Virtual Synchronous Generation Research Of Inverters In Microgrid

With gradual depletion of traditional energy resources,distributed generation sources(DGs)centered on new energy sources is on the rise.Constructing Microgrid,which as a way to make room for DGs has a promising prospects.Meanwhile,negative impacts have been brought by the autonomous power system where a lack of inertia is intensified due to the increasing application of power electronic devices.For instance,there are some negative impacts such as weak ability of overload,small output impedance and has barely no inertia.Since the most of DGs need inverters to connect the grid,the issue of lack of inertia has been studied in recent years.Therefore,the virtual synchronous generator(VSG)has been proposed to approach this difficult problem.Here are the research contents about this dissertation.First,we have introduced the fundamental conception of Microgrid including its characteristic and development process and the major control strategy of inverter.Secondly,we have elaborated the operational mechanism and the topology structure of VSG.Meanwhile,we have designed the on-off-grid switch strategy and have demonstrated the validity of this strategy.Thirdly,the relationship between frequency stability and J/D is introduced.The self-adaptive inertia and damping combination control(SAIDC)method is proposed to improve system stability.Finally,tests on the VSG model demonstrate the effectiveness of the proposed method.