Power grid network attack defense method and system based on node coupling degree

Abstract

The invention discloses a power grid network attack defense method and system based on node coupling degree, and the method comprises the steps: collecting power grid data, and building a power grid network-physical system coupling model. And designing an attack and defense process model and a continuous network attack model. And designing a node coupling degree index for measuring the association strength between the physical node and the network node, and proposing a defense strategy for continuous network attacks. According to the power grid network attack defense method and system based on the node coupling degree, the power grid load loss under the network attack can be effectively reduced, and the stability and safety of the system are remarkably improved. Under the condition of limited resources, compared with a traditional defense strategy, the method has a higher protection effect and higher attack resistance, and is suitable for various power grid network security defense scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid network security, and in particular to a power grid network attack defense method and system based on node coupling degree. Background Art

[0002] With the development of information and intelligence of power systems, the power grid has gradually evolved into a cyber-physical system (CPS), in which the network layer and the physical layer are tightly coupled to realize the monitoring, dispatching, data transmission and control of the power system. This highly integrated structure makes the operation of the power grid more efficient and intelligent, but it also leads to the increasingly serious risk of cyber attacks on the power grid. In recent years, the power grid has become a target of cyber attacks. These attacks mainly affect the stable operation of the physical system through the intrusion of the network layer, thereby posing a threat to the security and reliability of the power grid.

[0003] Most existing defense strategies focus on single protection at the physical layer or network layer, lacking overall protection for the network-physical system, and are unable to effectively resist the chain reaction caused by network attacks. Traditional methods usually allocate defense resources based on the load of physical nodes or adopt an average distribution strategy, but ignore the coupling relationship between network nodes and physical nodes, resulting in unsatisfactory defense effects when resources are limited. At the same time, existing power grid defense strategies also focus on static protection, lacking dynamic response capabilities for persistent network attacks (such as distributed denial of service attacks, persistent penetration attacks, etc.), making it difficult for the power grid to maintain system stability when it encounters a long-term attack.

[0004] In order to deal with the above problems, recent studies have begun to focus on the coupling characteristics of network-physical systems in power grids, and have proposed some defense methods that consider node coupling. For example, some studies have introduced resource allocation strategies based on node importance evaluation, incorporating the coupling relationship between network nodes and physical nodes into the resource allocation model to improve the defense effect. However, most of these studies focus on defense strategies under single attack scenarios, and the dynamic response and resource adjustment capabilities to continuous attacks are still insufficient. In addition, existing methods often lack a complete attack and defense process model to simulate the attack path and defense response process, making it difficult to fully evaluate the applicability and effectiveness of defense strategies. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by the present invention is that the existing power grid network attack defense method has insufficient consideration of network-physical coupling characteristics and is difficult to effectively respond to continuous network attacks.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for defending against power grid network attacks based on node coupling degree, comprising: collecting power grid data and building a power grid network-physical system coupling model.

[0008] Design attack and defense process models and continuous network attack models.

[0009] A node coupling index is designed to measure the strength of the association between physical nodes and network nodes, and a defense strategy against persistent network attacks is proposed.

[0010] As a preferred solution of the grid network attack defense method based on node coupling degree described in the present invention, the grid network-physical system coupling model is a coupling system of the access layer and the grid physical system in the grid structure. The physical system model of the grid is abstracted as a graph G = (V, E) consisting of a point set V and an edge set E. The physical devices in the grid are abstracted as PQ nodes V1, PV nodes V2, balancing nodes V3 and isolation nodes V4. The power lines are abstracted as the edges of the graph G.

[0011] As a preferred solution of the power grid network attack defense method based on node coupling degree described in the present invention, the attack and defense process model includes establishing a correlation between defense resources and node anti-attack capabilities by quantifying defense capabilities and attack strength. The attack strength of the network attack is abstracted as attack resources, which is expressed as:

[0012]

[0013] Among them, D i represents the defense capability of node i, θ represents the conversion coefficient, R i represents the defense resources of node i, p i represents the probability that node i fails due to network attack, A i Represents the attack strength of node i.

[0014] As a preferred solution of the node coupling degree-based power grid network attack defense method described in the present invention, the continuous network attack model is used to simulate the continuity of the attack in time and space, and describe the dynamic impact of the attack on the power grid system. When the network attack is successful and causes the physical node to fail, a network-physical coordination failure occurs, which is manifested as the load of the physical node being set to 0 and cannot be restored due to communication interruption.

[0015] As a preferred solution of the grid network attack defense method based on node coupling degree described in the present invention, the continuous network attack model includes selecting the DC optimal power flow to calculate the current after each grid structure change, and taking the proportion of grid loss load to the total load in the normal state as the loss function:

[0016]

[0017] Among them, loss represents the current load loss, and load represents the total load under normal conditions.

[0018] As a preferred solution of the network attack defense method based on node coupling degree described in the present invention, the node coupling degree index includes: the node coupling degree NCD is used to quantify the coupling strength between the physical nodes and the network nodes in the power grid, thereby reflecting the potential impact of network attacks on the physical layer. The specific value of NCD is obtained by calculating the fault risk gain generated by the synergy of physical faults and network faults, and the expression is:

[0019]

[0020] Among them, λ NCDi Represents the physical node p i The corresponding network node c i The coupling degree between them refers to p i Failure, c i Failure, p i With c i Damage caused by combined failure to distribution network. Represents node p i Is there a criterion for cooperation failure? i If the damage caused by the common failure to the system is greater than the sum of the damage caused by the failure of two independent nodes, the basic fault is judged to be a coordinated fault. i and c i The fault is two independent basic faults.

[0021] As a preferred solution of the power grid network attack defense method based on node coupling degree described in the present invention, the defense strategy proposed against continuous network attacks includes: i and its network node c i The status includes the following categories:

[0022] When p i Failure, c i When normal, it indicates that the network attack has not succeeded. i , is there other reasons causing p i Failed. Due to c i The cloud platform can monitor p in real time. i The fault is considered to be unlikely to expand further. It is expressed as:

[0023]

[0024] Among them, load i Indicates p i of load.

[0025] When p i Normal, c i When it fails, it indicates that the network attack caused c i Failed, but p i In this case, there is no apparent failure in the physical network. It is expressed as:

[0026]

[0027] When p i Failure, c i If it fails, it indicates that the information attack caused c i Failure, resulting in p i Failed. Due to c i A failure occurs and the cloud platform cannot monitor the i state and take measures against it. At this time, it is considered that p i The failure of will spread to its neighboring nodes. It is expressed as:

[0028]

[0029] in, Indicates that p i The sum of the loads of directly connected nodes.

[0030] The defense strategy takes into account both the NCD and the load of the physical node itself, which can be expressed as:

[0031]

[0032] Among them, R i Indicates p i defense resources, n represents the number of nodes in the grid, and F represents the total defense resources invested.

[0033] A power grid network attack defense system based on node coupling degree, characterized by: comprising:

[0034] Build model modules, collect power grid data, and build a power grid network-physical system coupling model. Design attack and defense process models and continuous network attack models.

[0035] A defense strategy module is proposed, a node coupling index is designed to measure the strength of association between physical nodes and network nodes, and a defense strategy against persistent network attacks is proposed.

[0036] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0037] A computer-readable storage medium stores a computer program, which implements the steps of the method described above when executed by a processor.

[0038] The beneficial effects of the present invention are: it can effectively reduce the load loss of the power grid under network attacks and significantly improve the stability and security of the system. Compared with traditional defense strategies, the present invention has higher protection effect and stronger attack resistance ability under limited resources, and is suitable for various power grid network security defense scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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 work. Among them:

[0040] Figure 1 An overall flow chart of a power grid network attack defense method and system based on node coupling degree provided in the first embodiment of the present invention.

[0041] Figure 2 A power information-physical system (CPS) architecture diagram of a power grid network attack defense method and system based on node coupling degree provided in the first embodiment of the present invention.

[0042] Figure 3 A diagram of the continuous network attack process of a power information-physical system (CPS) according to a power grid network attack defense method and system based on node coupling degree provided in the first embodiment of the present invention. DETAILED DESCRIPTION

[0043] 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.

[0044] Example 1, reference Figure 1 to Figure 3 , is an embodiment of the present invention, and provides a method for defending against power grid network attacks based on node coupling degree, comprising:

[0045] S1: Collect power grid data and build a power grid network-physical system coupling model.

[0046] It should be noted that the power grid network-physical system (CPS) model is a coupling system of the access layer and the physical system of the power grid in the power grid structure. The physical system model of the power grid is abstracted as a graph G = (V, E) consisting of a point set V and an edge set E. In order to facilitate power flow calculations, physical equipment such as power plants, substations, and busbars in the power grid can be abstracted as PQ nodes V1, PV nodes V2, balancing nodes V3, and isolation nodes V4. Power lines are abstracted as edges of the graph G. The structure of the power grid network system is generally divided into three layers: the core layer, the backbone layer, and the access layer. Since the core of the present invention is the access layer and the power grid. Therefore, the backbone layer and the core layer are regarded as permanent, highly protected, and invulnerable objects, while the access layer nodes are regarded as attackable objects. The present invention assembles all information devices of each physical node in the power network into a network node, and this network node forms a network-physical coupling with its corresponding physical node. At the network layer, all network nodes are interconnected. The power CPS architecture of the present invention is shown in reference. Figure 3 shown.

[0047] S2: Design attack and defense process model and continuous network attack model.

[0048] The attack and defense process model establishes the correlation between defense resources and node anti-attack capabilities by quantifying defense capabilities and attack intensity. Most smart grids are equipped with firewalls and intrusion detection / prevention systems (IDS / IPS), which can identify intentional and accidental anomalies at the beginning of an attack. In order to defend against network attacks and ensure the security of information exchange, various defense measures are set on ESP (electronic security perimeter) in various security areas. The attacker needs to match the network attack through the target ESP. The type of defense equipment installed on each ESP device, the number of operation and maintenance personnel and other related factors determine the node's ability to resist network attacks. There is a positive correlation between these national defense resources and national defense capabilities. Regarding the attack intensity of network attacks, the present invention abstracts it into attack resources and proposes:

[0049]

[0050] Where D i represents the defense capability of node i, θ represents the conversion coefficient, R i represents the defense resources of node i, p i represents the probability that node i fails due to network attack, A i Represents the attack strength of node i.

[0051] Furthermore, the continuous cyber attack process of the power cyber-physical system CPS includes:

[0052] The continuous network attack model is used to simulate the continuity of the attack in time and space, and describe the dynamic impact of the attack on the power grid system. When the network attack is successful and causes the physical node to fail, it means that a network-physical collaborative failure has occurred here, which is manifested as the load of the physical node is set to 0 and cannot be restored due to communication interruption. This paper chooses DC optimal power flow (DC-OPF) to calculate the current after each grid structure change for the following reasons: First, this paper focuses on the load loss of the power system. The current of active power in the power system is studied in detail. When only active power is considered, DC-OPF can solve this problem well. Secondly, the existing DC-OPF has the advantages of being simple, fast, and easy to calculate in real time, and has been widely used. In the network attack scenario, the requirement for computing time is very high. This is because the network attack occurs very quickly and needs to be judged quickly in a very short time, so the advantages of DC-OPF are needed. In this case, the defense strategy often needs to predict possible attacks in the future, so DC-OPF is a more appropriate method. The failure of network nodes may lead to the emergence of island power grids in the power system. This paper believes that the emergence of isolated power grids means that the power system can no longer independently deal with network attacks, so the emergence of isolated power grids means the end of continuous attacks. The proportion of power grid loss load to the total load in the normal state is used as the loss function:

[0053]

[0054] In the formula, loss is the current load loss, and load is the total load under normal conditions. The overall simulation process is as shown in the reference Figure 3 shown.

[0055] S3: Design a node coupling index to measure the strength of association between physical nodes and network nodes, and propose a defense strategy against persistent network attacks.

[0056] The defense strategy for continuous network attacks is based on the importance of node coupling and node load, and prioritizes the allocation of defense resources to key nodes. i and its network node c i The status is classified as follows:

[0057] 1) p i Failure, c i Normal. This indicates that the network attack did not successfully attack c i Other causes lead to i Failed. Due to c i The cloud platform can monitor p in real time. i state and controls it, so it is believed that the failure will not expand further. It can be expressed as:

[0058]

[0059] In the formula, load i Indicates p i of load.

[0060] 2) p i Normal, c i In this case, it indicates that the network attack caused c i Failed, but p i There is no failure due to this. In this case, there is no apparent failure in the physical network. It can be expressed as:

[0061]

[0062] 3) p i Failure, c i Failed. Information attack caused c i Failure, resulting in p i Failed. Due to c i A failure occurs and the cloud platform cannot monitor the i At this point, it is considered that p i The failure of a node will spread to its neighboring nodes. It is expressed as:

[0063]

[0064] In the formula, For i The sum of the loads of directly connected nodes.

[0065] In network attacks, NCD can effectively reflect the degree of coupling between physical nodes and network nodes, and can illustrate the importance of nodes under network physical coupling. In addition, the load of the physical node itself can directly illustrate its importance. Therefore, the defense strategy of the present invention takes into account the above two values ​​at the same time, which is expressed as:

[0066]

[0067] In the formula, R i Indicates p i The defense resources of the network are as follows: n represents the number of nodes in the grid, and F represents the total defense resources invested. The NCD and load ratio of the node are used as indicators of node importance, and defense resources are deployed based on these indicators. This deployment can effectively improve the utilization of defense resources and reduce the harm of network attacks.

[0068] From the above, it can be seen that the present invention can effectively improve the anti-attack capability of the power grid under continuous network attacks by introducing a defense strategy based on node coupling degree, realize the optimal allocation of defense resources, reduce load losses, ensure that the system can maintain stable operation when attacked, and significantly improve the safety and reliability of the power grid.

[0069] The above embodiments also include a power grid network attack defense system based on node coupling degree, specifically:

[0070] Build model modules, collect power grid data, and build a power grid network-physical system coupling model. Design attack and defense process models and continuous network attack models.

[0071] A defense strategy module is proposed, a node coupling index is designed to measure the strength of association between physical nodes and network nodes, and a defense strategy against persistent network attacks is proposed.

[0072] The computer device may be a server. The computer device includes a processor, a memory, an input / output interface (I / O for short) and a communication interface. The processor, the memory and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. 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, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data cluster data of a power monitoring system. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a method for defending against power grid network attacks based on node coupling is implemented.

[0073] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0074] Example 2 is an embodiment of the present invention, which provides a method and system for defending against power grid network attacks based on node coupling degree. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through simulation experiments.

[0075] To verify the effectiveness of the node coupling-based defense method against power grid network attacks, the experiment simulated the response of a power grid network-physical system under continuous network attacks. The defense method uses the node coupling index to measure the strength of the association between physical nodes and network nodes in order to allocate defense resources to deal with continuous attacks.

[0076] Existing technology: Traditional power grid defense methods adopt a uniform resource allocation strategy, which fails to fully consider the coupling relationship between nodes, making high-risk nodes prone to failure under attack.

[0077] The present invention introduces a defense strategy based on node coupling degree and dynamically adjusts defense resources. The attack process is simulated by a continuous attack model, and the DC optimal power flow (DC-OPF) method is used to calculate the grid load loss, giving priority to protecting nodes with high coupling degree to reduce overall losses.

[0078] Experimental steps:

[0079] Collecting grid data and building a coupling model: In the initial stage of the experiment, the physical and network layer data of each node in the grid are collected, including the node type (PQ, PV, balancing node, etc.) and its load and connection status. The present invention builds a grid network-physical system coupling model based on the coupling degree index between the nodes in the grid access layer and the physical nodes. In traditional methods, this type of coupling information is not collected, and the allocation of defense resources is mainly based on the load distribution.

[0080] Modeling of attack and defense strategies: In the prior art, defense strategies usually do not consider the attack path and node coupling strength, which easily causes failure of high-risk nodes. The present invention simulates the attack path and impact range in time and space dimensions through a continuous network attack model. The attack and defense process model uses node coupling degree and load weight to calculate the defense resource allocation plan.

[0081] Simulation and data collection: The experiment compares the defense effects of the present invention and the prior art with different attack intensities. The specific steps include:

[0082] The formula NCD = number of physical node failures / network node coupling strength is used to calculate the coupling degree and allocate defense resources. The DC optimal power flow (DC-OPF) method is used to evaluate the load loss, and the load loss ratio is used as the loss function. The load loss and node failure are recorded under different attack intensities. The experimental results are shown in Table 1.

[0083] Table 1 Experimental results

[0084]

[0085]

[0086] Experimental data show that the present invention is significantly superior to the prior art in a number of key performance indicators, as specifically analyzed below:

[0087] The prior art fails to effectively defend against nodes with high coupling degree due to uniform distribution of defense resources, resulting in a node failure rate of up to 35%. The present invention gives priority to protecting nodes with high coupling degree, reducing the node failure rate to 15%, with an optimization range of 57.14%.

[0088] In the prior art, due to unreasonable resource allocation, the defense of high-load nodes is insufficient, and the load loss rate is 30%. The coupling priority strategy of the present invention significantly reduces the failure of key nodes, and the load loss rate is reduced to 10%, and the optimization range reaches 66.67%.

[0089] In the traditional method, the protection rate of key nodes is only 50%, while the present invention increases it to 90% through a strategy based on node coupling degree, an increase of 80%. This strategy ensures the security of high-risk nodes and makes the system more stable under attack.

[0090] In the prior art, the utilization rate of defense resources is 60%, while the utilization rate of resources in the present invention reaches 95%, and the optimization range is 58.33%. This is due to the dynamic allocation of defense resources under the guidance of the coupling index, which improves the efficiency of resource use.

[0091] Under the traditional method, it takes an average of about 60 minutes to restore the power grid. The present invention locks the high-coupling nodes at the early stage of the attack and responds quickly, shortening the recovery time to 20 minutes, a reduction of 66.67%.

[0092] The response time of traditional technology is 5 seconds, while the present invention can detect attacks and defend against them in just 1 second, increasing the response speed by 80% and ensuring the system's ability to respond quickly in the early stages of an attack.

[0093] The traditional defense method requires 50,000 yuan of maintenance cost per year, but the system structure optimization and reasonable resource allocation of the present invention reduce the cost to 35,000 yuan, saving 30%.

[0094] In summary, the power grid network attack defense method based on node coupling degree shows significant advantages in node protection, load loss control, recovery time and defense resource utilization. In particular, the introduction of coupling degree strategy improves the agility and efficiency of the defense system.

[0095] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 method for defending against power grid network attacks based on node coupling degree, characterized in that: include: Collect power grid data and build a power grid network-physical system coupling model; Design attack and defense process models and continuous network attack models; A node coupling index is designed to measure the strength of the association between physical nodes and network nodes, and a defense strategy against persistent network attacks is proposed.

2. The method for defending against power grid network attacks based on node coupling degree according to claim 1, characterized in that: The power grid network-physical system coupling model is a coupling system of the access layer in the power grid structure and the power grid physical system; the physical system model of the power grid is abstracted as a graph G = (V, E) consisting of a point set V and an edge set E; the physical devices in the power grid are abstracted as PQ nodes V1, PV nodes V2, balancing nodes V3 and isolation nodes V4; and the power lines are abstracted as edges of the graph G.

3. The method for defending against power grid network attacks based on node coupling degree according to claim 2, characterized in that: The attack and defense process model includes establishing a correlation between defense resources and node anti-attack capabilities by quantifying defense capabilities and attack strengths; abstracting the attack strength of network attacks into attack resources, expressed as: Among them, D i represents the defense capability of node i, θ represents the conversion coefficient, R i represents the defense resources of node i, p i represents the probability that node i fails due to network attack, A i Represents the attack strength of node i.

4. The method for defending against power grid network attacks based on node coupling degree according to claim 3, characterized in that: The continuous network attack model is used to simulate the continuity of the attack in time and space, and describe the dynamic impact of the attack on the power grid system. When the network attack is successful and causes the failure of the physical node, a network-physical collaborative failure occurs, which is manifested as the load of the physical node being set to 0 and unable to recover due to communication interruption.

5. The method for defending against power grid network attacks based on node coupling degree according to claim 4, characterized in that: The continuous network attack model includes selecting the DC optimal power flow to calculate the current after each grid structure change, and taking the proportion of grid loss load to the total load in the normal state as the loss function: Among them, loss represents the current load loss, and load represents the total load under normal conditions.

6. The method for defending against power grid network attacks based on node coupling degree according to claim 5, characterized in that: The node coupling index includes: the node coupling degree NCD is used to quantify the coupling strength between physical nodes and network nodes in the power grid, thereby reflecting the potential impact of network attacks on the physical layer; by calculating the fault risk gain generated by the synergy of physical faults and network faults, the specific value of NCD is obtained, and the expression is: Among them, λ NCDi Represents the physical node p i The corresponding network node c i The coupling degree between i Failure, c i Failure, p i With c i Damage to the distribution network caused by combined failures; Represents node p i Is there a criterion for cooperation failure? If p i If the damage caused by the common failure to the system is greater than the sum of the damage caused by the failure of two independent nodes, the basic fault is judged to be a coordinated fault; otherwise, p i and c i The fault is two independent basic faults.

7. The method for defending against power grid network attacks based on node coupling degree according to claim 6, characterized in that: The proposed defense strategy against continuous network attacks includes: i and its network node c i The status includes the following categories: When p i Failure, c i When normal, it indicates that the network attack has not succeeded. i , is there other reasons causing p i Failed; due to c i The cloud platform can monitor p in real time. i The fault is considered to be unlikely to expand further. It is expressed as: Among them, load i Indicates p i Load; When p i Normal, c i When it fails, it indicates that the network attack caused c i Failed, but p i There is no apparent failure in the physical network in this case. It is expressed as: When p i Failure, c i If it fails, it indicates that the information attack caused c i Failure, resulting in p i Failed; due to c i A failure occurs and the cloud platform cannot monitor the i state and take measures against it; at this time, it is considered that p i The failure of will spread to its neighboring nodes. It is expressed as: in, Indicates that p i The sum of the loads of directly connected nodes; The defense strategy takes into account both the NCD and the load of the physical node itself, which can be expressed as: Among them, R i Indicates p i defense resources, n represents the number of nodes in the grid, and F represents the total defense resources invested.

8. A power grid network attack defense system based on node coupling degree using the method according to any one of claims 1 to 7, characterized in that: Build model modules, collect power grid data, and build a power grid network-physical system coupling model; design attack and defense process models and continuous network attack models; A defense strategy module is proposed, a node coupling index is designed to measure the strength of association between physical nodes and network nodes, and a defense strategy against persistent network attacks is proposed.

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 method according to any one of claims 1 to 7 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 method according to any one of claims 1 to 7 are implemented.

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