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Research Of Key Technologies Of Microgrid Inverter Control Based On Virtual Synchronous Machine

Posted on:2018-11-20Degree:MasterType:Thesis
Country:ChinaCandidate:X B CuiFull Text:PDF
GTID:2322330542452048Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
Microgrid has the huge advantage in the new energy access,which has been one of the main developing direction in the future and attracts a widely attention.Inverter plays a key role in the stability of the grid-connection.Virtual synchronous generator(VSG)control technology could make inverter simulate the inertia,damping,frequency modulation and voltage regulating characteristics of synchronous generator,not only can guarantee the stable operation,but also can realize good compatible with power grid.With reference to the operation of the synchronous generator characteristics,the thesis analyzes the related theory of VSG control,and builds base active-frequency and reactive voltage controller.By establishing virtual inverter simulation mathematical model and analyzing the external characteristic of VSG with synchronous generator,the thesis illustrates the feasibility of VSG control on inverter operation.To improve the performance of the VSG control system,the optimization design of power controller whose key parameters can be coordinated optimization has been put forward,which can avoid repeated trial and error process.Through introducing in the controller structure variables,the controller establishes the direct relationships of virtual inertial parameters,damping coefficient and droop coefficient of synchronous machine with the controller parameters.Based on the system performance requirements,by reference to the same capacity of synchronous generator,the virtual synchronous machine parameters can be set.This thesis gives the specific design method,this method not only can set up the relationship between parameters and convenient calculation quickly,also ensures the stable performance and dynamic performance of system.When VSG control system works in island mode,the inverter need to provide power support to the loads and maintain the system frequency and amplitude stability of the output voltage.This thesis explores the frequency and voltage stability of virtual synchronous machine in the islands,and implements the power allocation in inverter parallel cases.When VSG connects to the network system,it needs to be in accordance with the instructions to the grid power,participate in the power regulation and provide support for power grid frequency and voltage stability.To reduce the grid impact current,this paper designs a coordinated optimization controller based on synchronous parallel controller,the thesis gives the specific synchronous parallel steps to adjust the frequency,amplitude and phase values to be the same with the power grid,realizing smooth interconnection to the grid.Finally,this thesis builds the virtual simulation model of VSG system to validate the effectiveness and practicability of the presented theory and strategy.
Keywords/Search Tags:virtual synchronous generators, microgrid inverter, frequency and voltage controller, coordinate parameter design, pre-synchronization interconnection
PDF Full Text Request
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