Information physical system modeling method for active power distribution network

Abstract

The invention discloses a cyber-physical system modeling method for an active power distribution network. The cyber-physical system modeling method comprises the following steps: firstly, dividing a cyber-physical system of the active power distribution network into a physical layer model, a network layer model and a control layer model; physical system data, information system data and control strategy data of the active power distribution network are obtained respectively; and finally, establishing an actual physical layer model based on the physical layer and the physical system data, establishing an actual network layer model based on the network layer and the information system data, and establishing an actual control layer model based on the control layer and the control strategy data. According to the cyber-physical system modeling method for the active power distribution network, the cyber-physical system of the active power distribution network is described by utilizing a layering mechanism, the power-information coupling characteristic and the control strategy of the active power distribution network are considered, the model covers complete information flow, and a model basis is provided for operation analysis of the cyber-physical system of the active power distribution network.

Description

Technical Field

[0001] The present invention belongs to the technical field of active power distribution network and information-physical system modeling, and in particular relates to an information-physical system modeling method for an active power distribution network. Background Art

[0002] In order to reduce the adverse effects of high penetration renewable energy on the power grid, and to maximize the reliability and economy of distributed power access to the grid, active distribution network is an effective means to solve the problem of distributed power access and is one of the key technologies for building smart grids. Active distribution network coordinates and controls the connected distributed power sources, energy storage systems and adjustable loads to ensure continuous and reliable power supply to important loads in the power supply area and to achieve power transmission to the main grid. The electrical equipment, measuring devices and control units in the active distribution network form physical connections, data coupling and logical associations through the power network and the information network, making the active distribution network have the characteristics of a typical cyber-physical system. Therefore, analyzing the coupling relationship between the information system and the power system during the operation of the active distribution network and how to model the coupling of the cyber-physical system in the active distribution network have become current research hotspots. Summary of the invention

[0003] The purpose of the present invention is to provide a cyber-physical system modeling method for an active power distribution network, so as to provide a model basis for the operation analysis of the cyber-physical system of the active power distribution network.

[0004] The technical solution adopted by the present invention is: a cyber-physical system modeling method for an active distribution network, firstly dividing the cyber-physical system of the active distribution network into three-layer models of physical layer, network layer and control layer; then respectively obtaining the physical system data, information system data and control strategy data of the active distribution network; finally establishing an actual physical layer model based on the physical layer and physical system data, establishing an actual network layer model based on the network layer and information system data, and establishing an actual control layer model based on the control layer and control strategy data.

[0005] The present invention is also characterized in that:

[0006] The physical layer in the three-layer model includes power equipment and its corresponding information units, which are used to collect measurement data and execute control instructions. The data interface between the primary equipment and the secondary equipment reflects the direct coupling relationship between power and information in the distribution network, which can be described by the following formula:

[0007] L=(γ:δ) (1)

[0008] Where L represents the power-information coupling relationship; γ represents the information element; δ represents the power element.

[0009] The network layer in the three-layer model is described by the network topology. The physical devices in the distribution network communication network are defined as nodes, and the physical connections in the distribution network communication network are defined as edges. Then the distribution network communication network is abstracted as an undirected graph G = (V G ,E G ,A G ), where V G =(1,…,N) represents a non-empty finite set containing N nodes, represents the set of edges, (i,j)∈E G represents the physical connection between node i and node j, A G =[a ij ] represents the adjacency matrix, and the set of neighbor nodes of node i is defined as If (i,j) exists, then a ij =1, otherwise a ij =0.

[0010] The control layer in the three-layer model receives the operating data from the measurement nodes and power elements in the physical layer, generates control instructions according to various control strategies to adjust the operating state of the controllable power equipment, and responds to different physical operating scenarios, which can be described by the following formula:

[0011] u(N)=Ω(w(N))=Ω·w(N) (2)

[0012] Where w(N) represents the operating status data received by the control layer, u(N) represents the control instruction generated by the control layer, Ω represents the data mapping relationship, and N represents the discrete control cycle.

[0013] Various control strategies include state estimation, energy management, automatic generation control or automatic voltage control, and regulating the operating state of controllable power equipment includes protection device action, circuit breaker action, on-load tap-changing transformer tap adjustment, load switching or distributed power output.

[0014] The beneficial effects of the present invention are as follows: the cyber-physical system modeling method for active distribution networks of the present invention uses a hierarchical mechanism to describe the cyber-physical system of active distribution networks, takes into account the power-information coupling characteristics and control strategies of the active distribution networks, and the model covers the complete information flow, providing a model basis for the operation analysis of the cyber-physical system of active distribution networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of a cyber-physical system modeling method for an active power distribution network of the present invention;

[0016] Figure 2 It is a structural diagram of the active power distribution network information-physical system in Example 3 of the present invention. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Example 1

[0019] The present invention provides a cyber-physical system modeling method for an active power distribution network. First, the cyber-physical system of the active power distribution network is divided into three-layer models: a physical layer, a network layer, and a control layer. Then, the physical system data, the cyber-system data, and the control strategy data of the active power distribution network are respectively obtained. Finally, an actual physical layer model is established based on the physical layer and the physical system data, an actual network layer model is established based on the network layer and the cyber-system data, and an actual control layer model is established based on the control layer and the control strategy data.

[0020] Through the above method, the present invention uses a hierarchical mechanism to describe the information-physical system of the active distribution network, taking into account the power-information coupling characteristics and control strategies of the active distribution network. The model covers the complete information flow and provides a model basis for the operation analysis of the information-physical system of the active distribution network.

[0021] Example 2

[0022] The present invention provides a cyber-physical system modeling method for active power distribution networks, such as Figure 1 As shown, the following steps are included:

[0023] Step 10, the active distribution network cyber-physical system is divided into a three-layer model: physical layer, network layer and control layer;

[0024] Step 20: Acquire the physical system data of the active distribution network and establish an actual physical layer model based on step 10);

[0025] Step 30: Obtain active distribution network information system data and establish an actual network layer model based on step 10);

[0026] Step 40: Obtain active distribution network control strategy data and establish an actual control layer model based on step 10).

[0027] In step 10, the physical layer includes power equipment and its corresponding information units, such as circuit breakers and their control units, loads and their measurement units, distributed power sources and their controllers, and substations and their communication systems. The physical layer is responsible for collecting measurement data and executing control instructions. It reflects the direct coupling relationship between power and information in the distribution network through the data interface between the primary equipment and the secondary equipment, which is described by the following formula:

[0028] L=(γ:δ) (1)

[0029] In the formula, L represents the power-information coupling relationship; γ represents the information element; δ represents the power element; if the information element γ loses its function or cannot send and receive data, the corresponding power element δ cannot be observed or controlled by the control master station, or even stops working.

[0030] The network layer describes the data transmission process during the operation of the distribution network, which is described by the network topology: the physical devices in the distribution network communication network are defined as nodes, including communication devices (routers, switches, modulators, gateways and base stations, called network nodes), secondary devices in the power network (measurement terminals and controllers, called physical nodes), and computing units in substations and control master stations (called control nodes). The physical connection in the distribution network communication network is defined as an edge. Then the distribution network communication network can be abstracted as an undirected graph G = (V G ,E G ,A G ), where V G =(1,…,N) represents a non-empty finite set containing N nodes, Represents the set of edges in the graph, (i,j)∈E G represents the physical connection between node i and node j, A G =[a ij ] represents the adjacency matrix. The set of neighbor nodes of node i is defined as If (i,j) exists, then a ij =1, otherwise a ij =0.

[0031] The control layer receives the operating data from the measurement nodes and power elements in the physical layer, and generates control instructions based on various control strategies such as state estimation, energy management, automatic generation control and automatic voltage control to adjust the operating state of the controllable power equipment (including protection device action, circuit breaker action, on-load tap changer transformer tap adjustment, load switching, and distributed power output), so as to respond to different physical operation scenarios. It can be described by the following formula:

[0032] u(N)=Ω(w(N))=Ω·w(N) (2)

[0033] Where w(N) represents the operating status data received by the control layer, u(N) represents the control instruction generated by the control layer, Ω represents the data mapping relationship, and N represents the discrete control cycle.

[0034] Example 3

[0035] The structure of a cyber-physical system of an active distribution network is as follows: Figure 2 As shown, for this active distribution network, the actual model of the physical layer is as follows:

[0036] The measurement units corresponding to the 13 loads are Ai (i=1,…,13); the measurement units corresponding to the three photovoltaics PV1, PV2, and PV3 are A15, A16, and A17; the measurement unit corresponding to one wind turbine is A18, and the control unit corresponding to one energy storage is A14.

[0037] The actual model of the network layer is shown in Table 1:

[0038] Table 1 Network layer actual model

[0039]

[0040] The control strategy is based on voltage control, and the actual model of the control layer is shown as follows:

[0041]

[0042] Where LCTm is the total load shedding of the mth cycle; PD d and QD d is the active and reactive load of load node d; f d is the voltage state of node d, which will be described in detail later. l and QL l is the active and reactive power transmitted by power line l; PG g and QG g It is the gth distributed generation DG g Output active and reactive power; μ il is the node-line coupling coefficient: when node i is the starting point of line l, μ il =1, when node i is the end point of line l il =-1, otherwise μ il =0; N l is the total number of lines; κ ig is the node-power coupling coefficient: when node i has distributed power generation DG g Time ig =1, otherwise κ ig =0; N G is the total number of distributed generation; id is the node-load coupling coefficient: when node i has load d, λ id =1, otherwise λ id =0; N D is the total number of loads. V i is the voltage amplitude of node i; V1 is the voltage amplitude of the substation bus, which is generally set to 1.0pu; R ij and X ij is the line impedance. V max and V min is the voltage upper and lower limits of the distribution network; V i,n(n=1,2,3) is the component of node i in different voltage ranges; ε i,n (n=1,2,3) is a 0-1 variable, which indicates the state of the node i in different voltage intervals. For example: if V min <V i <V max , then V i,1 =0, V i,2 =V i , V i,3 =0,ε i,1 =0,ε i,2 =1,ε i,3 =0; f i Indicates the voltage state of node i: if the voltage amplitude is within the safe operating range, then f i =0, if the voltage amplitude exceeds the limit, f i =1.

[0043] The status information received by the control layer is the load power, the output power of photovoltaic and wind turbines, and the node voltage, and the control command generated is the output power of the energy storage.

Claims

1. A cyber-physical system modeling method for active power distribution networks, characterized in that: First, the information-physical system of the active distribution network is divided into three-layer models: physical layer, network layer, and control layer. Then, the physical system data, information system data, and control strategy data of the active distribution network are obtained respectively. Finally, the actual physical layer model is established based on the physical layer and physical system data, the actual network layer model is established based on the network layer and information system data, and the actual control layer model is established based on the control layer and control strategy data.

2. The cyber-physical system modeling method for active power distribution network according to claim 1, characterized in that: The physical layer in the three-layer model includes power equipment and its corresponding information unit, which is used to collect measurement data and execute control instructions. The data interface between the primary equipment and the secondary equipment reflects the direct coupling relationship between power and information in the distribution network, which is described by the following formula: L=(γ:δ) (1) Where L represents the power-information coupling relationship; γ represents the information element; δ represents the power element.

3. The cyber-physical system modeling method for active power distribution network according to claim 1, characterized in that: The network layer in the three-layer model is described by network topology. The physical devices in the distribution network communication network are defined as nodes, and the physical connections in the distribution network communication network are defined as edges. Then, the distribution network communication network is abstracted as an undirected graph G = (V G ,E G ,A G ), where V G =(1,…,N) represents a non-empty finite set containing N nodes, represents the set of edges, (i,j)∈E G represents the physical connection between node i and node j, A G =[a ij ] represents the adjacency matrix, and the set of neighbor nodes of node i is defined as If (i,j) exists, then a ij =1, otherwise a ij =0.

4. The cyber-physical system modeling method for active power distribution network according to claim 1, characterized in that: The control layer in the three-layer model receives the operating data from the measurement nodes and power elements in the physical layer, generates control instructions according to various control strategies to adjust the operating state of the controllable power equipment, and responds to different physical operating scenarios, which is described by the following formula: u (N)=Ω(w(N))=Ω·w(N) (2) Where w(N) represents the operating status data received by the control layer, u(N) represents the control instruction generated by the control layer, Ω represents the data mapping relationship, and N represents the discrete control cycle.

5. The cyber-physical system modeling method for active power distribution network according to claim 4, characterized in that: The various control strategies include state estimation, energy management, automatic power generation control or automatic voltage control, and regulating the operating state of controllable power equipment includes protection device action, circuit breaker action, on-load tap-changing transformer tap adjustment, load switching or distributed power output.

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