Ventana software support forum

Administrator wrote: ↑Wed Oct 24, 2018 10:18 am Have you looked at the sample model that comes with Vensim for the allocation functions?

Yes, I looked at them and as priority system does not have possibility for price preferences, I was just wondering how to model thess auctions( Uniform or Pay as bid) without using external function.

Hi, I want to simulate a pay as bid auction in which all suppliers can sell their electricty to auctioneer with their proposed price to fullfill the demand without using external function. Is it possible to model it in Vensim with some function like Allocate Available? The thing is that, how to impl...

If you search the source code of the external functions, do you see anything like "node descriptions"? I've never seen those before, and they mean nothing to me. And searching the Vensim source code gives no match on "node descriptions". It looks like some custom code that reads...

Administrator wrote: ↑Wed Oct 17, 2018 2:43 pm Is this from Vensim? I don't recognize the errors at all.

I have attached the error. My model has some external functions but its compiling process goes well and this error comes, when Vensim is simulating.

Hi, I have implemented new feature to my model but when I run it after completion of compiling process, I encounter with "floating point overflow-saving to time 167.000" error, but in command these errors are visible: ERROR: line 195 of input - wrong value of parameters in the arc line. ER...

Administrator wrote: ↑Tue Oct 09, 2018 9:33 am I'd assume each company has a price that they bid at, and you select a winner based on this price.

When the winner is selected, I'd use a level to store a value of 1 for 20 rounds. If the value is 1, make the price that they bid at very large.

Thanks a lot for your helpful suggestion.

Hi, I have one question, which is approximately related to first question of here. I want to model a repeated electricity auction. In this auction, winner of each auction, should be able to sell freely for 20 further rounds because by winning once, auctioneer gives him/her guaranteed purchase for ne...

tomfid wrote: ↑Mon Sep 24, 2018 12:31 pm If you need a trigger for the market event, PULSE TRAIN might be helpful.

Thank you so much. I just needed a function like what you suggested.

Hi, My model simulates electricty market(auction of electricity) houlry for 35 years. I am adding new capacity market for renewables to it which should be simulated each 3 months(4 times per year). I would like to ask you that is there any function which could be helpful for this modeling? Best Rega...

Do you simply want to change the time step? Yes but it should make sence from theorotical perspective as well. My model solves electricty market(dispatching) of european countries with houlry resolution but I want to generat data with more time reslotion(15 minutes). What is differnce between chang...

Hello, My model dispatches the whole electricity market hourly. It has an external optimization function that dispatches each hour separately, so hours (time steps) are not connected to each other like optimization models. I want to increase its time resolution to 15 min, which some changes to suppl...

I think the problem is exactly what the error message reports - you have different subscripts on the right and left side of the equation. "ps hydrostation small" vs. "ps hydrostation small group." That only works if you have one mapped to the other. Yes, your are right. I fixed ...

Can you upload the model? Unfortunatley, i am not allowed to upload it. When I added new region(country) to my model I did not get any error like this( of course because there is no subrenge for regions) but when I add new powerplant which is Pump hydro type that has such these subrenges I get this...

Hi, My model includes 387 power plants that for Hydro power plants it has 2 categories; pump hydro storage(it has two type small power plants and big power plants) and reservoirs hydro station. My problem is that when I add new small pump storage to it, I encounter attached error, however I have mad...

One strategy would be to replace the 24hr cycle with a 24-element array of hours of the day. However, that might wreck other time dynamics that play out during the day. A more sophisticated possibility might be to use the same array of 24hrs to contain expectations about the coming day, then optimi...

Given you are using external functions to do some sort of optimization, there is really very little we can suggest. Can you adapt your function to optimize over a 24 hour period? Thank you for response. Objective function of optimization problem is minizing cost of all power plants subject to grid ...

Hello, I am working on a big model which simulates an electricity market hourly for 30 years(30years*365days*24hours). This model is complied with C++ and an external function is used for optimizing model hourly. My question is that for optimizing the model daily(24_hours together) do I have to impl...

Thank you for your response.
Can I send them in form of private message or I should send them in this forum?

Hello,

When I run my model with new version of Vensim(6.3), I encounter with different results in comparision with previous version(5.7). Do you have any ideas to solve this problem? It is worth mentioning that the input data and model are same.

Best Regards,

Siamak Sheykhha

So a runs compare only makes sense, when I use a savelist with all my important (the ones directly stemming from external functions) variables, since I only compare the saved datasets, right? So I tried to find the variables via the text search. I looked up all my external functions in the equation ...

Alright, I will try that. Thanks for your help.

Hey everyone, in order to use an old model with the new vensim version I had to adjust and recompile my external functions. Unfortunatly now the results with the newer version are slightly different compared to the the results running with the older version. I think it might be because of my externa...

Alright, looks like it is read in right. I attached a screenshot so you can take a look. Looks like its working, doesnt it? VenSim_Table.jpg Still dont understand the difference between a model file and a changes file if they are both read in through "load changes from..." and fulfill the ...

Okey, so its a model file even though i load it in "load changes from..." ? This is what happens when I try to run it WITH the waves and tildes: "Reading changes from file data v65.cin ERROR: Bad line 2 in file data v65.cin not recognized. ~ ~ |. -^. Line 2 of file data v65.cin. ERROR...

Well its one of the files I specify in "load changes from.." before i start the simulation. What would be the difference to a model file and how could I tell? I mean the documentation states "The format for .cin (Constant INput) files is much the same as that of Constant and Lookup eq...