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Study On Control Strategies Of Inverter Based On Virtual Synchronous Generator(VSG) Model

Posted on:2014-06-08Degree:MasterType:Thesis
Country:ChinaCandidate:S ShaoFull Text:PDF
GTID:2252330425981782Subject:Power electronics and electric drive
Abstract/Summary:PDF Full Text Request
The current situation, topology and control strategies of a photovoltaic inverter fornew energy generation are analyzed in this paper, the simulation models based onVirtual Synchronous Generator (VSG) are built by means of analyzing Controlstrategies of the inverter based on VSG ideas, and the results of simulation areanalyzed briefly, which can be divided into four parts.Firstly, the current situation of inverter are introduced,the main structure ofinverter are listed, and the mathematical relationship are analyzed briefly as well asthe main control strategies of inverter are focused and summarized.Secondly, the control strategies of inverter based on VSG are analyzed: theworking principle of speed regulator and excitation regulator are elaborated from therotor mechanical equation and stator electrical equation of the actual synchronousgenerator. External characteristics of the Virtual Synchronous Generator, topology andworking principle of inverter are combined, and the control strategies of inverterbased on VSG ideas are proposed in this paper after a certain mapping and physicaltransformation, then the frequency, voltage and power regulation characteristics areanalyzed theoretically.Thirdly, the parameters of LCL filter are given and the frequency control model,voltage control model, power control model of the inverter based on VSG areestablished by MATLAB.1) Frequency control model. A closed-loop controller forspeed is taken as an example, the adjustment process caused by the dynamic changesof speed is analyzed systematically, moreover, the inpmortance to stablity of speed isanalyzed while the relationships between theoretical calculated value and referencevalue of electromagnetic power are considerated.2) Voltage control model. Anexcitation regulator for example, the principle and significance of excitation currentregulation which caused by the dynamic changes of voltage are illustrated, theimportance to stability of voltage is analyzed while the relationship betweentheoretical calculated value and reference value of reactive power are considerated,and the detection conditions of voltage are classified and discussed.3) Power controlmodel. The relationship between output power of inverter and the actual powercapacity carried by the load are analyzed, furthermore, the importance to maintainstability of frequency and voltage used by the output power of inverter is stated.At last, the system are simulated on the foundation of aforementioned models, and the experimental waveforms in tracking with the frequency, voltage and power areanalyzed in stand-along and grid state,meanwhile,the operating characteristics ofsystem are verified by the simulation and experimental results.
Keywords/Search Tags:Inverter, Control Strategy, Virtual Synchronous Generator (VSG), Regulator, LCL Filter
PDF Full Text Request
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