Research On Stability Analysis And Inertia Optimization Of Single-Phase Virtual Synchronous Generator

With the increasing penetration of renewable and distributed energy,the application of inverters has become more and more extensive.Since the conventional inverters have almost no moment of inertia,which may result in poor frequency stability of the inverter.When the number of inverters increases to a certain extent,the inertia of the whole power system will be greatly reduced,which will eventually threaten the normal operation of the power grid.Virtual synchronous generator technology makes the inverters have similar operation characteristics with synchronous generators,as a result,it is helpful to improve the total inertia and stability of power grid system.In recent years,it has attracted wide attention.However,there is a coupling relationship between the virtual inertia of traditional virtual synchronous generators and the stability of the system,which limits the selection of virtual inertia,and also limits the inertia support of virtual synchronous generators,reduces the practicability of virtual synchronous generators.In this dissertation,the control algorithm of virtual synchronous generator is studied as follows:Firstly,the coupling relationship between virtual inertia and its stability in traditional virtual synchronous generators is analyzed.The inherent problem of inertia limitation is revealed.The basic principle of hold filter is introduced.The low-pass and inertia characteristics of hold filter are revealed.Then,taking a single-phase virtual synchronous generator as an example,a hold filter is introduced into the forward path of the active power loop,and an inertia optimization method of the virtual synchronous generator based on hold filter is proposed,which realizes the decoupling between the inertia regulation and the system stability.The inertia optimization method can be used to adjust the inertia of single-phase inverters more freely according to the system requirements without affecting the frequency stability.A new degree of freedom is provided for the inertia optimization of single-phase inverters.Finally,the corresponding simulation and experimental platform is built to verify the correctness of the proposed method.Finally,the stability of single-phase virtual synchronous generator with hold filter is analyzed by small signal modeling method.A parameter design method of single-phase virtual synchronous generator considering the effect of hold filter is proposed.It provides some guidance for parameter design of power loop of single-phase virtual synchronous generator.The correctness of the analysis and the effectiveness of the proposed method are verified by simulation and experiment.