Research On Distributed Control Of Inverters In Microgrid Based On Consistency Theory

Microgrid is the main carrier for distributed power to connect to the grid.Three-phase voltage source inverters are often used as an important part of microgrids to connect distributed generation units.It is necessary to develop appropriate control methods to regulate and control them to ensure the stability of microgrid Reliable operation.Therefore,how to design an effective control method to ensure distributed power generation on demand,while eliminating voltage and frequency deviations,as well as circulation and oscillation problems caused by it,and effectively improving power quality is an important research topic.Therefore,on the basis of reading a lot of literature and research results,this paper conducts research on the control method of multi-inverter parallel system in island mode.The main work of the thesis is as follows:First,the working principle of droop control is analyzed in depth,the power transmission equation of droop control is deduced,and the meaning of droop curve is explained.After deriving the small signal model of the power supply,it is linked with the load small signal model to obtain the small grid system Signal model,and use the root locus method to analyze the influence of control parameters on system performance;verify the correctness of small signal analysis conclusions through MATLAB simulation,and provide theoretical support for the improved scheme of droop control in the following chapters.Secondly,it analyzes the principle of traditional droop control to realize the power distribution of parallel inverters in microgrid,and points out the shortcomings when considering the influence of line impedance.Designing virtual impedance loop in control system to solve multi-inverter The method of power distribution is not pressed,and the shortcomings of the method are analyzed.The distributed algorithm and consistency control theory are introduced.Based on the droop control,an improved power allocation strategy based on power deviation consistency is proposed.MATLAB simulates and analyzes the effectiveness of the proposed method and compares it with the power distribution method based on virtual impedance.Finally,the secondary control principle of the microgrid under the droop control mode is analyzed.In order to overcome the traditional centralized control of the secondary control structure,the communication network is complex,the communication volume is huge,and single points of failure are prone to occur.The disadvantages of scalability,combined with the distributed consistency control theory and droop control method,proposed a two-level coordinated control based on the consistency of the power deviation amount.This distributed structure can greatly reduce the communication volume and improve the system Stickiness and expansibility;use MATLAB tools to comprehensively simulate the proposed control strategy to verify the effectiveness of the proposed control strategy.