Improved Direct Power Control of a DFIG-Based Wind Turbine During Network Unbalance

Abstract

This paper proposes an improved coordinate direct power control (DPC) strategy for the doubly fed induction generator (DFIG) and the grid side converter (GSC) of a wind power generation system under unbalanced network conditions. Two improved DPC schemes for the DFIG and the GSC are presented, respectively. The DPC for DFIG is to eliminate the torque and stator reactive power pulsations, while the DPC for GSC is to compensate for the pulsations of stator active power. In order to provide enhanced control performance of the overall system, the resonant controllers tuned at the fundamental and double grid frequency are applied in the improved DPC to eliminate the torque and power pulsations produced by the transient unbalanced grid faults, so that the output power of DFIG and GSC can be directly regulated without any necessity of the positive and negative sequence decomposition. The effectiveness of the proposed DPC strategy is verified by the simulation results of a 2-MW DFIG system under unbalanced grid voltage conditions. Index Terms-Direct power control, doubly fed induction generator, network unbalance, resonant controller, wind turbine.

Enhancing the control of doubly fed induction generators using artificial neural networks in the presence of real wind profiles

“…the generated currents and poor current quality, leading to various faults [20,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]. This not only increases maintenance costs but also poses a risk to the grid.…”

“…As a result, adopting the DPC strategy becomes more costly and requires more experimentation. Another proposed solution includes the use of a backstepping controller to enhance the quality of the output current in DFIG system [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. However, the inclusion of a backstepping controller amplifies the complexity and execution challenges associated with Direct Power Control.…”

“…DPC provides a solution to the challenges posed by sensitivity to parametric variation. Research reveals that DPC significantly enhances dynamic response, allowing for rapid and precise control of generated power [ 31 ]. Furthermore, DPC proves effective in minimizing torque and power oscillations within the generator, resulting in a smoother and more stable operational performance [ 32 ].…”

Direct Power Control of Doubly Fed Induction Generator Under Distorted Grid Voltage

“…Several alternative control targets focusing on the elimination of negative component of stator/rotor current, as well as stator active/reactive power and electromagnetic torque pulsation were proposed. Zhou et al [10], [11] explicitly illustrated the unbalanced control strategy using the DPC technique with different stator power compensation item, in which the five different control targets were proposed to improve the DFIG operation ability under transient unbalanced grid voltage.…”

“…Nevertheless, all the aforementioned investigation on the DFIG system under the harmonic voltage is based on the VOC technique, which requires the decomposition of grid voltage fundamental and harmonic components; thus, the closed-loop operation stability and dynamic response of the entire control system will be deteriorated [10], [11]. The DPC technique has been proved to be preponderant for DFIG control, such as simple implementation, fast dynamic response, robustness against parameter variations, and grid disturbance [18], [19].…”