A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...

This approximate method of calculating PLAVG is used during system optimization.
However, during a final performance calculation (IPROB=O) the parasitic
losses are calculated and averaged over the days and times for which energy
calculation is accomplished, rather than depending on the approximation of hours
of storage and hours of receiver operation.
The parasitic losses described above are only calculated when the plant (i.e.,
turbine) is generating energy. However, the total power plant also requires en-
ergy at other times, to run such mundane things as lighting and building heat, as
well as to start and shut down equipment, such as unstowing the heliostat field
or preheating the receiver. Reference 33 provides empirical relationships for non-
operating parasitic losses as a function of rated gross electric power Pe,gross for
several different plant status conditions, such as at night, during maintenance
outages, and during startup and shutdown of the plant. Specifically,
startup/shutdown loss (MWe)
I 8 = PARLlq,+ PARL2 x Pe,gross
prestartup/postshutdown IOSS (MW,) = PARL3 + PARL4 x Pe,gross
nighttime loss (MWe) = PARL5 + PARL6 x Pe,gross
weather loss (MWe) = PARL7 + PARLS x Pe,gross
outage (PF) loss (MWe) = PARLS + PARLlO x Pe,gross
(I1I.G - 24)
All of the above parasitic losses need to be associated with some length of
time in order to calculate the lost energy. It is assumed that the time of the PF
outage (Namelist NLEFF) is (1 - PF) x 365 x 24 hours. Weather is assumed to
be a fraction of all remaining time of the year as defined by (1 - WEATH). Al-
though in reality weather only affects daytime operations, this approximation
is acceptable as long as the weather parasitic loss coefficients are not signifi-
cantly different from night time loss coefficients. Times for startup/shutdown
and prestartup/postshutdown operations are input by the user for the variables
TSTRT and TPRE (Namelist BASIC) as the average time to perform one oper-
ation (either startup or shutdown, or either prestartup or postshutdown) for one
day, in hours. Night time is defined to be the time left after all other times are
accounted for, including startup/shutdown, prestartup/postshutdown, mainte-
nance outages, weather outages, times when the receiver is operating (HROP),
and times when the receiver is shut down but energy is being generated from
storage. Note that startup and prestartup times do not reduce the hours of op-
eration, since hours of operation of the receiver are fixed by the user’s choice of
the variable ASTART.
88
Defaults for all parasitic loss variables are as follows:
PLREF (REFPRL) = 0.103
fa (FSP) = 0.66