A power distribution cyber-physical risk assessment method and system

Abstract

The present invention discloses a risk assessment method and system for power distribution cyber-physical systems, which relates to the technical field of power distribution cyber-physical system research, including a comprehensive assessment method for defining information system risks and physical system risks; assessing the potential threats to the safe operation of the distribution network caused by information flow interruption or tampering, and revealing the evolution mechanism of cross-space cascading failures; and verifying the effectiveness in different attack scenarios through case simulation to complete the risk assessment of power distribution cyber-physical systems. The present invention can effectively quantify the cross-space propagation impact of information system failures on physical systems, accurately assess the comprehensive risk level of information systems, physical systems, and cyber-physical systems, significantly improve the accuracy and efficiency of risk assessment, and can not only identify high-risk nodes, but also quantify the propagation mechanism of cascading failures, providing reliable support for the safe operation and planning design of power distribution cyber-physical systems, thereby improving the reliability and resilience of the distribution network.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution cyber-physical system research, in particular to a power distribution cyber-physical risk assessment method and system. BACKGROUND

[0002] At present, the power distribution network plays an increasingly important role in economic development, speeding up the construction of production and convenience for people's life. On the one hand, it is supported by the national strategic goal, and on the other hand, the operation of the power distribution network plays an increasingly key role. The power distribution network gradually develops in the operation of the overall power grid, integrates a large number of energy, communication and sensing, computing devices, and forms the characteristics of the gradual coupling of information systems and physical devices. It is generally believed that it constitutes a three-layer model of information system layer, information-physical coupling network layer and physical entity layer, which are mutually mapped and highly integrated with information and physics. Under the action of this model, the perception of information, the transmission and reception of data and the transmission of instructions have been improved. The originally isolated information transmission and physical control are becoming more and more closely combined.

[0003] At present, the control mode of the traditional power grid is relatively simple, which may lack the necessary development when the power supply continuity and stability requirements are not high, but the rapid development of today's economy and the rapid improvement of people's living conditions require the power distribution network to have more superior, fast control means and resources. In addition, under the double carbon target driving, the power distribution network will access a high proportion of renewable energy, and island as a fault recovery state will become an important operation mode. The supporting role of information systems in island operation is indispensable, so it is necessary to adopt power distribution cyber-physical system to realize information-physical integrated power distribution system analysis and control technology, and solve the problem of risk superposition effect on information-physical global system risk. SUMMARY

[0004] In view of the problems existing in the prior art power distribution cyber-physical risk assessment method and system, the present application is proposed.

[0005] Therefore, the present application aims to solve the problem of risk superposition effect on information-physical global system risk. The present application uses a power distribution cyber-physical risk assessment method to solve the problem.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for risk assessment of power distribution cyber-physical systems, which includes constructing a risk assessment model based on the islanded operating state of cyber-physical interaction mechanisms, establishing a probabilistic model of the islanded operating state through multi-scenario technology combined with source-load dual uncertainty, accurately quantifying the impact of cyber system failures on the physical system of the distribution network, and defining a comprehensive assessment method for cyber system risks and physical system risks;

[0008] Design a method to calculate the coupling and importance of information flows. By analyzing how information system failures propagate across space to physical systems, introduce the concepts of coupling and importance, assess the potential threats to the safe operation of distribution networks caused by information flow interruption or tampering, and reveal the evolution mechanism of cross-space cascading failures.

[0009] Based on the risk assessment indicators of information system failures in an isolated state, combined with the coupling degree and importance of information flow, the risks posed by information system failures to the security and stability of the distribution network are comprehensively quantified. The effectiveness in different attack scenarios is verified through case simulation to complete the risk assessment of distribution network information physics.

[0010] As a preferred solution of the risk assessment method of power distribution cyber-physical system described in the present invention, the risk assessment model of island operation state based on cyber-physical interaction mechanism includes evaluating the power balance of the distribution network in the island state. Under the power scenario s, the total load power of each node in the island state CPDS is The total output of unreliable DG is The equivalent load power for:

[0011]

[0012] The difference between the equivalent load power in the island and the output limit of the main power supply is for:

[0013]

[0014] in, They are the minimum and maximum outputs of the main power supply to maintain frequency and voltage stability in the island. When it is negative, energy storage and discharge are required; when When it is positive, energy storage and charging are required;

[0015] Under power scenario s, the power margin δ in the island CPDS 9s) It can be defined as:

[0016]

[0017] Where, The maximum charging and generating power for energy storage;

[0018] When δ (s) = 1, the main power supply in the island area can independently supply power to all loads, and the island state is recorded as δ1; δ (s) ∈ [0, 1), energy storage is needed to cooperate with the main power supply to maintain power balance in the island, and the island power margin state is recorded as δ2; δ s < 0, part of the load needs to be cut off to maintain power balance in the island, and the island power margin state is recorded as δ3; δ s > 1, the wind and light output needs to be limited, and the island power margin state is recorded as δ4.

[0019] As a preferred scheme of the power distribution cyber-physical risk assessment method, the comprehensive assessment method of the information system risk and the physical system risk comprises quantifying the influence of the cross-space propagation and cascading failure of the physical system caused by the interruption or tampering of the information flow by defining the coupling degree of the information flow, and the specific steps are as follows:

[0020] By affecting the decision-making process of the power distribution network dispatching center, indirect physical loss is caused, when the uplink information flow x k is interrupted and misleads the power distribution network dispatching center to issue incorrect energy storage regulation output or load shedding instructions, causing the system frequency to drop and triggering the low-frequency load shedding mechanism, the information fault is cross-space propagated to the physical system;

[0021] When the uplink information flow x k is interrupted and does not affect the judgment of the power distribution network dispatching center on the power margin, and the island is in the δ1 state, the information fault only causes the information system to lose the measurability of node k, that is, the fault does not cross-space propagate to the physical system, according to the above analysis, the coupling degree of the uplink information flow x k can be expressed as:

[0022]

[0023] Among them, is the probability of the power scenario s appearing; is the coupling degree of the uplink information flow x k under the power scenario s, and the calculation formula is as follows:

[0024]

[0025] Among them, δ (s) is the power margin under the power scenario s when the uplink information flow is complete; is the power margin under the power scenario s when the uplink information flow x k is lost;

[0026] ​The interruption of the downlink information flow also indirectly causes physical system loss by affecting the execution effect of the optimal load shedding instruction. The coupling degree of the downlink information flow y k may be represented as:

[0027]

[0028] wherein, is the coupling degree of the information flow y k under the power scenario s, under the power scenario s, the distribution network dispatching center does not include the load of node k in the load shedding combination decided by the distribution network dispatching center, the distribution network dispatching center does not issue an instruction to the IMD k, and there is no y k , at this time, the coupling degree of the downlink information flow y k Otherwise

[0029] As a preferred scheme of the power distribution cyber-physical risk assessment method, wherein: the uplink information flow includes complete power information X (s received by the distribution network dispatching center when the communication terminal is normally working; the power information received by the distribution network dispatching center in the power scenario s∈S when the uplink information flow x k is interrupted is The importance of the uplink information flow x k may be represented as:

[0030]

[0031] wherein, f(X (s) ) is the power dispatching instruction decided by the distribution network dispatching center when the power information is complete; is the power dispatching instruction decided by the distribution network dispatching center when the uplink information flow x k is interrupted;

[0032] The importance of the downlink information flow y k may be represented as:

[0033]

[0034] wherein, Y (s) is the load loss amount under the power scenario s∈S when each communication terminal is normally working; is the load loss amount under the power scenario s∈S when the downlink information flow y k is interrupted;

[0035] Information system loss caused by network attacks on the DG power control center is: ​​​​

[0036]

[0037] In the formula, c1 and c2 respectively represent DoS type and FDIA type network attacks; And Respectively, the information system loss when the unreliable DG control system suffers from c1, c2 type network attacks, the energy storage station control system suffers from c1, c2 type network attacks and the main power supply control system suffers from c2 type network attacks; Is the output of the attacked unreliable DG in the power scenario s∈S; Is the maximum charge and discharge power of the energy storage; Is the total load power in the power scenario s∈S.

[0038] As a preferred scheme of the power information physical risk assessment method described in the application, wherein: the risk assessment index for information system failure in island state includes establishing a probability model of island operation state, quantifying the influence of typical power scenario and its probability on information system failure in island operation, using Latin hypercube sampling technology to sample the distributed power DG output, generating a large number of sample matrix scenarios, and using synchronous back substitution reduction method to reduce the original scenario, and screening out a typical scenario set and its probability which can effectively describe the characteristics of random variables, and for the uncertainty of load power, the load points of load level on the annual load curve are merged into the same level through clustering technology, the distribution probability of each level is calculated, and the annual load probability model is constructed;

[0039] The typical scenarios of each random variable are arranged and combined in combination with the typical scenario distribution probability of load points and distributed power generation, to obtain discrete combination optimization scenarios as the basis for subsequent research, and the number of combined scenarios of all unreliable DGs and load levels in the island N s Is represented as:

[0040] N s = N wt *N pv *N load

[0041] Wherein, the probability of power scenario s occurring ρ s Is the probability product corresponding to the typical scenario, that is, the formula is:

[0042]

[0043] Wherein, Respectively, the probability of wind turbine, photovoltaic and load in scenarios s1, s2 and s3.

[0044] As a preferred scheme of the risk assessment method of the power distribution cyber-physical system, wherein: the risk of the overall quantitative information system failure to the safety and stability of the power distribution network includes the calculation of the expected failure probability of the information system, and the influence of the communication link failure on the power distribution cyber-physical system is quantified.

[0045] When the communication link between the communication terminal node k and the power distribution network dispatching center contains L communication paths, the lth communication path is composed of C information devices, and the deep search algorithm is used to find the information device c failure, the number of uplink communication paths UL(k) and the number of downlink communication paths DL(k) between the communication terminal node k and the power distribution network dispatching center, and the monitorable state M(k) of the communication terminal node k can be expressed as:

[0046]

[0047] Wherein, M(k) = 0 represents that the communication terminal node k is not measurable, and the uplink information flow x k is interrupted between the communication terminal node k and the power distribution network dispatching center.

[0048] The controllable state C(k) of the communication terminal node k can be expressed as:

[0049]

[0050] Wherein, C(k) = 0 represents that the communication terminal node k is not controllable, and the downlink information flow y k is interrupted between the communication terminal node k and the power distribution network dispatching center.

[0051] The N-1 failure traversal test is performed on the information system containing Nc information devices, and the probability P um (k) that the communication terminal node k is not measurable or the probability P uc (k) that the communication terminal node k is not controllable is respectively:

[0052]

[0053] Wherein, p c is the probability of failure of the information device c during the island duration, and the specific calculation is as follows:

[0054]

[0055] Wherein, T is the island duration, λ i is the annual failure rate of the information device i, and MTTP i is the average repair time of the information device i.

[0056] As a preferred scheme of the power distribution cyber-physical system risk assessment method, wherein: the risk assessment of the power distribution cyber-physical system comprises quantifying the cross-space cascading failure to the islanded condition CPDS by defining the information system risk, the physical system risk and the comprehensive risk of the information-physical system;

[0057] The risk source of the physical system is the random fluctuation of source load, and the physical system risk R P The expression is:

[0058]

[0059] In the formula, is the loss severity of the physical system; w s is the load loss amount in the power scenario s, is the total load power of the islanded condition in the power scenario s;

[0060] The risk R C of the information system is:

[0061]

[0062] In the formula, is the information failure event E j ; N e is the total number of failures contained in the information system failure set E; is the loss severity of the information system after E j ; I j is the information flow importance affected by the information failure event E j , and the calculation formula is the information flow coupling degree formula; is the information flow importance of the main power supply control center when the main power supply control center is subjected to the FDIA type network attack, and the specific calculation formula is the main power supply control center information system loss formula;

[0063] The comprehensive risk R CP of the information-physical system is the risk after superposition of the information system risk and the physical system risk, and the comprehensive risk R CP of the islanded condition CPDS is:

[0064]

[0065] In the formula, is the load loss amount of the islanded condition CPDS after E j ; is the loss severity of the islanded condition CPDS caused by E j when the source load fluctuation is considered.

[0066] In a second aspect, the embodiment of the present application provides a power distribution information physical risk assessment system, which comprises: a definition module, which establishes a probability model of island operation state, accurately quantifies the influence of information system failure on the power distribution physical system, and defines a comprehensive evaluation method of information system risk and physical system risk;

[0067] An analysis module, which introduces the concepts of coupling degree and importance by analyzing how the information system failure propagates across space to the physical system, evaluates the potential threat of information flow interruption or tampering to the safe operation of the power distribution network, and reveals the evolution mechanism of cross-space cascading failure;

[0068] An evaluation module, which comprehensively quantifies the risk of information system failure to the safety and stability of the power distribution network by combining the coupling degree and importance of the information flow, verifies the effectiveness under different attack scenarios through example simulation, and completes the power distribution information physical risk assessment.

[0069] In a third aspect, the embodiment of the present application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and wherein the processor implements any step of the power distribution information physical risk assessment method described above when executing the computer program.

[0070] In a fourth aspect, the embodiment of the present application provides a computer readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement any step of the power distribution information physical risk assessment method described above.

[0071] The present application has the following beneficial effects: by constructing an island operation state probability model based on multi-scene technology and combining the evaluation method of information flow coupling degree and importance, the present application can effectively quantify the cross-space propagation influence of information system failure on the physical system, accurately evaluate the comprehensive risk level of the information system, the physical system and the information physical system, significantly improve the accuracy and efficiency of risk assessment, not only can identify high-risk nodes, but also can quantify the propagation mechanism of cascading failure, provide reliable support for the safe operation and planning design of the power distribution information physical system, and thus improve the reliability and resilience of the power distribution network. BRIEF DESCRIPTION OF DRAWINGS

[0072] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor. Among them:

[0073] Figure 1 A specific flowchart of a power distribution information physical risk assessment method and system provided by an embodiment of the present application.

[0074] Figure 2 A physical system topology diagram of a power distribution cyber-physical risk assessment method and system according to an embodiment of the present application.

[0075] Figure 3 An information system topology diagram of a power distribution cyber-physical risk assessment method and system according to an embodiment of the present application. DETAILED DESCRIPTION

[0076] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the present application.

[0077] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details presented herein. In other instances, well-known methods have not been described in detail in order to avoid obscuring the present application. Therefore, the present application is not intended to be limited by the embodiments disclosed herein, which are well within the scope of the present application.

[0078] Secondly, the "one embodiment" or "embodiment" referred to herein can include specific features, structures or characteristics contained in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0079] The present application is described in detail in conjunction with the schematic diagram. In the detailed description of the embodiments of the present application, the cross-sectional view of the device structure is locally enlarged without the general proportion for the convenience of description, and the schematic diagram is only an example, which should not limit the scope of protection of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in actual manufacture.

[0080] Meanwhile, in the description of the present application, it should be noted that the terms "up, down, in and out" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first, second or third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0081] Unless otherwise defined, the terms "mounting, connecting, associating" in the present application should be interpreted broadly, for example: can be fixed connection, detachable connection or integral connection; can also be mechanical connection, electrical connection or direct connection, can also be indirectly connected through intermediate medium, can also be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0082] Embodiment 1

[0083] Reference Figures 1-3 For the first embodiment of the present application, the embodiment provides a power distribution information physical risk assessment method, comprising:

[0084] S1: constructing a risk assessment model based on the information physical interaction mechanism of island operation state, through the combination of multi-scene technology and source-load double uncertainty, a probability model of island operation state is established, the influence of information system failure on power distribution network physical system is accurately quantified, and a comprehensive evaluation method of information system risk and physical system risk is defined.

[0085] Wherein, the risk assessment model based on the information physical interaction mechanism of island operation state includes evaluating the power balance of the power distribution network in island state, the total power of the load carried by each node in the island state CPDS under the power scene s is The total output of unreliable DG is The equivalent load power is is:

[0086]

[0087] The difference between the equivalent load power in the island and the output limit of the main power source is is:

[0088]

[0089] Wherein, The minimum and maximum output of the main power source to maintain the frequency and voltage stability in the island are respectively, when When is negative, the energy storage needs to be discharged; when is positive, the energy storage needs to be charged;

[0090] The power margin δ of the island CPDS under the power scene s is (s) can be defined as:

[0091]

[0092] In the formula, is the maximum charging and discharging power of the energy storage;

[0093] When δ(s) =1, the main power supply in the island area can supply power to all loads alone, and the island state is recorded as δ1; δ (s) ∈[0,1), energy storage and main power supply need to cooperate to maintain power balance in the island, and the island power margin state is recorded as δ2; δ (s) When <0, part of the load needs to be removed to maintain the power balance in the island, and the island power margin state is recorded as δ3; δ (s0 When >1, it is necessary to limit the wind and solar power output, and the island power margin state is recorded as δ4.

[0094] Furthermore, a comprehensive assessment method for cyber and physical system risks is defined, including defining the coupling degree of information flows and quantifying the impact of information flow interruption or tampering on the cross-space propagation and cascading failures of physical systems. The specific steps are as follows:

[0095] By affecting the decision-making process of the distribution network dispatch center, it indirectly causes physical losses. k When an outage misleads the distribution network dispatch center into mistakenly issuing energy storage output adjustment or load shedding instructions, causing the system frequency to drop and triggering the low-frequency load reduction mechanism, this information fault propagates across space to the physical system;

[0096] When the upstream information flow x k When the interruption does not affect the power margin judgment of the distribution network dispatching center and all islands are in the δ1 state, this information failure only causes the information system to lose the measurability of node k, that is, the fault does not propagate across space to the physical system. According to the above analysis, the upstream information flow x k Coupling It can be expressed as:

[0097]

[0098] in, is the probability of power scenario s occurring; is the uplink information flow x under power scenario s k The coupling degree is calculated as follows:

[0099]

[0100] Among them, δ (s) is the power margin under power scenario s when the uplink information flow is complete; Upstream information flow x k Power margin under power scenario s when the power is lost;

[0101] Downstream information flow interruption also indirectly causes physical system loss by affecting the execution effect of the optimal load shedding instruction. k Degree of coupling It can be expressed as:

[0102]

[0103] in, is the information flow y under power scenario s k In the power scenario s, the load shedding combination decided by the distribution network dispatching center does not include the load carried by node k, and the distribution network dispatching center will not issue a command to IMD k, and there will be no y k , at this time the downstream information flow y k Coupling otherwise

[0104] Furthermore, DoS attacks do not directly cause physical losses, but indirectly cause physical losses by affecting the execution of instructions by DG. However, the main power control center does not communicate with the distribution network dispatch center, so it is subject to DoS network attacks. The main power control information flow c gas Coupling is 0.

[0105] After suffering a DoS-type network attack, the energy storage control information flow c bat Degree of coupling for:

[0106]

[0107] Where, is the energy storage control information flow c under power scenario s bat The coupling degree is calculated as follows:

[0108]

[0109] Unreliable DG control information flow c under DoS type network attack dg Coupling for:

[0110]

[0111] Where, c is the unreliable DG control information flow under power scenario s dg The coupling degree after a DoS-type network attack is calculated as follows:

[0112]

[0113] For FDIA-type network attacks, the attacker will actively release forged control information to maliciously manipulate the DG. However, if the power margin of the island is large at this time, no physical loss will be caused and the risk will be difficult to spread to the physical system.

[0114] The main power supply control center suffers from FDIA offline, loses voltage and frequency support in the island, all loads lose power, and the coupling degree of control information flow is 1; the main power supply control information flow c gas of the coupling degree

[0115] of the control information flow of the energy storage and the unreliable DG under the FDIA network attack can be represented as:

[0116]

[0117] wherein, and are the coupling degrees of the control information flow of the energy storage and the unreliable DG under the FDIA network attack in the power scenario s, and the specific calculation formula is as follows:

[0118]

[0119] wherein, is the power margin of the control information flow c k of the unreliable DG under the FDIA network attack in the power scenario s.

[0120] It can be seen that the greater the coupling degree of the information flow, the greater the probability of cross-space propagation of the information flow interruption or tampering to the physical system to trigger cross-information-physical cascading failure; when the coupling degree of the information flow is 0, the loss caused by the information failure is limited to the information system.

[0121] S1.1: The uplink information flow includes the complete power information X (s) received by the power distribution network dispatching center when the communication terminal is normally working; when the uplink information flow x k is interrupted, the power information received by the power distribution network dispatching center in the scenario s∈S is The importance of the uplink information flow x k can be represented as:

[0122]

[0123] wherein, f(X (s) ) is the power dispatching instruction decided by the power distribution network dispatching center when the power information is complete; is the power dispatching instruction decided by the power distribution network dispatching center when the uplink information flow x k is interrupted;

[0124] The importance of the downlink information flow y k can be represented as:

[0125]

[0126] Among them, Y (s) is the load loss amount under the power scenario s∈S when each communication terminal is working normally; is the downstream information flow y k The amount of load loss under the power scenario s∈S during the interruption;

[0127] Information system loss caused by cyber attack on DG power control center for:

[0128]

[0129] Where c1 and c2 represent DoS and FDIA network attacks respectively; and These are the information system losses when the unreliable DG control system is attacked by type C1 and C2 network attacks, the energy storage power station control system is attacked by type C1 and C2 network attacks, and the main power control system is attacked by type C2 network attacks; Provide power for the attacked unreliable DG in the power scenario s∈S; is the maximum charge and discharge power of energy storage; is the total load power in power scenario s∈S.

[0130] S2: Design a method to calculate the coupling degree and importance of information flows. By analyzing how information system failures propagate across space to physical systems, introduce the concepts of coupling degree and importance, evaluate the potential threats to the safe operation of distribution networks caused by information flow interruption or tampering, and reveal the evolution mechanism of cross-space cascading failures.

[0131] Among them, the uplink information flow includes the complete power information received by the distribution network dispatching center when the communication terminal is working normally, which is X (s) ; Uplink information flow x k The power information received by the distribution network dispatching center in the scenario s∈S during the outage is: Then the upstream information flow x k Importance It can be expressed as:

[0132]

[0133] Among them, f(X (s) ) is the power dispatch instruction decided by the distribution network dispatch center when the power information is complete; Upstream information flow x k The power dispatching instructions decided by the distribution network dispatching center during the outage;

[0134] Downstream information flow y k Importance It can be expressed as:

[0135]

[0136] where Y (s) is the load loss amount of each communication terminal under the power scenario s∈S when it is working normally; is the load loss amount of the downlink information flow y k under the power scenario s∈S when it is interrupted;

[0137] Information system loss caused by network attack on DG power control center is:

[0138]

[0139] where c1 and c2 represent the DoS type and FDIA type network attacks, respectively; and are the information system losses when the unreliable DG control system is attacked by c1 and c2 type network attacks, the energy storage power station control system is attacked by c1 and c2 type network attacks, and the main power supply control system is attacked by c2 type network attacks, respectively; is the output of the attacked unreliable DG in the power scenario s∈S; is the maximum charge and discharge power of the energy storage; is the total load power in the power scenario s∈S.

[0140] S3: The risk assessment index for information system failure in island state, which comprehensively quantifies the risk of information system failure to the security and stability of the distribution network by combining the coupling degree and importance of the information flow, and verifies the effectiveness under different attack scenarios through example simulation, and completes the risk assessment of the distribution information physics.

[0141] where the risk assessment index for information system failure in island state includes establishing a probability model of island operation state, quantifying the influence of information system failure on island operation through typical power scenarios and their probability description, using Latin hypercube sampling technology to sample the distributed power DG output, generating a large number of sample matrix scenarios, and using synchronous back substitution reduction method to reduce the original scenarios, and selecting the typical scenario set and its probability which can effectively describe the characteristics of random variables from them, and for the uncertainty of load power, the load points of load level on the annual load curve are merged into the same level through clustering technology, the distribution probability of each level is calculated, and the annual load probability model is constructed;

[0142] The typical scenarios of each random variable are arranged and combined in combination with the typical scenario distribution probability of the load point and the distributed power generation, to obtain discrete combined optimization scenarios as the basis for subsequent research, and the number of combined scenarios of all unreliable DGs and load levels in the island N s is represented as:

[0143] N s = N wt N pv N load

[0144] wherein the probability p s of the power scenario s occurring is the product of the probabilities of the corresponding typical scenarios, i.e. the formula is:

[0145]

[0146] wherein are the probabilities of the fan, photovoltaic, and load being in scenarios s1, s2, s3, respectively.

[0147] Further, the comprehensive quantification of the risk of information system failure on the security and stability of the power distribution network includes the calculation of the expected failure probability through the information system, and the quantification of the impact of communication link failure on the power distribution cyber-physical system.

[0148] When the communication link between the communication terminal node k and the power distribution network dispatching center contains L communication paths, the lth communication path is composed of C information devices, and the deep search algorithm is used to find the information device c failure, the number of uplink communication paths UL(k) and the number of downlink communication paths DL(k) between the communication terminal node k and the power distribution network dispatching center, and the monitorable state M(k) of the communication terminal node k can be represented as:

[0149]

[0150] wherein M(k) = 0 indicates that the communication terminal node k is not measurable, and the uplink information flow x k is interrupted between the communication terminal node k and the power distribution network dispatching center.

[0151] The controllable state C(k) of the communication terminal node k can be represented as:

[0152]

[0153] wherein C(k) = 0 indicates that the communication terminal node k is not controllable, and the downlink information flow y k is interrupted between the communication terminal node k and the power distribution network dispatching center.

[0154] The probability P um (k) that the communication terminal node k is not measurable or the probability P uc (k) that the communication terminal node k is not controllable is respectively:

[0155]

[0156] wherein p cThe probability of failure of the information equipment c for the duration of the island is calculated as follows:

[0157]

[0158] where T is the duration of the island, λ i is the annual failure rate of the information equipment i, MTTP i is the mean time to repair of the information equipment i.

[0159] Further, the risk assessment of the power distribution cyber-physical system includes quantifying the cross-space cascading failure to the islanded condition CPDS by defining the information system risk, the physical system risk and the integrated risk of the cyber-physical system;

[0160] The risk source of the physical system is the random fluctuation of source load, and the physical system risk R P is expressed as:

[0161]

[0162] where, is the loss of load severity of the physical system; w s is the amount of load loss in the power scenario s, is the total load power in the island in the power scenario s;

[0163] The risk R C of the information system is expressed as:

[0164]

[0165] where, is the probability of occurrence of the information failure event E j ; N e is the total number of failures contained in the information system failure set E; is the loss severity of the information system after suffering E j ; I j is the information flow importance affected by the information failure event E j , and the calculation formula is the information flow coupling degree formula; is the information flow importance of the main power control center when suffering the FDIA type network attack, and the specific calculation formula is the main power control center information system loss formula;

[0166] The integrated risk of the cyber-physical system is the risk after superimposing the information system risk and the physical system risk, and the integrated risk R CP of the islanded condition CPDS is:

[0167]

[0168] where, For power scenario s, the island state CPDS suffers from information failure event E j The amount of load loss after the event E; For the consideration of source load fluctuation, the information failure event E j The severity of the loss of load caused by the island state CPDS.

[0169] In a preferred embodiment, a power distribution information physical risk assessment system, the system includes a definition module, which establishes the probability model of island operation state, accurately quantifies the influence of information system failure on power grid physical system, defines the comprehensive evaluation method of information system risk and physical system risk;

[0170] Analysis module, by analyzing how the information system failure spreads across space to the physical system, introduces the concept of coupling degree and importance, evaluates the potential threat of information flow interruption or tampering to the safe operation of power grid, and reveals the evolution mechanism of cross-space cascading failure;

[0171] The evaluation module combines the coupling degree and importance of information flow, comprehensively quantifies the risk of information system failure to the safety and stability of power grid, verifies the effectiveness under different attack scenarios through example simulation, and completes the risk assessment of power distribution information physics.

[0172] The embodiment also provides a computer device suitable for the case of the multi-source power grid information fusion method based on the Internet of Things, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to realize the multi-source power grid information fusion method based on the Internet of Things as proposed in the above embodiment.

[0173] The computer device can be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control ability. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used for wired or wireless communication with external terminals. Wireless mode can be achieved through WIFI, operator network, NFC (near field communication) or other technologies. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, trackball or touchpad arranged on the shell of the computer device. It can also be an external keyboard, touchpad or mouse, etc.

[0174] In summary, by constructing an island operation state probability model based on a multi-scenario technology, and combining an information flow coupling degree and importance evaluation method, the cross-space propagation influence of information system failure on a physical system can be effectively quantified, the comprehensive risk level of an information system, a physical system and an information physical system can be accurately evaluated, the accuracy and efficiency of risk evaluation are significantly improved, not only high-risk nodes can be identified, but also the propagation mechanism of cascading failures can be quantified, reliable support is provided for safe operation and planning design of a power distribution information physical system, and therefore the reliability and resilience of a power distribution network are improved.

[0175] Embodiment 2

[0176] Reference Figures 1-3 For a second embodiment of the application, the embodiment provides a risk assessment method for a power distribution information physical system. In order to verify the beneficial effects of the application, a simulation experiment is performed for scientific demonstration.

[0177] In the application, a feeder 1 of a certain 62-node CPDS is taken as an example, a circuit breaker between node 2 and node 3 is a preset splitting point, and a gas turbine, an energy storage system, a wind turbine generator and a photovoltaic generator supply power to loads L3-L13 to form a planned island during island operation.

[0178] The distributed power supply parameters are shown in Table 1, the output fluctuation of the wind turbine and the photovoltaic generator is fitted by selecting wind speed data and light intensity data of a certain place for 8760h, the sampling scale is set to 500, the typical scene of the wind turbine, the photovoltaic generator and the load and the probability of occurrence are shown in Tables 2-4, the reliability parameters of the information equipment are shown in Table 5, and the expected information fault set and the probability are shown in Table 6 according to the shown example communication network topology and the information fault probability calculation method.

[0179] Table 1 Distributed power supply parameter table

[0180] Distributed generation Active power / kW Reactive power / kVar GAS 300 100 BAT 300 150 WT 150 40 PV 40 0

[0181] Table 2 Photovoltaic output scene and probability distribution

[0182] Photovoltaic power level Photovoltaic power peak percentage (%) Probability 1 0.0000 0.1814 2 13.4780 0.1785 3 35.4120 0.2044 4 60.7890 0.2568 5 100.0000 0.1789

[0183] Table 3 Wind power output scene and probability

[0184] Wind power level Wind power peak percentage (%) Probability 1 0.0000 0.1026 2 3.2550 0.1628 3 21.3200 0.0617 4 33.1950 0.0780 5 53.0100 0.1380 6 65.8750 0.1020 7 93.3700 0.1523 8 100.0000 0.2026

[0185] Table 4 Load level scene and probability

[0186] Load level Load power peak percentage Probability 1 0.3500 0.3857 2 0.7200 0.3797 3 1.0000 0.2346

[0187] Table 5 Information equipment fault parameters

[0188] Information equipment Annual failure rate Repair time / h Master station server 0.0013 times / a 8 Core switch 0.0500 times / a 12 Core router 0.0500 times / a 12 Area-level aggregation router 0.0500 times / a 12 Area-level aggregation switch 0.0500 times / a 12 Area-level switch 0.0500 times / a 12 Segmented switch FTU 0.0050 times / a 8 Circuit breaker DTU 0.0020 times / a 4 Unreliable DG IED 3 times / a 20 Energy storage IED 5 times / a 10 Gas turbine IED 5 times / a 10 Optical fiber 0.0040 times / (km·a) 24 OLT 0.0310 times / a 12 POS 0.0010 times / a 6

[0189] Table 6 Information system expected fault set

[0190]

[0191] It can be seen that the greater the coupling degree of the information flow, the greater the probability of cross-space propagation of the information flow interruption or tampering to the physical system to trigger a cross-information-physical chain failure; when the coupling degree of the information flow is 0, the loss caused by the information failure is limited to the information system.

[0192] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A risk assessment method for power distribution cyber-physics, characterized by: include, A risk assessment model for the islanded operating state based on the cyber-physical interaction mechanism was constructed. By combining multi-scenario technology with source-load dual uncertainty, a probabilistic model for the islanded operating state was established. This model accurately quantifies the impact of cyber system failures on the physical system of the distribution network and defines a comprehensive assessment method for cyber and physical system risks. Design a method to calculate the coupling and importance of information flows. By analyzing how information system failures propagate across space to physical systems, introduce the concepts of coupling and importance, assess the potential threats to the safe operation of distribution networks caused by information flow interruption or tampering, and reveal the evolution mechanism of cross-space cascading failures. Based on the risk assessment indicators of information system failures in an isolated state, combined with the coupling degree and importance of information flow, the risks posed by information system failures to the security and stability of the distribution network are comprehensively quantified. The effectiveness in different attack scenarios is verified through case simulation to complete the risk assessment of distribution network information physics.

2. The power distribution cyber-physical risk assessment method according to claim 1, wherein: The risk assessment model for island operation state based on cyber-physical interaction mechanism includes evaluating the power balance of the distribution network under the island state. Under power scenario s, the total load power of each node in the island state CPDS is The total output of unreliable DG is The equivalent load power for: The difference between the equivalent load power in the island and the output limit of the main power supply is for: in, They are the minimum and maximum outputs of the main power supply to maintain frequency and voltage stability in the island. When it is negative, energy storage and discharge are required; when When it is positive, energy storage and charging are required; Under power scenario s, the power margin δ in the island CPDS (s) It can be defined as: Where, The maximum charging and generating power for energy storage; When δ (s) =1, the main power supply in the island area can supply power to all loads alone, and the island state is recorded as δ1; δ (s) ∈[0,1), energy storage and main power supply need to cooperate to maintain power balance in the island, and the island power margin state is recorded as δ2; δ (s) When <0, part of the load needs to be removed to maintain the power balance in the island, and the island power margin state is recorded as δ3; δ (s) When >1, it is necessary to limit the wind and solar power output, and the island power margin state is recorded as δ4.

3. The power distribution cyber-physical risk assessment method according to claim 2, wherein: The comprehensive assessment method for defining cyber system risks and physical system risks includes defining the coupling degree of information flows and quantifying the impact of information flow interruption or tampering on the cross-spatial propagation and cascading failures of physical systems. The specific steps are as follows: By affecting the decision-making process of the distribution network dispatch center, it indirectly causes physical losses. k When an outage misleads the distribution network dispatch center into mistakenly issuing energy storage output adjustment or load shedding instructions, causing the system frequency to drop and triggering the low-frequency load reduction mechanism, this information fault propagates across space to the physical system; When the upstream information flow x k When the interruption does not affect the power margin judgment of the distribution network dispatching center and all islands are in the δ1 state, this information failure only causes the information system to lose the measurability of node k, that is, the fault does not propagate across space to the physical system. According to the above analysis, the upstream information flow x k Coupling It can be expressed as: in, is the probability of power scenario s occurring; is the uplink information flow x under power scenario s k The coupling degree is calculated as follows: Among them, δ (s) is the power margin under power scenario s when the uplink information flow is complete; Upstream information flow x k Power margin under power scenario s when the power is lost; Downstream information flow interruption also indirectly causes physical system loss by affecting the execution effect of the optimal load shedding instruction. k Coupling It can be expressed as: in, is the information flow y under power scenario s k In the power scenario s, the load shedding combination decided by the distribution network dispatching center does not include the load carried by node k, and the distribution network dispatching center will not issue a command to IMD k, and there will be no y k , at this time the downstream information flow y k Coupling otherwise 4. The power distribution cyber-physical risk assessment method according to claim 3, wherein: The uplink information flow includes the complete power information received by the distribution network dispatching center when the communication terminal is working normally, which is X (s) ; Uplink information flow x k The power information received by the distribution network dispatching center in the scenario s∈S during the outage is: Then the upstream information flow x k Importance It can be expressed as: Among them, f(X (s) ) is the power dispatch instruction decided by the distribution network dispatch center when the power information is complete; Upstream information flow x k The power dispatching instructions decided by the distribution network dispatching center during the outage; Downstream information flow y k Importance It can be expressed as: Among them, Y (s) is the load loss amount under the power scenario s∈S when each communication terminal is working normally; is the downstream information flow y k The amount of load loss under the power scenario s∈S during the interruption; Information system loss caused by cyber attack on DG power control center for: Where c1 and c2 represent DoS and FDIA network attacks respectively; and These are the information system losses when the unreliable DG control system is attacked by type C1 and C2 network attacks, the energy storage power station control system is attacked by type C1 and C2 network attacks, and the main power control system is attacked by type C2 network attacks; Provide power for the attacked unreliable DG in the power scenario s∈S; is the maximum charge and discharge power of energy storage; is the total load power in power scenario s∈S.

5. The power distribution cyber-physical risk assessment method according to claim 4, wherein: The risk assessment indicators for information system failures in an island state include establishing a probability model for the island operation state, describing the impact of information system failures on the island operation by quantifying typical power scenarios and their probabilities, sampling the output of distributed power sources (DGs) using Latin hypercube sampling technology to generate a large number of sample matrix scenarios, and using synchronous back-substitution reduction to reduce the original scenarios to screen out a set of typical scenarios and their probabilities that can effectively describe the characteristics of random variables. For the uncertainty of load power, clustering technology is used to merge load points of load levels on the annual load curve into the same level, calculate the distribution probability of each level, and construct an annual load probability model. Combining the typical scenario distribution probability of load points and distributed generation, the typical scenarios of each random variable are arranged and combined to obtain the discrete combination optimization scenario, which serves as the basis for subsequent research. The number of combination scenarios N of all unreliable DGs and load level levels in the island is s Expressed as: N s =N wt *N pv *N load Among them, the probability of power scenario s occurring ρ s is the probability product corresponding to the typical scenario, that is, the formula is: in, are the probabilities of wind turbine, photovoltaic and load being in scenarios s1, s2 and s3 respectively.

6. The power distribution cyber-physical risk assessment method according to claim 5, wherein: The comprehensive quantification of the risks of information system failures on the security and stability of the distribution network includes quantifying the impact of communication link failures on the distribution network cyber-physical system by calculating the expected failure probability of the information system; When the communication link between the communication terminal node k and the distribution network dispatching center contains L communication paths, the lth communication path consists of C information devices, and the deep search algorithm is used to find the fault of information device c, the number of uplink communication paths UL(k) and the number of downlink communication paths DL(k) between the communication terminal node k and the distribution network dispatching center, the monitorable state M(k) of the communication terminal node k can be expressed as: Among them, when M(k)=0, it means that the communication terminal node k is unmeasurable, and the uplink information flow x between the communication terminal node k and the distribution network dispatching center is k interruption; The controllable state C(k) of the communication terminal node k can be expressed as: Among them, C9k) = 0 means that the communication terminal node k is uncontrollable, and the downlink information flow y between the communication terminal node k and the distribution network dispatching center is k interruption; Perform N-1 fault traversal test on an information system containing Nc information devices. The probability P that the communication terminal node k is untestable is um (k) or the probability of being uncontrollable P uc (k) are: Where p c is the probability of failure of information device c during the island duration, which is calculated as follows: Where T is the island duration, λ i is the annual failure rate of information equipment i, MTTP i is the average repair time of information device i.

7. The power distribution cyber-physical risk assessment method according to claim 6, wherein: The completion of the risk assessment of power distribution cyber-physical system includes quantifying the cross-space cascading failures to island state CPDS by defining cyber system risk, physical system risk and comprehensive risk of cyber-physical system; The risk source of the physical system is the random fluctuation of the source load. The risk of the physical system R is defined as P The expression is: Where, is the load loss severity of the physical system; w s is the load loss in the power s scenario, is the total load power in the island in power scenario s; Information system risk C The expression is: Where: Information failure event E j Probability of occurrence; N e The total number of faults included in the expected fault set E for the information system; To suffer E j The severity of the loss of the post-information system; j For information failure event E j The importance of the affected information flow is calculated using the information flow coupling formula; The importance of information flow when the main power control center suffers from FDIA type network attack. The specific calculation formula is the information system loss formula of the main power control center; The comprehensive risk of the cyber-physical system is the risk after the superposition of the cyber-system risk and the physical system risk. The comprehensive risk of the isolated CPDS is defined as R CP for: Where, The CPDS in the island state suffers from information failure event E under power scenario s. j The amount of load loss after To take into account the source load fluctuation, the information failure event E j The severity of load loss caused to the islanded CPDS.

8. A power distribution cyber-physical system risk assessment system, based on the power distribution cyber-physical system risk assessment method according to any one of claims 1 to 7, characterized in that: include, The definition module establishes a probabilistic model of island operation status, accurately quantifies the impact of information system failures on the physical system of the distribution network, and defines a comprehensive assessment method for information system risks and physical system risks; The analysis module analyzes how information system failures propagate across space to physical systems, introduces the concepts of coupling and importance, assesses the potential threats to the safe operation of the distribution network caused by information flow interruption or tampering, and reveals the evolution mechanism of cross-space cascading failures; The assessment module combines the coupling degree and importance of information flows to comprehensively quantify the risks posed by information system failures to the security and stability of the distribution network. It verifies its effectiveness in different attack scenarios through case simulation and completes the risk assessment of distribution network information physics.

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 power distribution cyber-physical risk assessment 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 power distribution cyber-physical risk assessment method according to any one of claims 1 to 7 are implemented.

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