Contingency analysis

1. CONTINGENCY ANALYSIS
Technical Seminar Report On
“CONTINGENCY ANALYSIS”
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
under the guidance of
Mr. Debasis Jena
submitted by
SIGMA DASH EE200198046

2. CONTINGENCY ANALYSIS
INTRODUCTION
 Simulator that evaluates, provides and prioritizes the impacts
on an electric power system
 AC power flow method is expensive, computationally and time
taking.
 DC power flow equations and bus voltage equations
 Deterministic contingency analysis
 The algo in CA uses network parameters to model, calculate
& simulate the effects of removing equipment from the power
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
system.

3. CONTINGENCY ANALYSIS
DC POWER FLOW METHOD
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
N-1 in number, only the real power flow , all line resistances are
neglected
ö
æ
*
i
P Real V Y V i 2,........
N
i ij j
d q d
V e Y e V e
i ij j
ö çè
÷ø
Real
= æ
ö
÷ ÷ø
ç çè æ
=
= ÷ ÷ø
ç çè
=
å
å
å
+ -
-
i
j( )
i j
i
Real ij
j i
V V Y e
ij
j
j
i
j
ij
j
j
q d d
Line resistance is neglected so
Y ij= Gij + jBij = jBij

4. CONTINGENCY ANALYSIS
i i j ij i j P =åV V B d -d
sin( )
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
i
must be sufficiently small i j d -d
å å
= =+
Ultimately, P = K d + K d +
K
d
i ij j ii i ij j N
j i
1
i-1
j 1
or in matrix form P = Kd
If P has to be constant, K & d will change from base values
This provides the changes in the bus voltage angles
Dd = - (K0)-1 DKds

5. CONTINGENCY ANALYSIS
To study single contingencies, we use
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
D Kpp= Kpq
DKqq = Kpq
D Kpq = - Kpq
D K qp= - Kqp
Substituting these we get the matrix as
= - (K0)-1 (d psDK p+ d psDKq Dd ) pq
Changes in line flows due to the loss of line pq given are
obtained by substituting the appropriate elements of Ddpq

6. CONTINGENCY ANALYSIS
Z MATRIX METHOD
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
Methods include inverting Y bus matrix and injecting a
fictitious current into the bus
Converting the MVA loads to impedance loads using
Zload i =
2
*
i
V
i
S
Injecting a unit current, into the bus p which has to be removed
ù
ú ú ú ú ú ú
û
é
ê ê ê ê ê ê
V
.
.
V
ë
1
N
.
=
ù
ú ú ú ú ú ú
û
é
ê ê ê ê ê ê
ë
1P
Z
NP
.
.
.
Z

7. CONTINGENCY ANALYSIS
Ipq can be calculated using the equation
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
V V
p q
line pq
pq Z
I
-
=
An adjustment parameter, d, has to be used
S
pq
I
pq
I
d
D=
Due to the injection lp = d, the new current in other elements
d Z Z
( - )
ip jp
Z
line ij
I = pq
where ij is not equal to mn

8. CONTINGENCY ANALYSIS
The sought-after current flow changes due to removing line pq are
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
ij ij ij D I = I~ - I for all ij
Calculating the current flow pattern in the modified network,
in which line pq has been removed, requires only that we inject
current I p=d, as before, into the modified network.
ù
ú ú ú ú ú ú
û
é
ê ê ê ê ê ê
ë
=
ù
ú ú ú ú ú ú
û
é
ê ê ê ê ê ê
ë
N
~ ~ . . . ~
Z Z Z
11 12 1
.
.
.
N N NN
~
V
i
.
.
.
N
Z Z Z
V
~ ~ . . . ~
~
1 2
ù
ú ú ú ú ú ú
û
0
é
ê ê ê ê ê ê
.
d
0
ë
.
=
ù
ú ú ú ú ú ú
û
é
ê ê ê ê ê ê
ë
d
d
p
~
1
.
.
Np
Z
~
Z
.
The voltages are

9. CONTINGENCY ANALYSIS
POST CONTINGENCY EQUILLIBRIUM
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
Methods to compute the equilibrium condition immediately
following a disturbance to an electric power system
 Analysis by Integration
 Analysis by Simultaneous
Iteration
 Analysis by partitioned iteration

10. CONTINGENCY ANALYSIS
CONCLUSION
 Methods for evaluating both isolated and interconnected areas
Technical Seminar Presentation 2004 Presented by – SIGMA DASH
 Used as an online decision support tool
 Faster approximate methods for locating potential trouble spots

11. Technical Seminar Presentation 2004 Presented by – SIGMA DASH
CONTINGENCY ANALYSIS
THANK YOU !