Research On The Strategy To Enhance Resilience Of The Active Distribution Network Considering Flexible Resource Scheduling

In the past decades,the power system has been experiencing extreme events such as extreme natural disasters and man-made attacks.In particular,the distribution network is vulnerable to the impact of extreme events and the destruction of power infrastructure,resulting in huge economic losses,due to the fragile infrastructure such as lines and insufficient system reserve.In order to resist the impact of "low probability and high risk" extreme events on the distribution network,it is particularly important to enhance the " Resilience " of the power grid.The resilience enhancement strategy of Active Distribution Network(ADN)has always been an important research field of power system planning and operation.By combining the latest breakthrough technologies such as microgrid and smart grid,the resilience ofA DN is enhanced to reduce the impact of extreme events.The resilience enhancement strategy of ADN requires that ADN should have the ability to prevent,adapt and recover in the three stages before,during and after the occurrence of extreme events.At the current stage,the research on the resilience enhancement strategy of ADN is still at the initial stage,with insufficient depth and breadth.The main problems include:1)In the pre-disaster strategy stage,the active defense strategy for extreme events is not fully considered,and a complete pre-disaster integrated emergency response system is not established;2)In the disaster strategy stage,the utilization of various distributed energy sources is insufficient,and the flexibility of ADN is not fully utilized;3)In the post-disaster strategy stage,there is a lack of reasonable modeling for equipment maintenance and personnel scheduling,and there is a lack of coordination between distribution network sequence recovery and resource scheduling.In view of the above problems,the main contents and research of this paper are as follows:(1)An ADN active defense strategy considering gas and heat resource scheduling is proposed,which can improve the emergency response mechanism for extreme events and improve the resilience of ADN.The strategy first establishes a comprehensive pre-disaster emergency system,including disaster early warning,natural gas network outage,grid island mode operation and extreme events,and other landmark events.The defense model must strictly implement the dispatching instructions of the emergency system.Then,according to the interconnection characteristics of gas network,heat network and ADN,the interconnected power grid model,natural gas model and thermal network model are constructed.In addition,consider using flexible resources such as electric energy storage,dual-fuel DG,thermal energy storage and dual-fuel boiler to participate in active defense,and establish a gasoline storage model.Finally,natural gas resources and thermal resources are used to participate in the predisaster emergency scheduling,and the preparedness index and disaster preparedness index are defined to measure the resilience level of ADN,and the active defense strategy of ADN is solved through multi-objective optimization method.The proposed strategy makes full use of the initiative of ADN,enhances the active preparation of the system when disasters come,and improves the ADN’s ability to prevent extreme events.The effectiveness of ADN active strategy is proved by the simulation results of an example.(2)An ADN adaptive resilience enhancement strategy considering multiple DER scheduling is proposed,which can give full play to the flexibility of DER.In order to enhance the resilience of ADN during the occurrence of extreme events,this paper proposes a robust optimization model based on microgrid partition power supply.In this model,situational awareness technology is used to improve real-time support for ADN information.By actively controlling the opening and closing of the line switch and load shedding,the microgrid is formed to supply power in sections,while considering the uncertain characteristics of distributed energy(DER)such as wind power photovoltaic,energy storage power stations and electric vehicles.Considering the uncertainty of the output of wind power photovoltaic units,make full use of the limited energy storage plant and electric vehicle resources,and establish the min-max-min three-layer D-A-D robust optimization model,so that in the worst operating scenario,the economy is the best and the disaster loss is the smallest.In terms of solution method,CCG algorithm is used to transform the model into a min relaxation main problem and a max-min sub-problem,and dual theory is used to transform the sub-problem into a singlelayer max problem,and the optimal solution of the original problem is obtained through iterative solution.The proposed strategy fully considers the scheduling of DER and enhances the adaptability of ADN to extreme events.Finally,the effectiveness of the proposed method is verified by simulation results.(3)This paper proposes an ADN post-disaster collaborative recovery model considering maintenance resource scheduling,which can complete the rapid recovery of load after power failure and reduce the load outage time.In this paper,the line maintenance team scheduling model,the switch operation team scheduling model and the ADN recovery model are constructed respectively,and the coupling relationship between the models is studied,and the optimization model of model coordination is built to complete the rapid recovery after the extreme event.In the model,the line maintenance team is responsible for the maintenance of the fault line,and the switch operation team closes the manual switch with the load.Through the cooperative recovery model,the movement path,operation sequence and operation time of each maintenance team are calculated,and the optimal ADN disaster recovery strategy is solved.In addition,in order to reduce the scale of the model,this paper uses linearization and clustering methods to reduce the computational burden and improve the solution speed.The solution model proposed in this paper realizes the orderly collaborative processing of ADN topology reconstruction and personnel scheduling,and enhances the recovery ability of ADN after extreme events.Finally,the effectiveness of the proposed strategy is verified by numerical simulation.