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# Convertion unit MW --> MWh

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Hi everybody, I am trying to convert the unit power [mw] into the unit energy MWh] considerung the specific time duration per timestamp h] or qh]. Has anyone an idea how to solve that?

If you have the SI_Units for Power and Energy, then you will already have derived conversions in the Energy declaration. kWh will be available and you can declare a kkWh or MWh as you need.

These are the unit declarations I have

`Quantity SI_Energy {    BaseUnit: J = kg*m^2/s^2;    Conversions: {        MWh ->J : #-># * 3600000000,        MWqh->J : #-># * 900000000    }    Comment: "Expresses the value for the capacity to do work.";}`

`Quantity SI_Power {    BaseUnit: W = kg*m^2/s^3;    Conversions: MW->W : #-># * 1000000;    Comment: "Expresses the value for the amount of energy per time unit.";}`

`Quantity SI_Time_Duration {    BaseUnit: s;    Conversions: qh->s : #-># * 900;    Comment: "Expresses the value for the duration of periods.";}`

To get MWqh you could adjust the scaling factor with /4. Does this help ?

You can also review AIMMS Academy: Units of Measurement

Hello Mohan, thank you for your help. I defined the quantitys as suggested. But it seems, that the time per timestap (hour) is still not considered. That’s the original Problem:

Thanks, I understand better now. One remark, shouldn’t the unit of K_Boiler be Euro/h as you are multiplying MW with Euro/MWh ?

So, the derived unit kWh or MWh in the SI_Energy is not considering at as a product of the SI_Power unit MW and time unit h (hour) but just a conversion from J.

What you can do is, forget about the SI_Energy quantity and declare the MWh yourself as a unit parameter (read more here: Unit-valued Parameters — AIMMS Language Reference)

In SI_Time_Duration, you can add a conversion to hours as 3600s. You add a conversion in SI_Power quantity for MW as 10^6 * W.

Now declare a unit parameter named MWh with definition as MW*hour. Use this MWh in your variable and parameter declarations.

Thanks, I understand better now. One remark, shouldn’t the unit of K_Boiler be Euro/h as you are multiplying MW with Euro/MWh ?

So, the derived unit kWh or MWh in the SI_Energy is not considering at as a product of the SI_Power unit MW and time unit h (hour) but just a conversion from J.

What you can do is, forget about the SI_Energy quantity and declare the MWh yourself as a unit parameter (read more here: Unit-valued Parameters — AIMMS Language Reference)

In SI_Time_Duration, you can add a conversion to hours as 3600s. You add a conversion in SI_Power quantity for MW as 10^6 * W.

Now declare a unit parameter named MWh with definition as MW*hour. Use this MWh in your variable and parameter declarations.

It worked! Thank you very much :)