Title:Stability Analysis of Direct-drive Wind Turbines Connected To Weak Grid Using Linear Immunity Impedance Modeling
Volume: 18
Author(s): Can Ding, Houjun Yang*, Yudong Shi and Ying Bo Ji
Affiliation:
- China Three Gorges University College of Electrical Engineering & New Energy, Yichang, China
Keywords:
Weak Grid, LADRC, sequential impedance model, direct drive, permanent magnet, synchronous generator, SSO, sensitivity analysis.
Abstract:
Background: With the direct-drive wind turbine connected to the weak grid, subsynchronous
oscillation (SSO) problems occur frequently. The use of traditional control strategies to
inhibit it has a poor effect and will seriously threaten the stability of system operation.
Methods: This paper initially analyzes the factors that give rise to subsynchronous oscillation
(SSO) based on the established sequential impedance model for direct-drive wind power grid connection.
Through impedance sensitivity analysis of the control parameters, it is found that the proportional
gain of the current loop and that of the phase-locked loop are the dominant factors generating
the risk of SSO. Secondly, considering that Linear Active Disturbance Rejection Control
(LADRC) has a faster response speed and stronger anti-disturbance ability compared with the traditional
Proportional Integral (PI) control, this paper replaces the phase-locked loop and currentloop
PI control with the self-resistant controller. The second-order extended state observer is employed
to perform real-time estimation and compensation of system perturbations.
Results: After performing simulation and frequency domain analysis on the MATLAB/Simulink
platform, it is found that compared with traditional PI control and voltage feedforward control
strategies, the direct-drive wind power grid-connected system using LADRC control can effectively
suppress oscillations under different weak grids and possess better robustness.
Conclusion: The direct-drive wind power grid-connected system equipped with LADRC control
can effectively suppress oscillations under different weak grid conditions and shows good robustness.
