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Studies On Control Strategies Of Microgrid Inverter

Posted on:2012-08-30Degree:MasterType:Thesis
Country:ChinaCandidate:W B ZhangFull Text:PDF
GTID:2212330338964109Subject:Power electronics and electric drive
Abstract/Summary:PDF Full Text Request
Due to many issues such as power quality, reliability, economy, security, flexibility, in a large power grid with ultra-high voltage, centralized, long-distance transmission, the distributed generation technology with renewable energy begins to develop. With the decrease of traditional primary energy, the energy sources such as solar, wind, geothermal and other clean, environmentally renewable energy are becoming more and more attractive, then how to develop and use them are taken more and more attention. How to convert these new energies into electrical energy and the grid-connected power generation technology are current study key point. A small grid that connecting micro-sources and loads, is known as microgrid, which is controllable and can operate in both grid-connecting and islanding mode, is becoming current research emphasis, and represents a new developing trend.The research background, concept, domestic and overseas developments of microgrid are introduced first in this paper, then the microgrid operation requirements and control strategy are analyzed. Some controlling methods, such as microgrid PQ control, droop-control and reverse droop-control, are introduced respectively and analyzed according to their own advantages and disadvantages. A new control method, which is based on the idea of virtual synchronous generator control strategy, is applied consequently, and then a virtual synchronous generator model is established, which focus on the power/frequency controller and voltage controller designs. MATLAB/Simulink simulation results show that the established virtual synchronous generator, which is based on virtual synchronous generator electromechanical transient algorithms and control system, can simulate the actual output characteristics of synchronous generator, have a good steady-state and dynamic-state regulation performance, then can easily adapt to microgrid operation requirements. A virtual micro-source synchronous generator, consisting of main circuit and control system, is designed finally, in which the DSP TMS320F2808 chip is used as the main controller. The control framework of micro-source, hardware circuit and software for the control system are also designed. The microgrid inverter control strategy is mainly studied in this paper, and a new-type microgrid inverter, i.e. a virtual synchronous generator inverter, is proposed based on virtual synchronous generator. The model of this new-type microgrid inverter is studied and established. The simulation results show that the microgrid formed by this new-type inverters can both operates in grid-connected mode and achieves zero-error control of frequency in islanding operation mode.
Keywords/Search Tags:microgrid, virtual synchronous generator inverter, islanding operation, droop-control
PDF Full Text Request
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