Flexibility Studies Of Combined Heat And Power System Based On The Dynamic Characteristics Of Electrochemical Energy Storage

With the gradual increase of renewable energy power generation,China’s energy and power structure is constantly adjusted.Proposing higher requirements for the flexibility of cogeneration units.The power storage system has received extensive attention from researchers because of the high quality of electric energy,although the electrochemical power storage technique is relatively mature,but it’s difficult to analyze the mechanism of battery,there is still enough space for research.In this paper,a CHP system combined with electrochemical power storage is established which aimed to explore the influence of battery dynamic characteristics.In the first part of this paper,Ebsilon simulation software was used to build a single variable working condition model of a 2×25MW CHP system,and the deviation between the simulation and actual value under conditions of 100%THA,75%THA and 50%THA was compared according to the thermal diagram,and the system was reliable,the error does not exceed 5%.Based on the above model,the operation feasible region of CHP system is obtained.Finally,this paper discuss the thermodynamic characteristic of the system.In the second part,according to the Stefan-Maxwell equation and the liquid phase Ohm’s law,a partial differential equation model describing the internal reaction process of lead-acid batteries is established,the original equation is decoupled by the average reaction current density assumption,by solving the discrete difference equation.Compare the data obtained by the experiment,the error does not exceed 5%.Finally obtain the following three characteristics of the battery:the discharge characteristics of the battery under the condition of variable current,the capacity of the battery at different current densities,and the healthy estimation of the battery.The third part establishes a coupling model of CHP system considering the dynamic characteristics of the battery according to the work of above two chapters,reestablish the linear constraints of the original equation according to the conservation of energy and the discharge characteristic curve of the battery,successfully build a model considering dynamic characteristics of the battery,then,based on the genetic algorithm,the economical optimal operation mode of the system is obtained.The economic rate of return of the system was discussed,and the small-scale investment in the power storage system could be taken into account,by taking the peak shaving subsidies and carbon emission benefits into account.Finally,a dual-platform joint simulation model of Ebsilon and Matlab is established through C#to verify the strategy obtained above and obtain more accurate system dynamic characteristics.