Research On Physical Constraints Of Energy Storage And Parameters Online Setting Method For Virtual Synchronous Machine

In order to solve environmental problems and energy crisis,distributed generators(DGs)are quickly developing in recent years.Apart from DGs’ intermittent nature,most of the DGs do not contribute inertia or damping to maintain the system frequency stability.Inertia and damping in traditional power system mainly come from synchronous machines.In order to solve the low inertia and under damping problems,virtual synchronous machine(VSM)has been proposed.The VSM with energy storage system(ESS)can operate to provide inertia and damping through charging or discharging.And VSM is equivalent to traditional synchronous machine(SM)in partial band.Firstly,this paper summarizes and reviews the development status of VSM based on the existing literature at home and abroad.And this paper also summarizes the paper’s work.In order to solve the issues on parameters setting caused physical constraints,the mathematical model of VSM is built first.The volume of ESS equipment is usually determined by investment,installation environment and other factors.Once power and energy volume of ESS equipment are fixed,the possible inertia and damping characteristics that VSM could mimic are restricted.The physical constraints presented by inertia constant,damping factor and operating point are acquired through theoretical analysis in order to get the parameters setting range.And parameters setting range and the operating boundary of VSM are both studied.Simulation results are also presented once the physical constraints are broken.The power and energy margins of ESS is changing all the time.In order to make the inertia constant and damping factor always satisfy the physical constraints,this paper proposes the VSM parameters online setting method based on the physical constraints.And the online setting module program is also presented.The validity of the method is verified by simulations.Moreover,theoretical analysis and simulations are carried out based on the summary of the literatures to select the primary frequency modulation model.And it provides a theoretical basis for the selection of a primary frequency modulation model of VSM.Finally,this paper summarizes the research content and innovation points.Future works are also discussed.