| With the rapid increase of power generation from intermittent renewable energy,it is very challenging to maintain the power system safe and reliable operation.Meanwhile,the consumption of electricity is impossible to be kept at constant throughout time,which imposes the impact in balancing the grid load and power generation.This inevitably leads to installation of excessive generation capacity and results in the complexity of power grid.Electric Energy Storage(EES)is recognized as one of the most promising solutions to address this challenge.Compared with other EES technologies,Compressed Air Energy Storage(CAES)has the advantages of large energy storage capacity,long energy storage cycle,long working life and environment friendly.So CAES is a new EES technology with great development potential.However,its complex working conditions and thermodynamic characteristics make it difficult to understand CAES system dynamics and to obtain optimal operation status.It is very costly to use real CAES power plants to study various characteristics of CAES.Therefore,mathematical modeling becomes a feasible and economic approach which can provide more fundamental theoretical understanding of CAES behaviors under various operation conditions and provide prospective guidance for the development of CAES technology.This project is proposed with the following main research contents:Firstly,the research focuses on two operation processes of CAES system: energy storing and energy releasing.The working principle and basic structure of CAES system are introduced.From the point of view of thermodynamics,the core components of CAES system,compressor and expander,are modeled and analyzed.In addition,the mathematical model of other parts of the CAES system,such as the air storage chamber,heat exchanger,heat storage tank,generator,motor and so on,is also established by using the mathematical modeling method.Then,according to the mathematical model given in this thesis,the simulation models of compressor,expander,air storage chamber are built.At the same time,the accuracy of these model is verified.On this basis,their various thermodynamic characteristics are analyzed,and the influence of different operation conditions on their operation state is studied.Finally,this thesis builds a whole simulation model of the CAES system in megawatt level based on the mathematical model of each component of the compressed air energy storage system.The whole system includes five stages of compressors and four stages of expanders.Using this whole system model,the thermodynamic characteristics of the compressed air energy storage system in the two processes of compression,storage and expansion are studied in depth.The thermodynamic characteristics of CAES system which is a new type of energy storage technology are analyzed more comprehensively and systematically. |
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