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Instant load rejection - rotational speed of turbine

I am investigating the waterhammer in a penstock of a turbine. Simulating an instant load rejection (total simulated time 300 s)  in the transient analysis detailed report the table Time - Gate - Flow - Speed - Head of the turbine stops at 47 s. Is there a possible to see the rest of the data?

Thanks, Martha

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  • Hello Scott,
     
    thanks for your clear answer. But I am still wondering about the speed. I attach the diagram of the speed in the case of instant load rejection. Shouldn´t go down the speed faster? At 50 s the speed is still close to the maximum.
     
    Thanks for your answer! Martha
     
    Overspeed.xlsx
  • Hello Martha,

    This maybe related to the gate closure pattern. To look into this, I may need to see the model. There are two options for sharing your model files on BE Communities. If you would like the files to be visible to other members, compress the files into a zip file and upload them as an attachment using the ‘Advanced Reply editor’ before posting. If your data is confidential, you can follow the instructions in the link below to send it to us via Bentley Sharefile. Files uploaded to Sharefile can only be viewed by Bentley.

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    If you upload the model to Sharefile, please post here so that we know the model is available.

    Regards,

    Scott

    Answer Verified By: Martha 

  • I haven't really investigated your results, and I am not a hydro power expert, but if you have a big heavy turbine that suddenly has no load applied to it, it's going to speed up and keep spinning for quite a while.

    Even when the wicket gates are 20% open, you probably still have a decent amount of water going through them to keep the turbine spinning. And without a load on the generator to 'put the brakes on', there isn't much reason for the turbine to slow down, is there?  

    regards,

    Mal

          

    Answer Verified By: Martha 

Reply
  • I haven't really investigated your results, and I am not a hydro power expert, but if you have a big heavy turbine that suddenly has no load applied to it, it's going to speed up and keep spinning for quite a while.

    Even when the wicket gates are 20% open, you probably still have a decent amount of water going through them to keep the turbine spinning. And without a load on the generator to 'put the brakes on', there isn't much reason for the turbine to slow down, is there?  

    regards,

    Mal

          

    Answer Verified By: Martha 

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