Small signal stability analysis of LADRC based DFIG driven wind turbines during weak AC grid

Abstract

During weak power grid, the interaction between the doubly-fed induction generator (DFIG)-based wind turbines and the power grid impedance can easily induce system instability issue, and thus threaten the safety of the system. The linear active disturbance rejection control (LADRC) is a potential way in improving the damping of the DFIG system, due to its excellent anti-disturbance ability. In this paper, the small-signal impedance model of the DFIG with LADRC is established. Based on the proposed model, the interaction between the DFIG and the weak grid is analysed in detail. Electromagnetic simulations are then performed to validate the correctness of the theoretical analysis. It shows that compared with the traditional proportional integral control with the same control bandwidth, the LADRC can obviously improve the phase margin of the DFIG system, and thus enhance the small signal stability of the DFIG system.