Search found 148 matches
- Tue Sep 17, 2019 5:10 pm
- Forum: Vensim
- Topic: sensitivity analysis (vensim)
- Replies: 35
- Views: 16686
Re: sensitivity analysis (vensim)
1- Can we do these sentivity analysis in a model which has external function? I am asking this becasue I get this errors: {ERROR: Yearly Depreciation Factor not found or wrong type must be constant. ERROR: No sensitivity inputs marked in sensitivity file} These errors are nothing to do with externa...
- Tue Sep 17, 2019 4:51 pm
- Forum: Vensim
- Topic: sensitivity analysis (vensim)
- Replies: 35
- Views: 16686
Re: sensitivity analysis (vensim)
Hi, I have two questions regarding sensitivity analysis and stochastic programming in Vensim: 1- Can we do these sentivity analysis in a model which has external function? I am asking this becasue I get this errors: {ERROR: Yearly Depreciation Factor not found or wrong type must be constant. ERROR: ...
- Wed Aug 21, 2019 11:04 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
I've attached two models, neither of which is really right, but both in the ballpark. DEMAND AT PRICE elec 2.mdlDEMAND AT PRICE elec 1.mdl #1 implements what I originally suggested, which is that everyone bids close to MAX( marg cost, expected price ). That actually implements collusion, and the pr...
- Wed Aug 21, 2019 9:56 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
I mentioned noise for the following reason. If the auction is structured so that bids reveal true marginal costs, and that information is disclosed, then everyone has a pretty good idea what the aggregate supply curve looks like. Therefore they can do a pretty good job of anticipating the clearing ...
- Wed Aug 21, 2019 8:07 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
It seems like this should result in an outcome much like a single clearing price, but with a little more noise. If I'm running unit X, I don't want to bid my marginal cost. I want to figure out where the market is likely to clear next period, and bid just below that. However, the price in the next ...
- Wed Aug 21, 2019 7:55 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
Ah ... so the problem is more game theoretic. Each plant has to choose a bid that maximizes profit, subject to everyone else doing the same. We know the bid has to lie above marginal cost, and below a price cap (set by regulator?). Is the capacity constraint loose, in the sense that they want to ru...
- Wed Aug 21, 2019 7:46 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
Does your capacity constraint imply that A generates 100 to 300 or 0 ? That probably can't be done with the alloc functions. Not sure it could be done with FIND ZERO or even an LP either. It makes this more of a mixed integer programming problem, right? Sorry, it should be (0<Capacity of A<300). If...
- Wed Aug 21, 2019 7:19 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
Doesn't everyone who supplies > 0 get paid at the (single) market clearing price, rather than their bid price? No, they get paid exactly their bid. So bidders bid at their individual cost with a margin on top. However uniform auction can help me but my main concern is modeling this maximization rat...
- Wed Aug 21, 2019 6:51 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
The FIND ZERO example model in the Help system is already pretty close to what you need. I'll see if I have something better. Have you explored the allocation functions? That would be an even easier solution. Yes but maybe I did not use it correctly. I used "Allocation by priority", in th...
- Wed Aug 21, 2019 2:29 pm
- Forum: Vensim
- Topic: Integrating time step of optimization problem
- Replies: 32
- Views: 14906
Re: Integrating time step of optimization problem
The one thing you can't do is run the Vensim optimizer at intervals within the simulation. OTOH you can do some kinds of optimization with FIND ZERO - I've used that before to dispatch power plants in a model. Can you please describe or send a sample model how to model economic dispatch with Find Z...
- Mon Jul 22, 2019 5:27 pm
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
- Mon Jul 22, 2019 4:01 pm
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
Re: Somebody help me please!! ramp and pulse train combination
For debugging we really need the exact variables in the big model copy-pasted into a test model, with exactly the same time settings. Otherwise there are too many possible causes of variation. (However, if the copy-pasted version works for you, this probably won't help us diagnose.) Other things to...
- Mon Jul 22, 2019 3:58 pm
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
Re: Somebody help me please!! ramp and pulse train combination
Do they work in the large model if it's not compiled? (Note that if you've previously compiled it, you either have to change the model or delete the .dlls to run interpreted.) No, it is not related to compilation because it does not work with or without compilation. I was just wondering which time ...
- Sat Jul 20, 2019 7:35 pm
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
Re: Somebody help me please!! ramp and pulse train combination
Can you copy the parameters "pulse", "eeg start", "eeg repeat time", "eeg duration" and "eeg end time" and paste them into a blank model? I have attached the equations of the function. As you can see I have used very simple equations and they work i...
- Sat Jul 20, 2019 6:54 pm
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
Re: Somebody help me please!! ramp and pulse train combination
Unfortunately, I cannot send the model, it has also huge input files and external files which make sending hard.
Attached you can find my time setting and formula for repeat time of PULSE TRAIN. The rest of variable for this function are as simple as repeat time.
- Sat Jul 20, 2019 6:27 pm
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
- Fri Jul 19, 2019 3:29 pm
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
Re: Somebody help me please!! ramp and pulse train combination
Hard to say. I'd recommend copy-pasting your equation into a standalone model for testing. Be sure the time bounds are the same as the original. Also, be sure SAVEPER=TIME STEP; otherwise you might not see the pulses in the output. I checked all your suggestions. When I open another vensim file and...
- Fri Jul 19, 2019 10:08 am
- Forum: Vensim
- Topic: Somebody help me please!! ramp and pulse train combination
- Replies: 33
- Views: 14492
Re: Somebody help me please!! ramp and pulse train combination
Hi,
What kind of mistakes can cause a failure in PULSE TRAIN. I am using a PULSE TRAIN in a large-scale model but it produces nothing, although all 4 inputs of this fuction seems to be correct.
What kind of mistakes can cause a failure in PULSE TRAIN. I am using a PULSE TRAIN in a large-scale model but it produces nothing, although all 4 inputs of this fuction seems to be correct.
- Wed Jul 03, 2019 3:36 pm
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12649
Re: demand and supply at price
"No priority" = "priority vector with all values the same" would be one option. You can't change the type of an argument from a vector to a single value. Another, simpler option would be to use one of the one-sided ALLOC functions. In other words, add up the demands to a single ...
- Wed Jul 03, 2019 2:37 pm
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12649
Re: demand and supply at price
Hi,
How can I use FIND MARKET PRICE(dq,dp,sq,sp) when I have only multi suppliers and no priority for demanders?
I get this error: Argument 2 of FIND MARKET PRICE must be a normal variable
How can I use FIND MARKET PRICE(dq,dp,sq,sp) when I have only multi suppliers and no priority for demanders?
I get this error: Argument 2 of FIND MARKET PRICE must be a normal variable
- Sat May 11, 2019 2:54 pm
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12649
- Mon May 06, 2019 5:42 pm
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12649
Re: demand and supply at price
You could use a stock or SAMPLE IF TRUE to identify the winner and set their quantity to 0, or priority very low, for future auctions. Thanks. I still get this error for a part of model which is related to ALLOCATE AVAILABLE function: "Error in ALLOCATE_AVAILABLE/FIND_MARKET_PRICE - subscript ...
- Mon May 06, 2019 3:29 pm
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12649
Re: demand and supply at price
It sounds like we need something like an "ALLOC IF" function that's switchable, so it only executes when a flag is true. I just multiplied pluse train with allocation function. Do you have any suggestion for filtering the winner and looser of each auction. I want that looser can be able t...
- Mon May 06, 2019 1:35 pm
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12649
Re: demand and supply at price
You'll need to create a variable that is zero or one at those three times of the year. Then use SAMPLE IF TRUE to hold the winning value until the next round. VECTOR RANK can be used to work out which is the winner at each auction round. The thing is that I want the winners will be able to sell for...
- Sat May 04, 2019 4:33 pm
- Forum: Vensim
- Topic: demand and supply at price
- Replies: 29
- Views: 12649
Re: demand and supply at price
My model is an hourly based model which simulates electricity market for 35 years. I want to model the auction of technology X only three times per year and winners of auction X can be able to sell their energy for 10 years. Looser of auction X will sell their energy without any premuim, but they ha...