Research On Modeling And Control Method Of Multi-type Aggregate Thermostatically Controlled Loads

With the large-scale generation of renewable energy represented by wind power and photovoltaic connected to the grid,the randomness and volatility of its output will bring great challenges to the operation of the power grid.At the same time,demand-side load development has been extremely rapid in recent years.Among them,the proportion of temperature-controlled loads represented by electric water heaters,air conditioners,and refrigerators to the total power grid load has been especially increasing.And such loads have the characteristics of energy storage and flexible scheduling,which are good demand-side response resources.With the decrease of the flexibility of dispatching on the power generation side,the massive thermostatically controlled loads on the demand side provide abundant and high-quality adjustable resources for improving the utilization rate of renewable energy generation and ensuring the safety and stability of power grid operation.In this paper,aiming at the problems to be solved when the aggregated thermostatically controlled loads participates in the operation of power grid,the model establishment and control method of the aggregate thermostatically controlled loads are studied.The main work of the thesis is as follows:(1)First of all,an improved discrete bilinear model of control-oriented aggregated thermostatically controlled loads power was constructed.This paper analyzes the operating principle of thermostatically controlled loads,and establishes a single thermostatically controlled loads operating state description model.Based on the existing bilinear time-continuous model of thermostatically controlled loads aggregation,a modified discrete bilinear model for control-oriented aggregated thermostatically controlled loads aggregation power is deduced,and it lays the foundation for subsequent control algorithm research.(2)Based on the improved discrete bilinear model of aggregated thermostatically controlled loads power,a parameter identification method for the model was designed,and a control method for aggregated thermostatically controlled loads power was proposed using the inverse control principle.The system parameters of the bilinear model will change under the influence of external environment,and it is difficult to measure directly.In order to solve this problem,this paper designs a parameter identification method for the discrete model of aggregated thermostatically controlled loads by using the recursive least square method with forgetting factor of model decomposition,and identifies the actual system parameters.In view of the non-linear characteristics of the discrete model,based on the identified model parameters,a control method for the aggregated thermostatically controlled loads tracking intermittent power source power fluctuation control was designed using the back-push control principle.Simulation results show that the parameter identification method can quickly and accurately identify the parameters of the cluster thermostatically controlled loads,and the control method can realize the dynamic tracking of the reference thermostatically by the aggregate thermostatically controlled loads.(3)Based on user comfort,a task assignment model of aggregated thermostatically controlled loads was established.Based on this,a distributed and consistent control method of aggregate thermostatically controlled loads based on error compensation was proposed.When there is too much load in a single aggregated thermostatically controlled loads,and when the aggregator conducts coordinated control over several aggregated thermostatically controlleds load clusters under its jurisdiction,the transmission of control instructions may bring tremendous pressure to the communication system.In view of this problem,the thermostatically controlled loads of large cluster is divided into clusters according to the principle of regional homogeneity,and based on the distributed consistency control architecture,a distributed consistency control method of aggregate thermostatically controlled loads based on error compensation is proposed in thie paper.In order to reduce the comfort impact of thermostatically controlled loads regulation on users,this paper establishes a clustered task assignment model for thermostatically controlled loads of aggregator based on the comfort of cluster users,and quantifies the priority of aggregate thermostatically controlled loads control through cluster user comfort.Simulation results show that the control method can quickly and accurately track the dynamic reference power.(4)Based on the above research,the improved discrete bilinear model of aggregated thermostatically controlled loads based on parameter identification results provided in this paper provides a new idea for accurate modeling of aggregate thermostatically controlled loads.The control method proposed for power tracking of aggregated thermostatically controlled loads provides a solution for aggregated thermostatically controlled loads to participate in power grid operations,and provides a new way for demand-side resources to participate in grid operations.