Optimization On Microgrid With Integrated Power And Heat System

With the development of the energy internet, combined cooling, heat and power system and energy storage technology as well as the increment of the electrification level, the relationship among consumption, transmission and generation of power and heat is getting closer and closer, the trend that integration of power and heat system is inevitable. This paper establishes a new operation model of microgrid containing the dispatching strategy of energy storage and the integration of power and heat system, and investigates the solution for improving the operational flexibility of microgrid in large energy context, both from the energy supply side.First, the framework of the conventional integrated power and heat system is analyzed and corresponding elements are modeled first. The general model of coupled power and heat output constraint for combined heat and power unit is proposed. A linear model to simulate the charging and discharging process of the energy storage is proposed as well. Besides, the relationship between power and energy of the storage is characterized. In the meantime, the gird could be the powerful backup for microgrid for microgrid could exchange power with grid at any time. This part provides the basic models for the systematical analysis.Secondly, under the time-of-use (TOU) electricity price and the microgrid connecting to the grid, a dynamic model of combined cooling heating and power (CCHP) type of microgrid considering the additional opportunity income is proposed to better schedule energy storage, schedulable microsources and interaction power from the grid. A microgrid consisting of a wind turbine, a photovoltaic, an energy storage and a CCHP system is selected to obtain the optimal operation modes of microsources in the scheduling period using simulated annealing and particle swarm optimization (SimuAPSO) algorithm, and then compares the advantages between CCHP system and individual system. The validity of the proposed model and algorithm is proved. Under the condition that microgrid connecting to the grid, the dynamic model of CCHP type of microgrid could optimize the output of microsources and decrease the costs of the microgrid on the basis of the step utilization of the energy and the emission-reduction.Finally, along with the rapid development of energy internet, the closer relationship between power and heat and the implement of the "real time price (RTP)" policy, this part proposes the combined heat and power dispatch model for regional grid-connected microgrid. Taking into consideration energy storage and timing sequence characteristics of different types of load and distributed generators, a microgrid consisting of a wind turbine, a photovoltaic, a combined heat and power system, an electric boiler, a fuel cell and an energy storage system is selected. The optimization method based on GAMS with the Cplex solver is employed to obtain the optimal costs and operation modes of the microsources in the scheduling period, and then compares the model with two traditional methods of scheduling. Besides, this part discusses how the reliability differences between heat and power affected the operation. The simulation results indicates that the proposed model could balance the power and heat output, while proper use of their difference could further decrease the costs. This model can serve as references for the development of Energy Internet and power and heat scheduling.This paper provides a preliminary research on both the operation strategy of energy storage and the integration of power and heat system. Hoping that the outcome of this paper could provide some beneficial references to the development of energy internet.