Predictive Control Based Scheduling Control Of Aggregate Thermostatically Controlled Loads As Demand Side Resource

It is very important to keep the balance of power generation and power consumption in power system at all times,but the large-scale integration of intermittent new energy brings great challenges to the power system to maintain the power balance between power supply and load.In traditional methods,controllable power sources such as thermal power supply usually provide auxiliary services to make up for the power imbalance.However,on the one hand,it reduces the operation efficiency of the system,and on the other hand,the deep peak shaving of thermal power units also increases the operation cost of the system.The "fragmented" thermostatically controlled loads demand side resources with the characteristics of virtual energy storage and flexible scheduling,such as air conditioners,refrigerators and electric water heaters,have great adjustable potential after a large number of aggregation,which has become an alternative for the demand side to provide auxiliary services for the power system and also provides an alternative means for the power system to maintain power balance.Taking thermostatically controlled loads cluster as the research object,starting from the const ruction of thermostatically controlled loads aggregation model,this paper focuses on the control method of aggregating thermostatically controlled loads to suppress the power fluctuation of new energy.The main work of this paper is as follows:Firstly,an improved thermostatically controlled loads bilinear aggregation model based on the second-order equivalent thermodynamic parameter model is established to solve the problem that the first-order equivalent thermodynamic parameter model ignores the indoor material temperature,which leads to the low accuracy of the model.Based on the second-order equivalent thermodynamic parameter model of indoor air temperature and indoor material temperature,the existing bilinear aggregation model of thermostatically controlled loads is extended,and the actual load transfer rate is used to replace the average transfer rate to optimize the accumulated error,and a more practical and accurate bilinear aggregation model is established.Compared with the original bilinear a ggregation model,the proposed model is more suitable for load regulation.Secondly,in view of the shortcomings of the traditional model predictive control(MPC)which has a large amount of calculation and most of the current aggregate thermostatically controlled loads control methods ignore the user comfort,this paper proposes a MPC method based on Lyapunov function considering the user comfort,which realizes the aggregate thermostatically controlled loads to stabilize the power fluctuation of new energy.Firstly,PMV and PPD human thermal comfort evaluation indexes are used to obtain the indoor comfortable temperature range,and the maximum temperature fluctuation range between the two adjustments is further determined by combining with the experimental method;then,the comfortable temperature range and the maximum temperature fluctuation range are taken as constraints,and the output power of aggregation thermostatically controlled loads is adjusted by MPC method based on Lyapunov function to balance the power fluctuation of new energy.The control method reduces the computation and execution delay of the traditional MPC,ensures the convergence of the control with the help of Lyapunov function,and introduces the distributed control to reduce the requirements of the communication system.The simulation results show that the proposed control method can quickly balance the power deviation between power supply and consumption on the premise of considering the user’s comfort,and improve the power system’s ability to absorb intermittent new energy.Finally,to ensure the steady-state and transient performance of the MPC method,an improved MPC method with prescribed performance is proposed.Based on the improved bilinear aggregation model of thermostatically controlled loads,the error conversion method is combined with MPC based on Lyapunov function to make the power tracking error converge according to the designed performance function,so as to prevent the problem that the reference power cannot be tracked within the specified time due to the long convergence time.The simulation results show that the control method has smaller steady-state error and faster convergence speed after considering the prescribed performance.The above work improves the modeling accuracy of aggregation thermostatically controlled loads,and provides an operable control means for aggregation thermostatically controlled loads participate in new energy power fluctuation suppression.The research results of this paper provide a new id ea to absorb intermittent new energy from the load side and help to support the realization of China’s "30.60" carbon peak and carbon neutralization target.