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How to define a DLC load case in QBlade-CE?
Hi, I’m new to QBlade. If anyone could help on how I can define a DLC load case like 1.2, 1.4 and 1.5 in QBlade-CE?
I know QBlade-EE has the corresponding function easily, however I have to use QBlade-CE at current stage and need to generate DLC load simulation.
Thank you very much.
Your insight and help will be highly appreciated.
Hi,
it’s possible to generate the exact same DLC (Design Load Case) simulations in QBlade Community Edition (CE) as in QBlade Enterprise Edition (EE). The key difference is that QBlade EE provides full automation for this process, reducing setup time and minimizing manual work.
In QBlade CE, you can set up DLCs manually by configuring the appropriate boundary conditions (e.g., wind, waves, current, etc.) and operating conditions (e.g., power production states, fault scenarios, etc.) according to the specifications outlined in the relevant standards (such as IEC 61400-x). These conditions are then defined within your simulation setup.
Best regards,
David
Thank you David, let me have a try.
Quote from David on 11. April 2025, 13:38Hi,
it’s possible to generate the exact same DLC (Design Load Case) simulations in QBlade Community Edition (CE) as in QBlade Enterprise Edition (EE). The key difference is that QBlade EE provides full automation for this process, reducing setup time and minimizing manual work.
In QBlade CE, you can set up DLCs manually by configuring the appropriate boundary conditions (e.g., wind, waves, current, etc.) and operating conditions (e.g., power production states, fault scenarios, etc.) according to the specifications outlined in the relevant standards (such as IEC 61400-x). These conditions are then defined within your simulation setup.
Best regards,
David
Hi, David,
I have some more specific questions on design load cases perform in QBlade-CE, if you can kindly help. Thank you.
How should I do if I would like to perform the following design load cases 1.2, 1.4 and 1.5? Please see attached two picture files for detailed information.
1. How and where should I define “100s transient and 600s runtime” in QBlade GUI?
2. How and where should I define “six seeds per wind speed”? Should I input “6” in Windfield/Turb Sim/Seed [-]?
3. How and where should I define “V xxx with gust”? I find “NTM” in Windfield/Turb Sim/Wind types for DLC 1.2, however I can’t find “ECD” or “EWS” accordingly for DLC 1.4 and 1.5.
Best regards,
Jianxu
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Hello Jianxu,
aach Design Load Case (DLC) is defined in detail within the relevant IEC standard. Regarding your questions:
1. Simulation Length and Transient Phase
If you wantto run a simulation with a 100-second transient followed by a 600-second runtime, you can set the total simulation length to 700 seconds and discard the initial 100 seconds, which typically represent the turbine and controller startup phase. In QBlade, on the second tab of the Simulation Definition dialog under Stored Simulation Data, you can set “Store Output From” to 100s to exclude this initial transient from the output data.
2. Using Multiple Seeds per Windspeed
Running six seeds per windspeed means generating six distinct wind field realizations, each based on a different turbulence seed. These seeds are used in a pseudo-random but deterministic way to generate the turbulent fluctuations. Using multiple seeds helps ensure statistical convergence and more robust load predictions.
3. ECD and EWS Wind Input
ECD and EWS wind types are deterministic time series, not generated using a turbulence model. QBlade can import these as hub-height time series in the AeroDyn format. You can either generate these series yourself following the IEC definitions or use tools like IECWind to create the hub-height wind files, which can then be loaded into QBlade via the Simulation Definition dialog.
Best regards,
David
Quote from David on 23. April 2025, 22:32Hello Jianxu,
aach Design Load Case (DLC) is defined in detail within the relevant IEC standard. Regarding your questions:
1. Simulation Length and Transient Phase
If you wantto run a simulation with a 100-second transient followed by a 600-second runtime, you can set the total simulation length to 700 seconds and discard the initial 100 seconds, which typically represent the turbine and controller startup phase. In QBlade, on the second tab of the Simulation Definition dialog under Stored Simulation Data, you can set “Store Output From” to 100s to exclude this initial transient from the output data.
2. Using Multiple Seeds per Windspeed
Running six seeds per windspeed means generating six distinct wind field realizations, each based on a different turbulence seed. These seeds are used in a pseudo-random but deterministic way to generate the turbulent fluctuations. Using multiple seeds helps ensure statistical convergence and more robust load predictions.
3. ECD and EWS Wind Input
ECD and EWS wind types are deterministic time series, not generated using a turbulence model. QBlade can import these as hub-height time series in the AeroDyn format. You can either generate these series yourself following the IEC definitions or use tools like IECWind to create the hub-height wind files, which can then be loaded into QBlade via the Simulation Definition dialog.
Best regards,
David
Hi David,
Appreciated with your effort, they’re very helpful. I tried IECWind and generated corresponding DLC 1.4 load cases as inputs of simulation.
There’s some details need your further help and confirmation if possible, I used turbine models of IEA 15MW Monopile and IEA 15MW VolturnUS-S
downloaded from our website （qblade.org/downloads/). And I have the following three questions.
- The load calculated by the software does not include the safety margin (IEC defines 1.25 for load safty-factor), right? Because I calculated DLC1.4, the blade root Max My is about 73MNm, which is exactly 1.25 times different from the 93MNm reported by the IEA official report.
- Why is the load （blade root My as an example） of the floating model （IEA 15MW VolturnUS-S） lower than that of the single pile model （IEA 15MW Monopile）? It is generally believed that the load of the floating model is usually higher than that of the single pile under the same configuration?
- Why does the Cp of the turbine exceed 0.5 and the power exceed the rated value (15MW) during the simulation? I have not changed the default model parameters. Do I need any additional settings?
Best regards,
Jianxu
Hi Jianxu,
No safety factors are applied during the load evaluation in QBlade – these factors are incorporated during the post-processing of the DLC time series.
I can’t comment on why certain loads appear lower in some configurations, as this largely depends on the specific dynamics of each simulation. And these dynamics can be quite different between a bottom fixed and a floating configuration.
A Cp value greater than 0.5 is perfectly acceptable; the theoretical maximum is around Cp~0.59.
Regarding power output: please refer to the values in the Structural Time Graphs. The Aero. Power [W] variable can exceed the specified 15 MW, as it is calculated before accounting for generator and drivetrain efficiency. In contrast, the Gen. Elec. Power [W] should reach exactly 15 MW at above-rated wind speeds.
BR,
David
Thank you, David. They’re quite helpful.
However, I cannot find “Gen. Elec. Power [W]” in “Variables” tap of “Graph Settings” dialog.
By the way, I cannot find “tip-to-tower-clearance” either.
Do you know how and where I can find them? Thank you.
Best regards,
Jianxu
Hi,
Regarding power output: please refer to the values in the Structural Time Graphs.
To change graph types see:
- https://docs.qblade.org/src/user/guigraph/guigraph.html#graph-types
- https://docs.qblade.org/src/user/postprocessing/postprocessing.html#changing-graph-types
BR,
David
Hi David,
I have some doubts about my load calculation results for the DLC1.4 case (please refer to the attached ECD+R. wd for the wind file).
Taking the “Max My” calculated by the IEA_15MW1-Monoile-v1.2 model (downloaded from the QBlade official website) as an example, the calculated result is about 77MNm （please see attached picture Max_My）, which is significantly different from the calculated result of~90MNm in the IEA official report (refer to the attached Load_in_ Report image).
If you could kindly help me see where the problem lies? I actually did not modify the default configurations in the downloaded example model.
I am also attaching the QBlade project file in the attachment for your reference.
Thank you.
Best regards,
Jianxu
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