International Journal of Emerging Trends in Engineering & Technology (IJETET)
Vol. 02, No. 01, 2013
ISSN No. 2248-9592
“ROBUST UPFC DAMPING CONTROLLER
FOR DAMPING POWER SYSTEM
OSCILLATIONS”
Prof.P.P.Jagtap
Mr.R.H.Adware
Dr.J.B.Helonde
G.H.Raisoni College of Engineering,Nagpur
G.H.Raisoni College of Engineering,Nagpur
e-mail:-prashant.jagtap@raisoni.net
e-mail:-ram.adware@gmail.com
Electrical Engg.Department
ITM Engg. College Nagpur
Abstract- FACTS devices can help the damping of power system oscillations. The objective of this paper is to design and propose a systematic
approach for damping controller to validate results by comparing with lab prototype. This paper presents a control scheme, comprehensive analysis
and result obtained for the dynamic control of power transmission, damping of oscillations with Unified Power Flow Controller (UPFC) on the basis
of theory and computer simulations through MATLAB software. In this paper ability of UPFC for voltage support and dynamic stability
improvement using lab prototype is compared with MATLAB simulations result .Voltage sourced based converter is designed in laboratory.
Keywords- FACTS, Voltage sourced converter, UPFC, PSS, damping controller, transient stability.
1. INTRODUCTION
The power transfer depends on loading capability of transmission line, Thermal limit, and power transfer limit,
environmental constraint limits the transfer capacity of power system. Therefore it is required to provide compensation for
transmission line in integrated power system which is constrained by transient stability, voltage stability and small signal
stability. These constraints limit a full utilization of available transmission corridors. Flexible ac transmission system
(FACTS) is the technology that provides the needed corrections of the transmission functionality in order to fully utilize the
existing transmission facilities and hence, minimizing the gap between the stability limit and thermal limit [1].
Unified power flow controller (UPFC) is one of the FACTS devices, which can control power system parameters such as
terminal voltage, line impedance and phase angle. Therefore, it can be used not only for power flow control, but also for
damping power system oscillations. In view of the above the main objectives of the research work presented in the paper are,
1. To design UPFC based damping controllers.
2. To examine the relative effectiveness of modulating UPFC parameter with PSS
3. UPFC performance under various loading.
4. To validate simulation result with hardware model.
2. UNIFIED POWER FLOW CONTROLLER
Unified power flow controller (UPFC) is a combination of static synchronous compensator (STATCOM) and a static
synchronous series compensator (SSSC) which are coupled via a common dc link, to allow bi-directional flow of real power
between the series output terminals of the SSSC and the shunt output terminals of the STATCOM and are controlled to provide
concurrent real and reactive series line compensation without an external electric energy source.[2] The UPFC, by means of
angularly unconstrained series voltage injection, is able to control, concurrently or selectively, the transmission line voltage,
impedance and angle or alternatively, the real and reactive power flow in the line. The UPFC may also provide independently
controllable shunt reactive compensation. UPFC can also inject active power if supplied with energy storage. Viewing the
operation of the UPFC from the standpoint of conventional power transmission based on reactive shunt compensation, series
compensation and phase shifting, the UPFC can fulfill all these functions and thereby meet multiple control objectives by
adding the injected voltage VBt with appropriate amplitude and phase angle, to the terminal voltage V0. [3]
The Unified Power Flow Controller (UPFC) is the most versatile of the FACTS controllers faster than variable impendence
devices. Shunt controller mainly provides reactive compensation. Series controller mainly provides active power as well as
reactive power in series . It not only performs the function of STATCOM, TCSC, and the phase angle regulator but also
provides additional flexibility by combining some of the functions of above controllers. The main function of UPFC is to
control the flow of real and reactive power by injection of a voltage in series with transmission line. Both the magnitude and
©IJETET
Page 29
International Journal of Emerging Trends in Engineering & Technology (IJETET)
Vol. 02, No. 01, 2013
ISSN No. 2248-9592
the phase angle of the voltage can be varied independently. Real and reactive power flow control can allow for power flow in
prescribed routes; loading of transmission lines closer to their thermal limits with environmental constraints and improvement
in transient stability. The schematic of the UPFC is shown in fig.2.1
Fig 2.1:-Basic operating principle of UPFC
From the conceptual viewpoint, the UPFC is a generalized synchronous voltage source (SVS), represented at the
fundamental (power system) frequency by voltage phasor Vpq with controllable magnitude VH and angle p in series with the
transmission line, as illustrated for the usual elementary two-machine system shown in figure 2.2
UPFC consists of two voltage-sourced converters, as illustrated in Figure 2.2 .These back-to-back converters, labeled
"Converter I" and "Converter 2" in the figure, are operated from a common dc link provided by a dc storage capacitor. As
indicated before, this arrangement functions as an ideal AC-to-AC power converter in which the real power can freely flow in
either direction between the terminals of the two converters,. Moreover each converter provides independent reactive power
compensation. UPFC can be controlled in active power mode, reactive power mode .It can also operated in SSSC and
STATCOM model.
Converter 2 provides the main function of the UPFC by injecting a voltage Vw with controllable magnitude VM and
phase angle p in series with the line via an insertion transformer. This injected voltage acts essentially as a synchronous ac
voltage source. [1]
Fig 2.2: - Implementation of the UPFC by two back-to-back voltage sourced converter
The transmission line current flows through this voltage source resulting in reactive and real power exchange between it
and the ac system. The reactive power exchanged at the ac terminal (i.e., at the terminal of the series insertion transformer) is
generated internally by the converter. The real power exchanged at the ac terminal is converted into dc power which appears at
the dc link as a positive or negative real power demand. [7]
3 .SYSTEM MODEL
Figure 3.1 shows a system model for examine the operation of UPFC controller with series and shunt converter .It has
500 kV /230 kV transmission systems. It contains five buses (B1 to B5) interconnected through transmission lines (L1, L2, L3)
and two 500 kV/230 kV transformer banks Tr1 and Tr2. The plant models include a speed regulator, an excitation system and
Power system stabilizer. In normal operation, most of the 1200-MW generation capacity of power plant #2 is exported to the
500-kV equivalent through three 400-MVA transformers connected between buses B4 and B5.



The equipments specifications are as follows
Two Generators with capacity of 13. 8 KV, 1000 MVA, rotor type: salient pole each with mechanical input is 0.5 P.U.
Two Transformers connected in Delta / Star
Three Lines L1, L2, L3 each of 50 KM.
©IJETET
Page 30
International Journal of Emerging Trends in Engineering & Technology (IJETET)
Vol. 02, No. 01, 2013



ISSN No. 2248-9592
Five buses B1, B2, B3, B4, B5 of base voltage of 230 KV, and base power of 100 MVA.
Three phase voltage source in series with R-L branch having phase to phase rms voltage of 500 KV and X/R ratio of 10.
Three phase parallel RLC load of voltage 500 KV and power of 200 M.
Fig.3.1 Multimachine system With UPFC
Simulation Results:
We have studied the of effect of Unified Power Flow Controller (UPFC) & Power System Stabilizer with and without
fault under various fault conditions, which are as follows,
.
1. System with fault
2. Multimachine system with fault, power system stabilizer (No UPFC).
3. System without PSS but having UPFC.
4. System simulation with PSS and with UPFC.
a)
Simulation results indicating Rotor Speed (wm) and Load angle (Delta).
CHANGE IN SPEED
VARIATION IN DELTA Vs TIME
1.003
30
25
1.002
LOAD ANGLE( DELTA)
20
ROTOR SPEED
1.001
1
0.999
15
10
5
0
-5
0.998
-10
0.997
0
2
4
6
8
10
TIME
12
14
16
18
0
2
4
6
8
20
10
TIME
12
14
16
18
20
b) Simulation results of the above model Containing Multimachine system without PSS but having UPFC & fault, with
respect to Rotor Speed (wm) and Load angle (Delta).
VARATION IN LOAD ANGLE (DELTA) Vs TIME
VARIATION IN ROTOR SPEED VS TIME
30
25
CHANGE IN LOAD ANGLE(DELTA)
1.01
1.008
ROTOR SPEED(Wm)
1.006
1.004
1.002
1
0.998
0.996
20
15
10
5
0
0.994
-5
0.992
0.99
©IJETET
-10
0
2
4
6
8
10
TIME
12
14
16
18
20
0
2
4
6
8
10
TIME
12
14
16
18
20
Page 31
International Journal of Emerging Trends in Engineering & Technology (IJETET)
Vol. 02, No. 01, 2013
ISSN No. 2248-9592
Simulation results of the above model Containing Multimachine system without UPFC but having PSS & fault, with
respect to Rotor Speed (wm)
c)
VARIATION IN ROTOR SPEED Vs TIME
1.003
1.002
ROTOR SPEED Wm
1.001
1
0.999
0.998
0.997
0.996
d)
0
2
4
6
8
10
TIME
12
14
16
18
20
Improvement in performance showing damping of power system oscillations with PSS and UPFC
VARIATION IN ROTOR SPEED (Wm) VS TIME
1.008
CHANGE IN ROTOR SPEED(Wm)
1.006
1.004
1.002
1
0.998
0.996
0.994
0
2
4
6
8
10
TIME
12
14
16
18
20
4 .LAB PROTOTYPE
The Main Component of Lab Prototype are
1. Simulated Transmission line model
a) Transmission line simulator model 1(T* line 1)
b) Transmission line simulator model(T* line)
2. Voltage source Converter- 1&2
3. DSP Controller (TMS320FC2407)
4. Three phase Auto transformer
5. Isolation Transformer (230/110V)
6. DSP 2407 kit
7. Connectors and wires
8. RLC load of 5 Amps.
4.1 Connection diagram
©IJETET
Page 32
International Journal of Emerging Trends in Engineering & Technology (IJETET)
Vol. 02, No. 01, 2013
ISSN No. 2248-9592
4.2 Complete lab set up of VSC based converter of 1 KVAR capacity with 5 Amp load
4.3 PWM pulses generation for firing IGBT device
4.4 Voltage and Current waveform
©IJETET
Page 33
International Journal of Emerging Trends in Engineering & Technology (IJETET)
Vol. 02, No. 01, 2013
ISSN No. 2248-9592
Table no.4.1 Experimental reading showing improvement in receiving end voltage
Sr.
No.
Vs (V)
Vr (V)
Line
Current(A)
θ°
Vdc
1
43
21
0.31
0°
0
2
43
26
0.35
10°LD
33
3
42
34
0.4
41°LD
38
4
42
37
0.52
65°LD
39
5
42
39
0.55
72°LD
39
6
42
41
0.58
110°LD
40
7
42
31
0.4
10°LG
13
8
42
27
0.36
20°LG
19
9
42
26
0.34
30°LG
22
10
43
26
0.31
40°LG
25
11
43
25
0.29
70°LG
28
5 .CONCLUSION
A systematic approach for designing UPFC based controllers for damping power system oscillations as well as
improvement in voltage stability is observed by designing a VSC based lab prototype model of UPFC controller. UPFC not
only work in active power mode but also work in reactive
power compensation. Lab prototype successfully shows
improvement in voltage stability.
REFERENCES
Narain G. Hingorani, Laszlo Gyugyi. “Understanding FACTS”, IEEE Press, 2000.
H. F. Wang. „A Unified Model for the Analysis of FACTS Devices in Damping Power System Oscillations‟ — Part III: Unified Power Flow
Controller.‟ IEEE Transactions on Power Delivery, vol 15, no 3, July 2000.
[3] H. F. Wang. „Applications of Modeling UPFC into Multi-machine Power Systems.‟ IEEE Proceedings-C, vol 146, no 3, May1999.
[4] L Gyugyi. „Unified Power Flow Control Concept for Flexible ac Transmission Systems.‟ IEEE Proceedings-C, vol 139, no 4, July 1992
[5] A. Nabavi-Niaki M. R .Iravani. „Steady-state and Dynamic Models of Unified Power Flow Controller (UPFC) for Power System Studies.‟ IEEE
Transactions on Power Systems, vol 11, no 4, November 1996, p 1937.
[6] K .S .Smith, L. Ran and J .Penman. „Dynamic Modelling of a Unified Power Flow Controller.‟ IEEE Proceedings-C, vol 144, no 1, January 1997.
[7] N. Tambey and M.L. Kothari, "Damping of Power System Oscillations with Unified Power Flow Controller (UPFC)", IEEE Proc. - C, Vol. 150,No. 3.
Pp.129-140, March 2003.
[8] H. F. Wang, „Damping Function of Unified Power Flow Controller.‟ IEEE Proceedings-C, vol 146, no 1, January 1999, p 81.
[9] L. Gyugyi and C. D. Schauder, . „The Unified Power Flow Controller”: A New Approach to Power Transmission Control.‟ IEEE Transactions on
Power Delivery, vol 10, no 2, April 1995, p 1085
[10] A. Edris and K. Gyugyi,. „Proposed Terms and Definitions for Flexible ac Transmission Systems (FACTS).‟ IEEE Transactions on Power Delivery,
vol. 12, October 1997, p 1848.
[11] T. Makombe and N. Jenkins. „Investigation of a Unified Power Flow Controller.‟ IEEE Proceedings-C, vol 146, no 4, July 1999, p 400.
[1]
[2]
©IJETET
Page 34
International Journal of Emerging Trends in Engineering & Technology (IJETET)
Vol. 02, No. 01, 2013
ISSN No. 2248-9592
About the author(s)
P P Jagtap
received the B.E. degree in Electrical Engineering from Government Engineering college,
Amravati in 1996 .He completed M. Tech. (IPS) from VNIT, Nagpur in 2004 . He is currently pursuing Ph.D
.studies from R.T.M. Nagpur University. Currently he is working as Assistant professor in Electrical Engineering
department at G. H. Raisoni college of Engineering,Nagpur. His research interests includes power systems
,FACTS , HVDC systems..He has worked as Coordinator for the MODROBS project titled Automated power
distribution laboratory” funded by AICTE.
He has published 08 papers in international journals and 15 papers in international conferences
R.H.Adware received the B.E. degree in Electrical Engineering from K.D.K college of Engineering , Nagpur
in 2006 .He completed M. Tech. (IPS) from GHRCE, Nagpur in 2010. Currently he is working as Assistant
professor in Electrical Engineering department at G. H. Raisoni college of Engineering,Nagpur. His research
interests includes power systems ,FACTS , HVDC systems.
He has published 02 papers in international journals and 05 papers in international conferences
Dr.J.B.Helonde received M.Tech (IPS) degree from VNIT, Nagpur. He has received Ph.D.degree from R.T.M.Nagpur
University.Currently he is working as Principal at ITM Engineering college .Kamptee. His research interest includes power
systems ,FACTS , HVDC systems.He has published more than 50 papers in national , international conferences and reputed
journals
©IJETET
Page 35