Hello,

I’ve evaluated a “pseudo-steady” power curve for a turbine using a Taylor’s series approach with turbulence intensity for different wind speeds. I was provided with power/thrust curves for a range of different wind speeds and quoted turbulence intensities. My back-calculated steady-power coefficient looks very cubic all the way up to rated, which I found somewhat reassuring.

The problem that I have is now, given I’ve come up what I believe to be a sensible aerodynamic model and control system for the steady-state and zero turbulence performance, I barely see any variation in the binned power curve when I introduce turbulence into my simulations.

The true turbulent thrust and power curves I have available to me have a marked increase in smoothing as a function of turbulence intensity around rated speed, however my simulations are not capturing this at all.

In a helpful reply to another post I made, it was previously suggested I use peak-shaving and set-point smoothing to capture that effect. However, with regards to peak shaving, I no longer I believe I require it in steady-state and zero-turbulence because I think my power curve is fairly cubic in nature up to rated wind-speed. I’m am using set-point smoothing.

The turbulent simulations I’m running I believe are fairly realistic of a normal test situation. I modelling the problem aero-structurally, although I have disabled yaw and drive-train flexibility. All other DOFS are active and I’m using a ROSCO controller. I’m running ElastoDyn, AeroDynv15, SubDyn ServoDyn and InflowWind.

The difference between the power and thrust curves I’m evaluating for different turbulence intensities is essentially negligible which doesn’t make sense to me.

I’m evaluating turbulent thrust and power coefficients by taking the average generator power (W) / rotor thrust (N) and normalising by the standard terms using 10-minute average wind speed at hub height. I’ve included a power-law exponent of 0.1. Wind-speed at hub height, rather than equivalent wind speed is the method which was used by the provider of the turbulent power curves to me.

Are there possible aspects of a given simulation setup up (such disabling drive-train flexibility) which could explain this behaviour (no effect of turbulence of power/thrust curves) ? Should one expect the ROSCO controller inputs, such as target frequency and damping of VS and PC regions to effect the response under turbulence? Responding too quickly or slowly?

Additionally, because I’d specified the turbulence intensity in TurbSim, I’m not using any scaling in InflowWind (=0). I’m also using TSR tracking in the controller. Could this be the cause?

I’d appreciate any possible guidance.

Best wishes,

Sam