This technical seminar report discusses contingency analysis, which evaluates the impacts of removing equipment from a power system. It presents two main methods: the DC power flow method and the Z matrix method. The DC power flow method uses network parameters and bus voltage equations to model and simulate effects. The Z matrix method converts loads to impedances, injects a current, and calculates new current flows. It also discusses post-contingency equilibrium methods and concludes contingency analysis is used as an online decision support tool to quickly identify potential issues.

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 !