Draft an equation with particular $-condition

[tobster]

Dear GAMS-community,
i met a new GAMS problem in my powerplant-model that i cannot solve on
my own - but maybe with your help:

I try to build an equation, which sums up a number of power outputs "P
(i,j)", depending on the power plant "i" and the time step "j". The
sum of this power outputs should be equal to the load "L(j)" which has
to be covered in time step "j".
The problem is that I only want to sum up those power outputs "P
(i,j)", which are higher than the given value "Pmin(i)" of each power
plant.
I tried to write this in the following way:

**********************************
LoadCover(j)... sum(i,P(i,j)$(P(i,j) >= Pmin(i))) =e= L(j)
**********************************

The mip-solver gives two error-messages:
Error 57: Endogenous relational operations require model type "dnlp"
But the "dnlp" model type is not recommended in the GAMS manual and
moreover it would make me changing all the other equations.
Error 256: Error(s) in analyzing the solve statement.

Does anybody have an idea how i can draft my equation differently?

Thanks in advance,
Tobias

[Lenlendi]

$ operator can be used for conditional statements but GAMS compiler
encounters an error if we use $ in equation definitions! In fact, if
you change NLP to DNLP , "Error 53: Endogenous $ operation not
allowed" will appear! So, maybe you can define LoadCover in
conditional statement before equation part!