Dear AIMMS Team,

Trust this meets you well? Kindly assist on the problem explained below and find attached the AIMMS file I am working with.  

I have a variable StateofCharge(t) in which t is 1 to 24. 

I want to place StateofCharge(t) at t = 1 or StateofCharge(01) on the conditional statement below. 

if ( (Charging_Power_kW(01) + SoCMin) > SoCMax) then
     SocMax 
     else

Charging_Power_kW(01) + SoCMin
endif;

Note: Charging_Power_kW(01) is put as the value of variable Charging_Power_kW(t) at t=1

While StateofCharge(t) at t = 2,….24 should have the conditional statement below. The index t in the statement applies only from t = 2,….24. 

If Energy_Difference_kW(t) > 0 then
      if (StateofCharge(t-1) + Charging_Power_kW(t)) > SoCMax
       SoCMax
       else
       StateofCharge(t-1) + Charging_Power_kW(t)
     
elseif (Energy_Difference_kW(t)) < 0 then
       if (StateofCharge(t-1) - SoCMin) > Discharging_Power_kW(t)
       else 
       SoCMin
endif;

Also, if I have a parameter/variable, P(t), t=1,...24, how can I extract a cell? For example: P(5) or a parameter/variable with a double index P(t, k), t=1,..24 and k=1,...5, how can I write the value in cell P(2,4)?

Thank you.

Kind regards. 

Hi @Lawrence, you can write the definition of StateofCharge as follows:

if ( t = '01' ) then
    if (Charging_Power_kW(t) + SoCMin > SoCMax) then
        SocMax 
    else
        Charging_Power_kW(t) + SoCMin
    endif
elseif (Energy_Difference_kW(t) > 0) then
    if (StateofCharge(t-1) + Charging_Power_kW(t) > SoCMax) then
       	SoCMax
    else
       	StateofCharge(t-1) + Charging_Power_kW(t)
    endif
elseif (Energy_Difference_kW(t) < 0) then
    if (StateofCharge(t-1) - SoCMin > Discharging_Power_kW(t)) then
    	StateofCharge(t-1) - SoCMin
    else 
       	SoCMin
    endif
endif;

Or even better, use First(t) instead of ‘01’. That way you do not have to change this defintion if for some reason the first element changes (e.g., from ‘01’ to ‘1’ or ‘001’).

You should use single quotes if you want to refer to set elements: P(‘2’,’4’).

Hello @Marcel Hunting,

Thank you for your response. Most of the questions have been answered from the program you wrote. 

However, there is still an issue I am trying to address. 

I want the first conditional statement below to hold only for StateofCharge(t) at t = 1 only

if ( (Charging_Power_kW(01) + SoCMin) > SoCMax) then
     SocMax 
     else

Charging_Power_kW(01) + SoCMin
endif;

Note: This has been answered from your reply. 

……………………………………………………………………………………………………………………

So here is the issue….

However, I want the second conditional statement below to hold only for StateofCharge(t) at t = 2,….24 (or at t= 2 to the end) only

If Energy_Difference_kW(t) > 0 then
      if (StateofCharge(t-1) + Charging_Power_kW(t)) > SoCMax
       SoCMax
       else
       StateofCharge(t-1) + Charging_Power_kW(t)
     
elseif (Energy_Difference_kW(t)) < 0 then
       if (StateofCharge(t-1) - SoCMin) > Discharging_Power_kW(t)
       else 
       SoCMin
endif;

Thank you once again. 

Hi @Lawrence. The second conditional statement for StateofCharge(t) at t = 2,….24 is also handled in my answer. Note that the definition contains three blocks. The first block

if ( t = '01' ) then
    if (Charging_Power_kW(t) + SoCMin > SoCMax) then
        SocMax 
    else
        Charging_Power_kW(t) + SoCMin
    endif

handles the situation for t=01. For t unequal to ‘01’ the other two blocks will be used:

elseif (Energy_Difference_kW(t) > 0) then
    if (StateofCharge(t-1) + Charging_Power_kW(t) > SoCMax) then
       	SoCMax
    else
       	StateofCharge(t-1) + Charging_Power_kW(t)
    endif
elseif (Energy_Difference_kW(t) < 0) then
    if (StateofCharge(t-1) - SoCMin > Discharging_Power_kW(t)) then
    	StateofCharge(t-1) - SoCMin
    else 
       	SoCMin
    endif
endif;

Thank you. It is clear!