Slide

TCSC OPTIMAL LOCATION FOR
ATC ENHANCEMENT
1

Outline
• Abstract
• Introduction
• Literature Survey
• Problem Formulation
• Solution methods
• Problem definition
• Result
• Conclusion
• Appendix
2

ABSTRACT
This paper proposed an approach for a method using Genetic
Algorithm to determine the optimal location of FACTS device for
Enhancement of Available Transfer Capability (ATC) of power transactions
between source and sink areas in the deregulated power system. In this
project Thyristor Controlled series Capacitor(TCSC)
for enhancing the available transfer capability of the single area power
system . Repeated Power Flow method are used calculated and
enhancement of ATC with TCSC to compute ATC is used in IEEE14-
bus(single area)system are simulated.
3

Introduction
The new structures of power system become more complex.
These new structures have to deal with problem raised by the
difficulties in building new transmission lines and the significant
increase in power transactions associated to competitive electricity
markets. Thus a large interconnected system has been built in order
to be able to obtain a high operational efficiency and network
security.
4

In this situation, one of the possible solutions to improve the
system operation is the use of flexible AC transmission technologies
(FACTS). The implementation of the FACTS devices extends the
possibility that current through a line can be controlled at a reasonable
cost, enabling large potential of increasing the capacity of existing
lines, and use of one of the FACTS devices to enable corresponding
power to flow through such lines under normal and contingency
conditions FACTS technology not only provides solutions for efficiently
increasing transmission system capacity but also increases ATC, relieve
congestion, improve reliability and enhances operation and control.
5

Literature Survey
1. Manish Patel, Member, IEEE and Adly A. Girgis,Fellow, 2009
IEEE
This paper based on AC-PTDFs uses the derivatives around the
given operating point and may lead to unacceptable results when
used at different operating points to calculate ATC
2.R.Mohamad Idris, A.Khairuddin, and M.W.Mustafa(world
academy of Science,Engineering and technology 2009
This paper using bees Algorithm is proposed to
determine the optimal allocation of FACTS devices for
maximizing the Available Transfer capability using
TCSC,SVC.one of the drawbacks of the algorithm is the
number of tunable parameters used. Nevertheless, it is
possible to set the parameter values by conducting a small
number of trials.
6

3.k. Radharani , j.Amarnath (International journal of electrical
and electronic systems research vol 3,june2010) Flexibility
AC transmission system devices can be an alternative to
reduce the flows in heavily loaded lines, resulting in an
increased transfer capability. TCSC are used enhance ATC
using Genetic Algorithm.
4.M. Noroozian, L. Angquist, M. Ghandhari, g. andersson
(IEEE Transactions on Power Delivery, october 1997)
This paper investigates the performance of the UPFC for
power flow control . A mathematical model for UPFC which will
be referred as UPFC injection model can easily be incorporated
in the steady state power flow model. An algorithm is proposed
for determining the optimum size of UPFC for power flow
applications. The performance of UPFC is compared with that of
phase shifting transformer(PST)
7

5. Sh.Javadi,A.Alijani,A.H.Mazinan (2011)
(World Academy of Science , Engineering and Technology)
This paper injected power of SSSC definitely affects on the rate of
optimization in addition to optimize ATC on critical lines via SSSC
installation , its possible to improve ATC value of all transmission lines and
consequently will effect on total network.
6.Armando M. Leite da Silva, Fellow,, IEEE, Jaco Guilherme de carvalho
Costa, antonio da fonseea Manso, and George j. Anders, Fellow, IEEE
(IEEE Transactions on Power systems, August 2002)
The main objective of this work is to propose a new methodology to
determine the best points in the system to add new agents (sellers and
buyers), in order to maximize the ATC, without violating a pre-established
reliability level. In the process, the ATC probability density function is
determined considering uncertainties from equipment un-availabilities.
The proposed algorithm uses Monte Carlo simulation to select system
state and linear programming with a dc power flow model, to analyse and
optimize each selected state. The IEEE Reliability Test System (RTS) is used
to illustrate the proposed methodology.
8

7. R.Srinu Naik, Member IEEE,Prof.K.Vaisakh,Member IEEE,
K.Anand, M.E.student
This paper improve the transfer capability of power
system incorporating the reactive power flow in ATC
calculations by redistributing the power flow the ATC is
improved application of one type of Flexible AC Transmission
System (FACTS) device, the Thyristor Controlled Series
Compensator (TCSC) to improve the transfer capability
8.N. Schnurr and W.H. Wellssow, Membwr, IEEE conference in
2001.
This paper used superimposed power transits can be
evaluated regarding their feasibility and necessary installation of
Load-Flow Controllers (LFC) under consideration of contingency
cases. A method for the determination of the ATC for a certain
number of LFC is also presented. Finally an example of a
computer-aided determination of favourable LFC locations for
enhancing the ATC in extended power systems is discussed.
9

9. T.Nireekshana, Dr.S.Siva Naga Raju,Dr.G.Kesava Rao2011
IEEE conference paper
In this paper the line stability indices and the feasibility
limit at different cases of line outage and generator outages
are calculated security assessment techniques are used.
10.Santiago Grijalva, Member, IEEE, Peter W. Sauer, Fellow,
IEEE, and James D. Weber, Member, IEEE(IEEE Transaction 0n
power systems, may 2003)
This paper describes a fast algorithm to incorporate this
effect. The estimation of the line post-transfer complex flow is
based on circle equations and a megavar-corrected megawatt
limit. The method can be easily integrated into existing linear
ATC software because the computation remains based on active
power distribution factors. The algorithm is illustrated in a small
example and the error correction demonstrated for transfers in
larges systems. 10

Problem Formulation in power system
network
The power system network contingency condition like
line outage, short circuit between the lines, lightning strike in
those case various problems will occur in power system network
is
1. Transients
2. Interruptions
3. Sag / Under voltage
4. Swell / Overvoltage
5. Waveform distortion
6. Voltage fluctuations
7. Frequency variations
11

Solution
FACTS
Flexible AC Transmission System (FACTS) is a new integrated concept
based on power electronic switching converters and dynamic controllers to
enhance the system utilization and power transfer capacity as well as the
stability, security, reliability and power quality of AC system interconnections.
12

TYPES OF FACTS CONTROLLERS
Series Controllers
Static Synchronous Series Compensator (SSSC)
Thyristor Controlled Series Capacitor(TCSC)
Thyristor-Switched Series Reactor(TSSR)
Shunt Controllers
Static Synchronous Compensator(STATCOM)
Thyristor Switched Reactor(TSR)
Thyristor Switched Capacitor(TSC)
Combined Shunt and Series Controllers
Unified Power Flow Controller(UPFC)

CAPABLITIES OF DIFFERENT FACTS
CONTROLLERS
Controller Voltage
Control
Transient
stability
Damping
Power
Oscillations
Reactive
Power
Compensation
Power Flow
Control
SSR
Mitigation
STATCOM X x x x
SSSC X x x x x x
UPFC X x x x X
Svc x x
TCSC x x x x x x

TCSC
Thyristor Controlled Series Capacitors (TCSC) high speed switching
capability provides a mechanism for controlling line power flow, which
permits increased loading of existing transmission lines, and allows for rapid
readjustment of line power flow in response to various contingencies. The
TCSC also can regulate steady-state power flow within its rating limits.
The basic structure of TCSC
17

18
Principle of TCSC
The principle of TCSC in voltage stability enhancement is to
control the transmission line impedance by adjusting the TCSC impedance.
The absolute impedance of TCSC, which can be adjusted in three modes:
i. Blocking mode: The thyristor is not triggered and TCSC is
operating in pure capacity in which the power factor of TCSC is leading.
ii. By pass mode: The thyristor is operated in order to XL = XC.
The current is in phase with TCSC voltage.
iii. Capacitive boost mode: XC > XL and then inductive mode
XL > XC.

METHAMETICAL MODEL OF TCSC
• Pi (com) =Vi2 ΔGij-ViVj [ΔGijcos (δij) +ΔBijsin (δij)]
• Pj (com) =Vj2 ΔGij-ViVj [ΔGijcos (δij)-ΔBijsin (δij)]
• Qi (com) =-Vi2 ΔBij-ViVj [ΔGijsin (δij)-ΔBijcos (δij)]
• Qj (com) =-Vj2 ΔBij+ViVj [ΔGijsin (δij) +ΔBijcos (δij)]
20

ATC Assessment and Enhancement using NRLF –
Repeated Power Flow Algorithm
• Read Line data, Bus data, tolerance for ΔP and ΔQ
• Formulate Y-Bus matrix.
• Assume flat start for starting voltage solution
δio = 0, for I=1,…,N for all bused except slack bus
|Vio| = 1.0, for I=M+1,M+2,…,N (for all PQ buses).
|Vi| = |Vi| (spec) for all PV buses and slack bus.
• For PV buses, calculate Pical and Qical.
• For PV buses, Check for Q-limit Violation.
If Qi(min) < Qical < Qi(max), the bus acts as P-V bus.
If Qical > Qi(max), Qi(spec) = Qi(max).
If Qical < Qi(max), Qi(spec) = Qi(min), the P-V bus wioll act as P-Q bus.

• Compute mismatch vector using
ΔPi = Pi(spec) – Pical
ΔPi = Qi(spec) – Qi(cal)
• Compute
ΔPi(max) = max |ΔPi|; i=1,2,…,N except slack bus.
ΔQi(max) = max|ΔQi|; I-M+1,…N
• Compute Jacobian matrix vector using
∂Pi / ∂δ ∂Pi / ∂|V|
• J =
∂Qi / ∂δ ∂Qi / ∂|V|
• Update State correction Vector
Δ δ ΔP
= [J]-1
ΔV ΔQ

• Update State Vector using
Vnew = Vold + ΔV
δ new = δold + Δ δ
• The procedure is continued until
| ΔPi| < ε and | ΔQi| < ε, otherwise go to step 3.
• If the TCSC device is selected, then the rating of the device and its location is
identified and is used to calculate the load flow with TCSC device.
After calculating the load ability limit, go to step 3

• The violated buses in the load flow without TCSC device are found.
Then the violated buses from the load flow with TCSC device are found.
Thus the Voltage Deviation Index is calculated by the formula
• STOP

Improvement of power system network
problem by using FACTS-devices
• power flow control,
• increase of transmission capability,
• voltage control,
• reactive power compensation,
• Voltage stability improvement,
• power quality improvement,
• power conditioning,
• flicker mitigation,
• interconnection of renewable and distributed generation
and storages.
25

Problem Definition
• Available Transmission Capability(ATC)
The maximum power that can be transferred over the
existing amount is called the available transmission
capability
ATC=TTC-CBM-TRM-”Existing Transmission Commitments”
26

METHODS OF CALCULATING ATC
• Load flow / continuous power flow (CPF) /
Repeated Power Flow (RPF) methods.
• Optimization based methods
• Network sensitivity method

Methods of Load Flow Analysis
• Gauss- seidel method
• Newton – Raphson method
• Fast Decupled method
us Gauss
a
• Fast Decupled
29

Newton- Raphson Power Flow
• Advantages
– fast convergence as long as initial guess is close to
solution
– large region of convergence
– Newton-Raphson algorithm is very common in
power flow analysis
30

Power Transfer Distribution Factors
(PTDFs)
• PTDF: measures the sensitivity of line MW
flows to a MW transfer.
• Line flows are simply a function of the
voltages and angles at its terminal buses
• Using the Chain Rule, the PTDF is simply a
function of these voltage and angle
sensitivities.
31

To find AC- PTDFs
• PTDFij,mn= ΔPij/ΔT
• Where
• ΔPij is Change in real power flow on line
ij for a change of ΔPm occur at bus m.
• ΔPm =ΔT
32

Line Outage Distribution Factors
(LODFs)
• LODFl,k: percent of the pre-outage flow on Line
K will show up on Line L after the outage of
Line K
P
l k
LODF ,
l k P
• Linear impact of an outage is determined by
modeling the outage as a “transfer” between
the terminals of the line
33
k
,

 Change in flow on Line L
after the outage of Line K
Pre-outage flow on Line K

Results of ATC assessment using NRLF Repeated
power flow algorithm
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Line No
Line flow in p.u.
Without TCSC
With TCSC
Case 1: Normal Loading Condition

LINE NO START
BUS
END BUS LINE FLOW
WITHOUT TCSC WITH TCSC BETWEEN 6 & 9
1 1 3 0.6926 .6938
2 1 6 0.1754 .2628
3 1 7 -0.2464 -.5037
4 2 1 0.8500 .8501
5 2 7 0.1271 .2177
6 3 6 -0.5626 -.7838
7 4 11 -1.6300 -1.6304
8 4 12 0.7515 .8433
9 4 13 0.345 0.43
10 6 7 -0.5152 -.4295
11 6 8 0.432 0532
12 6 9 0.4356 0.9654
13 7 4 -0.8564 0.876
14 8 5 -0.234 0.321
15 8 9 0.45667 0.4335
16 9 10 0.12343 0.2130
17 9 14 -0.2124 0.214
18 10 11 -0.674 0.689
19 12 13 0.1235 0.245
20 13 14 0.5652 0.569

Case 2: Twice Normal Loading Condition
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Line No
Line Flow in p.u.
Without TCSC
With TCSC

LINE NO START
BUS
END BUS LINE FLOW
WITHOUT TCSC WITH TCSCBETWEEN 6 & 9
1 1 3 0.5249 .6938
2 1 6 0.1034 .2628
3 1 7 -0.212 -.5037
4 2 1 0.8565 .8501
5 2 7 0.1271 .2177
6 3 6 -0.4326 -.7838
7 4 11 -1.6300 -1.6304
8 4 12 0.7515 .8433
9 4 13 0.345 0.43
10 6 7 -0.245 -0.4595
11 6 8 0.2432 0.4532
12 6 9 0.2266 1.0023
13 7 4 -0.8564 0.5676
14 8 5 -0.0233 0.3713
15 8 9 0.2322 0.4335
16 9 10 0.12343 -0.441
17 9 14 -0.2124 -0.876
18 10 11 -0.674 0.789
19 12 13 0.1235 -0.4545
20 13 14 0.5652 0.677

Line
no
RATING 0.4
LOADING Loadability Limit
(%)
Voltage Deviation index
12 1.5 Times the normal loading 4 1.448*10-4
2 times the normal loading 7 5.4*10-5
3 Times the normal loading 18.72 0
2 Times the normal loading 5 1.72*10-4

RATING 0.6
Line no LOADING Loadability Limit
(%)
Voltage Deviation index
12 1.5 Times the normal loading 4.34 1.43*10-4
2 times the normal loading 7.23 2.32*10-5
2 Times the normal loading 5.21 1.98*10-4

CONCLUSION
• The optimal number and location of TCSC devices
• Benefits of applying FACTS technologies for increased
power transfers
• Increased load ability and reduced costs of approach

Example of Load flow Analysis
43

Bus Data for IEEE 14 Bus System
Sl.
No.
Bus
No.
P
Load
(p.u)
Q
Load
(p.u)
Bus
Type
Q
Generated
Max
(p.u)
Q
Generated
Min
(p.u)
Vm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1
2
3
4
5
6
7
8
9
10
11
12
13
14
0
0.217
0.942
0.478
0.076
0.112
0
0
0.295
0.09
0.035
0.061
0.135
0.149
0
0.127
0.19
0
0.016
0.075
0
0
0.166
0.058
0.018
0.016
0.058
0.05
3
2
2
1
1
2
1
2
1
1
1
1
1
1
0.1
0.5
0.4
0
0
0.24
0
0.24
0
0
0
0
0
0
-0.1
-0.4
0
0
0
-0.06
0
-0.06
0
0
0
0
0
0
1.06
1.45
1.01
1.019
1.02
1.07
1.062
1.09
1.056
1.051
1.057
1.055
1.05
1.036

Generator Data for IEEE 14 Bus
System
Bus Pg Qg Qmax Qmn Vg mBase Status Pmax Pmin
1
2
3
6
8
232.4
40
0
0
0
-16.9
42.4
23.4
12.2
17.4
10
50
40
24
24
0
-40
0
-6
-6
1.06
1.045
1.01
1.07
1.09
100
100
100
100
100
1
1
1
1
1
332.4
140
100
100
100
0
0
0
0
0

Line Data for IEEE 14 Bus System
DESIGNATION RESISTANCE
(p.u)
REACTANCE
(p.u)
LINE CHARGING
ADMITTANCE(p.u)
1-2 0.01938 0.05917 0.0264
2-3 0.04699 0.19797 0.0219
2-4 0.05811 0.17632 0.0187
1-5 0.05403 0.22304 0.0246
2-5 0.05695 0.17388 0.017
3-4 0.06701 0.17103 0.0173
4-5 0.01335 0.04211 0.0064
5-6 0 0.25202 0
4-7 0 0.20912 0
7-8 0 0.17615 0
4-9 0 0.55618 0
7-9 0 0.11001 0
9-10 0.03181 0.0845 0
6-11 0.09498 0.1989 0
6-12 0.12291 0.25581 0
6-13 0.06615 0.13027 0
9-14 0.12711 0.27038 0
10-11 0.08205 0.19207 0
12-13 0.22092 0.19988 0
13-14 0.17093 0.34802 0

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