Research On Control Of Distributed Generators Consist Of Solar And Storage Unit Based On Virtual Synchronization Generator

With the serious problems of energy and environment,more and more distributed energy,represented by photovoltaic,participate in power grid.However,a large number of inverters would cause the decline of rotation capacity and the instability of grid.To solve this problem,virtual synchronous generator(VSG)is proposed.It can simulate the characteristics of synchronous generators,increase the inertia of inverters and improve reliability of grid.In this paper,the coordinated control of photovoltaic with storage based on VSG is studied in depth.Firstly,the characteristics of synchronous generators is introduced.By establishing the model of VSG,the process of control is analyzed integrally.It has been proved that inertia is caused by the rotor equation in VSG model.Secondly,synchronous frequency resonance of VSG is introduced.Considering the effect of power coupling,the small signal model is established to explain this phenomenon.It prove that the resonance is associated with line impedance in gridconnected mode.An improved strategy for VSG is designed to damp the resonance and supply the inertia of VSG.After that,by building the models of small signal,synchronous generators and VSG on Simulink,the consistency is proved and the results of strategy meet expectation.Thirdly,a detailed model of photovoltaic is established to analyses operation characteristics.Two traditional maximum power point tracking(MPPT)algorithms are introduced and compared,which show some drawbacks.An improved MPPT algorithm is proposed to satisfy the requirements of photovoltaic with VSG strategy,which can also solve the drawbacks of the traditional algorithm.Finally,in view of the characteristics of photovoltaic,an architecture of photovoltaic with storage is proposed to deal with the fluctuation of solar intensity and temperature.The capacity ratio between photovoltaic and storage is analyzed theoretically,and a strategy of calculation is obtained to determine the capacity of the storage.Base on the physical platform composed of nine VSGs and one SVG,the theory in this paper is verified and applied.