Tutorial: Introduction to Transient Analysis using DIgSILENT PowerFactory.

Dr. Francisco M. Gonzalez-Longatt, fglongatt@ieee.org .Copyright © 2009 1/21
Allrightsreserved.Nopartofthispublicationmaybereproducedordistributedinanyformwithoutpermissionoftheauthor.
Copyright©2009.http:www.fglongatt.org.ve
Francisco M. Gonzalez-Longatt, Dr.Sc
Manchester, UK, September, 2009
Tutorial:
Introduction to Transient
Analysis with PowerFactory

This tutorial is a simple introduction to transient simulation
with PowerFactory
Tutorial:
Introduction to Transient
Analysis in PowerFactory
Francisco M. Gonzalez-Longatt, Dr.Sc
fglogatt@fglongatt.org.ve
Manchester, September 2009

1. Introduction
Introduction to Transient Phenomenon and
Modeling

1. Introduction
• Power system stability may be broadly defined as that
property of a power system that enables it to remain in a
state of operating equilibrium under normal operating
conditions ad to regain an acceptable state of equilibrium
after being subjected to a disturbance [1].
• The robustness of a system is defined by the ability of
the system to maintain stable operation under normal
and perturbed conditions [2].
[1] P. Kundur, Power System Stability and Control. New York:
McGraw- Hill, 1994.
[2] PowerFactory User’s Manual DIgSILENT PowerFactory Version
14.0. DIgSILENT GmbH, Gomaringen, Germany 2008

1. Introduction
• Dynamic process in electrical power system can be
characterized by various areas of consideration and their
characteristic time scales or frequency bands.

1. Introduction
• In general way, the transients in electrical power
systems are classified according to three possible
timeframes:
– Short-term, or electromagnetic transients;
– Mid-term, or electromechanical transients;
– Long-term transients.
Short Mid Long

1. Introduction
Classification of Power System Stability [1]
Power System Stability
Angle Stability Voltage Stability
Transient
Stability
Mid-term
Stability
Long-term
Stability
Large
Disturbance
Voltage
Stability
Small-Signal
Stability
Non-
oscillatory
Instability
Oscillatory
Instability
Small-
Disturbance
Voltage Stability
• Ability to remain in operating equilibrium
• Equilibrium between opposing forces
• Ability to maintain synchronism
• Torque balance of synchronous
machines
• Ability to maintain steady
acceptable voltage
• Reactive power balance
[1] P. Kundur, Power System Stability and Control. New York:
McGraw- Hill, 1994.
RECOMMENDED READ: P. Kundur, J. Paserba, V. Ajjarapu, G. Andersson, A. Bose, C. Canizares, N. Hatziargyriou, D. Hill, A.M.
Stanković, C. Taylor, T. Van Cutsem, V. Vittal, "Definition and classification of power system stability IEEE/CIGRE joint task force on
stability terms and definitions", IEEE Transactions on Power Systems, Vol. 19 , No. 3 , pp.1387 - 1401, Aug. 2004

1. Introduction
• PowerFactory allow the transient analysis in electrical
power systems according to three possible timeframes:
– Short-term, or electromagnetic transients;
– Mid-term, or electromechanical transients;
– Long-term transients.
Long-term
Transient
Short-term
Transient
Mid-term
Transient
Time
Electromagnetic
transients
Electromechanical
transients

1. Introduction
• PowerFactory is capable to do simulations in these
three different time bands because its modeling and
algorithm of solutions.
Long-term
Transient
Short-term
Transient
Mid-term
Transient
Electromagnetic
transients
Electromechanical
transients
≈µ sec frequency range of 0.1
Hz to 10 Hz, or with
typical time constants
between 10 s and 100
ms (50 Hz)
≈ hours to days

1. Introduction
• PowerFactory can analyse the complete range of
transient phenomena in electrical power systems.
• Three different simulation functions available:
1. Symmetrical steady-state (RMS) network model,
2. Three-phase for steady-state (RMS) network
model,
3. Electromagnetic transient (EMT) simulation
function using a dynamic network model.

1.1. Balanced RMS Simulation
• A basic function which uses a symmetrical steady-state
(RMS) network model for mid-term and long-term
transients under balanced network conditions;
Machine equations
in d & q
components (Rotor
flux diff. eqs. Inertia
swing eqs.
Efd
Pm
Inverse
d, q, 0
transf.
d, q, 0
transf.
id
iq
Network Z, Y
elements at rated
freq. (ω0) pos. seq.
ea1(jω0)
Phasor
(pos. seq)
ψd = eq
ψq = ed
θ
ia1(jω0)
Phasor
(pos. seq)

1.2. Three-Phase RMS Simulation
• A three-phase function which uses a steady-state (RMS)
network model for mid-term and long-term transients
under balanced and unbalanced network conditions, i.e.
for analyzing dynamic behaviour after unsymmetrical
faults;
Machine equations
in d & q
components (Rotor
flux diff. eqs. Inertia
swing eqs.
Efd
Pm
Inverse
d, q, 0
transf.
d, q, 0
transf.
id
iq
Network Z, Y
elements at rated
freq. (ω0) +Ve, -Ve
And 0 seq.
ea1(jω0)
Phasor
(pos. seq)
ψd = eq
ψq = ed
θ
ia1(jω0)
Phasor
(pos. seq)

1.3 Three-Phase EMT Simulation
• An electromagnetic transient (EMT) simulation function
using a dynamic network model for electromagnetic and
electromechanical transients under balanced and
unbalanced network conditions.
• This function is particularly suited to the analysis of
short-term transients.
va(t)
vc(t)
vb(t)
Ra La
Rb Lb
Rc Lc
Ca
Cb Cc

2. Transient Simulation

2. Transient simulation
• The process of performing a transient simulation typically
involves the following steps: Calculation of initial values
Definition of results variables
Definition of events
Definition of output graphs
Execution of simulation
Creating additional results
graphs
Iterative calculations, settings
Printing resuts
Calculation of initial values,
this include a load flow
calculation and all state
variable calculation

3. Balanced RMS
Simulation

3. Balanced RMS Simulation
• The balanced RMS simulation function are based in the
following conditions:
– Considers dynamics of electromechanical, control
and thermal devices.
– It uses a symmetrical, steady-state representation
of the passive electrical network.
– Only the fundamental components of voltages and
currents are taken into account.

3. Balanced RMS Simulations
• PowerFactory allow the following studies:
• PowerFactory allow various events that can be
included in the simulation.
• REMARK: the basic simulation function allows the
insertion of symmetrical faults only due to the
symmetrical network representation.
Transient
stability
Mid-term
stability
Oscilatory
stability
Motor
start-up
Studies
e.g. determination of
critical fault clearing
times
e.g. optimization of
spinning reserve and
load shedding
e.g. optimization of
control device to
improve system
damping
e.g. determination of
start-up times and
voltage drops

4. Recommended
Readings

4. Recommended readings
• P. Kundur, J. Paserba, V. Ajjarapu, G. Andersson, A.
Bose, C. Canizares, N. Hatziargyriou, D. Hill, A.M.
Stanković, C. Taylor, T. Van Cutsem, V. Vittal, "Definition
and classification of power system stability IEEE/CIGRE
joint task force on stability terms and definitions", IEEE
Transactions on Power Systems, Vol. 19 , No. 3,
pp.1387 – 1401.
• F.P. deMello, “Power System Dynamic Overview”
Proceedings of the Symposium on Adequacy and
Philosophy of Modeling Dynamic System Performance,
1975 IEEE Publication 75CH0970-4-PWR (808 kB)

4. Recommended readings
• F.P. deMello. “Process Dynamics in Electric Utility
Systems”. ISA Paper 505-70, International Conference
Exhibit of ISA, October 26-29, 1970, Philadelphia, Pa.

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http://www.fglongatt.org.ve
Comments and suggestion are welcome:
fglongatt@fglongatt.org.ve

Tutorial: Introduction to Transient Analysis using DIgSILENT PowerFactory.

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