© EPS Stromversorgung in 2022, this information is subject to change without notice
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3.11.15.6 Interpolation
The interpolation feature can calculate and set intermediate steps when running the PV function in day trend mode, i. e.
DAY
E/T
or
DAY U/I
. The calculation is always done between to succeeding points on the day trend curve. The dwell time of every
curve point is adjustable between 500 and 1,800,000 milliseconds (see above, format of the day trend data file). While there
are no extra points calculated when using the minimum time of 500 ms, following applies to higher dwell time definitions:
•
The number of intermediate steps is determined from the dwell time and spread as equally as possible, where any of the
steps can have its own dwell time between 500 and 999 ms
•
The intermediate steps also respect the slope between the current and the next day trend curve point and thus every step
also includes a corresponding value alteration
Visualization:
Without interpolation - the curve results in steps
With interpolation - the curve remains linear
An example: the dwell time of the 3450
th
curve point is defined as 3 minutes, which is 180 seconds. There will be 180 / 0.5 -1
= 359 intermediate steps calculated and set until reaching the 3451
st
point. In mode DAY U/I the MPP voltage changes from
75 V to 80 V and the MPP current changes from 18 A to 19 A. When calculated, this would mean a ΔU/Δt of 27.7 mV/s and a
ΔI/Δt of 5.5 mA/s. Depending on the device in use, such small steps in voltage or current may not be doable. However, the
device would try to set the first intermediate step with 75.0138 V and 18.0027 A.
3.11.15.7 Data recording
There is the option to record data during the simulation run, in any mode. The data can be stored to USB stick once the
simulation is finished or read via digital interface, which even allows for reading the data while the simulation is still running.
As long as the simulation is running, the device will record one data set every 100 ms into an internal buffer. This interval is
not adjustable. The max. number of data sets, here also called indexes, is 576,000. This results in a max. record time of 16
hours. The indexes are internally counted with every new record. When reaching the max. number, the index will restart from
1, overwriting former data. Every index will contain 6 values.
When configuring the PV simulation, the recording feature is locked at first (button grayed out). Only when stopping the
simulation and leaving the control screen back to the configuration, the button becomes accessible. It then allows to store
a CSV with a specific number of rows. This number depends on the current index counter. Contrary to remote control where
it’s possible to address every index of the max. 576,000 the save to USB feature will always store all indexes between 1 and
the counter. Every next simulation run also resets the counter.
CSV file format when saving the recorded data to USB stick (in the example all values are with unit):
Index
= Ascending number
Uactual
= Actual voltage on the DC output
Iactual
= Actual current on the DC output
Pactual
= Actual power on the DC output
Umpp / Impp / Pmpp
= Voltage, current and power in the MPP
of the currently calculated PV curve