Dear Diana,
I am sorry that despite my attempts I still have not been able to explain it well to you. However, for the sake of other Forum readers, I think I need to comment also on the new conclusion you made:
Diana> Yes, I had a misunderstanding, I thought that if I force an ACT_BND for a storage process, it was not going to be like an exogenous charge, I thought defining an activity bound will force a Fin until reaching that storage level. It did not occur to me that it will be like an exogenous charge because you have another attribute for that (which I have never used).
AL> That is not at all true: The ACT_BND(LO) you defined was NOT at all working like an exogenous charge. Could you please take a look at the documentation again, Part II, page 254. There you can see how an exogenous charge (STG_CHRG) would enter the storage equation:
Var_Act (T1) + Var_FIn(T1) – Var_FOut(T1) + STG_CHRG(T1) – LOSS(T1,T2) = Var_Act(T2)
As you can see, an exogenous charge would be an additional term in the balance, and treated similarly as the endogenous charge Var_FIn(T1). Any such exogenous charge would subsequently have to be discharged (or consumed for the losses) at some later timeslice. However, the ACT_BND(LO) you defined does not allow for any later discharging: the forced amount stored has to be retained in the storage, as you should immediately see from the equation, bearing in mind that the DAYNITE timeslices under each season form a cycle. So, if you force some storage level with ACT_BND(LO), it does not at all increase the amount of energy that can be discharged from the storage.
The only direct impacts of an ACT_BND(LO), forcing increased storage levels, are 1) it requires sufficient capacity to accommodate those increased storage levels, 2) it increases the costs on activity (if defined), and 3) it causes additional storage losses, as explained in the documentation. Consequently, ACT_BND(LO) would, in fact, tend to decrease the amount that can be discharged, assuming the amounts charged remain unchanged. That is so because the storage losses would then become higher (if the forced storage levels are higher than what they would otherwise be).
I am sorry that despite my attempts I still have not been able to explain it well to you. However, for the sake of other Forum readers, I think I need to comment also on the new conclusion you made:
Diana> Yes, I had a misunderstanding, I thought that if I force an ACT_BND for a storage process, it was not going to be like an exogenous charge, I thought defining an activity bound will force a Fin until reaching that storage level. It did not occur to me that it will be like an exogenous charge because you have another attribute for that (which I have never used).
AL> That is not at all true: The ACT_BND(LO) you defined was NOT at all working like an exogenous charge. Could you please take a look at the documentation again, Part II, page 254. There you can see how an exogenous charge (STG_CHRG) would enter the storage equation:
Var_Act (T1) + Var_FIn(T1) – Var_FOut(T1) + STG_CHRG(T1) – LOSS(T1,T2) = Var_Act(T2)
As you can see, an exogenous charge would be an additional term in the balance, and treated similarly as the endogenous charge Var_FIn(T1). Any such exogenous charge would subsequently have to be discharged (or consumed for the losses) at some later timeslice. However, the ACT_BND(LO) you defined does not allow for any later discharging: the forced amount stored has to be retained in the storage, as you should immediately see from the equation, bearing in mind that the DAYNITE timeslices under each season form a cycle. So, if you force some storage level with ACT_BND(LO), it does not at all increase the amount of energy that can be discharged from the storage.
The only direct impacts of an ACT_BND(LO), forcing increased storage levels, are 1) it requires sufficient capacity to accommodate those increased storage levels, 2) it increases the costs on activity (if defined), and 3) it causes additional storage losses, as explained in the documentation. Consequently, ACT_BND(LO) would, in fact, tend to decrease the amount that can be discharged, assuming the amounts charged remain unchanged. That is so because the storage losses would then become higher (if the forced storage levels are higher than what they would otherwise be).