8.2.23 Solar
Start Settings
P3.22.1.1 Start DC voltage
Start enable from solar condition needs that the DC
voltage is above the threshold in P3.22.1.1 (at least
for 5 s).
P3.22.1.2 Short restart delay
The drive starts and tries to reach minimum
frequency. If this doesn't happen within a defined
time, the drive will stop and retry only after the short
delay time P3.22.1.2 has elapsed.
P3.22.1.3 Short restart delay tries
P3.22.1.4 Long restart delay
After a certain number of failed attempts (P3.22.1.3),
the time between start attempts will change to long
delay time P3.22.1.4.
If the drive can run continuously for the same long
delay time, next start attempts will begin with short
delay again. The same sequence is applied in case a
running drive stops because of a temporary decrease
in solar power.
If the drive is supplied by mains, the drive
is always enabled to start from external
command.
MPPT
Generally, the MPP voltage of a panel is higher when
the available power is high (good irradiation, low
temperature).
The output power to the motor is considered an
indicator of the panel state: if the drive can
progressively increase motor speed and get a good
amount of power, it means that the panel has
basically "high" MPP voltage.
The DC voltage reference for the regulator is
automatically changed by the MPP Tracker.
It results from four parallel algorithms:
• Feed-forward controller
• Correction controller
• Oscillation damping regulator
• Local Maxima logic
MPPT feed-forward parameters
MPP feed-forward controller continuously changes
the reference from Vmp@10 % to Vmp@100 %,
according to actual motor power. The main purpose
of this term is to follow variation of irradiation.
P3.22.2.1 Vmp at 100 % power
P3.22.2.2 Vmp at 10 % power
The Vmp parameters should be obtained from panel
characteristics, considering standard temperature and
irradiation at 10 % and 100 % level.
If the second value is not known, subtract 50-60 V
from the first value as a rough estimation.
The accuracy of these values is not really critical,
because the correction logic can easily compensate
error of some tens of volts. It is better to set values
possibly higher than the real ones, and let the
correction decrease the voltage reference, to get
maximum power.
P.14.2.3 Panel/Motor power ratio
In case the solar panels have less maximum power
than the motor, a value lower than 100 % should be
set in P3.22.2.3.
MPPT regulator
The drive tries to get the maximum power from solar
panels by keeping the DC voltage at the optimum
point (Max Power Point).
There is a PI regulator that changes the internal
frequency reference, so that the power sent to the
motor keeps the panels working on MPP.
The voltage reference can be monitored (V2.3.1) and
compared to actual DC voltage (V2.3.10), to check
the effect of gain tuning.
Continuous, low amplitude and high frequency
oscillations mean gains too high.
Ramp times are meant to smooth the output
frequency, but without introducing significant delay in
response.
P3.22.2.4 P gain
Proportional gain [Hz/V]. If set to 1.000, a variation of
1 V on DC bus voltage causes a variation of 1 Hz on
frequency reference
P3.22.2.5 I gain
Integral gain [Hz/Vxs]. If set to 1.000, a variation of 1
V on DC bus voltage causes a variation of 1 Hz per
second on frequency reference.
P3.22.2.6 Acceleration time
Time from minimum to maximum frequency. Used
only when solar power is active.
P3.22.2.7 Deceleration time
Time from maximum to minimum frequency. Used
only when solar power is active.
MPPT correction parameters
This algorithm changes the DC voltage reference, to
compensate temperature variations (usually slow)
and to correct the error in feed-forward curve.
Correction can be up to +/- 150 V.
The correction term is determined by "perturb-and-
observe" logic (P&O).
P3.22.2.8 P&O update time
P3.22.2.9 P&O voltage step
DC voltage reference is periodically (at intervals
defined by P3.22.2.8) increased or decreased by a
small value (P3.22.2.9). If the variation brings a
higher motor power, next variation will follow the
same direction, otherwise it will be reversed.
163
English (GB)
To Next Page
Loading...
