Research On Operation Characteristics Of Inverter Distributed Power Supply Connected To Microgrid

In the simulation study of microgrid,it is not always necessary to build a detailed model for all research objects for different research purposes and applications.The model of some research objects can be appropriately simplified under reasonable assumptions.Based on the model simplification method under reasonable assumptions,not only can the simulation accuracy be guaranteed,but also the efficiency of the simulation experiment can be significantly improved,and the difficulty of establishing a distributed power supply and power electronic converter device model is greatly reduced.At present,there are many inverter-type distributed power models in related research,but there is no systematic classification.Therefore,this paper mainly studies the inverter-type distributed power model based on photovoltaic cells and fuel cells,including the construction of simplified models,the feasibility of simplifying the model by simulation and the application of the simplified model in micro-grid simulation.The research contents are as follows:(1)The working principle of photovoltaic cells and fuel cells are analyzed.The mathematical model is derived in detail and the model of inverter distributed generation system is completed.The simulation is verified by Matlab/Simulink.(2)An automatic piecewise linear fitting method is designed to simplify the inverter-type distributed power model.The method can automatically determine the segmentation point and give a linear expression of the piecewise function under the premise of setting the maximum error.Through automatic piecewise linearization,the relationship of the output characteristics of the inverter-type distributed power supply can be replaced by a multi-segment linear equation.Taking photovoltaic cells and fuel cells as examples,the automatic piecewise linear model can effectively replace the Simulink module model by comparing the Simulink module model with the automatic piecewise linear model output characteristic curve.This method is also applicable to other distributed power supplies with complex nonlinear static characteristics.(3)Starting from the inverter-type distributed power control strategy,the Droop control,V/f control and PQ control theory are combed.On this basis,the photovoltaic cells based on the simplified linear fitting linear model are built.Fuel cell grid-connected simulation model.The simulation results show that the automatic segmentation linear fitting model can improve the simulation speed of the system.(4)Based on the simplified model of photovoltaic cell and fuel cell,the operation control strategy of microgrid is studied,and the simulation platform of microgrid is built.The variation of power,bus voltage and frequency of photovoltaic cell and fuel cell is obtained.The operation characteristics of the microgrid in the operation mode switching and the common load switching state are verified.Figure [62] Table [7] Reference [54]...