How the SCR and X/R values are calculated in Type-4 Detailed Model Example?

Question

Engr_Mirza

How the SCR and X/R values are calculated in Type-4 Detailed Model Example?

Hi PSCAD community, I have a question, details are as follow;
When you scroll to Knowledge Base > PSCAD Enginnering Applications section on PSCAD website there is file named : Type 4 Wind Turbine Generators.
I have recently downloaded that Type 4 Wind Turbine Generator Example and Specification file from that section.
Now, I am facing a problem, In the Specification pdf file on page number 6 it is mentioned that SCR value is set to 10 to make the Grid stronger.

Kindly help me or guide me, how this SCR value of 10 is calculated ? I have been stuck on this issue from last few days. I myself cannot figure out this anymore without the support of PSCAD community. Kindly help me

Thanks in advance

Status: Open Feb 12, 2023 - 06:11 AM

scr, SCR and X/R ratio calculation

Comments (0) | New Comment

Do you have the same question? Follow this Question

Answer this question Report it

3answers

Voted Best Answer

Berwin

Feb 14, 2023 - 06:52 AM

SCR is the ratio of fault level MVA at the POI to the rated megawatt value connected generation.

1

0

Report it

Comments (5) | New Comment

By

Engr_Mirza

on 2/15/2023 4:12:36 AM | Like (0) | Report

Dear Berwin, Thank you for your reply. Community help is great for new comers like me.

Yes, I agree to your statement but when i try to mathematically calculate SCR value of type4 wind turbine, I am failing every time to match the exact answer of SCR 10 which is mentioned in Type4 Wind Turbine Pdf file in Engineering Application section.

Being my senior, please guide me with values of MVA at POI.

Thanks Berwin

By

Engr_Mirza

on 2/15/2023 6:20:39 AM | Like (0) | Report

OR
You can also help me with initial formula and values for exact SCR 10 value. I'm creating a study purpose project but stuck at this point from last 1 week.
Thanks in advance

By

Berwin

on 2/15/2023 6:28:46 AM | Like (0) | Report

Say if the wind farm rating is 200MW and if it need to have SCR ratio of 10, then fault level MVA of 2000MVA should be considered and this can be respresented as impedance in the source to which the wind farm is connected.(It is represented as voltage source with impedance in the snapshot you provided)
In other words, based on the fault level of the connected source and the rating of wind farm, you can calculate the SCR ratio to which the plant is connected.

By

Berwin

on 2/15/2023 6:29:24 AM | Like (0) | Report

I hope it helps

By

Engr_Mirza

on 2/15/2023 6:46:06 AM | Like (0) | Report

Please check new answer. thanks

Add New Comment

Answers

Engr_Mirza

Feb 15, 2023 - 06:45 AM

Thanks you Berwin for taking your time out to help me. Appreciated. This will also motivate me to help new comers on PSCAD when I will have enough expertise on this software.
Yes, I understand your statement that for SCR 10, 2000MVA /200 MW shall be considered. But if you see images below, In image 1 voltage source is used as a grid load and Sbase is 200 MVA not 2000 MVA and in image 2, what about impedance generated from transmission cables of 55 km, transformers and fault introduced. Can't find exact impedance values in parameters.
Thanks

0

Report it

Comments (1) | New Comment

Engr_Mirza

Feb 27, 2023 - 06:46 AM

Hello Berwin, Somehow I figured it out. Now, I need your approval on this. We also know that SCR= (rated voltage)^2 / Z(impedance) * Wind Turbine rated power
In wind turbine model 4 we have 1). rated volatege 230KV, Z= 26 ohms ( this impedance is at the volatge source which is representing grid, please see image attached ) and WT rated power is 200 MW.
Substituting these values (230KV)^2 / 26*200MV, we get SCR = 10.17 and same SCR = 10 is mentioned in pdf file of WT4 model.
Thanks

0

Report it

Comments (3) | New Comment

Answer this question

Share Your Own Experience & Expertise

We look to ensure that every question is answered by the best people with relevant expertise and experience, the best answers include multiple perspectives. Do you have relevant expertise or experience to contribute your answer to any of these commonly asked questions?

Dear Berwin, Thank you for your reply. Community help is great for new comers like me.

Yes, I agree to your statement but when i try to mathematically calculate SCR value of type4 wind turbine, I am failing every time to match the exact answer of SCR 10 which is mentioned in Type4 Wind Turbine Pdf file in Engineering Application section.

Being my senior, please guide me with values of MVA at POI.

Thanks Berwin
OR
You can also help me with initial formula and values for exact SCR 10 value. I'm creating a study purpose project but stuck at this point from last 1 week.
Thanks in advance
Say if the wind farm rating is 200MW and if it need to have SCR ratio of 10, then fault level MVA of 2000MVA should be considered and this can be respresented as impedance in the source to which the wind farm is connected.(It is represented as voltage source with impedance in the snapshot you provided)
In other words, based on the fault level of the connected source and the rating of wind farm, you can calculate the SCR ratio to which the plant is connected.
Please note if the impedance is in ohm then Sbase for voltage source won't be having any impact on fault level. Here, I can POI is after 55km transmission line. To get the short circuit MVA at POC, I would suggest to disconnect the wind turbine and apply fault on the location of interest.
To get the effective short circuit MVA please use the measured the short circuit current and with this calculate short circuit MVA by sqrt(3)*V (kV)*Irms (kA).
Yes. Effectively you are using Short circuit MVA/ Rated capacity to find SCR ratio. where, short circuit MVA is kV^2/Z

PSCAD™ Q&A

How the SCR and X/R values are calculated in Type-4 Detailed Model Example?

3answers

Voted Best Answer

Answers

Share Your Own Experience & Expertise

Browse by Topic

Recently Active Members

Tools