Research On Load Frequency Control Of Multi-area Power Systems Under Denial-of-service Attacks

The main purpose of load frequency control in power systems is to track load changes in the system and thus ensure that frequency deviations are reduced to within specified limits,which is extremely important for both the design and operation of power systems.As modern smart grids become larger and more interconnected,and due to the open nature of communication networks,network attacks can pose a huge threat to the security of power systems.Denial of Service(DoS)attacks interrupt normal communication for a period of time by interfering with transmission channels or blocking transmission nodes,thus reducing the performance of the control and causing a great impact on people’s daily life.Therefore,the following research has been done for the load frequency control of multi-area power systems under denial-of-service attacks:Firstly,this paper analyses the problems of multi-area power systems under DoS attacks,and elaborates and discusses the current status of research on multi-area load frequency control,and determines the use of sub-area control methods through analysis;then,it explains the attack principles of DoS attacks,attack strategies,the impact on power systems and how to defend against them,and separately models the attack methods of energy-limited DoS attacks and multi- area interconnected power systems are modelled;then,the control methods for interconnected load frequency control systems are studied in detail,which include the following two aspects:(1)Sliding Mode Control(SMC)is a special type of variable structure control strat-egy that enables a closed-loop system to have a predetermined performance despite re-ceiving perturbations or uncertainties,and therefore can effectively regulate the power system.Accordingly,this paper proposes an attack strength-based adaptive integral slid-ing mode control algorithm,which designs the integral sliding mode gain according to the estimated value of the DoS attack strength.The adaptive nature of the sliding mode gain makes the power system more resilient to uncertainty disturbances and network at-tacks,thus effectively mitigating the disturbances caused by external disturbances as well as DoS attacks.(2)The Distributed Model Predictive Control(DMPC)method is considered to cope with the multi-area power system load frequency control problem under DoS attacks.In this paper,the MPC optimization problem is introduced through a modified initial feasible set to satisfy the control input and state constraints.Using the μ-step positive invariant set,the maximum allowable DoS attack duration of the closed-loop system is obtained.It is also shown theoretically that under a DoS attack,the state trajectory starting from a given set will enter that set after μ steps.And the exponential stability of the power system in the presence of DoS attacks under distributed model predictive control is demonstrated by rational design of the MPC parameters.Finally,the two control algorithms are simulated separately,and the simulation re-sults show that both control methods adopted have good control effects and strong robust-ness in the load frequency control of power systems under DoS attacks.