Research On Load Shedding Coordinated Switching Control Strategy For Active Distribution Network

Distribution network contains a large number of users,and its operation directly affects user experience and power supply reliability.With the access of a large number of distributed generators and the application of advanced communication technology,the traditional distribution network is gradually developing into an active distribution network with multi-party coordinated control,and the uncertainty of both ends of source load increases the operation risk of active distribution network.In case of line failure or power shortage of the system,it is necessary to cut off part of the load to ensure the safe and reliable operation of the whole system.In recent two years,with the continuous tight supply of power and coal markets,a variety of adverse factors have led to different degrees of "power cut-off and power restriction" in most areas,and even the traditional "one size fits all" load cut-off scheme,which has a direct impact on the normal social and economic development and users’ living standards,and is easy to worsen the double end relationship between power supply and demand.Therefore,how to accurately implement the load shedding operation to ensure the continuous power supply in the non fault area,while considering the demand side user satisfaction and economic loss as much as possible,is an urgent problem to be solved.Taking the active distribution network load shedding as the starting point,this paper systematically studies the emergency coordinated control strategy of active distribution network load shedding from the perspectives of power supply side and load side.At the same time,considering the increasing scale of active distribution network in the future and the diversity and richness of distributed generation and switchable load,the information transmission in the process of load control will increase in geometric multiples under the interconnection thinking,and the event triggering mechanism can reduce unnecessary information transmission.Therefore,the research on zoning load shedding based on event triggering mechanism is of great significance to save communication resources.The main research contents of this paper include:(1)A multi-objective load shedding optimization strategy of distribution network considering user satisfaction is proposed.Aiming at the traditional extensive load shedding,which is easy to deteriorate the relationship between power supply and demand,a game model with minimum load shedding cost and maximum user satisfaction is established.The second-order cone relaxation method is used to relax the non convex nonlinear model into a linear solvable form;A multi-objective load shedding strategy based on hierarchy method is proposed,which comprehensively considers the demand response of price type and incentive type,so as to fully tap the potential of load shedding on the load side.Simulation results show that the proposed method can not only improve the power supply reliability under high penetration access of distributed generation,but also reduce the demand response cost and improve user satisfaction.(2)A layered and partitioned load shedding control strategy for distribution network based on event triggering mechanism is proposed.Aiming at the complex problem of operation information transmission in large-scale distribution network,the distribution network is divided into several sub regions by using the partition decoupling method,and the hierarchical and partition coordinated control architecture of active distribution network is established based on the event trigger mechanism;An active distribution network partition load shedding strategy based on event triggering mechanism is proposed,and a load shedding optimization model considering the constraints of safe operation and spatial coupling in the sub region is constructed.The simulation results show that compared with the traditional load shedding scheme,the proposed method can reduce the load shedding cost,improve the user satisfaction of the demand response mechanism,save the communication resources required for the hierarchical and zoning coordinated control of the distribution network,and alleviate the multi-level communication transmission pressure of the distribution network.