| Microgrid(MG)is a complete small power generation and distribution system,aiming to fully exploit the value and benefits of distributed power generation and efficiently utilize clean and renewable energy.It is of great significance for achieving the national strategic goals "carbon peak" and "carbon neutral".The purpose of microgrid technology is to effectively improve the quality and reliability of power supply through the control of distributed power sources.In this thesis,we consider a microgrid operating in an island mode,which means that the microgrid is not connected to the main grid.The island microgrid commonly adopts a hierarchical control strategy,i.e.,the primary control and secondary control.The former that is achieved by the droop control is mainly to maintain the voltage and frequency of the microgrid initially stable near the rated value,and to distribute power proportionally.The latter that is achieved via the distributed control,aiming to eliminate the bias between voltage and frequency in the primary control,and to achieve accurate allocation of active power.When implementing the secondary control,communication networks are required to transmit necessary system data.Unfortunately,information to be transmitted over communication network is vulnerable to FDI(False Data Injection)attacks,which could result in the deviations from its normal operating state and thus seriously reduce power supply quality and reliability.This thesis considers the distributed secondary control problem of island microgrid systems under FDI attacks,and adopts resilient control strategies to minimize the adverse effects of FDI attacks to ensure that the island microgrid system maintains the desired control performance.The research results of this thesis ensure that the island microgrid system can still operate stably even if the presence of the FDI attack.The proposed algorithm has important theoretical value and practical significance in engineering.This thesis focuses on the following research content:Firstly,this thesis systematically presents the primary control and droop control strategies of the island microgrid system.Then,the inverter based DG control method is formulated,and the nonlinear mathematical model of microgrid system is given.Subsequently,three kinds of cyber-attacks are modeled.Finally,a simulation example is provided to verify that the effectiveness of the primary control,i.e.,the microgrid initially achieves system voltage,frequency stability,and active power distribution after entering island mode.Secondly,this thesis designs a distributed second voltage resilient control algorithm for island microgrid based on auxiliary system.Specific FDI attack models are given for different attack locations and the adverse effects of the attacks are analyzed.Next,an auxiliary system is constructed to design a new distributed secondary voltage resilient controller to effectively suppress the impact of FDI attacks on the island microgrid system.The proposed distributed secondary voltage control scheme has a distributed control structure,which can effectively reduce the dependence on the central controller,reduce the requirements for communication networks,and further improve system reliability.Finally,simulation results are provided to show the effectiveness of the algorithm.Finally,this thesis proposes a compensation controller-based secondary frequency resilient control method for an island microgrid.A compensation controller that has a communication association with the original controller is constructed to compensate the attacked system.Via the Lyapunov stability,it is proved that the compensation controller can compensate for the deviations caused by the FDI attacks,thereby ensuring that the island microgrid system is effectively resistant to attacks.The effectiveness of the compensation controller and the robustness of the system are further demonstrated through MATLAB/Simulink simulation experiments. |
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