Application Of Source-Grid-Load Coordination Mechanism Based On Multi-Source Distribution In Disaster Recovery Of Receiving-End Regional Power Grid

With the rapid interconnection of regional power grids and the large-scale application of high proportion renewable energy,a multi-source distributed receivingend regional power grid has been formed.Most of the receiving-end regional power grids are typical high-load density networks with large transmission power flow and short-circuit capacity,which require high reliability of power supply and power quality.However,the multi-feed structure brings security risks such as commutation failure,power angle instability and harmonic effect,which may lead to cascading reactions and even large-scale power blackouts.In the process of disaster recovery of multi-source receiving-end power grids,the AC/DC power from interconnection of power grids as well as the adjustable units and renewable energy in the network provide a variety of black-start power for the recovery process of the system.This paper explores the restoration technology suitable for multisource receiving-end power grids under blackouts,lays a solid foundation for rational utilization of the abundant power resources brought about by interconnection of power grids and large-scale application of new energy resources,so as to restore the power loss area as soon as possible and improve the system recovery efficiency on the premise of ensuring stability.Firstly,this paper introduces the current development of regional power grid,analyses various problems that may arise from interconnection of power grids,understands the research status of source-network-load coordination optimization under multi-source distribution,and forms the research ideas of this paper.It focuses on the characteristics of receiving-end power grids and analyses their fault principles,and studies the disaster recovery mode based on HVDC transmission and micro-grid technology.Secondly,this paper establishes a multi-objective power dispatching model and its solution strategy under the disaster mode of the receiving end power grid,which is used to solve the initial power allocation problem of the system after a large blackout,and provides the dispatching power reference for the subsequent restoration process.The NSGA2 algorithm is used to deal with the multi-objective scheduling model.The simulation results show that the algorithm has the advantages of guaranteeing the diversity of results and obtaining a stable set of optimal solutions.The membership weighted sum method is used to select the optimal solution set.Thirdly,aiming at the problem of autonomous restoration of microgrid in islanding mode,this paper proposes a seamless grid-connected strategy for controllable inverted DG.By introducing presynchronization link and step compensation of control reference instruction at the instant of mode switching,the power fluctuation of grid-connected is suppressed,which lays a foundation for the establishment of stable islanding microgrid.Finally,aiming at the problem of large-scale load recovery in the later stage of recovery,the system state response caused by load input is analyzed,and the source-load matching index which can evaluate the impact of different characteristic load input shocks is constructed.The index is incorporated into the optimization objective of the load recovery model.An example is given to prove the contradictory relationship between the source-load matching index and the load recovery in this model,and then its practical significance is elaborated.