A robust control strategy to improve transient stability for AC-DC interconnected power system with wind farms

Abstract

In view of the variable parameters that affect the transient stability of electromagnetic torque and mechanical torque balance in AC-DC system, and the uncertainty of wind power in large-scale interconnection of wind farm. This paper proposes a linear parameter varying (LPV) robust feedback control method for transient stability of interconnected systems. The proposed LPV robust feedback control method uses the DC channel power control and the mechanical power in the interconnected system as the control target to improve the transient stability of the interconnected system with wind farm channel. Firstly, aiming at the strong nonlinear characteristics of the interconnected system, the power balance and the wind power output uncertainty in the transient process, the transient process is designed as a linear model of variable parameters. Then, the H∞ robust output feedback controller is designed according to the LPV model. The transient stability control strategy topology and transfer function of the interconnected system are proposed. Finally, the proposed scheme is verified by an interconnected system formed by four equal-value grids through AC and DC lines in a digital simulation platform. The results show that the LPV robust feedback control model proposed in this paper has better response characteristics and transient stability control effects for interconnected systems with wind power weak sending-end system.