Coordinated Operation Control Of Microgrid Based On Distributed Optimization

With the increasing global environmental pollution and energy crisis,it has effectively promoted the utilization and technology development of renewable energy in the world.However,the renewable energy represented by wind energy and solar energy is generally random and intermittent.After the Distributed generation(DG)is connected to the conventional distribution network,the distribution system is changed to an interconnected network of generations and loads.The system control and operation become more complex.Microgrid is proposed to solve the problem of safety,stability and reliability of renewable energy and distributed generation access to large power grid.Microgrid control includes centralized control,decentralized control and distributed control.Compared with traditional centralized control and decentralized control,distributed control has many advantages and has great potential in the field of microgrid control.With the support of the National Natural Science Foundation of China Project "Research on Power Quality Analysis and Control Method of Distribution System with Micronetwork "(Project No.51477070),Focusing on the demand of distributed optimal control of microgrid,this paper analyzes the practical requirement and technical challenge of distributed optimal control architecture in practical operation from aspects of theory and application.The influence of communication delay,communication interference and operation constraints on the control and optimization performance in the distributed optimal control of microgrid is systematically studied.The key technologies to ensure the distributed coordinated optimal operation and optimization control strategy of microgrid are proposed,so as to provide theoretical and technical support for the engineering practice of distributed control of microgrid.The main work of the thesis is as follows:(1)The distributed operation control system architecture of typical microgrid is established.The microgrid is divided into physical layer and information layer,and the requirements and characteristics of distributed operation of microgrid information layer are analyzed,summarizes the key factors that have great influence on microgrid distributed operation and control in the actual operation process,and establishes a mathematical model to describe the influence of related factors on microgrid distributed operation.It lays an important foundation for the study of coordinated operation control strategy of Microgrid based on distributed optimization.(2)A distributed operation control method of microgrid considering communication delay is proposed.Based on the distributed control strategy of microgrid based on average consistency control,the communication delay is divided into local processing delay and information transfer delay.The performance of this control strategy under different delay types and the influence of different delay on stability and convergence speed are analyzed.The correlation between communication delay margin and system eigenvalue is analyzed,and the influence of different communication system topology and communication mode on communication delay margin and convergence speed is studied.The research can be used to guide the optimization of better communication network structure to improve the stability of the system.(3)The distributed operation control method of microgrid considering communication interference is proposed.Aiming at the general communication interference,the steady state deviation of distributed active power control based on consensus control strategy is analyzed.The general form of communication interference is decomposed into constant component and alternating component.A distributed active power control strategy with state observer is proposed to suppress the constant component in communication interference.The variable control gain coefficient including event trigger mechanism is introduced to suppress the alternating component in communication interference.The research content can be used to improve the reliability of microgrid distributed operation control.(4)A distributed optimal control method for microgrid is proposed considering operation constraints.In view of the factors affecting the optimal control and economic scheduling in the long running process of microgrid,the typical operation constraints affecting the optimal power flow(OPF)of microgrid are considered,including the power generation constraints in microgrid,the line operation constraints and so on.To solve the accuracy problem of the conventional second order cone programming(SOCP)convex relaxation method in solving the OPF problem with operation constraints,an alternating direction multiplier method based on penalty term is proposed.In the case of SOCP convex relaxation inaccuracy,distributed solution OPF problem can still be realized,thus effectively improving the economy of microgrid operation.Focusing on the key scientific problem of microgrid distributed optimal operation control,this paper systematically studies the architecture of microgrid distributed operation control,and puts forward a systematic solution to the key factors that affect the distributed optimal operation control of microgrid.The related work can provide useful reference for the operation control and system optimization design of microgrid under distributed framework.