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System Advisor Model (SAM)

System Design exceeds Inverter Maximum DC current: No Error Message

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patrickbk
Topic Author

25 Nov 2021 11:23 - 30 Nov 2021 18:22 #10313 by patrickbk

System Design exceeds Inverter Maximum DC current: No Error Message was created by patrickbk

Hello Paul,
I have a the following components:

PV Module: Short circuit current (Isc) = 9.81 A
Inverter: Maximum DC current = 49.5 Adc

And the following System Design:

Number of inverters = 20
Strings in parallel in subarray = 120

Calculating the DC current:

Total PV: 9.81 A * 120 = 1177 A
Total Inverter: 49.5 Adc * 20 = 990 Adc
Results: 990 Adc < 1177 A

Hence, my PV output current exceeds the maximum inverter input DC current. But SAM does not show me any error message. Is this on purpose?

My SAM simulation file is attached.
Best,
Patrick

...21-11-30-2.sam

Last edit: 30 Nov 2021 18:22 by patrickbk. Reason: Input mistake in the attached SAM file: The Systen Design uses only one MPPT input but the inverter had two MPPT inputs defined, which results in an error in the simulation. Therefore, the new file.

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pgilman

30 Nov 2021 01:09 #10323 by pgilman

Replied by pgilman on topic System Design exceeds Inverter Maximum DC current: No Error Message

Hi Patrick,

During the simulation, SAM limits the inverter input voltage to the min and max MPPT voltage ratings and its AC output power to the rated AC output power, but does not check the input current.

You can check the short circuit current of each subarray in the outputs to see if it exceeds the rated limit. For example, on the Statistics tab of the Results page after running a simulation, look at the "Max" value of Subarray 1 String short circuit DC current (A).

Best regards,
Paul.

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patrickbk
Topic Author

30 Nov 2021 18:33 #10329 by patrickbk

Replied by patrickbk on topic System Design exceeds Inverter Maximum DC current: No Error Message

Thanks, Paul!

I followed your instruction and Subarray 1 String short circuit DC current (A) = 10.8 A

How is this possible when one module hence one string has a Short circuit current (Isc) = 9.81 A ? I assumed that the Subarray 1 String short circuit DC current (A)should never exceeds 9.81 A, but it does?

In my System Design with 120 strings in parallel, this would result in 120 * 10.8 A = 1296 A. This is significantly more than the 20x inverter's max. DC input current of 49.5 Adc per inverter, meaning 20 * 49.5 Adc = 990 Adc < 1296 A. Wouldn't be a warning by SAM useful?

Thank you again for your time! Best, Patrick

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