Low voltage modelling using PyPSA

[hzho...@gmail.com]

Hello, 

My name is Housheng and I am currently working on a project investigating the impacts of distributed PV and batteries on peak power and voltage within the context of low voltage networks. My question is in regards to the creation of the network in PyPSA to simulate the low voltage feeder. 

The feeder is rated at 400V/230V and has a 3 phase main line feeding down power to single phase households. From my understanding, the power flow equations in PyPSA are based on a balanced 3 phase analysis with the phase to phase voltage given at a particular bus and then use the real and reactive power flows on other buses to calculate the phase to phase voltage on the other buses. Since my load, PV and battery output data are single phase values, I am not sure how to set up the feeder in PyPSA to obtain the accurate voltage impacts on the buses with the PV and batteries. 

Just wondering if there are any suggestions on how to use PyPSA to model these kinds of networks?

Thanks in advance for your time.

Housheng 

[Tom Brown]

Dear Housheng,

That's a good question.

PyPSA only simulates balanced power flows and in principle you can use
it for any number of phases. The number of phases never enters the
calculations because we avoid outputting the current; we only output
voltage and power. This means it's safe to model single phase systems.
You cannot do unbalanced flows. It should be possible to combine
balanced three-phase with single-phase systems.

Best wishes,

Tom

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Karlsruhe Institute of Technology (KIT)
Institute for Automation and Applied Informatics (IAI)

Dr. Tom Brown
Energy System Modelling

Phone: +49 721 608 25737
Fax: +49 721 608 22602
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[hzho...@gmail.com]

Hi Tom,

Thanks for the reply. I am thinking of two different arrangements to simulate the network and want to know which one may be more appropriate in your opinion.

The first one is to have an external grid connected to a central bus with the nominal voltage set to the phase to neutral (230V) and then have 3 lines coming down from the central bus to represent the 3 phase main line, then attach the single phase loads and generators over the 3 lines with the p_set equal to their existing values.

The second one is to have an external grid connected to a transformer with the LV voltage set to the phase to phase (400V) and then just have 1 line coming down from the LV side then attach all the single phase loads and generators to it with the p_set equal to their existing values. 

My reasoning is that although PyPSA uses phase to phase voltage on default, but since you mentioned number of phases does not enter the calculation steps, using phase to neutral voltage in the calculations may produce more accurate results for single phase scenarios?

Regards,

Housheng