TY - THES
AU - Zhang, Peng
PY - 2009
TI - Shifted frequency analysis for EMTP simulation of power system dynamics
KW - Thesis/Dissertation
LA - eng
M3 - Text
AB - Electromagnetic Transients Program (EMTP) simulators are being widely used in power
system dynamics studies. However, their capability in real time simulation of power systems is
compromised due to the small time step required resulting in slow simulation speeds.
This thesis proposes a Shifted Frequency Analysis (SFA) theory to accelerate EMTP
solutions for simulation of power system operational dynamics. A main advantage of the SFA is
that it allows the use of large time steps in the EMTP solution environment to accurately
simulate dynamic frequencies within a band centered around the fundamental frequency.
The thesis presents a new synchronous machine model based on the SFA theory, which
uses dynamic phasor variables rather than instantaneous time domain variables. Apart from using
complex numbers, discrete-time SFA synchronous machine models have the same form as the
standard EMTP models. Dynamic phasors provide envelopes of the time domain waveforms and
can be accurately transformed back to instantaneous time values. When the frequency spectra of
the signals are close to the fundamental power frequency, the SFA model allows the use of large
time steps without sacrificing accuracy. Speedups of more than fifty times over the traditional
EMTP synchronous machine model were obtained for a case of mechanical torque step changes.
This thesis also extends the SFA method to model induction machines in the EMTP. By
analyzing the relationship between rotor and stator physical variables, a phase-coordinate model
with lower number of equations is first derived. Based on this, a SFA model is proposed as a
general purpose model capable of simulating both fast transients and slow dynamics in induction
machines. Case study results show that the SFA model is in excess of seventy times faster than
the phase-coordinate EMTP model when simulating the slow dynamics.
In order to realize the advantage of SFA models in the context of the simulation of the
complete electrical network, a dynamic-phasor-based EMTP simulation tool has been developed.
N2 - Electromagnetic Transients Program (EMTP) simulators are being widely used in power
system dynamics studies. However, their capability in real time simulation of power systems is
compromised due to the small time step required resulting in slow simulation speeds.
This thesis proposes a Shifted Frequency Analysis (SFA) theory to accelerate EMTP
solutions for simulation of power system operational dynamics. A main advantage of the SFA is
that it allows the use of large time steps in the EMTP solution environment to accurately
simulate dynamic frequencies within a band centered around the fundamental frequency.
The thesis presents a new synchronous machine model based on the SFA theory, which
uses dynamic phasor variables rather than instantaneous time domain variables. Apart from using
complex numbers, discrete-time SFA synchronous machine models have the same form as the
standard EMTP models. Dynamic phasors provide envelopes of the time domain waveforms and
can be accurately transformed back to instantaneous time values. When the frequency spectra of
the signals are close to the fundamental power frequency, the SFA model allows the use of large
time steps without sacrificing accuracy. Speedups of more than fifty times over the traditional
EMTP synchronous machine model were obtained for a case of mechanical torque step changes.
This thesis also extends the SFA method to model induction machines in the EMTP. By
analyzing the relationship between rotor and stator physical variables, a phase-coordinate model
with lower number of equations is first derived. Based on this, a SFA model is proposed as a
general purpose model capable of simulating both fast transients and slow dynamics in induction
machines. Case study results show that the SFA model is in excess of seventy times faster than
the phase-coordinate EMTP model when simulating the slow dynamics.
In order to realize the advantage of SFA models in the context of the simulation of the
complete electrical network, a dynamic-phasor-based EMTP simulation tool has been developed.
UR - https://open.library.ubc.ca/collections/24/items/1.0067234
ER - End of Reference