Protection method and device for power grid information physical system

Abstract

The invention relates to a protection method for a power grid information physical system. The method comprises the steps that attack scenes are determined based on the structure of a power grid information physical system (CPPS) interaction model, different attack scenes correspond to attack targets, and defense targets are different; obtaining a CPPS vulnerability assessment framework based on defense targets of the attack target in different attack scenes; obtaining a CPPS active load loss model based on a Newton-Raphson power flow calculation equation and a preset power constraint condition; based on the CPPS vulnerability assessment framework and the CPPS active loss model, obtaining defense resources allocated to the attack target; and based on the structure of the CPPS interaction model and the defense resources allocated to the attack target, establishing a CPPS attack and defense game model and designing an attack and defense game scene, and based on the game theory, obtaining a CPPS protection scheme. By adopting the method, the structure of the interaction model of the power grid information physical system can be considered, and an optimal defense resource allocation strategy is given.

Description

Technical Field

[0001] The present application relates to the field of information and communication technology, and in particular to a protection method and device for a power grid information-physical system. Background Art

[0002] In recent years, driven by the rapid development of information and communication technology, modern power grids are transforming into smarter, broader and safer systems, and gradually evolving into cyber physical power systems (CPPS). The information control system and the physical power system are tightly coupled and interact with each other, so the security of the power grid also needs to be considered from the perspective of information security and physical security. Information attacks take advantage of the CPPS's dependence on information networks, destroy the weak links of the information system, and even transmit the fault chain to the physical side, endangering the security of the entire system. Information attacks against CPPS seriously threaten the safe and stable operation of the system.

[0003] Among the related technologies, game theory methods are widely used in power grid security research because they can reflect the interactive mechanism of attack and defense behaviors and capture multiple decision-making processes. Many scholars have established CPPS attack and defense game models based on game theory, such as the CPPS attack and defense game model under remote attacks with false authentication information injection and the CPPS dynamic attack and defense game model under coordinated cyber-physical attacks. However, there is no specific analysis combined with attack scenarios and attack targets. Summary of the invention

[0004] Based on this, it is necessary to provide a protection method and device for a power grid cyber-physical system to address the above-mentioned technical issues.

[0005] In a first aspect, the present application provides a method for protecting a power grid cyber-physical system. The method comprises:

[0006] Determine the attack scenario based on the structure of the power grid cyber-physical system interaction model, where different attack scenarios include different attack targets and defense targets;

[0007] Based on the defense objectives of the attack targets in different attack scenarios, a vulnerability assessment model for the cyber-physical system of the power grid is obtained;

[0008] Based on the Newton-Raphson power flow calculation equation and the preset power constraints, the active load loss model of the power grid cyber-physical system is obtained;

[0009] Based on the grid cyber-physical system vulnerability assessment framework and the grid cyber-physical system active load loss model, obtaining defense resources allocated to the attack target;

[0010] Based on the power grid information-physical system interaction model and the defense resources allocated to the attack target, an attack and defense game model of the power grid information-physical system is established and an attack and defense game scenario is designed to obtain a protection plan for the power grid information-physical system.

[0011] In one embodiment, the structure of the power grid cyber-physical system interaction model includes:

[0012] An upper layer information network, the upper layer information network comprising a plurality of information nodes and information channels;

[0013] A lower-layer physical network, wherein the lower-layer physical network includes a plurality of physical nodes and a physical channel;

[0014] An intermediate interaction channel, wherein the intermediate interaction channel is used to connect the information node and the physical node.

[0015] In one embodiment, the power grid cyber-physical system vulnerability assessment model is constructed in the following manner:

[0016] R T =TVC;

[0017] In the above formula, R T represents the expected value of the loss of the attack target, T represents the probability of the attack target being attacked, V represents the probability of successfully capturing the attack target, and C represents the active load loss of the attack target.

[0018] In one embodiment, the defense resource allocation process includes:

[0019] In the absence of defense resources, the active load loss under different attack scenarios is obtained based on the active load loss model of the power grid cyber-physical system;

[0020] Obtain the total amount of defense resources, and obtain the amount of each defense resource based on the preset defense resource allocation accuracy and the total amount of defense resources;

[0021] The active load loss amounts are sorted in descending order, and each portion of the defense resource amount is sequentially allocated to the first N active load loss amounts after sorting until the total amount of defense resources is allocated, where N is a positive integer greater than or equal to 1.

[0022] In one embodiment, the CPPS attack and defense game optimization model includes a planning model, and the structure of the planning model includes:

[0023] An upper-level planning model, wherein the decision variables of the upper-level planning model include defense resources allocated to the attack target;

[0024] A middle-level planning model, wherein the decision variables of the middle-level planning model include physical attack resources on physical channels and information attack resources on information nodes;

[0025] A lower-level planning model, wherein the decision variables of the lower-level planning model include the load amount to be reallocated to the CPPS.

[0026] In one of the embodiments, the CPPS attack and defense game optimization model includes a three-layer planning model;

[0027] The decision variables of the next-level planning model depend on the decision variables of the previous-level planning model; the decision variables of the next-level planning model will be fed back to the previous-level planning model as the decision variables of the previous-level planning model change.

[0028] In one embodiment, the process of conducting an attack and defense game based on the attack and defense game optimization model of the power grid cyber-physical system includes:

[0029] Based on the Newton-Raphson power flow calculation equation, an initial power flow of the power grid cyber-physical system is obtained;

[0030] Traversing all attack scenarios, and obtaining the active load loss amount based on the active load loss model of the power grid cyber-physical system;

[0031] Obtain information nodes under a preset active load loss amount and determine attack targets;

[0032] The defense resources allocated to the attack target are obtained based on the initial power flow and the allocation process of the defense resources.

[0033] In one of the embodiments, the attack-defense game scenario includes a defender and an attacker;

[0034] In the upper-level planning model, the defense resources pre-allocated by the defender are determined, and the defense resources are used to reduce the probability of the node being successfully captured;

[0035] In the middle-level planning model, determining the planned attack strategy of the attacker, wherein the planned attack strategy is used to increase the loss of the power grid cyber-physical system;

[0036] In the lower-level planning model, the defender's reallocated resources are determined.

[0037] In one embodiment, the resource reallocation process includes:

[0038] Based on preset rules, the balancing nodes of the isolated network that was disconnected after the power grid cyber-physical system was attacked are reselected, and the nodes and lines of the isolated network are renumbered.

[0039] In a second aspect, the present application further provides a protection device for a power grid cyber-physical system, the device comprising:

[0040] A confirmation module, used to determine an attack scenario based on the structure of the power grid cyber-physical system interaction model, wherein different attack scenarios correspond to different attack targets and defense targets;

[0041] An assessment module is used to obtain a vulnerability assessment model of the power grid cyber-physical system based on the defense targets of the attack targets in different attack scenarios;

[0042] A load calculation module is used to obtain an active load loss model of the power grid cyber-physical system based on the Newton-Raphson power flow calculation equation and preset power constraints;

[0043] A resource allocation module, configured to obtain defense resources allocated to the attack target based on the vulnerability assessment model of the power grid cyber-physical system and the active power loss model of the power grid cyber-physical system;

[0044] The game calculation module is used to establish an attack and defense game model of the power grid information-physical system and design an attack and defense game scenario based on the structure of the power grid information-physical system interaction model and the defense resources allocated to the attack target, so as to obtain a protection plan for the power grid information-physical system.

[0045] In a third aspect, the present disclosure further provides a computer device, wherein the computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the protection method of the power grid cyber-physical system are implemented.

[0046] In a fourth aspect, the present disclosure further provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the protection method for a power grid cyber-physical system when executed by a processor.

[0047] In a fifth aspect, the present disclosure further provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the protection method of the power grid cyber-physical system are implemented.

[0048] The above-mentioned protection method of the power grid cyber-physical system has at least the following beneficial effects:

[0049] The embodiment scheme provided by the present disclosure predetermines possible attack scenarios, attack targets, and defense targets based on the structure of the power grid information-physical system interaction model, and generates defense resources allocated to attack targets based on the power grid information-physical system vulnerability assessment model and the power grid information-physical system active load loss model. On the basis of allocating defense resources in advance, an attack and defense game model of the power grid information-physical system is established to obtain different attack and defense game scenarios. During the actual operation of the power grid information-physical system interaction model, when attacked, the protection plan of the power grid information-physical system will be readjusted according to the attack scenario, attack target, and defense resources, thereby improving the accuracy of defense resource allocation.

[0050] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 A diagram of an application environment of a method for protecting a power grid cyber-physical system in an embodiment;

[0053] Figure 2 A schematic diagram of the node-channel relationship of a power grid cyber-physical system in an embodiment;

[0054] Figure 3 A schematic diagram of a flow chart of a method for protecting a power grid cyber-physical system in one embodiment;

[0055] Figure 4 A defense resource allocation process in one embodiment;

[0056] Figure 5 A 14-node power distribution system in one embodiment;

[0057] Figure 6 is a channel relationship diagram of a 14-node power distribution system in one embodiment;

[0058] Figure 7 It is a flowchart of an algorithm for simulating the attack and defense game of a power grid cyber-physical system in one embodiment;

[0059] Figure 8 Graphs showing particle swarm iteration results under three attack scenarios in one embodiment;

[0060] Fig. 9It is a structural block diagram of a protection device for a power grid cyber-physical system in one embodiment. DETAILED DESCRIPTION

[0061] In order to enable ordinary persons in the art to better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings.

[0062] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described here can be implemented in an order other than those illustrated or described here. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are only examples of devices and methods consistent with some aspects of the present disclosure as detailed in the attached claims. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, product or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements inherent to such process, method, product or device. In the absence of more restrictions, it is not excluded that there are other identical or equivalent elements in the process, method, product or device including the elements. For example, if the words first, second, etc. are used to represent the name, they do not represent any specific order.

[0063] The present disclosure provides a protection method for a power grid cyber-physical system, which can be applied to Figure 1 In the application environment shown in the figure. Considering the interaction between physical components and information components in CPPS, CPPS is abstracted into a node-channel model. The information network includes C nodes (information nodes) and CC (Control Center, CC) channels. The physical network includes P nodes (physical nodes) and PP channels (physical-physical channels). The information network and the physical network are connected through CP channels (interaction channels). Among them, physical components, information components, information nodes, physical nodes, and interaction channels can be the attack targets mentioned below.

[0064] In some embodiments of the present disclosure, the structure of the CPPS interaction model includes:

[0065] An upper layer information network, the upper layer information network comprising a plurality of information nodes and information channels;

[0066] A lower-layer physical network, wherein the lower-layer physical network includes a plurality of physical nodes and a physical channel;

[0067] An intermediate interaction channel, wherein the intermediate interaction channel is used to connect the information node and the physical node.

[0068] The CPPS interaction model is a three-layer structure, such as Figure 2 As shown, it is a schematic diagram of the node-channel relationship of the information-physical system of the power grid in one embodiment. The upper information network includes a communication system and an information system, wherein the C node (information node) represents the control center (CC) and the information terminal. Generally, the information components are arranged in conjunction with the physical components. These information components can perform data collection and control signal transmission on the matching physical components, such as the remote terminal unit (RTU). The CC channel represents the communication connection of the C node, and each C node should maintain a connection with the control center through the C node channel.

[0069] The physical network of the lower layer refers to the power equipment on the physical side, where P nodes (physical nodes) represent generators and loads, and PP channels (physical-physical channels) represent transmission and distribution lines. Transformers and substations are used for voltage and current conversion in the transmission and distribution process, and when they are used for distribution terminals to distribute electric energy to loads, they are all intermediate processes for the transmission of electric energy from generator nodes to load nodes. In order to simplify the model and calculation, the present invention regards transformers and substations as PP channels. Failure of the P node will cause the corresponding generator node to be unable to adjust the generator output power, or the load node to be unable to perform load shedding, and failure of the PP channel will cause the corresponding line to be disconnected.

[0070] The interactive channel in the middle layer is the CP channel, which is realized through terminals (data collection) and wires (power supply). It represents the connection between the P node and the corresponding C node. When the information component collects data through the CP channel, the physical component also supplies power to the local information component through the CP channel, forming a two-way communication.

[0071] However, in the actual power grid, the interaction relationship between the P node and the C node is varied, including one-to-many, many-to-one, one-to-many or no correspondence. According to the specific situation in the actual power grid, this embodiment simplifies the correspondence between the P node and the C node as follows:

[0072] (1) When the number of P nodes and C nodes is one-to-many, different C nodes connected to the P node generally have different functions. By simplifying the combination of all C nodes corresponding to the same P node into a single C node that integrates all functions, the one-to-many situation of P nodes and C nodes can be treated as a one-to-one mapping;

[0073] (2) When the number of P nodes to C nodes is many-to-one, the disconnection of all paths connecting all P nodes to a certain C node will cause the C node to be decoupled. At the same time, P nodes connected to the same C node generally have the same control requirements or similar characteristics. Therefore, all P nodes connected to the same C node can be regarded as a generalized P node, and the many-to-one situation of P nodes and C nodes can be treated as a one-to-one mapping;

[0074] (3) When there is no correspondence between the P and C nodes, one is that the P node has no corresponding C node. These P nodes can be equivalent to backup power supplies or protected generator nodes; the other is that the C node has no corresponding P node. These nodes are generally used for information transmission within the control system and do not directly correspond to specific P nodes. They can be equivalent to protected information nodes. Therefore, when there is no correspondence between the P node and the C node, the P node and the C node can be regarded as protected nodes in the physical system and the information system respectively, and are not the objects of attack and defense in the CPPS attack and defense game model established in this embodiment.

[0075] In summary, in order to simplify the model expression, this embodiment has been reasonably simplified according to the actual situation, and the situations where there is a one-to-many, many-to-one or no correspondence between P nodes and C nodes are properly handled as the assumption of a one-to-one mapping between P nodes and C nodes, thereby forming a one-to-one corresponding, two-way communication CP channel.

[0076] In some embodiments of the present disclosure, Figure 3 As shown, a protection method for a power grid cyber-physical system is provided. In a specific embodiment, the method may include the following steps:

[0077] S302: Determine an attack scenario based on the structure of the power grid cyber-physical system interaction model, where different attack scenarios correspond to different attack targets and defense targets.

[0078] Some embodiments provided by the present disclosure can determine possible attack targets and attack scenarios through the structure of the grid information-physical system interaction model, and then improve the security of the operation of the grid information-physical system by evaluating the vulnerability of the grid information-physical system for different attack targets and attack scenarios. The CP channel is usually an internal connection that provides power to information equipment and is not an easy target for attackers to attack; in the information subsystem, the CC channel is often a cable or wireless, which is relatively reliable and not vulnerable to attack, but the C node is easy to become an attack target; in the physical subsystem, the PP channel is usually the most vulnerable. Therefore, it is determined that the targets of the information attack are the PP channel and the C node. Therefore, the collaborative information-physical attack behavior discussed in this embodiment is to simultaneously carry out a physical attack on the PP channel and an information attack on the C node. The attack target in some embodiments can be the selected attack target in this embodiment, and it can also be other implementation methods and attack targets without limitation.

[0079] When the attacker attacks the PP channel and the C node at the same time, the PP channel fails due to the physical attack, which will affect the distribution of the power flow of the system and may cause some line flows to exceed the limit. The power flow refers to the process in which the current or power flows from the power supply through the various system components into the load and is distributed throughout the power grid under the stimulation of the power supply potential when the power system is running. At this time, the power grid defender needs to cut off the seriously exceeded line through the first line of defense of the power system - relay protection, and even needs to adjust the generator output and load shedding through the second line of defense of the power system - overload shedding load stabilization device to return the system to a stable working state, but these operations will cause load loss. The control center can also send control commands to adjust the status of some P nodes, but because the C node that is attacked by the information fails at this time, the communication of some P nodes is blocked, which will cause the P nodes connected to the damaged C node to be unable to adjust the generator output or refuse to shelve the load, further increasing the load loss. It can be seen that attacking the components on either the physical side or the information side of the CPPS will affect the other side and increase the load loss. Since the defense strategy of the defender studied in this embodiment is to trip the line and cut the load, without considering out-of-step separation, frequency or voltage emergency control, etc., the third line of defense of the power system is not involved.

[0080] In summary, this embodiment proposes at least three attack scenarios that can be applied and clarifies the corresponding defense objectives of power grid defenders:

[0081] 1) Scenario 1: A physical attack is conducted on one PP channel. The grid defender uses relay protection to defend against the attack on the PP channel.

[0082] 2) Scenario 2: Coordinated cyber-physical attack on one PP channel and one C node. The defender uses relay protection and overload shedding and load stabilization devices to simultaneously defend against attacks on both the PP channel and the C node.

[0083] 3) Scenario 3: Collaborative cyber-physical attack on one PP channel and two C nodes. The defender uses relay protection and overload shedding and load stabilization devices to simultaneously defend against attacks on the PP channel and C nodes.

[0084] S304: Based on the defense targets of the attack targets in different attack scenarios, a CPPS vulnerability assessment model is obtained.

[0085] This embodiment studies the impact of collaborative cyber-physical attacks on the security of CPPS by evaluating the vulnerability of system components. In a specific implementation, a CPPS vulnerability assessment model can be constructed: T =TVC(1)

[0086] Where: Risk R T(Risk) represents the expected value of the loss of the attacked component; Threat T (Threat) represents the probability of the component being attacked; Vulnerability V (Vulnerability) represents the probability of the component being successfully attacked; Consequence C (Consequence) represents the amount of loss caused by the attacked component.

[0087] The CPPS vulnerability assessment result is more realistic due to the introduction of two probability values ​​T and V. In the context of collaborative cyber-physical attacks, this embodiment quantifies the three factors of "consequence" C, "vulnerability" V, and "threat" T in formula (1), thereby constructing a CPPS vulnerability assessment framework, which provides a basis for building an attack and defense game model.

[0088] The system loss is measured by the active load loss caused by the CPPS under the coordinated cyber-physical attack, and the active load loss caused by the successful attack of component i (PP channel or C node) is defined as Ci, where CPPS may include n components, and component i is one of the n components.

[0089] Obviously, the vulnerability V of a component in CPPS is related to the attack and defense resources allocated to it. The more defense resources allocated, the lower the probability of being successfully attacked; the more attack resources the component obtains, the easier it is to be destroyed. To simplify the calculation, this embodiment mainly quantifies V from the perspective of the power grid defender. Let di be the defense resources allocated to component i by the power grid defender, and define the probability Vi of component i being successfully attacked depends on the amount of defense resources allocated di, and the calculation formula is:

[0090] In terms of quantifying the threat T, the present invention assumes that the probability Ti of component i being attacked varies with the amount of defense resources allocated di. The probability Vi of component i being successfully attacked is obtained from formula (2), and the expected value ViCi of the system active load loss after the defense resources are allocated is obtained. If there are n components in the CPPS, the maximum value of the expected value of the system active load loss after the defense resources are allocated to these components is recorded as VCmax:

[0091] VC max =max(V i C i ) i=1,2,……,n (3)

[0092] If m of the n components are the maximum expected value of the system active load loss VC max The components are:

[0093]

[0094] The calculation formula of component i's attack probability Ti is as follows:

[0095]

[0096] S306: Based on the Newton-Raphson power flow calculation equation and the preset power constraint conditions, a CPPS active load loss model is obtained.

[0097] The present invention adopts the optimal load reduction and generator output power adjustment operation to ensure that the system pays the least price to restore stable operation. The load shedding method is to cut the active and reactive power of the load node in proportion. The load shedding principle is to minimize the active load loss. The particle swarm optimization algorithm is used to solve the optimal load shedding model. Based on the Newton-Raphson power flow model, the minimum active load loss model is determined:

[0098]

[0099] satisfy:

[0100] 0≤η i ≤1 (7)

[0101]

[0102] Where: L = {L a ,L off}, L a / L off Respectively represent the set of controllable or uncontrollable load nodes in the system; Respectively represent the active and reactive losses of load node i, represents the initial amount of active load at load node i, η i Indicates the load shedding ratio of load node i, with a value range of 0 to 1; Respectively represent the upper and lower limits of active power of load node i, Respectively represent the upper and lower limits of reactive power of load node i; P i , ΔP i represents the actual active power and actual active power loss of node i, Q i , ΔQ i represents the actual reactive power and actual reactive loss of node i, U i represents the voltage amplitude of node i; δ ij Represents the voltage phase angle difference of branch ij; G ij , B ij represents the conductance and susceptance of branch i; N represents the set of all nodes, N PV 、N PQ The load node in this embodiment refers to a component in the power grid cyber-physical system.

[0103] Formula (6) gives the optimal load shedding target, Formula (7) is the load shedding ratio constraint, Formula (8) is the proportional shedding constraint of active and reactive power at the load node, Formulas (9)-(11) are the active and reactive constraints of the load node, and Formulas (12)-(13) are Newton-Raphson power flow calculation equations. The optimal generator output regulation scheme is the same as above.

[0104] S308: Based on the CPPS vulnerability assessment framework and the CPPS active power loss model, obtain the defense resources allocated to the attack target.

[0105] Since the attack and defense game of CPPS is a limited rational behavior, that is, under the condition of limited resources of both sides, the attacker and the defender seek their own maximum interests. The defender of the power grid minimizes the loss of active load of the system by allocating limited defense resources, and the attacker maximizes the loss of active load of the system by allocating limited attack resources to vulnerable components through coordinated cyber-physical attacks. The sum of the benefits of both sides is zero, which constitutes a zero-sum game. The Nash equilibrium of the attack and defense game of CPPS refers to the attacker and the defender obtaining their respective optimal strategies after confrontation, at which time both sides have the maximum benefits. Therefore, under the condition of limited rationality of both sides, the attack and defense game of CPPS can eventually obtain the only Nash equilibrium solution, and the defense resource strategy at this time is the optimal.

[0106] S310: Based on the structure of the CPPS interaction model and the defense resources allocated to the attack target, a CPPS attack and defense game model is established and an attack and defense game scenario is designed to obtain a CPPS protection plan.

[0107] The upper planning model of the constructed three-layer CPPS attack and defense game optimization model is the first step in the attack and defense game scenario. Based on the three-layer attack and defense game optimization model, the defender predicts the attacker's attack strategy and attack results by calculating the minimum system active load loss caused by the three attack scenarios when the total amount of initial defense resources is zero, so as to obtain the optimal defense resource allocation strategy.

[0108] In the protection method of the above-mentioned power grid information-physical system, possible attack scenarios, attack targets, and defense targets are determined in advance based on the structure of the power grid information-physical system interaction model, and defense resources allocated to the attack targets are generated based on the power grid information-physical system vulnerability assessment model and the power grid information-physical system active load loss model. On the basis of allocating defense resources in advance, an attack and defense game model of the power grid information-physical system is established to obtain different attack and defense game scenarios. During the actual operation of the power grid information-physical system interaction model, when attacked, the protection plan of the power grid information-physical system will be readjusted according to the attack scenario, attack target, and defense resources, thereby improving the accuracy of defense resource allocation.

[0109] In some embodiments of the present disclosure, the power grid cyber-physical system vulnerability assessment model is constructed in the following manner:

[0110] R T =TVC;

[0111] In the above formula, R T represents the expected value of the loss of the attack target, T represents the probability of the attack target being attacked, V represents the probability of successfully capturing the attack target, and C represents the active load loss of the attack target.

[0112] CPPS vulnerability assessment model: R T =TVC,

[0113] Where: Risk R T (Risk) represents the expected value of the loss of the attacked component; Threat T (Threat) represents the probability of the component being attacked; Vulnerability V (Vulnerability) represents the probability of the component being successfully attacked; Consequence C (Consequence) represents the amount of loss caused by the attacked component.

[0114] In some embodiments of the present disclosure, the defense resource allocation process includes:

[0115] In the absence of defense resources, the active load loss under different attack scenarios is obtained based on the active load loss model of the power grid cyber-physical system;

[0116] Obtain the total amount of defense resources, and obtain the amount of each defense resource based on the preset defense resource allocation accuracy and the total amount of defense resources;

[0117] The active load loss amounts are sorted in descending order, and each portion of the defense resource amount is sequentially allocated to the first N active load loss amounts after sorting until the total amount of defense resources is allocated, where N is a positive integer greater than or equal to 1.

[0118] Figure 4 The following is a defense resource allocation process in one embodiment.

[0119] 1) Calculate the minimum expected value of system active load loss VC when there is no defense 0 , that is, when the total amount of initial defense resources D 0 =0, we have:

[0120] VC 0 =C (14)

[0121] 2) Assume that the defense resource allocation accuracy K = 10000, and take the total defense resource D as 50% of the total vulnerable components (PP channels and C nodes), then each defense resource is D / K.

[0122] 3) For the three attack scenarios, a defense resource D / K is allocated to VC max The PP channel and C node combination of the value is as follows:

[0123]

[0124] 4) If the defense resources have been allocated, output the results of the defense resources allocated to the vulnerable components under the three attack scenarios; otherwise, return to step 3 and continue to allocate defense resources.

[0125] In one embodiment of the present disclosure, the CPPS attack and defense game optimization model includes a planning model, and the structure of the planning model includes:

[0126] An upper-level planning model, wherein the decision variables of the upper-level planning model include defense resources allocated to the attack target;

[0127] A middle-level planning model, wherein the decision variables of the middle-level planning model include physical attack resources on physical channels and information attack resources on information nodes;

[0128] A lower-level planning model, wherein the decision variables of the lower-level planning model include the load amount to be reallocated to the CPPS.

[0129] Based on the CPPS vulnerability assessment framework and the attack and defense scenario design, a three-layer mathematical programming model is constructed to quantitatively analyze the attack and defense game problem of CPPS, and discuss the security impact of CPPS under coordinated cyber-physical attacks. This paper proposes a simplified three-layer CPPS attack and defense game optimization model based on non-cooperative dynamic incomplete zero-sum game:

[0130] Upper level planning model:

[0131]

[0132] satisfy

[0133] h u (d,ω,f)≥0(17)

[0134] Mid-level planning model:

[0135]

[0136] satisfy

[0137] h m (d,ω,f)≥0(19)

[0138] Lower level planning model:

[0139]

[0140] satisfy

[0141] h l (d,ω,f)≥0(21)

[0142] In the formula: the goal of the grid defender is to minimize the system loss, d is the defender's defense resource allocation strategy, which is the decision variable of the upper-level planning model, including the defense resources allocated to the PP channel and the C node, and the defense resources are limited; the goal of the attacker is to maximize the system loss, ω is the attacker's attack strategy, which is the decision variable of the middle-level planning model, including physical attacks on the PP channel and information attacks on the C node, and the attack resources are also limited; f is the remedial measures activated by the grid defender in response to the damage to the system, which is the decision variable of the lower-level planning model, including reallocating power flow to the system, tripping the most serious line over-limit, adjusting the generator output power and shedding the load, etc. The g function in formula (16) is a function of parameters d, ω, and f, which is the expected value of the final system loss.

[0143] In one embodiment of the present disclosure, the CPPS attack and defense game optimization model includes a three-layer planning model;

[0144] The decision variables of the next-level planning model depend on the decision variables of the previous-level planning model; the decision variables of the next-level planning model will be fed back to the previous-level planning model as the decision variables of the previous-level planning model change.

[0145] In one embodiment of the present disclosure, the process of conducting an attack and defense game based on the CPPS attack and defense game optimization model includes:

[0146] Based on the Newton-Raphson power flow calculation equation, an initial power flow of the power grid cyber-physical system is obtained;

[0147] Traversing all attack scenarios, and obtaining the active load loss amount based on the active load loss model of the power grid cyber-physical system;

[0148] Obtain information nodes under a preset active load loss amount and determine attack targets;

[0149] The defense resources allocated to the attack target are obtained based on the initial power flow and the allocation process of the defense resources.

[0150] The model solving algorithm proposed in the present invention takes the IEEE 14-bus system (14-bus distribution system) as an example. Figure 5 A 14-node power distribution system in one embodiment, Figure 6 A channel relationship diagram of a 14-node power distribution system in one embodiment. Figure 7 This is a flowchart of an algorithm for simulating the attack and defense game of a power grid cyber-physical system in one embodiment. The algorithm flow is described in detail as follows:

[0151] 1) Construct a CPPS interaction model.

[0152] 2) Calculate the system power flow. Based on the Newton-Raphson power flow model, the power flow distribution when the system is operating normally is calculated as the initial power flow state of the system.

[0153] 3) Traverse all attack scenarios. Select an attacker's attack scenario (PP\(PP+C)\(PP+C+C)), and use the particle swarm optimization algorithm to calculate the system's minimum common load loss and optimal generator output regulation scheme under the collaborative cyber-physical attack.

[0154] 4) Search for the worst-case attack C node combination. Information attacks on different C nodes have different effects on system security. In fact, during the simulation process, the failure of certain C nodes will cause communication interruption, making it impossible to monitor or control some physical components, resulting in the worst-case attack C node combination that causes the greatest loss of system active load. To simplify the calculation, when the attack scenario is scenario 2 or scenario 3, the present invention considers the worst-case attack C node combination and uses a particle swarm optimization algorithm to solve the attack C node combination that causes the greatest loss of system active load.

[0155] 5) Determine the attack target. Attack scenario 2 and attack scenario 3 refer to information attacks on the worst-case attack C node combination found in step 4 and physical attacks on one PP channel.

[0156] 6) If all attack scenarios are listed, continue to step 7, otherwise return to step 3

[0157] 7) Calculate the optimal defense resources of the components. According to the optimal defense resource allocation strategy in Section 2.2, firstly, the minimum active load loss of the vulnerable components (C nodes and PP channels) under three attack scenarios is solved when there is no defense; secondly, defense resources are allocated to PP channels and C nodes.

[0158] 8) Evaluate CPPS vulnerability. Based on the CPPS vulnerability assessment model in step 3), the vulnerability analysis of the components can be performed.

[0159] In one embodiment of the present disclosure, the attack-defense game scenario includes a defender and an attacker;

[0160] In the upper-level planning model, the defender pre-allocates defense resources to reduce the probability of a node being successfully captured;

[0161] In the middle-level planning model, the attacker plans the attack strategy to increase the CPSS loss;

[0162] In the lower-level planning model, the defender reallocates resources to reduce CPSS losses.

[0163] This embodiment is based on game theory. Under the condition of limited rationality of both the attacker and the defender, and taking into account that the strategies selected by both parties have a certain order, a dynamic attack and defense game model is established. The external attacker aims to maximize the system loss, while the power grid defender is the opposite. The sum of the benefits of the two is zero, which constitutes a zero-sum game. The attacker usually develops an attack strategy after hacking into the system to steal the defense strategy, and the defender does not necessarily know the other party's strategy in advance, which is called an incomplete information game. At the same time, the attacker and the defender are opposite and have no agreement, so it is a non-cooperative game.

[0164] In summary, the CPPS attack and defense game behavior discussed in this invention is a non-cooperative dynamic non-complete zero-sum game. Designing the attack and defense game scenario consists of the following three steps:

[0165] 1) The grid defender predicts the attack strategy and attack results, and pre-allocates defense resources to the PP channels and C nodes that may be subjected to coordinated cyber-physical attacks under the condition of limited total defense resources, so as to reduce the probability V of components being successfully attacked in advance before the system is attacked. This step corresponds to the upper-level planning model shown in equation (16) in the three-layer CPPS attack and defense game model, and the goal is to minimize system losses;

[0166] 2) The attacker illegally invades the system, steals the defense strategy, and then plans an attack strategy to make the system loss as high as possible. The attacker coordinates the information and physical attack on the C node and the PP channel to increase the probability V of the component being successfully attacked. The PP channel under physical attack trips due to failure, affecting the power flow distribution of the system. At the same time, the P node connected to the C node under information attack fails, and the generator output cannot be adjusted or the load is cut off. The above faults may cause the power flow to exceed the limit, and the remedial measures in step 3 are required to restore the system to stable operation. This step corresponds to the middle-level planning model shown in equation (18) in the three-layer CPPS attack and defense game optimization model, and the goal is to maximize the system loss;

[0167] 3) The power grid defender takes further remedial measures to reduce the final system loss according to the damage to the system. When the line attacked physically in step 2 is disconnected, the defender needs to recalculate the flow. If there is a line flow exceeding the limit, the line with the most serious flow exceeding the limit will be tripped; the system flow is calculated again. If there is still a line flow exceeding the limit, the flow of other lines is kept within the limit by adjusting the generator output or cutting the load. The optimal generator output adjustment plan and load cutting plan are shown in step 4). At the same time, the P node connected to the C node due to the information attack fails, causing the P node to be unable to adjust the generator output and refuse to cut the load. The flow needs to be calculated again. If there is still a line flow exceeding the limit, the above-mentioned adjustment of the generator output and load cutting actions are repeated. This step corresponds to the lower-level planning model shown in formula (20) in the three-layer CPPS attack and defense game optimization model, and the goal is to minimize the final system loss.

[0168] In one embodiment of the present disclosure, the resource reallocation process includes:

[0169] Based on the preset rules, the balancing nodes of the isolated network disconnected after the CPSS was attacked are reselected, and the nodes and lines of the isolated network are renumbered to form a new topological structure.

[0170] If the grid topology is split into multiple isolated networks due to line disconnection, it is necessary to reselect balancing nodes for the networks without balancing nodes. The new balancing nodes are selected based on the principle of maximizing the generator capacity (active power), and the nodes and lines of these isolated networks are renumbered to form new topological structures and redistribute the power flows of each isolated network.

[0171] In addition, the simulation analysis method of the CPPS three-layer attack and defense game optimization model specifically includes the following contents:

[0172] Assuming that the line power flow limit is 1.3 times the initial state power flow, if the line power flow value after being attacked exceeds 1.2 times the power flow limit, the line power flow is considered to be out of limit. The first step in allocating optimal defense resources is to calculate the minimum active load loss of the system when there is no defense. At this time, all components will fail once attacked.

[0173] In order to intuitively show the difference between the impact of coordinated cyber-physical attacks and single physical attacks on CPPS security, the present invention defines the proportion of additional active load loss generated by attack scenario 2 based on scenario 1:

[0174]

[0175] Similarly, compared with attack scenario 1, the proportion of additional active load loss in attack scenario 3 to the system is:

[0176]

[0177] Where: C 1 , C 2 , C 3 They correspond to the minimum active load loss of the system under the three attack scenarios. If the minimum active load loss of the system caused by attack scenario 2 or attack scenario 3 is greater than the loss caused by attack scenario 1, σ is a positive number, otherwise, σ is a negative number.

[0178] Based on Matlab R2016a, the present invention uses the IEEE 14-node system as an example to simulate and analyze the above model. The IEEE 14-node system includes 14 nodes and 20 lines, which is the CPPS physical system in the simulation example of the present invention. According to the one-to-one mapping principle, the information system is generated based on the network topology of this physical system, and node 5 is used as the control center of the information system. Figure 5 As shown, the node-channel relationship is shown in Figure 6 The simulation results are as follows:

[0179] When the defense resource is 0, the minimum active load loss of the IEEE 14-node system caused by three attacks is shown in Table 1. Among them, the first column is the PP channel that fails due to physical attack; the second column is the PP channel with the most severe power flow over-limit that is disconnected; the third and fourth columns are the 1 C node and 2 C nodes that suffer the largest active load loss due to information attack; the fifth, sixth and eighth columns are the minimum active load loss of the system under the three attack scenarios when there is no defense, all of which are per unit values; the seventh and ninth columns are the percentage of additional active load loss caused by scenario 2 and scenario 3 compared with attack scenario 1.

[0180] For example, line 2-4 fails due to physical attack. Figure 8 : This is a particle swarm iteration result diagram under three attack scenarios in an embodiment, and the particle swarm optimization algorithm is used to calculate the iteration results of the minimum system active load loss under the three attack scenarios. Figure 8 As shown in the figure, the solution algorithm proposed in the present invention can converge within a limited number of iterations in three attack scenarios, which verifies the effectiveness of the algorithm in solving the model.

[0181] The minimum active load loss of the system without defense can be shown in the following table:

[0182] Table 1 Minimum active load loss of the system without defense

[0183]

[0184] From the analysis of Table 1, it can be seen that when lines 1-2 and 1-5 fail, the system minimum active load loss in attack scenarios 2 and 3 is smaller than that in scenario 1, and when line 5-6 fails, the system minimum active load loss in attack scenario 3 is smaller than that in scenario 1; but when 4-9 fails, the system minimum active load loss in attack scenario 3 is larger than that in scenario 1, and when 5-6 fails, the system minimum active load loss in attack scenario 2 is larger than that in scenario 1; when lines 2-4, 2-5, 4-5, 4-7, 6-12, and 6-13 fail, the system minimum active load loss in attack scenarios 2 and 3 is larger than that in scenario 1, especially, the system minimum active load loss in attack scenario 2 when lines 6-12 and 6-13 fail is 61.5% higher than that in scenario 1. It can be concluded that physical attacks on different PP channels will cause different system minimum active load losses, and both physical and information attacks will have an impact on the physical side of CPPS, and coordinated information-physical attacks will increase additional load losses on the basis of single physical attacks.

[0185] According to the defense behaviors of the power grid defenders corresponding to the three attack scenarios proposed above, the optimal defense resource allocation strategy can be obtained by solving the three-layer attack and defense game optimization model. For the IEEE 14-node system, 14 C nodes and 20 PP channels are vulnerable to malicious attacks, so these vulnerable components need to be defended. Assume that the total amount of defense resources is 50% of the vulnerable components, that is, the total amount of defense resources, which represents the sum of defense resources allocated to PP channels and C nodes.

[0186] The optimal amount of defense resources d allocated to vulnerable components under three attack scenarios PP or PP,C The expected value VC of the minimum active load loss of the system after allocating defense resources is shown in Table 2:

[0187] Table 2 Optimal defense resource allocation strategy

[0188]

[0189] In Table 2, except for lines 2-3, 3-4, 6-11, 7-8, 9-10, 9-14, 10-11, 12-13, and 13-14, all lines are allocated certain defense resources. Among them, lines 2-4 and 4-5 get the most defense resources. In particular, due to the limited total amount of defense resources, some lines, such as line 2-5, are not allocated defense resources under attack scenarios 2 and 3. As shown in formula (14), the minimum system without defense is

[0190] The expected active load loss is the minimum system active load loss. Compared with Table 1, the expected value of the minimum system active load loss is significantly reduced after allocating defense resources. Therefore, the grid defender can allocate defense resources according to the degree of component damage, and by allocating the optimal defense resources, the degree of system damage can be minimized.

[0191] Get the minimum system active load loss expectation in Table 2 as the maximum value VC max Components, that is, components allocated to defense resources, are very likely to be attacked. Therefore, it can be determined as shown in formula (4), and the probability of component being attacked T is obtained, as shown in formula (5). Finally, the risk value R of the component is obtained according to formula (1): T , see Table 3, which is arranged in descending order according to the amount of allocated defense resources. In the table, columns 1-5 represent the PP channel under security threat in attack scenario 1, the amount of defense resources allocated to the PP channel (same as Table 2), the probability of the PP channel being attacked T, the expected value of the minimum active load loss of the system after allocating defense resources VC, and the risk value R T The same is true for Table 4 and Table 5. If the components in the system are allocated with defense resources, it means that these components have a high probability of facing security threats and are the key defense targets of the power grid defenders. The more defense resources these components are allocated, the higher their vulnerability. The vulnerable components that are threatened by security in attack scenario 1 are shown in Table 3:

[0192] Table 3 Vulnerable components that are subject to security threats under attack scenario 1 (D=17)

[0193]

[0194] The vulnerable components that are subject to security threats in attack scenario 2 are shown in Table 4:

[0195] Table 4 Vulnerable components that are subject to security threats under attack scenario 2 (D=17)

[0196]

[0197] The vulnerable components that are subject to security threats in attack scenario 3 are shown in Table 5:

[0198] Table 5 Vulnerable components that are subject to security threats under attack scenario 3 (D=17)

[0199]

[0200] Comparing the data in Tables 3 to 5, we can see that the parameter values ​​VC, T and R under the coordinated cyber-physical attack TThey are higher than those under a single physical attack, which also verifies the above simulation analysis conclusion (about the simulation analysis of the minimum active load loss of the system when there is no defense) that collaborative cyber-physical attacks will cause additional load losses to the system.

[0201] In addition, when the total amount of defense resources D = 17, under the same attack scenario, the parameter values ​​of different components VC, T and R T This is the result of defense resource allocation. The allocation of defense resources results in the expected maximum value VC of the minimum system active load loss caused by different vulnerable components. max The values ​​of m are approximately the same, as shown in Table 2. Therefore, the probability of all components being attacked T is also the same. Finally, the system risk value R is obtained by T, V, and C. T The data in the above three tables will change when the total amount of defense resources is changed. When the total amount of defense resources is 7, the vulnerable components that are threatened by security in attack scenario 1 are shown in Table 6:

[0202] Table 6 Vulnerable components that are subject to security threats under attack scenario 1 (D=7)

[0203]

[0204] The vulnerable components that are subject to security threats in attack scenario 2 are shown in Table 7:

[0205] Table 7 Vulnerable components that are subject to security threats under attack scenario 2 (D=7)

[0206]

[0207] The vulnerable components that are subject to security threats in attack scenario 3 are shown in Table 8:

[0208] Table 8 Vulnerable components that are subject to security threats under attack scenario 3 (D=7)

[0209]

[0210] By changing the total amount of defense resources, the above conclusions can be confirmed again. Comparing Tables 3-5 with Tables 6-8, it can be seen that the vulnerable components under security threats and their vulnerability rankings in the same attack scenario are related to the degree of damage to these components, which is determined by the attacker's attack behavior and has nothing to do with the total amount of defense resources; while the vulnerability assessment results of system components are affected by the total amount of defense resources.

[0211] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0212] Based on the same inventive concept, the disclosed embodiment also provides a protection device for a power grid information-physical system for implementing the protection method for the power grid information-physical system involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in the embodiment of the protection device for the power grid information-physical system provided below can refer to the limitations of the protection method for the power grid information-physical system above, and will not be repeated here.

[0213] The device may include a system (including a distributed system), software (application), module, component, server, client, etc. using the method described in the embodiments of this specification and a device in combination with necessary implementation hardware. Based on the same innovative concept, the device in one or more embodiments provided in the embodiments of the present disclosure is as described in the following embodiments. Since the implementation scheme and method for solving the problem of the device are similar, the implementation of the specific device in the embodiments of this specification can refer to the implementation of the aforementioned method, and the repetitions will not be repeated. As used below, the term "unit" or "module" can implement a combination of software and / or hardware for predetermined functions. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0214] In one embodiment, Fig. 9 As shown, a protection device 900 for a power grid cyber-physical system is provided, and the device may be the aforementioned server, or a module, component, device, unit, etc. integrated in the server. The device 900 may include:

[0215] A confirmation module 902 is used to determine an attack scenario based on the structure of the power grid cyber-physical system interaction model, where different attack scenarios correspond to different attack targets and defense targets;

[0216] An evaluation module 904 is used to obtain a vulnerability evaluation model of a power grid cyber-physical system based on the defense targets of the attack targets in different attack scenarios;

[0217] The load calculation module 906 is used to obtain an active load loss model of the power grid cyber-physical system based on the Newton-Raphson power flow calculation equation and the preset power constraint conditions;

[0218] A resource allocation module 908, configured to obtain defense resources allocated to the attack target based on the power grid cyber-physical system vulnerability assessment framework and the power grid cyber-physical system active power loss model;

[0219] The game calculation module 910 is used to establish an attack and defense game model of the power grid information-physical system and design an attack and defense game scenario based on the structure of the power grid information-physical system interaction model and the defense resources allocated to the attack target, so as to obtain a protection plan for the power grid information-physical system.

[0220] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0221] Based on the description of the above method embodiments, the present disclosure also provides other device implementation schemes corresponding to the method embodiments, for example, it may include a first module, which implements the method step functions corresponding to the structure-related method embodiment of the CPPS interaction model. Or it may include a second module, which implements the processing method step functions of the allocation of the defense resources. Similarly, it may include a third module, a fourth module, etc. to implement the method processing step functions of the corresponding method.

[0222] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method described in any embodiment of the present disclosure is implemented.

[0223] In one embodiment, a computer program product is provided, including a computer program, which implements the method described in any embodiment of the present disclosure when executed by a processor.

[0224] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0225] The above-described embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the attached claims.

Claims

1. A protection method for a power grid cyber-physical system, characterized in that: The method comprises: Determine the attack scenario based on the structure of the power grid cyber-physical system interaction model, where different attack scenarios include different attack targets and defense targets; Based on the defense objectives of the attack targets in different attack scenarios, a vulnerability assessment model for the cyber-physical system of the power grid is obtained; Based on the Newton-Raphson power flow calculation equation and the preset power constraints, the active load loss model of the power grid cyber-physical system is obtained; Based on the grid cyber-physical system vulnerability assessment framework and the grid cyber-physical system active load loss model, obtaining defense resources allocated to the attack target; Based on the power grid information-physical system interaction model and the defense resources allocated to the attack target, an attack and defense game model of the power grid information-physical system is established and an attack and defense game scenario is designed to obtain a protection plan for the power grid information-physical system.

2. The method according to claim 1, characterized in that: The structure of the power grid cyber-physical system interaction model includes: An upper layer information network, the upper layer information network comprising a plurality of information nodes and information channels; A lower-layer physical network, wherein the lower-layer physical network includes a plurality of physical nodes and a physical channel; An intermediate interaction channel, wherein the intermediate interaction channel is used to connect the information node and the physical node.

3. The method according to claim 1, characterized in that The power grid cyber-physical system vulnerability assessment model is constructed in the following way: R T =TVC; In the above formula, R T represents the expected value of the loss of the attack target, T represents the probability of the attack target being attacked, V represents the probability of successfully capturing the attack target, and C represents the active load loss of the attack target.

4. The method according to claim 1, characterized in that The defense resource allocation process includes: In the absence of defense resources, the active load loss under different attack scenarios is obtained based on the active load loss model of the power grid cyber-physical system; Obtain the total amount of defense resources, and obtain the amount of each defense resource based on the preset defense resource allocation accuracy and the total amount of defense resources; The active load loss amounts are sorted in descending order, and each portion of the defense resource amount is sequentially allocated to the first N active load loss amounts after sorting until the total amount of defense resources is allocated, where N is a positive integer greater than or equal to 1.

5. The method according to claim 1, characterized in that: The attack and defense game optimization model of the power grid cyber-physical system includes a planning model, and the structure of the planning model includes: An upper-level planning model, wherein the decision variables of the upper-level planning model include defense resources allocated to the attack target; A middle-level planning model, wherein the decision variables of the middle-level planning model include physical attack resources on physical channels and information attack resources on information nodes; A lower-level planning model, wherein the decision variables of the lower-level planning model include the amount of load reallocated to the cyber-physical system of the power grid.

6. The method according to claim 5, characterized in that The attack and defense game optimization model of the power grid cyber-physical system includes a three-layer planning model; The decision variables of the next-level planning model depend on the decision variables of the previous-level planning model; The decision variables of the next-level planning model will be fed back to the previous-level planning model along with the changes in the decision variables of the previous-level planning model.

7. The method according to claim 4, characterized in that The process of attack and defense game based on the attack and defense game optimization model of power grid cyber-physical system includes: Based on the Newton-Raphson power flow calculation equation, an initial power flow of the power grid cyber-physical system is obtained; Traversing all attack scenarios, and obtaining the active load loss amount based on the active load loss model of the power grid cyber-physical system; Obtain information nodes under preset active load loss and determine attack targets; The defense resources allocated to the attack target are obtained based on the initial power flow and the allocation process of the defense resources.

8. The method according to claim 6, characterized in that The attack and defense game scenario includes defenders and attackers; In the upper-level planning model, the defense resources pre-allocated by the defender are determined, and the defense resources are used to reduce the probability of the node being successfully captured; In the middle-level planning model, determining the planned attack strategy of the attacker, wherein the planned attack strategy is used to increase the loss of the power grid cyber-physical system; In the lower-level planning model, the defender's reallocated resources are determined.

9. The method according to claim 8, characterized in that The resource reallocation process includes: Based on preset rules, the balancing nodes of the isolated network that was disconnected after the power grid cyber-physical system was attacked are reselected, and the nodes and lines of the isolated network are renumbered.

10. A protection device for a power grid cyber-physical system, characterized in that: The device comprises: A confirmation module, used to determine an attack scenario based on the structure of the power grid cyber-physical system interaction model, wherein different attack scenarios correspond to different attack targets and defense targets; An assessment module is used to obtain a vulnerability assessment model of the power grid cyber-physical system based on the defense targets of the attack targets in different attack scenarios; A load calculation module is used to obtain an active load loss model of the power grid cyber-physical system based on the Newton-Raphson power flow calculation equation and preset power constraints; A resource allocation module, configured to obtain defense resources allocated to the attack target based on the vulnerability assessment model of the power grid cyber-physical system and the active power loss model of the power grid cyber-physical system; The game calculation module is used to establish an attack and defense game model of the power grid information-physical system and design an attack and defense game scenario based on the structure of the power grid information-physical system interaction model and the defense resources allocated to the attack target, so as to obtain a protection plan for the power grid information-physical system.

11. 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 9 are implemented.

12. 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 9 are implemented.

13. A computer program product, comprising a computer program, 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 9 are implemented.

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