L2 Disturbance Suppression Controller Design for Multiple Time Delays Offshore Wind Turbines

Abstract

With the large-scale development of offshore wind power and the rapid development of smart grid, more and more attention has been paid to the stable operation of wind turbines under various conditions. In the actual operation process of wind turbines, there are inevitably many kinds of uncertain time delays, and also external or parameter disturbances, which affect the stable operation of wind turbines and make the system deviate from the original stable state. Based on Hamiltonian energy theory, the disturbance rejection of doubly fed wind turbines with multiple time delays is studied in this paper. Firstly, the doubly fed wind turbine is Hamiltonian realized to obtain its port controlled Hamiltonian with dissipation(PCH-D) model. Then, aiming at the PCH-D model, a multiple time delays controller is designed based on Casimir function, which can make wind turbines run stably under multiple time delays. Furthermore, based on the passive control theory, L2 gain disturbance rejection control technology is introduced to eliminate the steady-state error caused by external disturbance and improve the stability of wind turbines. Finally, the simulation results show that the proposed controller can effectively solve the multiple time delays and disturbance problems in the system, and improve the stability and anti-interference of wind turbines. INDEX TERMS Offshore wind power, doubly fed wind turbines, multiple time delays, Hamiltonian energy theory, Casimir function, L2 disturbance attenuation.

Finite Frequency H∞ Control for Doubly Fed Induction Generators with Input Delay and Gain Disturbance

“…Theorem 4. For any time delay 0 < τ < τ m , there exists a controller (4) with gain disturbance ∆K = RU(t)TK constrained by (5) such that the closed-loop system ( 6) is asymptotically stabilized and satisfies the FF H ∞ performance, if there exist matrices P…”

“…Using these notations, we can claim the following theorem. constrained by (5) such that the closed-loop system ( 6) is asymptotically stabilized and satisfies the FF H ∞ performance, if there exist matrices…”

“…In DFIG-based wind farms, DFIGs cannot ignore time delay in their input. In [5], considering time delay uncertainties in wind turbines, a multi-delay stabilization via the Casimir function was developed. In [6], a compensator was installed to overcome time delay effects.…”

Recent developments in offshore wind energy systems: Technologies and practices

“…This was done in order to guarantee both safety and a high degree of power tracking capacity. The steady functioning of offshore wind turbines under different time delay circumstances has been analyzed by Tang et al [39] in order to remove the steady state error induced by external disturbance and increase the stability of wind turbines.…”