DFIG with grid-connected rotor for wind energy conversion system

Improved efficiency of DFIG wind energy conversion systems by operating in the rotor-tied configuration

“…For these wind turbine parameters, the wind speed range of v w = [4,12] m/s corresponds to the slip range of |s| > 2 and ω r = [−3π60, −π60] rad/s. This region results in the stator power converter handling up to one third of the maximum power output [2].…”

“…In the analysis and experiments performed here, only the hysteresis component of the core loss is accounted for, estimated using [2], [3] …”

“…We lack accurate knowledge of the core dimensions of the machine under test. Therefore, to avoid disassembling the machine, we estimate the core volumes using the method described in [2]. Tooth and yoke regions are considered separately, with assumptions made regarding the machine design that lead to simplified volume approximations requiring only the air-gap radius and stack length.…”

“…The steady-state operation of a rotor-tied DFIG was recently studied in the context of a variable-speed wind energy conversion system [2]. Therein, an appropriate operating region was determined based on the requirement to maintain a similarly partially rated power electronic converter.…”

The doubly-fed induction generator in the rotor-tied configuration

“…As a means to improve the energy conversion efficiency of the machine, we consider reversing the connections so that the rotor windings are connected directly to the grid, whereas This idea was recently proposed by You et al [11], where it was concluded that the physical size of the machine can be reduced when designed specifically for rotor-tied operation. Steadystate operation of such a DFIG was studied in the context of a variable-speed wind energy conversion system in [16]. Therein, an appropriate operating region (slip and rotor speed) was determined based on the electronic power converter maximum power rating.…”