Powerflow fails on huge converted GLM

2013-01-11
2013-03-16
  • David Pinney

    David Pinney - 2013-01-11

    Hi Forum,

    I've got a glm that won't run and was wondering if you all have any debugging ideas. Voltage outputs are lots of 0s and -1.#IND float overflows.

    The glm in question is here. It was created by converting a Windmil feeder definition.

    I've tried… many debugging attempts. I've removed almost everything but lines, nodes, transformers and loads; given every class of object the same configuration; and I've used the safest default values I could find. Still won't run.

    What I've tried so far is in this document here.

    Have I clearly missed some debugging approach? Is there a tool that's handy for debugging glms that won't run?

    Thanks,
    dpinney

     
  • Jason Fuller

    Jason Fuller - 2013-01-12

    dpinney,

    That was a tough one to track down.  Looks like we have been missing an error check on the center tap transformers.  This has been corrected in time for the v2.3 release, so thanks for catching it.

    The center tap transformers act not only as a step down from (say) 2400 V to 120 V, but also as a translation between the three-phase (ABC) system to the split-phase (S) system.  On the split-phase side of the model, we use triplex_node, triplex_meter, and triplex_line to indicate the split-phase 120/240 volt system.

    For the implementation, look at (we are still working on this, but the center tap example is already done):

    https://sourceforge.net/apps/mediawiki/gridlab-d/index.php?title=Beginner%27s_Guide_to_GridLAB-D

    There is also a little bit more explanation on another forum post (with a nice, fun ASCII drawing):

    https://sourceforge.net/projects/gridlab-d/forums/forum/842562/topic/5094520

    But, effectively, you will to make your model look something like this:

    object node {
       phases ABC;
       name node1;
       ...
    }
    object transformer { 
       configuration object transformer_configuration {
          powerC_rating 50 kVA; 
          primary_voltage 2400.0; 
          secondary_voltage 120.0;  
          connect_type SINGLE_PHASE_CENTER_TAPPED;  
          ...
       };   
       phases CN;  
       from node1;  
       to triplex_node1;  
    }; 
    object triplex_node {
       phases CS;
       name triplex_node1;
       ...
    }
    

    You can add your loads back in, but you will need to use the triplex "load" format:

    object triplex_node {
       phases CS;
       name triplex_node1;
       power_1 1000; // Watts on the #1 120 V circuit
       power_2 1000; // Watts on the #2 120 V circuit
       power_12 1000; // Watts across the phase 1-2 240 V circuit
       // use power_12 if you don't care about secondary phase imbalances
    }
    

    Hope this helps.

     
  • Jason Fuller

    Jason Fuller - 2013-01-12

    Oops, sorry.  Typo.  The transformer object phase should be "CS"

     
  • David Pinney

    David Pinney - 2013-01-19

    Thanks, jcfuller.

    I fixed the triplex system, and that pretty much did the trick. After that was in there, the gridlab process caught a few more problems with the glm: convergence errors, getting rid of some <1 foot lines and 0.0004 W constant power loads fixed that. Now it runs and the voltages look great.

    Help much appreciated!

     

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