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Small Signal Stability Analysis For Microgrid Based On Droop Control

Posted on:2018-12-31Degree:MasterType:Thesis
Country:ChinaCandidate:W B JiFull Text:PDF
GTID:2322330518453869Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
With the depletion of fossil fuels,the increase of environmental pollution and the safety of traditional power grid,countries have to speed up the study of distributed power generation technology.Distributed power generation technology has the advantages of flexible operation mode and strong environment friendliness,but it has a large interference with large power grid,which restricts its large-scale use.Microgrid concept put forward to solve the contradiction situation between distributed power generation and large power grid.Micropower through the power electronic converter access microgrid,with a flexible control and operation.But because of its inertia is small,when subjected to disturbance,the system will occur oscillation instability.So compared with the traditional power grid,microgrid stability analysis is quite different.Aiming at this problem,this paper makes a small signal stability modeling and analysis on the microgrid using droop control.Firstly,the output power transmission characteristics of the micro power supply are analyzed and the control method of the inverter is introduced.The parameters of the inverter are designed,and the virtual impedance is added to the control ring,reducing the impact of line parameters on the output impedance,remain inductive.Then,the expression of the inverter,the load and the large power are linearized to get its own small signal model,and the equivalent circuit.On the basis of this,the obtained component model is transformed into the common coordinate system,and The power closed-loop characteristic equation of the whole microgrid is obtained.Find the closed-loop eigenvalue according to the equation and plot the root trajectory.Finally,based on Matlab/Simulink to build microgrid simulation and verify the correctness of the model.Simulated the two cases,which one is a virtual impedance,the other without a virtual impedance.Verify the validity and necessity of adding the virtual impedance.The influence of load reactance and virtual inductance on the stability of the system is analyzed by using the root trajectory diagram.The increase of load reactance and the decrease of virtual inductance reduce the stability of the system.The correctness of the conclusion is verified by simulation.
Keywords/Search Tags:Microgrid, droop control, virtual impedance, small signal stability analysis
PDF Full Text Request
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