30-12-2016, 07:14 AM
Please find below my quick answers:
1. As clearly stated in the documentation, using discrete capacity units is not at all required for modelling partial load efficiencies.
2. The amount of capacity on-line at any given timeslice is currently not available in reporting parameters (as it is an operational detail usually of not much interest), but you can always check the full solution from the GDX file (the variables giving the on-line/off-line capacity are described in the documentation). You can also define a non-binding user-constraint for custom reporting of the on-line capacity of any process(es), by using the UC_ATTR(ONLINE) modifier for the CAP component.
3. How much capacity is shut down by the model, and what type of start-up is being used (cold, hot, warm) is neither directly available in the reporting parameters (again a fine operational detail that has not been requested to be reported). As above, you can check the full solution form the GDX file, which includes the start-up variables (cold, hot, warm). Note that in your example case, WARM start-ups would actually never occur due to the parameter values you have chosen, and so all daily start-ups would inevitably be HOT, and all seasonal start-ups would be COLD.
4. I don't see you having missing any parameters for correctly modelling the partial load efficiency of a process (see my test below). But make sure that you have read the documentation and understand that when using the LP formulation, there are no discrete-size units.
As mentioned in the documentation, all the start-up and shut-down costs are reported separately under the activity cost reporting parameter, and all the energy flows and activities reported are of course fully consistent with e.g. any partial load operation, when such occurs.
I also tested an example process otherwise just like yours, but with the following small changes in the input parameters:
• ACT_LOSPL (UP) – 0.80 (corresponding to 91% load level, 0.85 seemed a bit high)
• ACT_UPS (ANNUAL, LO) – 0.06 (5 MW per hour seemed a bit too slow)
• ACT_UPS( ANNUAL ,UP) – 0.06 (5 MW per hour seemed a bit too slow)
• NCAP_AFA(LO) – 0.3 (0.55 seemed a bit high if you want to model daily cycling)
With these small modifications, I tested how the process behaves in a model with two seasons, 24 hours each, simulating a daily cycling situation by fixing the activity to zero in four consecutive timeslices (H05, H06, H07, H08). The operational results for the process modelled are shown in the figure below (for the daily cycle in one season):
![[Image: attachment.php?aid=23]](http://iea-etsap.org/forum/attachment.php?aid=23)
As you can see, the results are beautifully symmetric with respect to the process operation, and all the results are fully in accordance with the documentation. For example, the process efficiency varies between the full efficiency (30%) and the partial load efficiency at the minimum stable load (27.985% at 55% load), exactly as defined by the ACT_LOSPL parameter (7.2% loss at minimum stable load). You can also clearly see that in the LP formulation the load never falls below the minimum stable load (because the on-line capacity changes linearily during the start-up and shut-down phases). Therefore, the process efficiency remains at 27.985% throughout the start-up and shut-down phases. If you want more accurate modeling and discrete-size units, you can use the MIP option.
1. As clearly stated in the documentation, using discrete capacity units is not at all required for modelling partial load efficiencies.
2. The amount of capacity on-line at any given timeslice is currently not available in reporting parameters (as it is an operational detail usually of not much interest), but you can always check the full solution from the GDX file (the variables giving the on-line/off-line capacity are described in the documentation). You can also define a non-binding user-constraint for custom reporting of the on-line capacity of any process(es), by using the UC_ATTR(ONLINE) modifier for the CAP component.
3. How much capacity is shut down by the model, and what type of start-up is being used (cold, hot, warm) is neither directly available in the reporting parameters (again a fine operational detail that has not been requested to be reported). As above, you can check the full solution form the GDX file, which includes the start-up variables (cold, hot, warm). Note that in your example case, WARM start-ups would actually never occur due to the parameter values you have chosen, and so all daily start-ups would inevitably be HOT, and all seasonal start-ups would be COLD.
4. I don't see you having missing any parameters for correctly modelling the partial load efficiency of a process (see my test below). But make sure that you have read the documentation and understand that when using the LP formulation, there are no discrete-size units.
As mentioned in the documentation, all the start-up and shut-down costs are reported separately under the activity cost reporting parameter, and all the energy flows and activities reported are of course fully consistent with e.g. any partial load operation, when such occurs.
I also tested an example process otherwise just like yours, but with the following small changes in the input parameters:
• ACT_LOSPL (UP) – 0.80 (corresponding to 91% load level, 0.85 seemed a bit high)
• ACT_UPS (ANNUAL, LO) – 0.06 (5 MW per hour seemed a bit too slow)
• ACT_UPS( ANNUAL ,UP) – 0.06 (5 MW per hour seemed a bit too slow)
• NCAP_AFA(LO) – 0.3 (0.55 seemed a bit high if you want to model daily cycling)
With these small modifications, I tested how the process behaves in a model with two seasons, 24 hours each, simulating a daily cycling situation by fixing the activity to zero in four consecutive timeslices (H05, H06, H07, H08). The operational results for the process modelled are shown in the figure below (for the daily cycle in one season):
As you can see, the results are beautifully symmetric with respect to the process operation, and all the results are fully in accordance with the documentation. For example, the process efficiency varies between the full efficiency (30%) and the partial load efficiency at the minimum stable load (27.985% at 55% load), exactly as defined by the ACT_LOSPL parameter (7.2% loss at minimum stable load). You can also clearly see that in the LP formulation the load never falls below the minimum stable load (because the on-line capacity changes linearily during the start-up and shut-down phases). Therefore, the process efficiency remains at 27.985% throughout the start-up and shut-down phases. If you want more accurate modeling and discrete-size units, you can use the MIP option.