Dynamic Characteristics Analysis Of Power System With Controllable Inertia Generators

The characteristics of the renewable energy generators represented by wind generation are highly random.The variable speed wind turbines,due to the converter control link,which is electrolytically coupled and present a large characteristic difference with the traditional generators.Wind turbines with additional inertia control can respond to the dynamic behavior of the grid.Large-scale access to the grid means that the system will have a large number of controllable inertia,which will affect the dynamic characteristics of the grid.This paper mainly studies the influence of controllable inertia double-fed induction generator on the system.The research contents are as follows:1)The mathematical model of DFIG is established,and the working principle of the main control system is studied.The response process of DFIG's additional inertia control system and the influence of DFIG speed protection module on the response process are analyzed in detail.Based on this,the DFIG simulation model with additional inertia control is established to lay the foundation for the follow-up work.2)Clarifying the state variables introduced by the DFIG additional inertia control.The influence of the DFIG wind farm access position and control gain of additional inertia control on the system oscillation mode is studied by modal analysis.The analysis results show that the influence of control gain on the oscillation mode is related to the access area.3)Based on the theory of Center of Inertia(COI)?establish COI model that takes DFIG with the additional inertia into account,and the power angle motion equation of the inertial center synchronous machine is derived.The equation shows that the power angle acceleration of the inertial center will be affected by DFIG..4)Based on the principle of inertia control,the dynamic characteristics of DFIG in the transient process are studied.The influence of the operating limit and the operating mode on the dynamic behavior is analyzed.Combined with the derived power angle motion equation of inertia center,the key factors that DFIG with additional inertia control affecting the transient stability of the power system are obtained.