Research On High-Risk Tracing Screening And Risk Mitigation Strategy Of Cyber-Physical Power System

With the step-by-step development of UHVDC construction in China,great changes have taken place in the structure and characteristics of power grids.It is UHV AC/DC technology that makes the power grid stronger,but the characteristics of strong,direct and weak AC also bring many problems to the security and stability of the power grid.Futhermore,the interconnection between the information layer and the physical layer of AC/DC hybrid power grid is deepening day by day.When the information layer or the physical layer in the Cyber-Physical power system is attacked,cascading failures are prone to occur.After multi-level cascading failures,the whole network will be endangered,which may lead to the collapse of the whole network or major blackouts On the other hand,the access of new energy and power electronics technology has led to a serious decline in the regulation and energy-saving capacity of the power grid,and the stability of the receiving end power grid has become more prominent than before Among them,frequency stability and voltage stability are particularly important Thus,it is important to establish the system protection framework based on AC/DC hybrid power grid.In addition,the system protection frequency control model and the system protection voltage control model is also very important.This paper focus on the deterioration of system protection frequency control and system protection voltage control performance under the scenario of static node failure and dynamic information transmission failure,and so as to propose the corresponding risk mitigation strategies.Firstly,the frequency control model of system protection will be established based on the protection framework of AC/DC hybrid system.This paper will do some research on the deterioration of system protection frequency control performance under the scenario of node failure and information transmission failure.On the basis of the output of considering DC coordinated control,cutting pump control,excision interruptible load control and conventional units,then do some risk simulation on IEEE-39 node system and defined the risk index and risk level of the system protection frequency control.By comparing the risk index and risk level of each node,the large-capacity generator nodes,topological connection nodes,and heavy-duty nodes are selected as important nodes,Secondly,the system protection voltage control model is established,and this paper studies the deterioration of system protection voltage control performance under the scenario of static node failure and dynamic information transmission failure.On the basis of the output of considering cut-off interruptible load control,reactive power control of converter station,reactive power compensation and the output variation of conventional units,then do some risk simulation on IEEE-39 node system and defined the risk index and risk level of the system protection voltage control.By comparing the risk index and risk level of each node,there are some nodes selected as important nodesFinally,this paper proposes some mitigation strategies,such as DC coordinated control,cutting pump control,excision interruptible load control,reactive power control of converter station,reactive power compensation and important nodes protection,to reduce the risk of Cyber-Physical Power System(CPPS).It is verified that the protection of important nodes can effectively reduce the impact of node failure and information transmission failure on system protection frequency control performance It is also proved that adding Reactive Power Compensation(RPC)can effectively reduce the impact of node failure and information transmission failure on system protection voltage control performance.The conclusion proves the effectiveness of the risk grading and high-risk screening of Cyber-Physical Power System and the corresponding mitigation strategies for reducing the system risk.