Small Signal Stability Analysis Of Virtual Synchronous Generator Based On Reachability Analysis

Due to the aggravation of the global energy crisis and the continuous deterioration of the ecological environment,the traditional fossil energy as the dominant energy structure began to adjust turning to the clean energy for sustainable development in a large scale around the world.Thanks to the maturity of distributed generation technology,a large number of distributed generation systems(DG)are connected to large power grids with grid-connected inverters.Compared with the large-scale renewable energy generation combined to the grid,one of the great advantages of distributed generation is that it has less impact on the stability of power grid.The ongoing evolution of the power system implies a dominant role of power electronic converters,but poses strict requirements on their control strategies to preserve stability and controllability.Therefore the control strategy of these inverters impose a crucial impact on the grid performance.Traditional inverter control strategies,such as PQ control,droop control and so on,can not meet the need of independent autonomy of distributed power supply,and can not provide necessary support for the voltage and frequency of the power system.For the same effect,much of the research activity is focused on virtual synchronous generator(VSG)technology.In this paper,the general control strategy of virtual synchronous generator is discussed in detail,and then its control model is established,including rotor motion model,frequency control model,voltage control model and so on.In order to further study the stability of the control system of virtual synchronous generator,a small-signal model is established based on its mathematical model,and the influence of each parameter variable to the stability of the system is analyzed by the eigenvalue analysis method,.The relationship between the parameters of different variables and the characteristics of the dynamic process of the system is determined.Considering the uncertainty of distributed power generation,it is necessary to linearize the system at the new stable point when the variable parameter deviates from the stable operating point,which brings great difficulties to the analysis of the system.In this paper,the reachability analysis theory is introduced to deal with the influence of the multivariable parameter variation in a certain range on the system,which greatly simplifies the calculation steps,and the results of multiple variables disturbance can be obtained by one calculation.Finally,Finally,the simulation model of the system is built under the environment of MATLAB/Simulink software,which verifies the effectiveness ofthe technology.