Typical Applications of PSAS Softwares
Power flow, voltage drop and short circuit study of
transmision or distribution systems containing generations, transformers (fixed
tap, auto tap, phase shifter), power lines and motor loads. Motors (ie synchronous
or induction) are modelled as generators with negative generation in the study.
The effects of generator Mvar limits, automatic voltage control and automatic
transformer tapping control can be considered. The results are displayed on
single line diagram and in tabular form for easy interpretation.
Both balanced and unbalanced faults can be examined
including three phase fault, phase to phase fault, single phase to ground fault
and double phase to ground fault with or without fault resistance. Fault currents
under transient or subtransient conditions are separately assessed using different
generator transient impedances. Faults can be applied at different locations
in the system in a single study. The unbalanced fault module provides the voltages
and current flow across the whole system under the specified fault conditions
which can be used to determine system voltage drop and relay co-ordinations.
Fault current contribution from the motors can be accounted for by modelling
them as generators with negative generation and transient impedance equal to
their locked rotor impedance.
Harmonic distortion assessment of transmission or distribution
systems containing abnormal loads such as arc furnace, converter equipment and
electric traction loads at different locations. The total harmonic voltage distortion
and harmonic current flow in the entire system are evaluated. The program can
highlight the possibility of harmonic resonance and the risk of overloading
in the neutral conductor by zero sequence harmonic currents such as the third
harmonics. The use of harmonic filters to suppress harmonic distortion can be
examined using typical filter configurations or user defined arrangements.
Contingency analysis of transmission and distribution
systems under circuit outages to assess whether the equipments are secured against
overloading. The assessment is completely automatic and a complete report will
be provided for all single circuit contingencies that will result in overloading.
As an educational tool for undergraduate and postgraduate
studies in the field of electrical power systems analysis in universities. The
single diagram and graphical presentation of the results will facilitate the
teaching and learning process. The complete package can be operated with limited
computer resources.
Induction motor starting and the effect of system faults
on motor recovery can be investigated within the transient stability module.
The induction motors are modelled in detail including the effect of rotor electrical
transients, mechanical transient and load torque characteristics.
The effect of static var compensator in voltage stabilisation
can be examined with user defined control parameters in the transient stability
module. User defined control parameters are also available for governor and
exciter models.
Fully featured transient stability module allows the
assessment of the stability performance of private generators connecting to
a utility grid. Various system disturbances can be instigated such as fault
inception, generator tripping, circuit tripping and load shedding. The program
automatically calculates the critical clearance time for a specified fault condition.
Open circuit step response of the generator excitation system is automatically
studied to ensure a stable setting of the AVR.
The performance and operation of protective relays under
fault conditions can be investigated in the transient stability module. The
program will monitor and report the tripping operations of all specified relays.
The types of relays that can be modelled include distance relays, overcurrent
and earth fault relays with fixed time delay or IDMTL (inverse definite minimum
time lag) characteristics and under/over voltage sensing relays.
The stability performance of the generator under steady
state operation conditions can be assessed using the dynamic stability module.
The module calculates the eigenvalues which will quantify the degree of stability
of the system. The automatic voltage regulators of the system can be modelled
in detailed and their settings can be optimised using the sensitivity analysis
module to ensure stable system operation.
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