Grid-Forming Type Vpss Control Method Based On Double-Loop Architecture Combining Virtual Angle With Virtual Excitation

Because the new energy power generation unit does not have inertia and damping characteristics,the anti-disturbance ability of the power system is weak and has great operation risk.However,due to the introduction of the traditional rotor motion equation of synchronous generator,the dynamic stability of synchronous motor is also introduced into the active support control.Therefore,this paper mainly studies the stability of new energy grid connection,and based on the third-order model,designs the virtual excitation PSS link based on active support control by simulating the traditional PSS control principle.At the same time,because the power oscillation problem is essentially the continuous increase oscillation of power angle caused by negative damping,this paper designs the virtual power angle PSS link based on the flexibility of power electronic devices,which directly controls the power angle,further restrain the power oscillation caused by new energy units and further enhance the dynamic stability of new energy power system.Firstly,this paper presents the network active support control strategy based on the third-order model of synchronous generator,and gives the control models of virtual governor and virtual impedance in detail.At the same time,the linearization model of single-machine infinite bus system is constructed to facilitate the subsequent damping characteristic analysis of active support control new energy units.Finally,by building a four-machine two-zone simulation model in the simulation software,the active support third-order model and the traditional second-order model are simulated and verified,and their support ability to the parallel node voltage in case of system failure is compared.Secondly,due to the rigid rotor structure of the traditional synchronous generator,it can not be directly controlled when the system power angle-oscillates.Therefore,this paper proposes a virtual PSS control method based on virtual power angle excitation double-loop architecture,which can effectively solve the power oscillation problem caused by the active support new energy unit connected to the power grid.At the same time,the power oscillation principle of the actively supported new energy unit is analyzed by using the damping torque method,and the parameters of the virtual power angle-excitation double-loop architecture are configured to improve the control effect of the virtual PSS.Then,this paper designs a variable coefficient control link of virtual PSS,which optimizes the control effect of virtual PSS by flexibly adjusting the gain coefficient of virtual PSS.Furthermore,a single-machine infinite bus system simulation model is built in the simulation software,and the simulation results verify the proposed method.Finally,the control effect of virtual power angle PSS in multi machine power system is mainly analyzed.Firstly,the state equation of multi-machine power system is derived,the oscillation mode of the system is analyzed by calculating the eigenvalues,and the PSS parameters of virtual power angle are set by residue method.Then,a simulation model is established to verify the control strategy in a multi-machine system.