Not a bug : Can pp handle multiple control on trafo end

[AnkurArohi]

Lets say we have a trafo and on one end of this trafo there is a ratio tap changer control as well as phase shift control

Can this be handled ?

[rbolgaryn]

take a look at the parameter tap_shift_degree

[AnkurArohi]

@rbolgaryn Thanks for your reply, yes this i am aware of but for instance the other important inputs for calculation similar to the ratio tap changer cannot be set as they are already set by the Ratio tap changer

These are tap_max
tap_min
tap_neutral
tap_pos
shift_degree
tap_step_percent

shift_degree I can take over as it does not overlap with Ratio tap changer properties. But the other are also relevant for Ratio tap changer and this is where we have an issue

[AnkurArohi]

For example the trafo modelling will pick up only one tap position but if we have two controllers then (Ratio and Phase shift) then it has to be picked up from both, this is the problem

[AnkurArohi]

@rbolgaryn I dived in more, considering the documentation https://pandapower.readthedocs.io/en/v2.6.0/elements/trafo3w.html I found two things

Trafo3w There is no explanation of the usage for Phase shift values in case of trafo3w, from the formula I could understand that only ratio tap changer/longitudnal (Längs) is being supported, So, Is Quer regelung/Logitudnal Control and/or Phase shift control not supported for trafo3w?

Trafo2W As for Transverse (Quer) control in case of trafo2w documentation we need to use this parameter

tap_step_degree

But in the above case the solution is _limited to the same tap_neutral and tappos So, for example if the trafo has different tap positions and neutral positions for ratio tap changer and Phase shifter(Active control), the additional angle change calculation will not work, it can only work if both controls have the same tap position and tap_neutral.

Similarly in case of Ideal Phase shift trafo, as mentioned in the documentation , one can have either Phase shifter or ratio tap changer but not both and the distinguishing factor is parameter tap_phase_shifter Then the angle change parameter to be defined are tap_st_degree , or, tap_step_percent this is the same also for Longitudnal control(Längs Regelung/Ratio Tap changer)

[rbolgaryn]

Dear @AnkurArohi ,

for trafo3w, the phase shift is not implemented.

For trafo 2W - is it common for transformers to have unequal tap positions separately for longitudinal and transverse control?

Roman

[rbolgaryn]

With the existing implementation, you could model an ideal phase shifter in series to a transformer with a longitudinal tap shifter.

[rbolgaryn]

Otherwise, there needs to be an adjustment to the implementation.

[rbolgaryn]

Thanks for the info. Currently, the trafo3w is not implemented for phase shifting.

Do you know if it is also common for trafo 2W to have different tap parameters for longitudinal and transverse?

[AnkurArohi]

Yes @rbolgaryn It is also common for trafo2W to have ratio as well as Phase shifting

[rbolgaryn]

I see.

We don't support such a case at the moment. The implementation for that case would have to be adjusted.

Roman

[AnkurArohi]

But if the neutral step for both are same then atleast Longitudnal and Latitudnal cases can work, but PST not For PST to work it has be on a different end @rbolgaryn then it should work right? Or, as I am trying now to implement ideal PST in series , but this will lead to changed power flow results (a bit) and incrased losses. What PP can support and I can imagine that it can work is the case above when on the same end we have two controls Ratio and the Phase shift and if they have the same tap_neutral then according to the formula one could calculate the angle shift with the tap position as well and augment it to Ratio tap changer. But in this case also the end result can only be one tap_pos for both phase shift and ratio tap changer. Otherwise we need input of tap_pos (current) also for PST and then implement it (This case same tap_neutral) is not required, which means using Ideal PST calculations and augment the ones of Ratio tap changer together

[AnkurArohi]

Dear @rbolgaryn Do you know what exactly is the difference between Longitudnal control(PP documentation) and Phase shift control, In CGMES they are both the same but in PP Documentation they are differently handled and the details I have already mentioned above. Can you please let me know?

Second question is yes I do know that trafo3w has no Ideal PST support , but is the longitudnal control for trafo3w possible in PP?

Thanks

[AnkurArohi]

To put in other words the

shift_degree parameter is used when pf is run in voltage angle true Mode

then for each step there is also a value of tap_step_degree that one can define for longitudnal Regulator.

But longitudnal Regulator cannot work if the neutral pos and current pos of tap is different as compared to latitudnal Regulator because Trafo can have only one tap_pos which is coming from ratio/latitudnal control. I think this should be mentioned in pp document.

Is this correct interpretation?

Another issue Let's say I have the value of shift degree which changes with each tap_pos and I am using it for voltage angle based pf now if for ideal pst I define tap_step_degree for ideal PST, now according to formula this should be same to the case of longitudnal regulation if in both cases rap_pos and tap_neutral is same and there is no latitudnal Regulator, isn't it?