EnergySpectrum - Issue 1, Vol. 5, 2010
www. energyspectrum.net
MODELS AND TRANSIENT PHENOMENA IN PSLF
Vladimír Krištof 1), Stanislav Kušnír2), Daniel Hlubeň3)
Technical University of Kosice, Faculty of Electrical Engineering and Informatics, Department of Electric Power
Engineering, Mäsiarska 74, 041 20 Kosice, Slovak republic, http://web.tuke.sk/fei-kee/kee-s.html
1)
tel: +421 55 602 3566, email: vladimir.kristof@tuke.sk
2)
tel: +421 55 602 3566, email: stanislav.kusnir@tuke.sk
3)
tel: +421 55 602 3559, email: daniel.hluben@tuke.sk
ABSTRACT
In practise situations occur which differ from normal
operational conditions of power system. It is very difficult to
simulate these phenomena in real network or equipment.
For this reason software support resources based on mathematical model of power system are used. Created models
allow monitoring and analysing of electric power system
under normal or fault conditions. In this article PSLF (Positive Sequence Load Flow) is used.
Keywords: dynamic models, PSLF, simulation
1 INTRODUCTION
The basic operational status of each power system is its
stable operation based on steady-state operational (state electrical and mechanical) parameters of the system. Any change
of operational conditions results in disturbance of steady-state
and means formation of transient phenomenon. Transient
phenomena in the electric power system always arise during
transition from one steady-state to other steady-state.
2 DIVISION OF TRANSIENT PHENOMENA
Transient phenomenon is understood as a change in time
during which certain amount of energy bound to a given
electrical or electromechanical circuit is changed to another
form of energy and therefore this transient phenomenon can´t
change immediately, but according to valid laws of physics,
which describe these conditions. From this point of view the
transient phenomena can be divided into:
- Transient wave phenomena (e.g. atmospheric overvoltages; duration from milliseconds to microseconds),
- Electromagnetic transient phenomena (e.g. shortcircuit; duration from 0,1s to 5 seconds)
- Electromechanical transient phenomena (e.g. power
swing; duration from tenths of a second to several seconds) [4].
This article is especially focused on modelling of electromagnetic and electromechanical transient phenomena.
3 ELECTROMAGNETIC TRANSIENT PHENOMENA
IN PSLF
Short-circuits, ground connections, formation of local current and voltage asymmetry, impact excitation synchronous
machines are the most common causes of electromagnetic
transient phenomena in the electric power system. In this
chapter modelling of the most frequent electromagnetic transient phenomena - short circuits will be described. The shortcircuit is defined as an undesirable conductive connection
between phases, phase and ground, which leads to a reduction
of impedance in electrical circuits, and thus to the flow of
undesirable short-circuit current[2]. It is necessary to know
short-circuit conditions in the electric power due to its safe
operation.
PSLF program allows calculation of all types of faults
(metallic, non-metallic, arc) and ground connections. Consider a system according to Fig. 1. Parameters of the network are
as follows:
Generators:
U n  20 kV, Pn = 900 MW, xd =1,8, xq =1,7, xd = 0,3,
xq = 0,55, xd = 0,25, xq = 0,25, xl = 0,2, ra =0,002, Td = 8 s,
Tq = 0,4s , Td = 0,03, Tq = 0,05, T f = 13 s.
Transformers:
U nh = 230 kV, U n  20 kV, S n = 1 200 MVA, R= 0.0018
p.j., X= 0.025 p.j., B = -0.0054 p.j.
Power lines:
W1, W6: U n  220 kV, R = 0.002 p.j., X = 0.025 p.j.,
B = 0.0043 p.j.
W2, W5: U n  220 kV, R = 0.001 p.j., X = 0.010 p.j.,
B = 0.0017 p.j.
W3, W4 : U n  220 kV, R = 0.022 p.j., X = 0.220 p.j.,
B = 0.385 p.j.
Loads:
SB1 = 967 + j 100 MVA
SB2 = 1 767 + j 100 MVA
ISSN: 1214-7044
37
EnergySpectrum - Issue 1, Vol. 5, 2010
Supply:
SG1 = 700 + j154 MVA
these correction factors are not considered. According to the
standard the maximum tolerance of deviation is ±5 %[2] .
SG2 = 700 + j167 MVA
SG3 = 719 + j 162 MVA
SG4 = 700 + j 168 MVA
4 ELECTROMECHANICAL TRANSIENT
PHENOMENA
In an investigation of electromechanical transient phenomena it is necessary to determine whether the system is
stable or not. The stability of the system is the ability of the
system to restore steady-state or self-launch a new steadystate operation in one or more changes of operating parameters. Fact that the stability of the power system is very extensive problem also confirms division of stability by IEEE and
CIGRE [5] (Fig. 3).
Fig. 1 Model of power system
Fig. 2 Model of power system in PSLF
Single-line diagram of the electric power system modelled in PSLF is in Fig. 2. Suppose three-phase short-circuit
at bus no. 7.
Some data (e.g. R, X, B) are entered into PSLF in relative
(per unit) values, therefore the resulting symmetrical shortcircuit current is also in per unit values (our case). Tab. 1
shows results of calculation of short-circuit current in PSLF,
and the results of calculation according to STN IEC 60 909.
Tab. 1 Comparison of calculation of short-circuit in point of
fault
Shortcircuit
current
Calculation
according to
STN IEC
60909
Calculation
in PSLF
Deviation
I´´k3 (kA)
12,6
12,21
-3,09 %
Fig. 3 Classification of power system stability according to
IEEE a CIGRE
Modelling of stability in PSLF will be described in this
chapter. Examined power system could be stabilised in a new
steady-state operation through electromechanical phenomenon or due to the rotor oscillation a generator could loss a
synchronism.
Consider again the power system according to Fig. 1. For
the calculation of dynamic stability it is necessary to specify
the following dynamic models, e.g. model of generator, excitation model, model of power system stabilizer, turbine model. It is difficult to create a dynamic model in PSLF due to
extent of input data necessary for the accurate calculation of
dynamic stability. Further it is considered that at time t = 0.1s
occur three-phase short-circuit on line W3. In Fig. 9 can be
seen the initial conditions for the stability calculation.
Deviation is calculated according to the following formula:
D
I kB  I kA
100%
I kA
(1)
Where:
- IkB is value calculated in PSLF,
- IkA is the reference value (according to STN IEC 60909).
The deviation in the calculation is due to the fact that in
the calculation according to the STN IEC 60909 considers
correction factors prescribed by the standard, while in PSLF
ISSN: 1214-7044
Fig. 4 The initial conditions of dynamic calculation
Figures 5, 6, 7 shows progress of rotor angles of generators 1, 2 and 3. Fig. 8 shows graphical output for generator
38
EnergySpectrum - Issue 1, Vol. 5, 2010
no.1 (vt - Terminal voltage, p.u. efd - Field voltage, p.u., it Terminal current, p.u., pg - Electrical power, MW, spd Shaft speed, p.u., qg -Reactive power, MVAR).
tricity. PSLF software package offers the user a wide range of
computing and modelling features designed to analyse networks.
ACKNOWLEDGEMENTS
This work was supported by Scientific Grant Agency of
the Ministry of Education of Slovak Republic and the Slovak
Academy of Sciences under the contract No. 1/0166/10 and
by Slovak Research and Development Agency under the
contract No. APVV-0385-07 and No. SK-BG-0010-08.
REFERENCES
Fig. 5 Course of rotor angle of generator no.1
Fig. 6 Course of rotor angle of generator no.2
Fig. 7 Course of rotor angle of generator no.3
Fig. 8 Graphical output for generator no.1 : vt - Terminal
voltage, p.u. efd - Field voltage, p.u., it - Terminal current,
p.u., pg - Electrical power, MW, spd - Shaft speed, p.u., qg Reactive power, MVAR for generator 1
[1] Venikov, V.A: Perechodnyje elektromechaničeskije
procesy v električeskich sistemach. Moskva Vysšaja
škola 1978
[2] Mešter, M. – Výpočet skratových prúdov v trojfázových striedavých sústavách. ABB-elektro, s.r.o., 2005.
ISBN 80-89057-10-1
[3] Software documentation PSLF 17.0_05
[4] Kolcun, M. – Chladný, V. – Varga, L. – Beňa, Ľ. Ilenin, S. – Leščinský, P. – Mešter, M.: Analýza elektrizačnej sústavy, časť: Skraty a stabilita v ES. Košice
2005
[5] Mešter, M. – Hvizdoš, M. – Rusnák, J. – Szathmáry, P.
- Vargončík, M.: Stabilita elektrizačnej sústavy. Equilibria 2006. ISBN 80–969224–9-1
[6] VARGA, Ladislav - ILENIN, Stanislav - LEŠČINSKÝ,
Peter: Prenos a rozvod elektrickej energie. Košice :
Mercury - Smékal, 2003. 172 s. ISBN 80-89061-85-0.
[7] CIGRE: Advanced Angle stability controls. CIGRÉ
Technical Brochure. International Conference on Large
High Voltage Electric Systems 1999
[8] MEŠTER, M. – CHLADNÝ, V.: Metodiky výpočtov
dynamickej stability v reálnom čase. Zborník: I. Medzinárodné vedecké sympózium Elektroenergetika, Vysoké Tatry – Stará Lesná, 2001, SR, ISBN 80-88922-34-8
[9] Daneshjo, Naqib (2003): Modelovanie a simulácia,
Strojárstvo. roč. 7, č. 12 (2003), s. 45. ISSN 1335-2938.
[10] Noháčová, L.; Martínek, Z. (2008): Development and
current situation of renewable energy resources from
the point of view of wind power energy in the EU. Komunalna energetika = Power engineering, 2008.
[11] Szkutnik J. (2005): Wykorzystanie algorytmów zadań
transportowych do optymalizacji dystrybucji energii
elektrycznej Prace Naukowe Akademii Ekonomicznej
nr. 1078, Wrocław 2005 r., s. 277-283
5 CONCLUSION
Due to the increasing electricity consumption and economic and time consuming construction of new power lines,
existing networks are operated more at the limits of their
possibilities and they are just an ultimate of stability of power
system. Therefore it is necessary to make more accurate analysis of power system, both under normal operating conditions
or under fault conditions to ensure a reliable supply of elecISSN: 1214-7044
39