Welcome to the world of Optimizations

In this blog concepts of conventional and unconventional optimization techniques are discussed.

Friday, November 12, 2010

Power Flow Analysis: Transmission and Distribution Systems: An Introduction

Power flow or load flow is one of the important power system analyses. Problem. This problem is determining the unspecified (dependent) parameters of the power network by some specified (independent) parameters.

It is known that the power system consists of generators, loads, transformers, transmission lines and other protective devices. In power flow every bus (node) is having four parameters.
1. Real Power P
2. Reactive power Q
3. Voltage magnitude [V]
4. Voltage magnitude φ
Depending on the type of the bus two out the four variables are specified and the remaining two has to be determined. The specified two variables and unspecified two variables of each bus are related by the kirchoff’s network laws.

The network elements are modeled according to their steady state characteristics.
1. Generator –voltage source with series impedance
2. Loads: constant power or constant admittance (impedance)
3. Transmission line: pi model
4. Transformers are to be incorporated in the transmission line model.

The specified and unspecified parameters
Type of the bus
Specified variables
Unspecified variables
Q, φ
Load(Constant power)
[V], φ

When the power is transmitted from the generators to the loads through the transmission line the loss occurring in the transmission line is unavoidable. It is call the transmission loss and it not known in advance so there must be a provision that a generator should include the transmission loss in its generation.

This is the reason why the slack bus concept is included in the power flow analysis. The generator having largest capacity is chosen as the slack bus. Depending on the selection of the slack bus generator the power flow solution will vary.

Procedure to solve transmission system power flow

The following steps are to be followed to carry out power flow analysis. Here it is assumed that the three phase network is a balanced one.

  1. Collect the specified data of generators, loads, transmission lines, and transformers. You can follow some matrix format like matpower.
  2. Convert the network as per unit equivalent.
  3. Formulate the equations as per kirchooff’s law.

These equations can be written in either polar form or rectangular form. In polar form no of equation are to be solved in 2(n-1)-m, wherein the rectangular form the no of equations are 2(n-1).
  1. The system of non linear (polar trigonometric, rectangular quadratic) equations are to be solved by numerical methods only because so far no analytical solution is derived to sole this problem.
  2.   Newton Raphson method, Decupled and gauss seidal are methods used to solve this problem. Among this N-R and Decoupled are preferred for their quadratic convergence.
Distribution Power flow.
The distribution systems are characterized by their nature of high R/X ration and radial nature (no loop).The admittance matrix is sparse and the Newton Raphson method may fail to converge for some networks. So the modeling of the problem as well as the solution methodology is different.

 The power flow equations for a radial distribution system are derived as the relationship between the specified complex bus powers and the bus voltages. If the network has n (total number) buses and ‘m’ generator buses the power flow equations are written as follows
k(i) is the set of nodes connected to node i, and Pi /Qi denote the real/reactive power at node i. The complex non linear equations (B2) are to be solved to determine the bus voltages. So many methods ranging form sweep methods to conic programming methods available in the literature 
 to solve this problem..



myun said...

nice post....
please visit OUR PAGE ok!!

Anonymous said...

please can any one tell me if load flow can be done on secondary distribution system (11/.415kv)

Anonymous said...

I have been browsing online more than three hours today, yet I never found
any interesting article like yours. It is pretty worth
enough for me. Personally, if all site owners and bloggers made
good content as you did, the net will be much more useful than ever before.

Here is my weblog - a free dating website

Anonymous said...

Hi my friend! I wish to say that this article is awesome, nice written and include approximately all vital infos.
I would like to see more posts like this.

Check out my webpage ... outbacknomads.timdiekman.com

Anonymous said...

You actually make it appear so easy together with your presentation however I in
finding this topic to be actually something that I feel I might never understand.

It seems too complicated and extremely vast for me.
I'm taking a look ahead to your subsequent publish, I will attempt to get the dangle of it!

Review my site: fadaf.de

Anonymous said...

I like the helpful info you provide in your articles.
I will bookmark your blog and check again here
frequently. I'm quite certain I will learn a lot of new stuff right here! Good luck for the next!

Here is my web-site ... mediawiki.metageny.com

Anonymous said...

row you out into the bad house quick.

Stop by my web-site ... 2chooz.com

Anonymous said...

Thank you for the good writeup. It in reality was a enjoyment account
it. Look advanced to far introduced agreeable from you!
By the way, how can we be in contact?

Here is my website: best online dating sites

Anonymous said...

Everyone loves it when individuals get together and share views.
Great site, keep it up!

Look at my blog; Enduros Male Enhancement Free Trial

Anonymous said...

Very good post. I am going through a few of these issues as well.

My web-site :: Pureberry Max Raspberry Ketone Select

Anonymous said...

I was recommended this blog by my cousin. I'm not sure whether this post is written by him as nobody else know such detailed about my trouble. You are incredible! Thanks!

my weblog :: offer

Anonymous said...

Howdy! Thiѕ iѕ kind of off topic but I nеed some helр from an establishеԁ blog.
Is it dіfficult to sеt uр your oωn blog?
I'm not very techincal but I can figure things out pretty quick. I'm thinking about setting uρ
mу οwn but I'm not sure where to start. Do you have any tips or suggestions? Cheers

Also visit my homepage; purchase omega 9

Anonymous said...

Hey! This is kind of off topic but I need some help from an established blog.
Is it difficult to set up your own blog?
I'm not very techincal but I can figure things out pretty quick. I'm thinking
about creating my own but I'm not sure where to start. Do you have any ideas or suggestions? With thanks

Feel free to visit my page: facebook sex

Anonymous said...

wonderful post, very informative. I wonder why the other experts
of this sector do not notice this. You must continue your writing.
I'm confident, you have a great readers' base already!

my webpage - facebook sex

Anonymous said...

Of course, what a great website and informative
posts, I definitely will bookmark your blog.Have an awsome day!

Also visit my site; facebook for sex

Anonymous said...

My brother recommended I would possibly like this website.

He was once totally right. This post truly made my day.

You cann't consider just how much time I had spent for this info! Thank you!

Look at my weblog; 121 dating

Anonymous said...

Hey! I'm at work surfing around your blog from my new apple iphone! Just wanted to say I love reading your blog and look forward to all your posts! Carry on the fantastic work!

Also visit my homepage waist to hip ratio calculator

Miracle Electronics said...

Thank you for Posting And sharing such great information.
Power transformers in India | Transformer manufacturer in India

kishore said...

i like your blog shared valuable information about In power system networks, protection has to be designed such that protective relays isolate the faulted portion of the network, to prevent equipment damage, injury to operators and to ensure minimum system disruption enabling continuity of service to healthy portion of the network. please visit Relay Coordination

Post a Comment