Aggregation Modeling,optimal Dispatch And Control Strategies For Thermostatically Controlled Loads In Microgrid

With the large-scale integration of intermittent renewable energy,there is increasing demand for economic and reliable ancillary service in the power system.In some special applications(such as industrial parks,etc.),the load has become a flexible regulation resource.By regulating power consumption within a certain range,some controllable loads on demand side can act as virtual energy storage to compensate for the lack of power generation.To make full use of the controllable loads,it is important to explore their regulation capability and formulate practical dispatch and control strategies.This thesis focuses on the aggregation model,optimal dispatch and control methods for typical thermostatically controlled loads(TCLs)in microgrid.The main work in this thesis can be summarized as follows:1)Due to the small rated capacity,large total number and multiple operating modes of air conditioning loads(ACLs),full derivations of the upper and lower bounds of the aggregated power for ACLs is provided for convenience of load dispatch.The effectiveness of the proposed method is verified by Monte Carlo simulation and ACL parameter analysis is also conducted.2)As a widely-used central ACL,water-loop heat pump(WLHP)load has multiple variables and is nonlinear.Considering that,a priority list based on the state of temperature index for each heat pump unit(HPU)is developed.Further,a WLHP aggregation model for full working modes is established and then applied for a tie-line power leveling dispatch problem in microgrid.A bi-section based bang-bang control algorithm is developed to determine HPUs’ switching states.Several test cases confirm that the proposed method can effectively smooth power fluctuations of tie-line as well as guarantee user’s comfort.3)A two-stage economic dispatch in grid-connected community microgrids considering ACLs’ regulation capacity is investigated to minimize the total operation cost of the microgrid.A dynamic optimizer based on receding-horizon optimization is designed with the supply and demand side power balanced according to their fluctuation characteristics,which can effectively reduce the operation loss for ESSs while ensuring user’s comfort.The variable temperature dead zone control is implemented for real-time load power tracking,which shows better control flexibility and economic benefits by quantitative analysis.