Optimal Operation Of Distribution And Consumption Level Energy Internet With Integrated Energy Subnetwork

The focus of Energy Internet is to promote the development of distributed renewable energy and the local consumption of high proportion of renewable energy in the distribution network.Therefore,the research of Energy Internet starts from the distribution and consumption level Energy Internet.Connecting the distributed renewable energy to the distribution network in the form of energy subnetwork can effectively reduce the impact on the distribution network caused by the decentralized access,and an integrated energy subnetwork including electricity,heat,cooling and other forms of energy can further reduce the renewable energy curtailment and decrease the operation cost through multi energy complementary.Therefore,this paper takes the distribution and consumption level Energy Internet with integrated energy subnetwork as the object,studies the modeling of distribution and consumption level Energy Internet based on multi-port energy router,and the coordinated operation optimization of integrated energy subnetwork and distribution network.This paper has got the following achievements:(1)A general model of multi-port energy router in the distribution and consumption level Energy Internet is established.Combined with the structure of multi-port energy router,its operation principle is explained.And the port loss model,port power constraint and power balance constraint of the energy router are established,which constitute the general mathematical model of multi-port energy router in the distribution and consumption level Energy Internet steady state analysis and lay the foundation for the optimal operation of the distribution network.(2)The optimal operation model of the integrated energy subnetwork considering the flexibility of multi energy is established.This paper analyzes the principles of combined heat and power-concentrated solar power,electricity to heat,heat storage system and electricity storage system to mitigate the wind and solar curtailment.The basic reason for wind and solar curtailment is the lack of system flexibility.The model defines the flexibility of multi-energy,analyzes the flexibility demand of the renewable energy and load and the flexibility supply of flexibility resources.Multi energy flexibility conversion mechanism is proposed and the flexibility evaluation index is put forward.The optimized operation model of integrated energy subnetwork considering the flexibility of multi energy is established,in which makes full use of flexibility supply and multi energy flexibility conversion to realize the clean and low-cost utilization of integrated energy.(3)An optimal operation model of the distribution and consumption level Energy Internet based on subnetwork adjustable power and semidefinite programming is established.This model solves the problem of coordinated optimal operation of distribution network and integrated energy subnetwork.This model includes subnetwork level and Energy Internet level,subnetwork level is the local operation optimization of the integrated energy subnetwork,and the subnetwork level passes the surplus and shortage power and adjustable power range of the subnetwork to the Energy Internet level.The Energy Internet level is the optimal power flow of the AC-DC distribution network which minimizes the system operation cost and network loss,and the semidefinite relaxation is used.The subnetwork adjustable power,buying and selling power,receiving and sending power are obtained and fed back to the subnetwork level.