Atec Elgar_TerraSAS - Manual (Page 2)

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functions available locally through the controller
are also available remotely.
Description
As shown in the rack drawing, the TerraSAS
consists of programmable DC power supplies,
a rack mounted controller, keyboard and LCD
display with control software and GUI interface,
output isolation and polarity reversing relays and
a unique PV simulation engine that controls the
power supply. This combination of hardware
allows the TerraSAS to simulate most test
protocols or combination of events that a solar
installation will be subjected to. Power supplies
are available in 1-15KW increments to simulate
arrays up to 1MW.
The included software, as displayed below, allows
modeling of a PV panel without an extensive
knowledge of solar array parameters. The only
parameters required for a simulation are the open
circuit voltage and short circuit current. The slope
of the VI curve can then be modified by the peak
power parameters, Vmpp and Impp. Changes to
these parameters will allow the shape of the VI
curve to be adapted to any fill factor between
0.5 and 1. Once an IV curve has been generated,
changes to the irradiation level or temperature
can be changed on the fly so that the behavior
of a grid tied inverter can be tested under realistic
conditions for cloud shadowing and panel
temperature rise. Long term weather simulations
can be run to determine the amount of energy
delivered in a given situation. Inverters can be
optimized for real MPP search modes, because
shadowing and temperature changes can be
simulated realistically.
The PV simulation software allows definition of
key parameters like Voc, Isc, Vmpp and Isc at 25
°C and 1000W/m2, so that the resulting VI curve
is calculated according to a standard solar cell
model.
The PV simulator has the ability to simulate
ideal IV curves as well as irregular characteristics
for peak power tracking that result when solar
panels with different output characteristics are
paralleled as shown on the following two graphs
below. With the simulator programmed for
different values of irradiance or temperature,
the characteristic “multiple hump” IV curve will
result. By programming the changes in irradiance
and temperature in a table, dynamic simulation
of compressed time profiles of a 24 hour day can
be run in a loop to simulate the day and night
periods for extended periods of time.
Dynamic simulation showing changes in Irradiance and Temperature over time
Elgar TerraSAS
2