cpVal function: Possible typo about windpowerplants HOT 8 CLOSED

Thank you very much for your message. You are right, my equation in both the Modelica library and the paper "Open Source Library for the Simulation of Wind Power Plants" are wrong.

I fixed the issue in the Modelica library and created the new version v0.9.7 in d36d549.

from windpowerplants.

For the sake of completeness:

Impact of the performed bug fix: All simulation results of the library are now deviating from previous simulation results.

from windpowerplants.

Thank you so much for your attention. I will be using your library for my master thesis, it's great!. For the record, the following are two samples of the error introduced by the typo, calculated by gnu/octave. I don't think it's so bad :)

lambda = 5; beta = 5;
CpHeier(lambda, beta)_100
ans = 14.874
CpHeierTypo(lambda, beta)_100
ans = 12.793
lambda = 8; beta = 0;
CpHeier(lambda, beta)_100
ans = 41.092
CpHeierTypo(lambda, beta)_100
ans = 41.055

from windpowerplants.

Should it be 0.08beta (as proposed by @pablus) or 0.089beta (as in v0.9.7)?

from windpowerplants.

The equation for lambda1 is still not correct as

lambda1 := 1 / (1 / (lambda + 0.089*beta) - 0.035 / (beta ^ 3 + 1));

is used instead of

lambda1 := 1 / (1 / (lambda + 0.08*beta) - 0.035 / (beta ^ 3 + 1));

Fix is performed in 724ae6f.

from windpowerplants.

New release 0.9.8 is created.

from windpowerplants.

OK. Thanks. I just was wondering which coefficient is the right one ...

from windpowerplants.

The new equation of v0.9.8 may cause some numerical problems when simulating, e.g., WindPowerPlants.Examples.GenericPlantElectricRealData. Therefore, I added a numeric "offset" in the equation to achieve stable example simulations:

I thus changed
lambda1 := 1 / (1 / (lambda + 0.08*beta) - 0.035 / (beta ^ 3 + 1));
to
lambda1 := 1 / (1 / (lambda + 0.08*beta + Modelica.Constants.eps) - 0.035 / (beta ^ 3 + 1));

This change which does not affect the overall energy and power harvest.

from windpowerplants.