Improved Control Method Of Grid-Forming Converter Considering Grid Stability

New energy power generation is connected to the grid through power electronic equipment,which does not have the inertia,which makes the ability of power grid to ensure grid stability worse,and brings severe stability challenges to power grid.In order to solve this problem,the new grid forming converter simulates the function of synchronous motor through control method,provides inertia and stability adjustment mechanism,and improves the stability of high penetration power grid of new energy.In this paper,aiming at the shortcomings of traditional grid-forming converter,it is further designed1.This paper analyzes the DC side voltage collapse problem of grid forming converter control strategy under large load disturbance,and proposes a control strategy based on DC side voltage feedback to solve the DC side voltage collapse problem under large load disturbance;By using Lyapunov method,the stability of VSG control with DC voltage feedback is proved theoretically.Finally,ieee-9 bus system and dual area four machine system are used to verify the effectiveness of the proposed method.2.This study shows that several traditional control methods of grid forming converter have the problem of DC voltage collapse when the load is large disturbance.Combining the DC voltage feedback control strategy with other grid connected control strategies,including the traditional droop control strategy and the schedulable virtual oscillator control strategy,can effectively solve the problem of voltage collapse.In theory,this method can make the DC side and AC side coordinated control,ensure the AC test performance and the stability of DC side.Finally,ieee-9 bus system and dual area four machine system are used to verify the two improved control strategies.The results show that the droop control combined with DC side voltage feedback and schedulable virtual oscillator control can avoid DC voltage collapse and improve the anti-interference performance of the system.At the same time,it shows that the control strategy based on DC side voltage feedback proposed in this paper is universal.3.The new energy grid controlled by virtual synchronous machine has the similar low-frequency oscillation problem of traditional synchronous generator.When the system is excited rapidly,the low-frequency oscillation of frequency and power will occur.According to the solution of low-frequency oscillation in synchronous generator control,this paper gives the voltage control a superimposed compensation voltage to act as the power system stabilizer in synchronous machine,It can effectively counteract the negative damping of the system,stabilize the system voltage and suppress the low-frequency oscillation of other electrical quantities in the system.4.Starting from the overall situation,the traditional generators,new energy grid connected equipment,loads and energy storage equipment are abstracted into nodes in the graph,and the frequency stability of power system is connected with the eigenvalue property of Laplace matrix of complex network graph.The frequency stability of power grid is analyzed from the perspective of complex network,and the theorem to ensure the frequency stability of power grid is given,It is proved theoretically.