Direct Active and Reactive Power Regulation of DFIG Using Sliding-Mode Control Approach

Abstract

This paper presents a new direct active and reactive power control (DPC) of grid-connected doubly fed induction generator (DFIG)-based wind turbine systems. The proposed DPC strategy employs a nonlinear sliding-mode control scheme to directly calculate the required rotor control voltage so as to eliminate the instantaneous errors of active and reactive powers without involving any synchronous coordinate transformations. Thus, no extra current control loops are required, thereby simplifying the system design and enhancing the transient performance. Constant converter switching frequency is achieved by using space vector modulation, which eases the designs of the power converter and the ac harmonic filter. Simulation results on a 2-MW grid-connected DFIG system are provided and compared with those of classic voltage-oriented vector control (VC) and conventional lookup table (LUT) DPC. The proposed DPC provides enhanced transient performance similar to the LUT DPC and keeps the steady-state harmonic spectra at the same level as the VC strategy. Index Terms-Constant switching frequency, direct power control (DPC), doubly fed induction generators (DFIGs), sliding-mode control (SMC), wind power. NOMENCLATURE I s , I r Stator, rotor current vectors. L m Mutual inductance. L s , L rStator, rotor self-inductances. L σ s , L σ r Stator, rotor leakage inductances. P s , Q s Stator output active and reactive powers. R s , R r Stator, rotor resistances. U s , U r Stator, rotor voltage vectors. θ r Rotor angle. ψ s , ψ r Stator, rotor flux linkage vectors. ω 1 , ω r , ω slip Stator, rotor, and slip angular frequencies. Subscripts α s , β sStationary α s β s axis. α r , β r Rotor α r β r axis.

A Complete Modeling and Control for Wind Turbine Based of a Doubly Fed Induction Generator using Direct Power Control

“…The eight voltage vectors of a two-level RSC which the vector plane is divided to six sectors Instantaneous active and reactive powers can be estimated from relationships [12]:…”

“…In order to overcome the aforementioned problems, different nonlinear control methods such as direct torque control/direct power control (DTC/DPC) have been proposed of DFIG based wind turbine systems has proposed recently [11], [12]. These control methods directly detect the error of torque, flux, active power and reactive power and then choose the desired rotor voltage to IGBTs via a lookup [13].…”

Sliding-Mode Control for a DFIG-Based Wind-Power Generation System with Series Grid-Side Converter under Unbalanced Grid Voltage Conditions

“…In [18][19][20], Sliding-Mode Control (SMC) method has been introduced for DFIG control because of its easy implementation and robustness. SMC has been recently introduced for DFIG control connected to the ideal grid voltage because of its easy implementation and robustness [21][22][23][24]. In [25][26][27], SMC has been used to cancel the fluctuation in the electromagnetic torque and output power, but the final performances of applying these control methods are still not satisfactory.…”

A Novel Current Controller Scheme for Doubly Fed Induction Generators

“…Direct Power Control (DPC) techniques which control machine power without the necessity of inner rotor current control loops [7,8] are robust against parameter deviations and grid voltage disturbances. There are reputable studies which use DPC techniques [9][10][11] that system performance is independent on machine parameters and robust against grid voltage problems.…”