Modeling dynamic stall of an airfoil with vortex generators using a double-wake panel model with viscous–inviscid interaction

Vortex generators (VGs) have been widely applied to wind turbines thanks to their potential to increase aerodynamic performance. Due to the complex inflow perceived by a rotor and the proneness to flow separation, VGs on wind turbines usually experience highly unsteady flow. While there are models that exist to simulate the steady effects of...

Controlling dynamic stall using vortex generators on a wind turbine airfoil

Vortex generators (VGs) have proven their capabilities in wind turbine applications to delay stall in steady flow conditions. However, their behaviour in unsteady conditions is insufficiently understood. This paper presents an experimental study that demonstrates the effect of VGs in unsteady flow, including controlling and suppressing the...

Electrical modeling of cylindrical dielectric elastomer transducers

Dielectric elastomer transducers (DETs) are commonly modeled by lumped-element models (LEMs), however such models do not capture the cutoff behavior that manifests at relatively low frequencies due to the high resistivity of the stretchable electrodes. Moreover, the contribution of the electrodes into the lumped series resistance is not...

An integral boundary layer engineering model for vortex generators implemented in XFOIL

To assess and optimize vortex generators (VGs) for flow separation control, the effect of these devices should be modelled in a cost and time efficient way. Therefore, it is of interest to extend integral boundary layer models to analyse the effect of VGs on airfoil performance. In this work, the turbulent boundary layer formulation is...

Lifetime comparison of power semiconductors in three-level converters for 10MW wind turbine systems

The power electronic converter, especially the power semiconductor, is a major contributor to the failure rates of the wind turbine drivetrain. As the temperature is a major driving factor behind the failure mechanisms of these power semiconductors the choice of topology and switching strategy can have a significant effect on the reliability...

Experimental parameter study for passive vortex generators on a 30% thick airfoil

Passive vane-type vortex generators (VGs) are commonly used on wind turbine blades to mitigate the effects of flow separation. However, significant uncertainty surrounds VG design guidelines. Understanding the influence of VG parameters on airfoil performance requires a systematic approach targeting wind energy-specific airfoils. Thus, the 30...

A Review of Methods to Increase the Availability of Wind Turbine Generator Systems

Availability is an important factor to be considered when designing wind turbine generator systems. The quest for increasing availability is based on the following five design approaches - design for component reliability, active control for reliability, design for fault tolerance, prognostics, and design for maintainability. This paper reviews...

New bearingless generator with buoyant rotor for large direct-drive wind turbines

Energy Storage and Power Management for Typical 4Q-Load

Diesel generators in small electricity grids are mostly not used in a very efficient way. The reason for this is twofold. First of all, the efficiency of a diesel generator is dependent on the ratio determined by the average power divided by the peak power of the generator. The smaller this ratio is, the lower the efficiency. Furthermore, some...

Investigation on the Possible Use of Magnetic Bearings in Large Direct Drive Wind Turbines

A direct drive generator used in wind turbine has high energy yield compared to other drivetrain topologies and low maintenance is expected as the technology matures. On the other hand direct drive generator weight and size increases rapidly when scaled up to larger units. This paper will investigate the possibility of weight reduction of large...

Operation of grid-connected DFIG under unbalanced grid voltage condition

Doubly fed induction generator (DFIG) still shares a large part in today's wind power market. It provides the benefits of variable speed operation cost-effectively, and can control its active and reactive power independently. Crowbar protection is often adopted to protect the rotor-side voltage source converter (VSC) from transient overcurrent...