مطالعه دقیق توربین های بادی بر اساس ژنراتور القایی دو سو تغذیه برای غلبه بر خطاهای شدید شبکه

This paper studies the effects of voltage sags caused by faults on doubly-fed induction generators to overcome grid faults. A wide range of sag duration and depth values is considered. It is observed that sag duration influence is periodical. Sag effects depend on duration and depth and on the fault-clearing process as well. Two approaches of the model are compared: the most accurate approach, discrete sag, considers that the fault is cleared in the successive natural fault-current zeros of affected phases, leading to a voltage recovery in several steps; the least accurate approach, abrupt sag, considers that the fault is cleared instantaneously in all affected phases, leading to a one-step voltage recovery. Comparison between both sag models reveals that the fault-clearing process smoothes sag effects. The study assumes that the rotor-side converter can keep constant the transformed rotor current in the synchronous reference frame, thus providing insights into wind turbine fault ride-through capability. The voltage limit of the rotor-side converter is considered to show the situations where the rotor current can be controlled. Finally, a table and a 3D figure summarizing the effects of the most severe grid faults on the rotor-side converter to overcome the most severe faults are provided.