Analysis of Doubly Fed Induction wind-power generators in LVRT field testing

Doubly Fed Induction Generator (DFIG) is emerging as the most preferred technology on Chinese wind farms. Advantages of DFIG include wide-range speed variability and independent active and reactive control in a cost effective way; the major drawback is its poor dynamic behavior during grid voltage dips. Unlike other published papers that validated low voltage ride through (LVRT) strategies through computer simulations, this paper is the first in China to demonstrate results of real field LVRT tests, thus whether a specified wind turbine satisfies SERC Grid Code or not is justified. The field tests were realized by a voltage emulator connected on the wind turbine low voltage side (690V). Various control strategies such as active/passive crowbar and chopper protections were discussed and verified later in this paper.