The Topology And Parameters Configuration Of Phase Locked Loop In Virtual Synchronous Generator

For inverters using Virtual Synchronous Generator(VSG)control strategy,Phase Locked Loops(PLL)could provide the frequency and phase information of the Point of Common Coupling(PCC).However,the characteristics of the PLL will be included in the frequency measured,which will affect the dynamics of the VSG.Therefor,this paper has considered the characteristics of the PLL during the process of VSG model building.In addition,the verifications of the model and the control strategy have been given.On the basis of this model,the influence on the VSG of PLL has been analized.According to the analysis,the configuration method of VSG and its PLL has been provided.Based on this method,the parameters of VSG with PLL can be accurately configured to make sure the expected dynamics will be met.Based on the thinking above,this paper firstly researched on the inertia and damping characteristics affectted by the PLL.According to the research results,the mathmatical model including PLL of VSG was provided.The model could accurately describe the VSG's inertia and damping characteristics.This paper provided the verification of the contol effects of the model,such as the power reference following,vitual inertia,virtual damping,primary frequency modulation,secondary frequency modulation,the power dispatching among multiple VSGs,the prevention of the circulation current and the seamless transfer.Moreover,based on the model verified,The mechanism of influence of PLL on the VSG connected to the power grid has been reaserched.For the grid-tied VSGs,a method for calculating the variation of inertia and damping coefficients referring to the pre-set ones has been given,together with its verification in both time and frequency domains.Base on the method,configuration curves of the parameters above and PLL's PI parameters were provided,which can be easily used in engineering projects to fastly configure VSG and its PLL's parameters.For the case that VSG functioning in the island mode,a caomparison between two kinds of primary frequency control was provided and a recommended way was provided to more conveniently configure VSG and its parameters.Additionally,the steady running of VSG with PLL will be promised.