Nahid Hossain 6/17/2013

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Hi there, so far I have enjoyed the LEAP training exercises very much and completed first two modules. However I am facing difficulty to understand the idea of “System Load Shape”. Though the exercise-1/sub-section-1.4.2 describes the system load shape as the electric load that varies from hour to hour within each year, the idea is not clear to me. I do not understand why the system load shape is highest at 0000 to 1000 hours (time slice of the year) and decrease gradually. Is it just the assumed system load shape for Freedonia? Is it possible that I design my own system load shape, such as (say, for example) peak at 4000 to 5000 hours (time slice of the year) then decrease gradually, reach to lowest value at 8000 to 8760 hours (time slice of the year), then rise gradually and reach to peak again at 0000 to 1000 hours (time slice of the year), just like a cycle.
I am thinking this way, as my idea of system load is the variation of electricity demand in the different time slices of the year (for example, summer/winter season). Please clarify me, if I have the misconception about the system load and time slices of the year. Thanks

Taylor Binnington 6/19/2013
 

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Hi Nahid,

They key to understanding system peak load curves (you will sometimes hear them referred to as load-duration curves) is recognizing that the hours along the x-axis do not follow any chronological order. Instead, they indicate the bulk number of hours during the year (occurring at any time throughout the year) during which system load is at least some percentage of its peak. Duration curves have a distinct shape because there are usually very few hours during which load is near it peak, while a much smaller fraction of peak load is experienced during the majority of hours.

Have a look here: http://www.rmi.org/RFGraph-load_duration_curve

Hope this helps,

Taylor

Madeleine McPherson 7/15/2013
 

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Hi Taylor,

Do you know if it is possible to create two different time slices? For example, I would like the System Energy Load Shape of my Generators to be on a daily basis (with 365 time slices), but then I would like each of my Generators to have their own Maximum Availability Yearly Shape that are defined on a monthly basis (so there would be 12 time slices). It seems to me that when I go to the General > Time Slices > Setup, I can EITHER have 365 days OR 12 months, but not both (one that would apply the to the Load Shape and the other that would apply to the Maximum Availability). Do you know if there is a way to have different time slices for different variables in the same Area?

Thanks,
Madeleine

Taylor Binnington 7/15/2013
 

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Hi,

Only one division of the year into time slices is permitted. You can get around this by choosing to setup your time slices according to your data that is most finely resolved in time (in your case, Madeleine, 365 days), recognizing that for data of a lower resolution, you would simply have many consecutive time slices containing the same information. So for your monthly shapes, you would have a whole month of days, but each with the same value.

Best,

Taylor

Ralf Dyllick 7/17/2013
 

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Hi Taylor,

do you happen to have an exercise off the shelf to familiarize myself with the load shapes and time slices functions in LEAP?

I noted that the topic is touched upon in exercise 1.6. I was just hoping that I could test my comprehension of the functions and the handling of the two respective screens with a somewhat more complex exercise.

Thanks in advance and best regards,
Ralf

Taylor Binnington 7/17/2013
 

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Hi,

There aren't a great deal of separate training modules for exactly this purpose, but have a look at Exercise 6 of the same training materials document that you're already looking through:

http://www.energycommunity.org/documents/LEAPTrainingExerciseEnglish2012.pdf

In completing this exercise, you'll learn a little bit more about time slices and duration curves, but also how LEAP can interact with Excel to make importing data easier.

I also find it's useful to just spend some time experimenting on your own (colouring outside the lines of the exercise, so -to-speak), as you read through the online help documentation, to gain a thorough understanding of LEAP's calculations. This page http://www.energycommunity.org/WebHelpPro/Transformation/Peak_Load_Data.htm is a good place to start, and then you can follow the links from there.

Hope this helps,

Taylor

Ralf Dyllick 7/24/2013
 

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Hello Taylor,

thank you for your previous answer. Exercise 6 was in fact helpful to get a little more familiar with the load shapes in LEAP.

Can I request your help one more time? I failed to create an exemplary set of time slices and was hoping you could help me. What I would like to do is to create 8 representative days (4 seasons and in every season one week day and weekend) with a hourly resolution. In other words, I would like to specify the yearly shape for 192 slices (4 seasons x 2 rep. days x 24 hours) based on empirical data and have LEAP use the same data for the remaining days of the year.

Based on your comments in another thread (I think it was with Madeleine McPherson), I understood that you have to start with the highest desired granularity. In my case, this are hours. So I used the Time Slices Wizard in the Time Slices Screen to create a yearly shape with 8760 hourly time slices ("8760 Hours") and 4 groups ("4 Seasons (Spring, Summer, Fall, Winter)"). Then I wanted to aggregate the time slices using the detailed time slices screen (the More-button). This is about as far as I got.

At the core of the problem is that I do not really understand what I see in the detailed yearly shape screen. How can one time slice of the length of an hour start on 0 and end on 24? Similarly, how can it be on Monday through Sunday?

2 Questions: 1.) Is my approach correct? 2.) In view of the hold-up I encounter when my computer updates the time slices screen, I can only picture that the computation of results will be extremely time consuming. Can a modern standard Windows PC handle the granularity of time slices I seek?

Thanks again!
Ralf

Taylor Binnington 7/24/2013
 

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Hi Ralf,

In the Time Slices window, one full day runs from the beginning of 'hour 0' to the beginning of 'hour 24' (so, 24 hours in total). Weeks run from Monday through the following Sunday (seven days in total), only because LEAP lists weekdays before weekends (rather than a week starting on Sunday, as you see in many wall calendars, it starts on Monday).

The time slices that you're trying to create do in fact require a bit more massaging in order to build into LEAP. Even the detailed setup options, under General:Time Slices, don't quite give you the amount of flexibility that you need. You'll have to build the time slices you want outside of LEAP, but in a way that they can be imported.

My advice would be to use LEAP's time slices setup tool in the same way that you have, but then export the slices to Excel. That way you'll be able to modify them without interrupting the formatting. One you're done tinkering, use the Import button in the Time Slices window to pull them back into LEAP.

I've gone ahead and started this, so you know what I mean. You can find a sample file here:

ftp://forums.seib.org/areas2012/sample_time_slices.xlsx

NB: At least for the time being - again, we're working to address this - there is a small problem with the way LEAP allocates load data to each of the hourly slices, in the Yearly Shapes screen. After properly setting your time slices, and then importing a yearly shape, you may find that for the time slice corresponding to hour 0 - 1 the percentage of annual energy load is 2X what it should be, yet the time slices from hour 23 - 24 contains no data. You will have to manually edit the curve for these two time slices.

Regarding the computational effort needed to resolve hourly time slice data, I think you should be okay here. You're still only considering 192 slices per year (rather than 8760, if you wanted to resolve each hour individually). The computational time will probably be more affected by the number of scenarios that you're running, and the number of years in these scenarios.

Good luck,

Taylor