09-02-2013, 03:54 PM
Effects of power system parameters on critical clearing time:
comprehensive analysis
Effects of power system parameters.pdf (Size: 215.93 KB / Downloads: 82)
Abstract
In this paper, the effects of various power system parameters on the critical clearing time are presented. The various parameters
for which the analysis is presented include the machine parameters, i.e. damping, inertia constant and transient reactance, and
system parameters, i.e. line impedance, transformer impedance and fault impedance. Various configurations of faults are also
investigated. The simplest single machine infinite bus power system was simulated. Plots and relationships for each parameter are
presented and conclusions are drawn from their behavior. The paper is a comprehensive treatment of the time domain method
to the single machine system and is particularly helpful to the utility power engineers and researchers in the electric machines area
to comprehend the system behavior for various system parameters. The results can be generalized to the large scale multimachine
power systems as well.
Introduction
Power system transient stability [1] is introduced to
the senior level undergraduate students in the course
‘Power System Analysis’. In some schools, this course is
an electrical engineering elective, while in others it is a
mandatory course in ‘Power Option:Stream’. Only one
chapter in [2] covers it, and very little detailed information
is normally covered due to shortage of time. Following
degree completion, the students who continue
for the graduate program in ‘Power Option:Stream’
take a series of other mandatory courses in addition to
research in their field of interest. One of those courses is
‘Power System Modeling and Dynamics’. The first
building block of teaching power system modeling is
the introduction of the single machine infinite bus
power system (SMIB) followed by the large-scale multimachine
power system model. The course covers modeling
issues of rotating components (electric machines,
i.e. generators, motors) and static components (i.e.
transformers and transmission lines).
Variation in machine damping
In this section, the variation in electric machine
damping coefficient (D) and its effect on the system
stability has been investigated for the test system selected
in Section 2.
The machine damping is varied in the range (0–20
pu) and normally includes the turbine damping, generator
electrical damping and damping of electrical loads
[7]. The CCT was computed using the TD method. All
fault and clearing conditions were investigated.
Variation in inertia constant
In this section, the variation in electric machine
inertia constant (H) and its effect on the system stability
has been investigated for the test system selected in
Section 2. Damping and X%d were kept constant during
the simulation.
The machine H was varied in the range (0–20 pu)
[7]. The CCT was computed using the TD method. All
fault and clearing conditions were investigated. The
behavior (Figs. 4 and 5) is almost similar to the effect
of damping, except that the CCTs vary nonlinearly.