Influence of rotor structural dynamics representations on the electrical transient performance of FSIG and DFIG wind turbines

Abstract

An assessment of the impact that the representation of rotor structural dynamics has on the electrical transient performance of fixed-speed induction generators (FSIGs) and doubly fed induction generators (DFIGs) wind turbines is presented. A three-mass model that takes into account not only the shaft flexibility but also the blade flexibility in the structural dynamics is developed and used to derive an effective two-mass model of the drive train dynamics, which represents the dominant natural frequency of vibration of the rotor structure. For the purposes of this investigation, the dynamic performance of both FSIG and DFIG wind turbines is evaluated during electrical transients such as a three-phase fault in the network. The studies are conducted in the software code Bladed, where a detailed representation of the structural dynamics is used to derive the three-mass model and the effective two-mass model. Simulation results which illustrate how these representations of the rotor dynamics affect the response of the wind turbine during the fault are presented and discussed

Active damping of torsional vibrations in the drive train of a DFIG wind turbine

“…However, the rotor of modern wind turbine is large and long and cannot be simply considered as a rigid body. In the study of electrical transient performance, it is also important to consider the turbine rotor dynamics [14]- [15]. The reason is that the blade edgewise symmetrical mode couples directly to the drive train so if this mode is excited it will also lead to the torsional vibration.…”

Reduced-Order Models of Squirrel-Cage Induction Generators for Fixed-Speed Wind Turbines Under Unbalanced Grid Conditions

“…In practice, a two-mass model ( Fig. 1) is accurate enough to represent the dynamics of a fixed-speed WT [12]- [13]. Considering the motor sign convention and referring all the values to the high-speed shaft (noted with a prime), the mechanical equations of this model are [14]:…”

Offshore Wind Energy Conversion System Connected to the Electric Grid: Modeling and Simulation

“…The connection between the three masses is made through elastic couplings [11]. This three mass model has been proven as a good option [1] to study the system behavior in response to heavy disturbance.…”

“…An equivalent three-phase active symmetrical circuit given by a series of a resistance and an inductance models the electric grid. Thus, the electric current injected into the electric grid is given by: 6 M. Seixas et al (11) In transient simulations this is the model that is normally used and corresponds to the model of an infinite grid linked by the equivalent series impedance.…”