Research On Resilience Enhancement Methods For Distribution Systems With Multi-resource Coordination Under Extreme Events

With the increasing frequency of the blackouts caused by extreme events,it is of great strategic significance to enhance the resilience of the power system to effectively address the challenges brought by extreme events.The process of the distribution system to resist to,respond to,and recover from extreme events is extremely complex.The multiple stages,including the planning stage,the prevention stage,and the response and recovery stage,are complexly coupled,and the multiple resources,including power supply resources,switch resources,monitoring resources,human resources are complexly utilized.Therefore,to improve the abilities of the distribution system to resist to,respond to and recover from extreme events,it is necessary to comprehensively consider the multi-stage coupling process of the distribution system and the multi-resource coordination at different stages.To this end,corresponding research work has been carried out in this thesis.Details are shown as follows:1)A resilience-oriented fault location,fault isolation,and service restoration method for the distribution system based on multi-resource coordination is proposed.The models of the functional modules are formulated for the faulted-section location process,the line patrolling process,and the fault isolation and service restoration process.Based on the coupling relationships between the modules,flexible response and recovery strategies can be formed for different scenarios.Through the faultedsection location model based on the indications of fault indicators(FIs),the faulted sections can be determined,and the faulted-section location model also applies to distribution systems with multiple distributed generations,multiple faults,flexible network topology,or local loops;through the line patrolling model considering the optimal dispatching of crews,the faulted sections can be quickly patrolled by crews;and through the fault isolation and service restoration model considering the coordinated operation of remote-controlled switches(RCSs)and manual switches(MSs),the optimal dispatching of crews,the coordination of MS and RCS,and the coordination of fault isolation and service restoration can all be realized.Case studies show that,based on the proposed method,the response and recovery abilities of the distribution systems after extreme events can be efficiently improved.2)A resilience enhancement method considering the coordination of the prevention stage and the response and recovery stage is proposed.The model of the multi-stage response and recovery process,which includes the degradation stage,the fault isolation stage,and the service restoration stage,is formulated.Based on the coordination of the prevention stage and the multi-stage response and recovery process,the pre-event proactive islanding based on RCSs and MSs are considered to ensure the survivability of critical loads,and the post-event fast reponese based on RCSs are considered to isolating the faults and restoring the loads in non-faulted zones.Case studies show that,the continuous power supply and fast restoration for critical loads,as well as the resilience level of the distribution system during the degradation stage,the fault isolation stage,and the service restoration stage,can be ensured.3)A resource allocation method to improve the response and recovery abilities of distribution systems under extreme events is proposed.To cope with the complex scenarios with multiple distributed generations,multiple faults,flexible network topology,the fictitious-flow based FI allocation method is proposed.In the FI allocation method,the flowing of fault currents and the evaluation of FI allocation schemes are simulated based on the fictitious-flow model which formulates the relationships between the locations of power supplies and faults,the network topology,and the distribution of fault currents.The RCS allocation method is proposed with consideration of the network reconfiguration of distribution systems in the prevention stage and recovery stage.Through the pre-event network reconfiguration based on RCSs and MSs and the post-event network reconfiguration based on RCSs,the flexible topology of the distribution system can be considered,and the RCS can be efficiently allocated.Case studies show that the proposed FI allocation method and RCS allocation method can effectively realize the optimal allocation of resources and improve the response and recovery abilities of distribution systems.