Research On VSG Control Of Adaptive Inertia Damping Cooperative Control

With the exhaustion of fossil energy,new energy resources as the main part of Distributed Generation Sources begins to rise.The new energy is used for power generation,whether it is integrated into a large power grid or a single load for power supply,and the power generation of new energy needs to be transformed by the technology of power electronic transformation,so that a standard power supply can be obtained.But the power electronic conversion equipment does not have the advantages of inertia,large damping,large output impedance of the traditional Synchronous Generator and the like.In the case of distributed energy with high permeability,a large number of power electronic inverters are introduced,resulting in system frequency and power oscillation under the action of disturbance.In order to solve the above problems,a control strategy of Virtual Synchronous Generator based on mathematical model to simulate the external characteristics of SG is adopted.In view of the fact that the traditional VSG control strategy does not significantly improve the stability of grid-connected frequency and power,a VSG control strategy with adaptive inertia and damping collaborative control is proposed.The research contents of this paper are as follows:1.Mathematical modeling of VSG.According to the working mechanism of traditional SG,the inverter control shows the characteristics of inertia and damping.At the same time,the virtual exciter and virtual governor are built to realize the functions of regulating primary frequency and voltage of VSG.In the case of load surge,the inverter based on VSG control strategy can run stably in off-grid and grid-connected control mode,which lays a foundation for the adaptive inertia and damping collaborative control.2.Research on Synchronous Grid Connection Control of VSG.A key technology such as Presynchronous Grid Connection Control based on Phase Locked Loop is designed to achieve the VSG smooth and grid,which is the precondition of grid-connected control model of VSG.3.Analysis of small signal model.The influence of main circuit parameters and inertial parameters on power is analyzed by small signal model.Then,filter parameters are designed according to circuit constraints.Finally,the small signal equation is used to design the parameters of controller.The simulation validates the rationality of designing parameters and guarantees the normal operation of VSG.4.Adaptive inertia and damping control of VSG.The influence of virtual inertia and damping on operation characteristics of VSG is analyzed from the physical characteristics.At the same time,the dynamic response process of VSG under disturbance is studied.An adaptive inertial and damping cooperative control method is proposed and the principle of designing system parameters are given.Then,Lyapunov method is used to judge the stability of the system.It is proved that the system based on the proposed control strategy can run stably.Finally,a VSG control model based on the control strategy is established and compared by simulation.The simulation results show that the overshoot is small and the steady state time is short under the control strategy,which verifies the superiority of the control strategy.