Research on control strategy of improved VSG with power angle compensation and reactive power support capability suitable for hybrid multi-terminal HVDC system

Given the shortcomings of traditional virtual synchronous generator (VSG) strategies, such as poor power angle stability and the inability of reactive power control to be combined with fault ride-through requirements, this paper proposes an improved VSG (IVSG) scheme and applies it to a hybrid three-terminal LCC/VSC-HVDC network to improve the system's fault blocking capability. Firstly, this paper presents the power angle compensation factor β in the active power control loop, which is physically equivalent to increasing the electromagnetic power when the system fails, thereby suppressing the power angle δ rise. Secondly, a reactive power self-adjusting controller is intended to compensate for voltage sag. Meanwhile, the maximum reference reactive power is derived by evaluating the relationship between the suppression of fault current and reactive power, which is coupled with the self-adjusting reactive power to obtain the reference value of the reactive power loop. Finally, a large number of simulation experiments based on Matlab / Simulink compare the proposed method with the traditional VSG strategy to highlight its advantages.