Maximum Delay Calculation Of Real Time Data Encryption For Smart Grid Based On Information Flow Model And Time-delay Power Grid Stability

With the development of computer technology and network communication technology,great changes have taken place in the industrial control system.Networked control system(NCS)came into being,its main sign is to introduce the computer network into the control system,so that a large number of sensors,actuators,controllers and other major functional components can be connected through the network,the related signals and data are transmitted and exchanged through the communication network,avoiding the laying of point-to-point private lines and increasing the flexibility and reliability of the system.Malicious tampering attacks on critical data can cause system out of control.Network-oriented performance and data-oriented collaborative attacks will likely lead to a complete system crash.Using digital authentication or data encryption and decryption technology will extend data transmission and control Real-time;coupled with the network communication has inevitable delay in transmission,packet loss and other issues,Networked control is difficult to be widely applied in industrial control field.Obviously,the smart grid has the material conditions of networked control,but some of the most basic applied theoretical research is still inadequate.This paper tries to study some key problems.First,the status of the smart grid information flow model for predicting the information flow distribution and the delay of important data transmission under various scenarios is particularly important,it can be used as the basis for the design of smart grid communication system,and it also can be compared with the switch port traffic detection,so that the abnormal flow and even the virus attack can be predicted or warned;because the data encryption and decryption also takes time,it can be used to determine whether the increase in data transmission delay plus data encryption and decryption is feasible.In contrast to the three most popular information flow models in academia at home and abroad,this paper takes substation communication system as an example,Based on the network Calculus and transmission Path based Junction flow method(CPJ),the matrix definition and algorithm of smart grid information flow distribution are derived.A clear and detailed quantitative analysis and calculation process is formed,and verified by actual cases.Second,the essence of NCS is a time-delay control system.For the stability of the time-delay control system,the academic circle is also hard to explore.To obtain the result of the stability of the time-delay control system is also difficult to the academic circle.For smart grid,the most harmful information attack is to make the power grid lose its stability,Therefore,it is very important to study the smart grid information security measures through the grid stability calculation,especially considering the delay of data encryption and decryption with the integrated delay of data transmission and processing.The solution method based on the stability of time delay control system,we take the single machine Infinite system as a study,in this paper,it is linear time delay,then the small signal stability analysis is carried out and establish the state equation for it,and then we rely on the established linear time delay stability calculation model for iterative calculation and design the corresponding control gain K,finally,the maximum allowable delay parameters are obtained.It provides a quantitative basis for the time delay that need to be considered when designing the data encryption algorithm.