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Research On Circulating Current Control Strategy Of Micro-grid Parallel Inverter

Posted on:2021-01-05Degree:MasterType:Thesis
Country:ChinaCandidate:H P RenFull Text:PDF
GTID:2392330614461193Subject:Control theory and control engineering
Abstract/Summary:PDF Full Text Request
With the improvement of science and technology level and the rapid rise of industrial production capacity,the society's demand for electric energy is increasing day by day.As a new type of power generation system,microgrid has been widely concerned by researchers with its advantages.The inverter plays a central role in the microgrid,so choosing an effective control strategy has a decisive impact on the security,stability,and high-quality power output of the whole microgrid system.Most of the distributed microgrid power generation systems are geographically dispersed,operating in island mode or incorporated into the massive grid as a supplementary part.Therefore,it is of considerable significance to study the inverter's control strategy in the microgrid system.In this study,the stability of a single microgrid system is analyzed,and the topology is applied to multiple microgrid inverters.The simulation platform of multiple microgrid systems is established,and the stability of the system and the parallel circulation characteristics of the microgrid system are analyzed.From the Power Point of view,the traditional droop control strategy is improved to obtain a robust droop control strategy.By setting appropriate parameters,the power matching between parallel systems can be realized.The simulation structure shows that the introduction of a robust droop control strategy can reduce the circulating current between parallel inverters and make the output power of inverters more stable,which can effectively reduce the system fault Generation.In the microgrid system,with the access of distributed power supply,the inertia of power system is lost,and when the inverter is connected to the load through different inverter lines,the system's output power will be unbalanced.The traditional synchronous generator has excellent grid connection characteristics.It can not only realize the compensation of the moment of inertia but also distribute the power according to the capacity.By simulating the operation mechanism of the traditional synchronous generator,the virtual synchronous generator control strategy(VSG)is introduced.The system not only supports the inertia but also distributes the active power accurately.The reactive power control of a virtual synchronous generator can also distribute the reactive power accurately.In the microgrid system,the line presents different impedance characteristics,which affect the selection of a droop control strategy.Based on the VSG control strategy,the virtual impedance is introduced.The equivalent impedance of the inverter can be improved by adjusting the virtual parameters,but the output power of the parallel inverter can be decoupled better.By analyzing the outputpower and circulation diagram of parallel inverters,it is verified that the VSG control strategy with virtual impedance can reduce the circulation between parallel inverters under different loads.
Keywords/Search Tags:parallel inverter, virtual synchronous generator, robust droop control, microgrid, circulation suppression
PDF Full Text Request
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