Performance enhancement of DFIG-based wind turbines close to the rated operation

Abstract

The reactive power demand of the induction generator is significantly increased when the generator runs close to the rated operating point. The losses are increased due to the increased reactive power flow. Due to the limitation of converter ratings in the doubly fed induction generator (DFIG) system, power clipping may occur at turbine-rated conditions. In this paper, an optimum strategy for reactive power flow in the DFIG scheme is proposed to capture maximum wind power with minimum total losses. The proposed strategy considers the machine-copper loss, converters' loss, and filter loss. Reasonable values for converter ratings are investigated and compared. The modeling of the DFIG-based wind turbine along with its control scheme is designed in Matlab/Simulink environment. Simulation results are presented to ensure the validity and feasibility of the proposed strategy for reactive power management.Index Terms-doubly fed induction generator, reactive power management, loss minimization of wind generation schemes, and wind-based distributed generation.

Loss minimizing operation of doubly fed induction generator based wind generation systems considering reactive power provision

“…1, the steadystate stator and rotor voltages are presented in the following formula [5,11]. Note that all of variables are in per unit (pu) system in the following expression.…”

“…In the control process, the controller should look up the tables to decide the optimal reactive power currents, which would be time consuming. The optimal rotor reactive current formula was derived in [11]. The loss of converters is piecewise linearized in order to derive the optimal rotor reactive current.…”

Flicker minimization of DFIG based wind turbines with optimal reactive current management

“…Consequently, the equivalent resistance of each converter, R con , can be given by piecewise linearization of the relation of converter loss with the square of the current [10], [11].…”

“…However, the algorithm, presented in [5], does not consider the flow management of reactive currents inside the DFIG scheme Typically, the flow of reactive current component in DFIG schemes is associated with power losses. To reduce these losses, numerous management strategies for reactive currents have been addressed in [6]- [11]. The optimal rotor reactive current value was derived for minimal machine-winding copper losses in [6] and [7].…”

“…In [8] and [9], an optimized splitting of the reactive power burden over the rotor-and gridside converters was iteratively investigated. An optimum strategy for reactive current flow, based on total losses minimization, has been analytically derived [10], [11]. Worth mentioning, the aforementioned strategies for reactive current flow are based on enforcing unity power factor at the DFIG terminals.…”