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IICPE.2016.8079489

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Impact of FACTS Devices in Automatic
Generation Control of a Deregulated Power
System
Kamlesh Pandey
Research Scholar, AKTU, Lucknow
Assistant Professor, Department
of EEE, Amity University Uttar
Pradesh, 201313
S. K. Sinha
Professor, Department of EEE,
Amity University Uttar Pradesh,
201313
Abstract - In this paper, the impact of integration of FACTS
devices viz. TCPS and TCSC on Automatic Generation
Control (AGC) of a two area thermal-thermal deregulated
power system have been studied in order to enhance the
performance of responses such as frequency deviation and
oscillation damping, deviation of tie line power between the
areas and power generated by GENCOs. The comparison of
results between those obtained with inclusion and exclusion
FACTS devices in the system has been shown using
simulations.
Keywords - AGC, Thyristor Controlled Phase Shifter,
Thyristor Controlled Series Compensator, Tie Line,
Deregulated Power System.
NOMENCLATURE
aij
= Area capacity ratio
bi
= Frequency bias
f
= Rated frequency
Δf i = Frequency Deviation
Kp = Gain of generator -load system
¨Pg = GENCO’s incremental power generation
¨Ptie = Deviation in tie-line power between areas
R
= Speed regulation of governor
Tt
= Time constant of turbine
Tp = Time constant of generator-load system
Tg = Time constant of governor
I. INTRODUCTION
Controllability of transmission systems such as
stabilization of system frequency and tie line power
deviations when load changes is a big challenge today.
With restructuring in progress the transmission systems
are were subjected to may changes in different countries.
Thus, there is necessity of flexibility that transmission
systems gets adapted to these changes more quickly and
act accordingly depending on available distinct generation
and diferent patterns of load [1]. FACTS technology
978-1-5090-4530-3/16/$31.00 ©2016 IEEE
Ashish Shrivastava
Professor, Department of EE,
JSSATE, Noida, Uttar Pradesh201301
responds to such needs and were used in improvement of
power transfer and controling capability of the system
resulting in improvement of system performance
particularly in the case of transient response oscillation
damping. FACTS devices and their utilization in AGC
has been researched and further advancements were
suggested by several researchers [2-5].
Our work depicts simulation of AGC with fuzzy
controler along with FACTS devices carried out in
MATLAB. The simulation damps out oscillations of
frequency and tie line power transient responses in a
thermal-thermal deregulated power system. Experiments
were carrie dout to establish that AGC accomplishes
improvement when Intelligent devices works in tandem
with FACTS devices.Two types of FACTS devices viz.
Thyristor controlled phase shifter (TCPS) and Static
synchronous series compensator (TCSC) were
appropriated in this study for performance improvement
mainly in oscillation damping in the AGC proceedings.
Knowledge based techniques along with FACTS
devices which resulted in transient responses were
compared with those outcomes obtained when controller
used is of conventional integral type under various
conditions and constraints with and without FACTS
devices.
II. THYRISTOR CONTROLLED PHASE SHIFTER
Thyristor Controlled phase Shifter (TCPS) lowers the
oscillations frequency of the system for this it changes the
phase angle of the system. Fig 1. Shows the two
respective areas of the TCPS connnection with the system.
The power system model provides the flow of power
in tie line of the two area system ΔPtie12 which is given
by [5]:
VV
ΔPtie12 = 1 2 cos(δ1 − δ 2 + φ )(Δδ1 − Δδ 2 + φ )
(1)
X 12
equipped with TCSC is obtained as
P=
Fig. 1.
Taking synchronizing power T12 as:
δ1 = 2π ³ Δf1dt and
k=
and
δ 2 = 2π ³ Δf 2 dt
Using laplace transform of equation (1) and
K
ϕ ( s ) = ϕ ΔError
1 + Tϕ
Where, ¨Error= ¨F1(s)
2π
Kϕ
s
1 + Tϕ
ΔPtie12 ( s ) =
T12 (ΔF1 ( s ) − ΔF2 ( s )) + T12
X ij (1 − k )
sin (δ ij )
where, k is the TCSC compensation level given by
TCPS in two area system
VV
T12 = 1 2 cos(δ1 − δ 2 + ϕ )
X 12
ViV j
X TCSC
X ij
(2)
The equivalent reactance of TCSC is given as
(3)
X TCSC =
ΔF1 ( s ) (4)
III. THYRISTOR CONTROLLED SERIES COMPENSATOR
(TCSC)
TCSC regulates the real power flow andr the current
magnitude of a transmission line. This is done by varying
the series reactance of TCSC. TCSC consists of a
capacitor in parallel with a thyristor controlled reactor..
Series compensation is very effective in increasing the
capability of power transfer and stability. Hence, the
TCSC has been used to improve AGC of the power
system.
The real power flow through the transmission line
X C X L (α )
X C − X L (α )
XL is reactance and Į is the thyristor firing angle.
Fig. 2. TCSC in two area system
IV. CASE STUDY: TWO THERMAL AREAS
DEREGULATED POWER SYSTEM
A deregulated power system having two inter-connneted
areas along with TCPS cascaded with the tie line is
Fig. 4. Two area system with a FACTS Device
0.03
0.02
0.01
V. RESULTS AND DISCUSSIONS
Two different scenarios were simulated and the
obtained results were compared.
Case(i): FACTS devices were not connected in the
system and system is simulated
Case(ii): FACTS devices of only one type i.e. either
TCPS or TCSC is connected at a time and system is run.
The deregulated power system model has been
simulated in MATLAB for two different situations.
Firstly, none of the FACTS devices have been connected
and the model has been run with integral controller.
Secondly, TCPS and TCSC devices have been connected
one by one and model has been run in each case. The
results obtained from the simulation of the power system
model with and without FACTS (TCPS and TCSC) have
been plotted and shown in Fig 3 and Fig 5-Fig 10.From
the figures it can be easily inferred that both the FACTS
devices help in fast oscillation damping and peak value
reduction. Settling time is also reduced when either of
TCPS or TCSC is included in the model.
In Fig. 3 and Fig 5, where the change in frequency in
area 1 and area 2 respectively have been compared with
and without FACTS devices, it can be inferred that there
is sharp reduction in frequency oscillation damping and
significantly small settling time.
Fig. 6 is plot of deviation in tie line power in the
presence and absence of FACTS devices. Here also
-0.02
-0.03
delf1
delf1TCPS
delf1TCSC
-0.05
-0.06
0
5
10
15
Time (Sec)
0.25 0.0 0.30 º
0.25 0.0 0.0 »»
0.25 1.0 0.7 »
»
0.25 0.0 0.0 ¼
Fig. 3 Response of del f1
0.04
0.03
0.02
del f Area 2 (Hz)
As per the DPM matrix each DISCOM demands 0.02
pu MW power from GENCO. With refernce to the given
area participation factors apf1,apf2,apf3 and apf4 are 0.75,
0.25, 0.50 and 0.50 respectively. GENCOs participate in
AGC. The loads which are not contracted have been
assumed to be zero.
0
-0.01
-0.04
0.01
0
-0.01
-0.02
-0.03
delf2
delf2TCPS
delf2TCSC
-0.04
-0.05
0
5
10
15
Time (Sec)
Fig. 5 Response of del f2
-3
10
x 10
delptie
delptieTCPS
delptieTCSC
8
del ptie (pu MW)
ª 0.5
«0.20
DPM = «
« 0.0
«
¬0.30
similar kind of results is obtained.
del f Area 1 (Hz)
depicted in Fig: 4 Different types of loads stipulated by a
distribution company are treated as local loads. UCL1,
UCL2, UCL3, and UCL4 are un-contracted loads. The
loads stipulated by a Distribution Company k is
notationed cpfjk which depicts contracted load fraction by
the company k from a Generation Company j.
Information are sent through these signals about a Genco
following a stipulated load of a distribution company [6].
By applying the below constraints the simulation of AGC
of subjected deregulated power system (thermal-thermal)
were carried out. Distribution Companies contract with
the Generation companies in accordance with the
following Disco Participation Matrix:
6
4
2
0
-2
0
5
10
15
Time (Sec)
Fig 6 Response of del Ptie
Figs. 7 to 10 show the power generated by the GENCO
1, 2, 3 and 4 respectively. The graphical values and
computed values of generated power give almost identical
values. In Fig. 7 to Fig. 10, the incremetal power
generated by four GENCOs have been shown and
compared for the above cases. It is evident from the plots
that there are distinct improvement in the performance
when either of TCPS and TCSC is included in the system,.
In all these plots oscillations damping and peak
overshoots have reduced when the FACTS devices are
included in the system. Comparing different FACTS
devices, TCSC gives better results than TCPS for this
system.
= 0.021 puMW
ΔPg 2 = 0.20 × 0.02 + 0.25 × 0.02 + 0.0 + 0.0
= 0.009 puMW
ΔPg 3 = 0.0 × 0.02 + 0.25 × 0.02 + 1.0 × 0.02 + 0.7 × 0.02
0.04
delpg1
delpg1TCPS
delpg1TCSC
0.035
The incremental generated power by GENCOs are as
follows:
ΔPg1 = 0.5 × 0.02 + 0.25 × 0.02 + 0.0 + 0.3 × 0.02
= 0.039 puMW
ΔPg 4 = 0.3 × 0.02 + 0.25 × 0.02 + 0.0 + 0.0
del pg1 (pu MW)
0.03
X: 13.45
Y: 0.02111
0.025
= 0.011 puMW
0.02
0.025
0.015
0.01
delpg4
delpg4TCPS
delpg4TCSC
0.02
0
0
5
10
15
Time (Sec)
Fig 7 Response of del Pg1
delpg4 (pu MW)
0.005
0.015
0.01
X: 13.45
Y: 0.01108
0.025
0.005
delpg2
delpg2TCPS
delpg2TCSC
0.02
0
0
5
10
15
d e l p g 2 (p u M W )
Time (Sec)
Fig 10 Response of del Pg4
0.015
X: 12.55
Y: 0.008878
0.01
0.005
0
0
5
10
15
Time (Sec)
Fig 8 Response of del Pg2
0.05
d e l p g 3 (p u M W )
0.04
X: 13.19
Y: 0.03908
VI. CONCLUSIONS
FACTS devices and their applications were simulated
and the results in a deregulated power system(thermalthermal) were depicted throughout the research. It is also
observed that FACTS devices incorporated with
Knowledge based systems like Fuzzy controllers very
effectively damp out frequency changes and deviations,
tie-line power exchange and oscillations in power
generated. The results also depict peak deviation
reduction on either side of zero. It is also observed that
the settling time also reduces in different scenarios.
Better results are obtained when FACTS devices are
incorpoated with Intelligent controllers as compared to
the results attained using conventional integral control.
0.03
f = 60 Hz
Tg = 0.08 sec
0.02
delpg3
delpg3TCPS
delpg3TCSC
0.01
0
0
5
10
Time (Sec)
Fig 9 Response of del Pg3
R = 2.4 Hz/p.u. MW
Tt = 0.3 sec
b= D+1/R = 0.425
H= 5 sec
Kps = 120
Pr1 = Pr2 =2000 MW
15
D= 8.33*10-3 p.u. MW/ Hz
Ptie, max = 200 MW
Tps=20 sec
REFERENCES
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