Scheduling Strategy For Flexible Substation And AC/DC Power Grid

With the progress of new energy,distributed generation,energy storage and power electronics,the demand for two-way interaction between the power grid and the users and the various levels of the power grid is increasing.A demonstration project in the north of Zhangjiakou is building a flexible substation with four ports witch can connect the main power grid at medium AC voltage,new power supply at medium voltage and load at low pressure DC and AC voltage,become a control point of a variety of power resource.According to the needs of the area with flexible substation,which has a large number of new energy and distributed power sources,including new energy elimination on the spot and the safe,stable and economic operation of power grid,it needs unified scheduling of the resources including power supply,load and energy storage.In order to organize the electric power recourses in the AC/DC distribution network area,control multiple power supply and load in a coordinated way,effectively control the flow of the flow and provide optimal scheme for the operation and scheduling of flexible substations,the main work and achievements of this article are listed as follows:(1)The running characteristics and scheduling mode of the schedulable power system resources in flexible substation and AC/DC distribution network are analyzed,and meanwhile their mathematical models are set up.Multi time scale scheduling model for source-load-storage optimization is studied,and its scheduling framework and implementation based on an automated system is put forward in the paper.(2)The multi-objective optimization model of day-ahead source-load-storage scheduling is established based on the study of source load storage characteristics.The goals of the model of AC/DC distribution area are the lowest peak valley difference and the lowest operating costs,considering the power balance constraints,demand response constraints,energy storage constraints,new energy consumptive ability and peak regulating ability of the grid with higher level.The particle swarm optimization(PSO)algorithm based on differential evolution(DE)is used to solve the model based on the overall planning of new energy consumptive and economic benefits,so that day-ahead scheduling scheme is solved and the actual power grid operation is satisfied.(3)Based on the day-ahead source-load-storage scheduling scheme,aiming at the problem of accuracy of new energy prediction,optimal scheduling strategy of multi time scale is proposed.Combined with the new energy rolling prediction and day-ahead prediction,fast response and flexible storage load resources are used to modify the scheduling scheme in the short time,so that the influence of prediction error of new energy on the day-ahead scheduling strategy is reduced and the new energy consumptive rate is improved.