Decoupled Power Flow AlgorithmsLecture #23EEE 574Dr. Dan Tylavsky

Decoupled P.F. Algorithms

We know that for the full Newton power flow we interleave P, P and , Vas shown.

Decoupled P.F. Algorithms

An alternate ordering which will still preserve the quasi-diagonal dominance property is:Symbolically we can write this as:The draw back to this ordering is the increased fill.

Decoupled P.F. Algorithms

Consider the following 3 bus system:Conventional Ordering:No FillNew Ordering:Much Fill

Decoupled P.F. Algorithms

Claim: There exists only weak coupling between:P and V,Q and ;(Said another way, changes in P have little effect on Q and vice versa.)hence N and J can be ignore. Recall the Jacobian is a linear approximation, ignoring N and J, simply makes the approximation less accurate.

Decoupled P.F. Algorithms

For typical power system branches: X/R >> 1. ik > 1:For ik < 200:

Decoupled P.F. Algorithms

For the reactive power flow equation:For ik < 200:For X/R >> 1:(Recall Bik

The End

Instructional ObjectivesAt the end of this lecture:a) you will be able to describe in lay terms the information contained in an electrical schematic diagram,b) you will be able to describe the difference between a discrete and a continuous system,c) you will be able to describe the difference between a digital or binary discrete system and an arbitrary discrete system.