Why I get Nan values in when i connect an inverter into a 11kV grid feeder?

Hello.

I have a simulink model with a power grid with 3 feeders in 11kV. In each feeder i have connected several load profiles and everything is working. When i try to connect a PV inverter on the feeder, i get 'Nan' at the output of the inverter (e.g., for voltage, active and reactive power etc). The inverter is connected through a transformer 11lV to 400V and a filter.

Something weird is that when i connect the inverter close to the source ( between the source and a load), i don't get these Nan values, while when connecting the inverter more away from the source, the Nan vlues appear.

Any idea why is this happening?

Thanks.

[Franklin]

#Itemone #Itemtwo act or effect of amending, of rectifying a fault or defect; correction.

"e. to a book"

[Walter Roberson]

@Franklin

Sorry, I do not understand how your response will aid @Eleni Tekki in solving the problem?

Answer 1

[Sayan]

Hi Eleni T,

I understand from your issue that you are using a "PV Array" block as a source to run the inverter in your model to feed power to your grid with the 3 feeders. However, the inverter output is 'Nan'.

The possible reasons for the issue and their fixes are mentioned below:.

• The “PV Array” block (available at Simscape / Electrical / Specialized Power Systems / Sources) has an internal algebraic loop that is not solvable for the sample time defined in the model to solve the ineternal non-linear diode characteristics of the block.
• The "Break algebraic loop in internal model" option in the "Advanced" tab of the “PV Array” block needs to be selected to break the algebraic loop.

If the above-mentioned solution does not work, you can follow these alternative steps to fix the issue.

• Verify that there is no division by zero operation in your model.
• Try changing the solver type and step size in your model.

For better understanding, you can refer the following MATLAB Answers post. A similar issue regarding the “PV Array” block is addressed in this post:https://www.mathworks.com/matlabcentral/answers/466337

You can further find more information on the "Break algebraic loop in internal model" section of the “PV Array” block in the following MATLAB documentation

https://www.mathworks.com/help/sps/powersys/ref/pvarray.html#:~:text=25%20(default)-,Break%20algebraic%20loop%20in%20internal%20model,-%E2%80%94%20Break%20algebraic

Hope this helps in resolving the issue.