant node in cluster k is defined as shown in formula (4): ω=max{ζ o ·O k +g m ·M k } (4) In the formula, ζ o and m Respectively represent the weight coefficients of observability and controllability, ζ o +ζ m =1.

4. The distribution network cluster voltage control method suitable for risk prevention and control according to claim 1, characterized in that: The power flow constraints of the distribution network specifically include: Where P i,t , Q i,t They represent the active power and reactive power injected into node i at time t respectively; G ij , B ij are the line impedance and admittance between nodes i and j respectively; θ ij,t is the phase angle difference between nodes i and j at time t; are the active and reactive power of the load at node i at time t respectively; are the active and reactive power of distributed photovoltaic power station i at time t respectively.

5. The distribution network cluster voltage control method suitable for risk prevention and control according to claim 1, characterized in that: The distributed photovoltaic power generation output constraints specifically include: or i ≥η min (11) In the formula, is the capacity of distributed photovoltaic at node i; T is the scheduling period, which is 24h; η i is the photovoltaic utilization rate of node i in period T; is the theoretical output of distributed photovoltaic power generation at node i at time t; η min is the photovoltaic utilization rate limit.

6. The distribution network cluster voltage control method suitable for risk prevention and control according to claim 1, characterized in that: The voltage amplitude constraint specifically includes: IN max ≤U i,t ≤U min (12) Where U max , U min Respectively represent the upper and lower limits of the node voltage amplitude. According to the provisions of GB / T 40427-2021, the node voltage constraint range is set to 0.93U N ~1.07U N , where U N is the rated voltage (the per-unit value is 1). The branch power constraint specifically includes: In the formula, Respectively represent the upper and lower limits of branch power.

7. A distribution network cluster voltage control system suitable for risk prevention and control, based on the distribution network cluster voltage control method suitable for risk prevention and control according to any one of claims 1 to 6, characterized in that: include: The objective function building module of the cluster voltage control model is used to obtain the objective function of minimizing the node voltage deviation and system loss; A module for establishing a dominant node selection method of a cluster voltage control model is used to select a node that can represent the voltage level of nodes in the cluster. The dominant node selection method is based on observability and controllability indicators. The constraint condition establishment module of the cluster voltage control model is used to establish distribution network flow constraints, distributed photovoltaic power generation output constraints, voltage amplitude constraints, and branch power constraints; The cluster voltage control model establishment module is used to establish the cluster voltage control model. It adopts the dominant node selection method based on observability and controllability indicators, monitors the voltage level of each cluster through the dominant node, and regulates the system voltage based on the distributed photovoltaic active / reactive output connected to the dominant node. The control variable is the adjustable resource output power of each cluster dominant node.

8. The distribution network cluster voltage control system suitable for risk prevention and control as claimed in claim 7, characterized in that: The constraint condition establishment module of the cluster voltage control model is based on a 50-node example, and the advantages of the cluster voltage regulation method are verified through comparative experiments with no active voltage regulation and centralized voltage regulation.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the distribution network cluster voltage control method suitable for risk prevention and control described in any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the distribution network cluster voltage control method suitable for risk prevention and control described in any one of claims 1 to 6 are implemented.

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