Synergi --> OpenDSS impedance matrices are off

[NicolasGensollen]

Hi @xzhu1991,

Pete and I are trying to convert some feeders from Synergi to OpenDSS and it seems like the impedance matrices in the output are off.

Looking at the reader code, it looks like this is where the conversion between sequence impedances and phase matrices takes place:

https://github.com/NREL/ditto/blob/5a7c5029320fa2d97a16618436a6f8e6ed91b959/ditto/readers/synergi/read.py#L702-L757

I think there are a few things that we should change (but I might be wrong since I don't know Synergi):

• The 1/3 coefficient seems to be missing
• The 10^-3 coefficient is probably not right. We need to convert the sequence values to Ohms per meters since DiTTo is in meters, so we assume here that the values are given in kilometers.

I looked a little bit in the tables and most attributes end with per_LUL, per_MUL, or per_SUL. I assume these mean large unit length, medium unit length, and small unit length but this is just a guess. Do you know more about this?

Also, the table SAI_Equ_Control seems to have a field called LengthUnits (set to English2 in my case). I looked at the Synergi software with Pete and I believe that you can have three possibilities:

• Metric: LUL=km, MUL=m, SUL=mm
• English1: LUL=kft, MUL=ft, SUL=mft
• English2: LUL=miles, MUL=??, SUL=??

Again, this is just a guess... Do you know more on this?

[xzhu628]

I could not open Synergi on my laptop. If you open Synergi, you should be able to see the length unit of the lines.

I asked Aadil before about the length unit. It should be mile.

I updated the coefficient on my new code. But I haven't push them to github yet.

The correct one should be: coeff = 1/4827 , basically from mile to meter ( 1/1609), and multiply 1/3.

On Wed, Aug 1, 2018 at 1:29 PM, Gensollen notifications@github.com wrote:

Hi @xzhu1991 https://github.com/xzhu1991,

Pete and I are trying to convert some feeders from Synergi to OpenDSS and it seems like the impedance matrices in the output are off.

Looking at the reader code, it looks like this is where the conversion between sequence impedances and phase matrices takes place:

https://github.com/NREL/ditto/blob/5a7c5029320fa2d97a16618436a6f8 e6ed91b959/ditto/readers/synergi/read.py#L702-L757

I think there are a few things that we should change (but I might be wrong since I don't know Synergi):

• The 1/3 coefficient seems to be missing
• The 10^-3 coefficient is probably not right. We need to convert the sequence values to Ohms per meters since DiTTo is in meters, so we assume here that the values are given in kilometers.

I looked a little bit in the tables and most attributes end with per_LUL, per_MUL, or per_SUL. I assume these mean large unit length, medium unit length, and small unit length but this is just a guess. Do you know more about this?

Also, the table SAI_Equ_Control seems to have a field called LengthUnits (set to English2 in my case). I looked at the Synergi software with Pete and I believe that you can have three possibilities:

• Metric: LUL=km, MUL=m, SUL=mm
• English1: LUL=kft, MUL=ft, SUL=mft
• English2: LUL=miles, MUL=??, SUL=??

Again, this is just a guess... Do you know more on this?

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Xiangqi Zhu

[NicolasGensollen]

Thanks for your answer @xzhu1991

This is the solution I came up with for now (see ff6d8a90adbb78ff647b1650b9b8798edb392767):

# If LengthUnits is set to English2 or not defined , then assume miles
if LengthUnits == "English2" or LengthUnits is None:
    coeff = 0.000621371
# Else, if LengthUnits is set to English1, assume kft
elif LengthUnits == "English1":
    coeff = 3.28084 * 10 ** -3
# Else, if LengthUnits is set to Metric, assume km
elif LengthUnits == "Metric":
    coeff = 10 ** -3
else:
    raise ValueError("LengthUnits <{}> is not valid.".format(LengthUnits))

coeff *= 1.0 / 3.0

I still need to make sure the conversion is not introducing other errors in the impedance matrices.

[NicolasGensollen]

Hi @xzhu1991, I'm not sure I understand this code in the Synergi reader when you compute the impedance matrix for a two phase line:

if NPhase == 2:
    impedance_matrix = [[coeff * complex(float(r0), float(x0))]]

It seems like r1 and x1 are not used.