02-10-2023, 03:43 PM
Sorry if I interfere, but I can also explain this, possibly even better than Amit. 
The original design of TIMES does not sufficiently allow distinguishing between endogenous and exogenous capacity of any vintage V. As I am sure you know, the vintages V of new capacities in any period are the Milestone years V=T. And by default, any capacity installed in period T (and has no NCAP_ILED), is assumed to be commissioned at the beginning of the year B(T). Therefore, specifying NCAP_PASTI(r,t,p) = C would cause the capacity to be installed in the year B(T) instead of the Milestone year.
It would be a relatively a big effort to eliminate this small shortcoming in the original design of TIMES by revising the implementation. And therefore, a work-around has been implemented: If the user wants to specify exogenous capacity additions within the model horizon accurately in the year specified, one can use this INT_DEFAULT('PASTI') option, which makes these adjustments whenever "past investments" are specified at Milestone year(s). According to the original design, NCAP_PASTI was supposed to be specified only for vintages before the model horizon, and this issue was thus by design non-existent.
The original design of TIMES does not sufficiently allow distinguishing between endogenous and exogenous capacity of any vintage V. As I am sure you know, the vintages V of new capacities in any period are the Milestone years V=T. And by default, any capacity installed in period T (and has no NCAP_ILED), is assumed to be commissioned at the beginning of the year B(T). Therefore, specifying NCAP_PASTI(r,t,p) = C would cause the capacity to be installed in the year B(T) instead of the Milestone year.
It would be a relatively a big effort to eliminate this small shortcoming in the original design of TIMES by revising the implementation. And therefore, a work-around has been implemented: If the user wants to specify exogenous capacity additions within the model horizon accurately in the year specified, one can use this INT_DEFAULT('PASTI') option, which makes these adjustments whenever "past investments" are specified at Milestone year(s). According to the original design, NCAP_PASTI was supposed to be specified only for vintages before the model horizon, and this issue was thus by design non-existent.
Anyways, thank you both for your responsiveness !