Problems for Assignment 7 - Electrical Machine Design | ECE 598, Assignments of Electrical and Electronics Engineering

Material Type: Assignment; Class: Electrical Machine Design; Subject: Electrical and Computer Engr; University: University of Illinois - Urbana-Champaign; Term: Fall 2007;

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ECE 598GG Fall 2007
Prof. George Gross
Room 339 Everitt Lab
Homework 7
due Thursday, October 18, 2007
Problem 1. [40 points] Impacts of a double-line outage contingency
We consider the simultaneous outage of two lines
and
. Let
Δf
denote the changes
in the active power line flow on line
due to the simultaneous outage of lines
and
.
We express
Δf
as the linear combination of the pre-outage active power line flows on lines
and
:
Δf=
χ
f
+
χ
f
where
χ
and
χ
are called LODFs for two line outage contingencies. Use two different
schemes to determine
χ
and
:
i)simultaneous outages
ii)sequential outages
Show that the two schemes lead to identical results.
Problem 2. [40 points] UTC evaluation considering two – line outage contingency
In the evaluation of the UTC
um,n
, we have considered the active power line flow constraints
for the base case and single line outage contingency cases. Now, we want to take into
account also the constraints for contingencies in which two lines are outaged
simultaneously. Formulate the optimization problem using the appropriate distribution
factors to determine
um,n
considering the constraints for all the following conditions:
i)the base case
ii)the set of single line outage contingencies for the subset
L=
1,2,,
L
{ }
L
: each line in the subset
L
is outaged individually
pf2

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ECE 598GG Prof. GeorgeFall Gross 2007

Room 339 Everitt Lab Homework 7

due Thursday, October 18, 2007

Problem 1. [40 points] Impacts of a double-line outage contingency We consider the simultaneous outage of two lines  ′and  ′′. Let

Δ f  denote the changes in the active power line flow on line  due to the simultaneous outage of lines

 ′and

We express Δ f  as the linear combination of the pre-outage active power line flows on lines  ′and  ′′: Δ f  = χ  ′ f (^)  ′+ χ (^)   ′′ f (^) ′′ where χ  ′and χ  ′ ′are called LODF s for two line outage contingencies. Use two different schemes to determine χ  ′and χ  ′ ′: i ) simultaneous outages ii ) sequential outages Show that the two schemes lead to identical results.

Problem 2. [40 points] UTC evaluation considering two – line outage contingency In the evaluation of the UTC u m,n^ , we have considered the active power line flow constraints for the base case and single line outage contingency cases. Now, we want to take into account also the constraints for contingencies in which two lines are outaged simultaneously. Formulate the optimization problem using the appropriate distribution factors to determine u m,n^ considering the constraints for all the following conditions: i ) the base case ii ) the set of single line outage contingencies for the subset

L = {  1 ,  2 ,,  L} ⊂ L : each line in the subset L is outaged individually

iii ) the set of double-line outage contingencies for the subset L : each pair of lines in L is outaged simultaneously

Problem 3. [40 points] Impacts of the load levels on the sensitivity matrix

The ISF s are approximations of the sensitivity matrix d d^ fp s(^0 )

whose values depend on the

load level of the system. We investigate the impacts of the nodal injections on the sensitivity matrix by studying the sensitivity of each element in the sensitivity matrix to the injection

vector p : (^) dd p^ ⎡ ⎣ ⎢ (^) d^ d pfn ⎤ ⎦ ⎥ s(^0 )

. We consider a lossless system with the load level close to zero,

i.e., θ (^0 )^ ≈ 0 , p(^0 )^ ≈ 0 ; we assume that the reactance compensation is sufficient at each node so that the voltage magnitude at each node is constant and close to 1.0 p.u. Prove that, if the Jacobian matrix J θ = 0 ,V = 1 is nonsingular, then

d d p

d fd pn

⎣^ ⎢^

⎦^ ⎥ θ = 0 ,V = 1 ≈^0 ∀^ ^ ∈^ L^ ,^ ∀^ n^ ∈^ N^.

State any additional assumptions that you require.