Dear all,
I am trying to run a load flow analysis of relatively unknown power grid. However, one of many problem i am facing is that the network consists of 132 kV branch or line and 66 kV lines as well. I could opt for using the lumped representation of the 66 kV segment but it would make the analysis more unrealistic. Also, if i try to consider two different voltage level for the load flow analysis, i might face the problem of Per unit representation.
How could i proceed? I would highly appreciate any help in this topic.
Regards,
Bishal
1. You can do LFA using per unit values. What is the problem you have with pu values?
2. There s a way to include even transformer tap changes using an alpha factor.
Bishal,
To add to Sudha's reply, you actually should convert everything to per-unit and execute power flows only in terms of per-unit.
It has been shown that convergence of a power flow is not assured if you run the iterations in mutiple absolute units.
Once results are available post convergence, they can always be scaled back to the correct absolute units.
-Sanjay
Dear Sanjay Sir and Sudha Ma'am,
Thanks. Actually, that is what i meant. Instead of converting the power network in PU values and back to real values again, i was thinking if it is a possibility to carry out the LFA in reference to the Absolute value itself? Would it still converge?. Or is it worth a try?
Thanks to you, I think now i am clear in this matter, at least.
Because of different voltage level (132 kV and 66 kV) , i am somehow feeling uncomfortable to convert the absolute system parameters to PU values and vice-versa as it would be difficult to loop them up in MATLAB program.
Regards.
Dear Bishal,
The pu system is exactly for handling different voltage levels on a power system, among other things. Why should you be uncomfortable? It is true that you cannot, rather you should not use tools like MATLAB without understanding the essence of the system you are modelling. Don't we live in a world, comfortably, with different currency, even valued differently in each country? I think that the pu conversion will help you to be more careful about the results and not complacent as is the unfortunate case when some youngsters use tools.
Please sir,
refer to the book: FACTS - Modeling and Simulation in Power Networks. (Acha et al.)
Dear all,
Thanks a lot for your insights and help. As a matter of fact, it solved my problem for now. The PU representation simplified my network much more then i expected and solved the problem of different voltage levels during load flow analysis in my test-network.
Will keep you updated.
Regards,
Bishal
Dear all,
quiet a resourceful discussion. Per unit conversion and network analysis is such a powerful method, even it helped us to solve the network problems manually when such user friendly softwares were not available.
The veterans will agree with me.
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