Enhancement of the LVRT Capability for DFIG-Based Wind Farms Based on Short-Circuit Capacity

In this article, an advanced transient voltage control (A-TVC) strategy is proposed to enhance the low-voltage ride-through (LVRT) capability of a doubly fed induction generator (DFIG)-based wind farm (WF). In severe voltage dip (VD) conditions, the DFIG-based WF should stay online to support the grid voltage. However, it may lead to transient voltage instability in the grid. This article proposes a novel A-TVC, which follows the VD conditions and, consequently, improves the LVRT capability of the DFIG-based WF. In this approach, a lookup table is presented to control the transient voltage based on the short-circuit capacity at the point of common coupling (PCC), VD index on the grid, and generated power limitations of the DFIG. By applying the proposed control strategy, the DFIG could not only smooth the dc-link voltage fluctuations and reduce the stator and rotor overcurrents in a faulty grid but also increase the PCC and stator voltages and, thus, enhance the transient voltage stability. Simulations and control-hardware-in-the-loop experimental results validate the effectiveness of the proposed control strategy for improving the LVRT capability of the DFIG in severe balanced and unbalanced VD conditions.