Control of Doubly Fed Induction Generator Based on State Dependent Riccati Equation

Integrated wind turbines are required to have LVRT abilityduring grid fault according to Chinese national standards, i. e., they are supposed to remain grid-connected within certain realms of voltage sag and offer dynamic reactive power support, etc. In order to improve LVRT ability of DFIG, a controller based on state-dependent Riccati equation (SDRE) is proposed in this paper. Due to its design flexibility, SDRE controller can optimize system's dynamic response and guarantee asymptotic stability in a large scope through real-time optimization of state-dependent coefficients. For DFIG, this paper proposes SDRE controller in cooperation with active crowbar circuit to comply with national standards. In comparison with commonly used PI controller and strategy of crowbar circuit being continuously on during the fault, simulation under threephase fault shows that the proposed control strategy has better LVRT performance.