Research On Intermittent Multi-microgrid Emergency Scheduling Strategy

With the development of distributed power and microgrid technology,the connection of microgrids in a certain area is closer,and forming a multi-microgrids system.When large power grid separates into several parts or even blackouts,the multi-microgrids system will switch to the islanding operation mode to ensure the power supply requirements of important loads within the system.In the absence of power supported by the large power grid,emergency power support between each microgrid in the multi-microgrids system can increase the flexibility and economy of the system operation.Therefore,the optimal scheduling of interconnected multi-microgrids system with different interconnected topologies is discussed.The main contributions of the paper are as follows:Considering the characteristics of the integration of the power sources and loads of microgrid,numbers of wiring modes which are suitable for different types of multi-microgrids system are proposed.Typical wiring modes for multi-microgrids system are composed of single bus and single bus segmentation mode,double buses and double buses segmentation mode,cell mode,bridge mode,angle mode,and net mode.The power supply reliability of different wiring modes is analyzed.The scenarios that different wiring modes are adapted are obtained according to the characteristics of different wiring modes,the number of microgrid in the multi-microgrids system and the distributed power supply and load composition.A comprehensive load importance assessment index considering life safety,economic benefit,quality and historical contribution rate is proposed.The emergency load blackout loss model is established combined with the comprehensive load importance index,and the emergency load shedding strategy is proposed for the multi-microgrids system.Through the example verification,in the single bus mode,the power outage loss under the bus fault condition is higher than that under the normal condition of the bus;in the single bus segmentation and the angle mode,the power outage losses are different according to the location of emergency and the microgrid load composition,and the more the load is shedded,the higher the power outage loss is not necessarily.For the interconnection topology of each micro-network is different,the multi-microgrids system interconnection topology is regarded as an undirected graph,and the interconnection matrix is established.The power generation scheduling strategy of interconnected multi-microgrids system in emergency situation is proposed,and an emergency power generation scheduling model is established combining with the interconnection matrix and scheduling strategy.In the simulation study,the emergency power support of the multi-microgrids system of three typical interconnected topologies which are chain,ring and strong connectivity is compared.The results show that the closer the connection between the microgrids,the more ways of power interaction.And the power outage loss is reduced compared to the case where the interconnection topology is not considered.An emergency power generation scheduling strategy for interconnected multi-microgrids system is proposed.After considering the importance of load and the interconnection topology,the power outage loss in emergency situation is effectively reduced,which can provide reference for the emergency operation of multi-microgrids system.