Resilience Assessment And Optimization Of Power Networks Under Seismic Disasters

The continuous and stable operations of power networks have received considerable concerns from both academia and industry.However,power networks are exposed to a high risk of seismic,which can not only cause large outages in power systems but also lead to serious economic damage.Therefore,the ability of power networks to resist seismic and quickly recover after seismic plays a crucial role in the safety and stability of power systems.The resilience has become an emergency research topic in the field of power system.Due to the uncertainties associated with the magnitude and occurrence time of seismic,it is difficult to precisely characterize the system performance of power networks under seismic.Additionally,infrastructure networks,such as power distribution networks and water distribution networks,are typically interdependent.The interdependencies between infrastructure networks can improve operational efficiency and increase seismic vulnerability,which cannot be ignored in resilience assessment and optimization.To improve the defense and recovery capabilities of power networks against uncertain seismic,the dissertation takes ultra-high voltage converter stations and interdependent urban power networks as the research objects and devotes to conducting seismic resilience assessment and optimization.The research contributions are summarized as follows:(1)Development of a comprehensive resilience assessment method for ultra-high voltage converter stations under seismic considering the defense and recovery capabilities of ultra-high voltage converter stations.The mainshock-aftershock sequence simulation method is developed.The composition structure,operation mode,and seismic vulnerability analysis model of ultra-high voltage converter stations are described in detail.By analyzing the important attributes of ultra-high voltage converter stations seismic resilience,a simulation-based seismic resilience assessment method for ultra-high voltage converter stations is proposed.The results from a practical example show that the seismic resilience of the ultra-high voltage converter station is at a low level,and the devices such as transformers,smoothing reactors,and earthing switches significantly impact the seismic resilience of the ultra-high voltage converter station.(2)Development of a resilience optimization method for ultra-high voltage converter stations under mainshock-aftershock sequences.A three-level optimization framework is developed to maximize the seismic resilience of ultra-high voltage converter stations.The device hardening strategy is utilized to reduce the seismic vulnerability of ultra-high voltage converter stations,and the spare parts strategy is utilized to improve recovery efficiency.The uncertainties associated with mainshock-aftershock sequences are formulated as a two-stage stochastic programming model,and a linearization as well as a reformulation technique are customized to simplify the model.A sample average approximation algorithm and a progressive hedging algorithm are proposed to solve the model efficiently.The illustrative example shows that the two proposed preparation strategies can significantly improve the seismic resilience of the ultra-high voltage converter station.The device hardening strategy tends to harden a circuit to ensure the lowest performance of the ultra-high voltage converter station,and spare parts are needed for the converter transformer,one of the main components in ultra-high voltage converter stations.(3)Development of a seismic resilience optimization method for urban power networks considering interdependencies between infrastructure networks and uncertainties of seismic damage from a preparedness perspective.The interdependency between infrastructure networks is characterized by a two-way physical interdependency,that is,the state of one infrastructure network is dependent on that of another infrastructure network,and vice versa.Furthermore,the multi-state characteristics of infrastructure networks are considered and accommodated to the studied physical interdependency.A tailored two-stage stochastic programming framework,which is able to deal with the uncertainties associated with seismic damage,is put forth to facilitate an effective resilience enhancement strategy under limited budget.The illustrative example shows that the proposed method can maintain a high seismic resilience of interdependent infrastructure networks in coping with uncertain seismic damage.Meanwhile,the seismic resilience of urban power networks is determined by factors such as seismic events,interdependencies,and network structures.