Research On Economical And Optimal Operation Of The Microgrid Containing Distributed Generations

With the decrease of fossil energy and the aggravation of environmental pollution,the development of clean and low-carbon energy is the general trend.In the context of the energy revolution,due to the rapid development of distributed energy,the microgrid system can better solve the technical and market problems caused by the large number of distributed power sources connected to the grid,so the microgrid is an important form of future power system,which is of great significance to Chinese energy strategy.Meanwhile,the combined cooling,heating and power system(CCHP)has the advantages of higher energy utilization efficiency and less pollutants discharged,and it can provide rich energy forms such as cooling,heating and power energy to residents at the same time,thus the combination of the microgrid system can get good results.This paper mainly studies the operation optimization of a single power supply microgrid and a combined cooling heating and power supply microgrid.That is,under the condition of determined equipment capacity,the output of controllable microsources and energy storage devices in the system can be optimized,to make the system run economically and environmentally.The main research work of this paper is as follows:(1)This paper summarizes the development status of the microgrid and the combined cooling heating and power system,as well as the operation optimization method of the microgrid.Then we establish mathematical models of the main part of the microgrid and the combined cooling heating and power system.According to the equipment operation characteristics of different uncontrollable distributed power,such as the wind power generation unit(WT)and the photovoltaic power generation unit(PV);controllable distributed power supply such as fuel cell(FC),diesel generator(DE),etc.The emphasis is on modeling the structure of the combined cooling heating and power system.And energy storage equipment such as battery storage system(BSS),heat storage tank(HST),cold storage tank(CST);as well as some auxiliary equipment such as electric chiller(EC),electric boiler(EB)to conduct modeling,for the subsequent establishment of the optimal scheduling model to provide a basis.(2)An optimization scheduling model is established for the operation optimization of a single power supply microgrid.Taking the total operation and maintenance cost and environmental protection cost of the system as the objective function,and based on the constraints of electric power balance,output of each equipment,battery state and power transmission of the power grid,the optimization scheduling model of a single power supply microgrid is established.At the same time,the water cycle algorithm is proposed to solve the model,and the principles of the water cycle algorithm(WCA),differential search algorithm(DSA),internal search algorithm(ISA)and genetic algorithm(GA)are expounded.And we apply these methods to determine the output of each part of the system,the results obtained can be compared.The case shows that the water cycle algorithm is more effective than some traditional intelligent algorithms in solving the optimal scheduling problem of the microgrid,which can be used as a reference for the optimal scheduling of the microgrid.(3)For about the CCHP microgrid,this paper analyzes its traditional operation mode of the follow the heat load,follow the electric load as well as economic optimal operation mode.This paper focuses on the economic operation of the microgrid,so the optimal scheduling model is established based on the economic optimal operation model.To build a CCHP microgrid that includes WT,PV,FC,CCHP system,three forms of energy storage systems such as BSS,HST and CST,EB,EC and so on,the network storage characteristics,the running characteristics of distributed power supply and power balance all sorts of constraints are considered in this paper,the minimum operation cost and environmental cost taken as the objective to optimize the output in each part of the microgrid.The scheduling model is constructed as mixed integer nonlinear programming model and solved by an optimization solver Lingo,and we apply the traditional intelligent algorithm such as GA to solve the model.The example shows the integrity and effectiveness of the model.The CCHP microgrid system makes the system run stably and can dispatch three energy forms flexibly.It is shown that the optimization solver can be used to solve the optimization scheduling problem of the CCHP microgrid system relatively quickly and accurately.