Research On Heat Transfer Modeling And Control Strategy Of Solid Electric Heat Storage System

New type of energy storage is an important equipment foundation and key supporting technology for building a new power system and promoting the green and low-carbon transformation of energy.It is an important guarantee for achieving the goals of "carbon peaking" and "carbon neutralization".In areas rich in wind,solar and hydropower resources,a variety of energy storage technologies such as pumped storage,electrochemical energy storage and solid energy storage are the key to solving the peak shaving of power grid,among them,the electric heat storage system in solid energy storage is a new mode of residential heating in winter in northern China.Although solid electric heat storage system plays an important role in replacing coal-fired boiler heating,due to its short development time,there are some disadvantages in practical application,such as single model of electric heat storage system,low heat transfer efficiency of the system,slow response speed of heating effluent temperature and unstable temperature.Taking the solid electric heat storage system as the research object,this thesis studies the heat transfer modeling and control strategy around the solid electric heat storage system.The specific research contents are as follows:Firstly,the structural composition of solid electric heat storage system and the working principle of heating heat transfer are studied.Based on the heat transfer theory,the heat transfer mode and typical heat load demand of electric heat storage system are analyzed.The heat transfer control is theoretically analyzed according to the change of heat load demand.Secondly,the heat transfer model of the heat storage body on the heat storage side of the solid electric heat storage system is studied by numerical solution method.The influence of the structure of the heat storage body on the outlet air temperature is studied on the basis of the single channel model and the double channel model.On the heat exchange side,the mechanism model of outlet water temperature heat transfer and the system identification model based on historical data are studied according to the characteristics of the heat exchanger,the identification model and mechanism model with the highest identification degree are selected for step response simulation verification.The verification results show that the second-order inertial transfer function model with lag is the optimal outlet water temperature heat transfer model.Finally,because the solid electric heat storage system has the characteristics of long time delay,nonlinearity and time-varying parameters,the generalized predictive control algorithm（GPC）is used to control the outlet water temperature.In order to change the disadvantages of long time-consuming and large amount of calculation of generalized predictive control strategy,combined with implicit generalized predictive control（IGPC）improved implicit PI generalized predictive control strategy（PIGPC）,under the square wave signal,the response characteristics when the outlet water temperature changes are verified by three control strategies.The simulation results show that the overshoot of PIGPC system is small and the response speed to the target temperature is fast.Compared with the traditional PID control,the control effect is better in the case of disturbance,which can provide opinions a reference for the current solid electric heat storage system to control the outlet water temperature.