Cyber Attack Intrusion Detection Research For Smart Grids Based On Graph Theory Analysis

With the rapid development of embedded technology,sensor technology and network control,the smart grid system,which integrates computing,computer network and physical control,has attracted more and more attention.The system structure is complex,the large number of structural uncertainties and equipment unreliability may lead to instability of the system.In order to ensure the safe and reliable operation of the power system,in this paper,based on graph theory analysis,we study the detectability of the interference of the grid system.Through the design of attack detection and judgment algorithm,this paper analyzes fundamentally the structural vulnerability caused by the cyber attack,and improves the security and reliability of the power system.Firstly,aiming at the hidden structural vulnerability of the power system,this paper puts forward the strategy to eliminate the attack.Based on the structural digraph of power grid,this paper proposes a series of properties,and presents an algorithm to obtain the output position of the attack detection to ensure the left reversibility and observability of the power system.In addition,this paper also proposes a structural vulnerability judgment algorithm to determine whether there is a structural vulnerability in the power system which has set the inputs and outputs,that is whether the system can detect attacks.Secondly,taking into account the vulnerability of the undetectable attack in the grid system,we propose a distributed attack detection and location algorithm on the basis of solving the vulnerability.First define the concept of mixed cycle,and design digraph decomposition algorithm.Furthermore,the algorithm of distributed detection and location is proposed to detect and locate the possible attacks in the power grid,and the undetectable attacks can be avoided.The effectiveness and feasibility of the algorithm are verified by an application example.At last,for the existence of a variety of attacks in the grid system,a dynamic and static detection method is designed to achieve the overall observation of the power grid.The method of setting the power measurement point is used to realize the static detection,which is to detect the bus angle and voltage in the grid system by adding the detection points between the grid buses.The phasor measurement device is used to observe the states of the generator to realize dynamic detection.Thus,the full observation of the power grid is realized.The simulation results show that some attacks can be effectively detected,and the security and reliability of the power system can be improved.