Research On Smooth Swicthing Control Strategy Of Microgrid Based On VSG Inverter And FSMC

With the deepening research on micro-grid control technology,the operation requirements for microgrid are also gradually improving,and the effective realization of dual-mode operation of microgrid has become a basic requirement.In order to adapt to the dual-mode operation characteristics of the microgrid,it is not only necessary to ensure the safe and stable operation of the microgrid in the two different operation modes,but also to require that the switching process of the two different operation modes will not cause adverse effects on the system.In other words,the selected control strategy shall meet,to a certain extent,the smooth switching between the operation mode of microgrid grid-connected to island and island to grid-connected island.Combined with the current energy demand and technology research hotspots,it is of great practical significance and role to study the control strategies of wind/PV/storage integrated microgrid with a variety of different micro-generators under different operation modes.The main research contents of this paper are as follows:(1)To analyze the working principles of the wind power generation system,photovoltaic power generation system and energy storage system respectively,establish the corresponding mathematical model,and select the corresponding control mode,and build the corresponding simulation model in the Matlab/Simulink environment.The maximum power point tracking(MPPT)control is realized by disturbance observation method in the photovoltaic power generation system.The wind power generation system adopts the closed-loop control of the macro variable paddle to realize the wind energy MPPT.In order to realize the bidirectional flow of energy,the energy storage system adopts Buck/Boost bidirectional DC-DC converter as the control system infrastructure,and realizes the charge and discharge process by predicting the current control strategy,so as to achieve the purpose of stable internal operation of the microgrid system.Finally,the three distributed power sources are integrated into a complete microgrid system.By setting the corresponding parameters,the designed microgrid system can operate independently and stably.(2)Based on the ideal model of synchronous generator,the overall system model of VSG control is designed and built.The VSG control principle is analyzed in detail,and the corresponding simulation model is built in Matlab/Simulink.At the same time,the static stability of VSG control is analyzed,and the influence of key parameters in VSG control algorithm on system stability is discussed,which provides a reference for the selection of parameters in the simulation experiment.In order to improve the robustness and response speed of the system,the VSG Control strategy was improved by combining with Fuzzy Sliding Mode Control(FSMC).Through the simulation analysis,the correctness of the designed control mode and the improved designing of the control mode are verified.(3)The wind/PV/storage microgrid is combined with VSG control.In the process of island-connected operation,considering that the presynchronization condition of island-connected operation can be successfully realized,a presynchronization control strategy based on VSG control is proposed,and the corresponding controller is designed.By comparing the simulation results of the proposed model switching between two different operating modes,the rationality of the proposed microgrid system and the feasibility of VSG control in the smooth switching control process are further verified.