Multi-stage optimization with investment periods of varying lengths may result in incorrect discount factors

[ran1988]

GenX.jl/src/multi_stage/dual_dynamic_programming.jl

Line 580 in 5100d17

DF = \frac{1}{(1+WACC)^{L*(p-1)}}

I have reviewed the calculation method for the discount factor and noticed that it assumes equal lengths for each investment period. If I want to perform an optimization with [5,5,5,10] investment periods, what should I do?

[sambuddhac]

PR #672 fixes this

[lbonaldo]

Thank you, @ran1988, for opening this issue. To perform an optimization with periods of different length, you need to edit the StageLengths parameter of the multi_stage_settings.yml:

StageLengths: [10,10,10] # Length of each model stage (years)

The implementation of the discount factor calculation included in the initialize_cost_to_go function works with periods of different length, and we updated the docstring to reflect the code. Please let us know if this addresses your question.

[ran1988]

Thank you for your attention and efforts! I have performed a optimization with the updated initialize_cost_to_go function, but it still didn't solve the problem.
The revised code is : "DF = \frac{1}{(1+WACC)^{L_{p}*(p-1)}}"
If a [5,5,5,10] investment period setting is applied, then the DF for the fourth stage is 1/(1+wacc)^30. It should be 1/(1+wacc)^15, isn't it?

[ran1988]

The latest update works! Thanks!