Security Of Distribution Network Cyber-Physical System With Distributed Cooperative Control Mode

Due to increasing concern about the environment and skyrocketing cost for fossil fuels,low carbon economy,energy diversity and sustainable development have been the focus of power industry.On this background,renewable energy distributed generation has gradually been an effective important supplement form of conventional centralized generation.Meanwhile,Distributed cooperative control mode is an effective approach to overcome the problem of integrating multiple and strongly random distributed generators(DGs)into power systems,which should be supported by the distribution network cyber-physical system(CPS).The distribution network CPS includes the ability of perception and control to physical devices,and could promote the efficient utilization of bidirectional information flow.However,due to the integration between cyber and physical layers,cyber attacks could threat the safe and stable operation of power system through invading the cyber system,which poses serious challenges to the future power system.Given these backgrounds,this dissertation mainly focus on distribution network CPS with a high penetration of renewable energy generators,and aims to analyze and establish distributed cooperative control system for future distribution network CPS,which enables high penetration renewable energy generators to participate in the grid as well as to guarantee the security,reliability,efficiency and economy in the operation of future power system.The detailed contents of the dissertation are as follows:Firstly,with respect to the research of the control architecture with high penetration renewable energy generators,the dissertation designs a cooperative control architecture of distribution network CPS,which prepares the conditions of the advanced control strategy that enables the power in the distribution network to be overall managed.A framework of the distribution network CPS with the connection of active distribution network and microgrid is firstly designed.On that basis,with the characteristics of multi-dimension and distributed coupling in the distribution network CPS,a cooperative control architecture is proposed,which includes a distributed physical architecture with sensor,computation and control technologies and controlled objects,and a hierarchy abstract architecture with the internal unity and external interconnectivity.Secondly,with respect to the research of robust control method of high penetration renewable energy generators in distribution network CPS,the dissertation proposes a robust distributed economic dispatch strategy of virtual power plant under cyber-attacks,which aims to mitigate the problem that schemes of network control system in distributed economic dispatch are susceptible to cyber-attacks.The proposed strategy not only could solve the economic dispatch problem in power systems in distributed manner,but also robust to any type of cyber-attacks and communication failure.With properly design of communication network,each DG can monitor the behavior of its in-neighbors according to its performance and the network connectivity information,and gradually isolate the misbehaving DGs(when present)from the network so that the affect of malicious information can be eliminated,and the remaining well-behaving DGs could still accomplish the economic dispatch.The effectiveness of the proposed strategy is illustrated through simulations on the IEEE 123-bus test system.Thirdly,with respect to the research of the performance assessment of distribution network CPS with distributed cooperative control mode,the dissertation proposes a dynamic attack-defense game model based security assessment of distributed cooperative control against distribution network CPS,the objective of which is to quantify the performance of distribution network CPS with cooperative control strategy from the side of security.The proposed method effectively integrate cooperative control strategy of DGs and the characteristic of cyber-attack and defense.With properly design of dynamic Stackelberg game and the risk assessment architecture of general CPS,the risk assessment results for distribution network CPS could be acquired.The effectiveness of the proposed method is verified through simulations involving the IEEE 34-bus test feeder.