Research On Adaptive Control Technology Of Microgrid

With the development of renewable energy such as wind power and photovoltaic power generation,distributed generation system can not only meet the need of increasing load,but also reduce environmental pollution.As an efficient way of networking distributed energy,microgrid can make full and reasonable use of new energy and greatly promote the development of new energy in China.As the proportion of distributed energy in power supply system increases gradually,the coordinated control strategy in microgrid becomes more and more important.In DC microgrid,the fluctuation of bus voltage and power mismatch caused by parallel connection of different power levels are discussed.In this paper,a control strategy based on model reference adaptive droop resistance is proposed to stabilize bus voltage and realize proportional power distribution in distributed generation.In this paper,DC converters,inverters and adaptive droop characteristics in DC microgrid are discussed as well.(1)Firstly,three control strategies of microgrid are described: master-slave control,peer-to-peer control and hierarchical control.Secondly,the basic topological model of microgrid was introduced in detail,and two working modes of Boost step-up chopper circuit on DC side of microgrid are analyzed,and two mathematical models are deduced.Then the bipolar modulation principle of AC side single-phase full-bridge inverter circuit is analyzed,the parameters of LC filter are designed,and the closed-loop control strategies of the two circuits are designed respectively.Finally,by imitation.The correctness of the controller is verified.(2)The bus voltage fluctuation and power matching in DC microgrid are studied.Firstly,the mathematical model of DC microgrid is established,and the small signal analysis of the system is carried out.Secondly,the relationship between bus voltage and current and sag resistance is deduced,and the limitation of traditional sag control of DC microgrid is analyzed.Then,the control strategy of microgrid based on hierarchical control is described,and on this basis,an adaptive sag resistance control based on model reference is proposed.The reference model and actual model of the system are established,and the adaptive law is deduced.Finally,the feasibility of the algorithm is verified by the simulation of MATLAB/Simulink.(3)Designing the microgrid experimental platform from both hardware and software aspects.Hardware design includes Boost inductor design,power switch selection,DC bus capacitor,sampling circuit,driving circuit,etc.Software module is designed based on TMS320F28035 chip,including control loops,algorithm implementation,over-current protection,over-voltage protection,etc.Finally,the validity of model reference adaptive control is verified by the experimental platform.