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292 Transient studies of FACTS and Custom Power equipment

the above simulators can be used to model a power system network, different
difficulty in developing appropriate models for the system can be experienced. The
reason being that they have been designed for various purposes. For instance,
some have been designed for electronic circuits and their models for the various
semiconductors can be more sophisticated (i.e. SPICE) than the ones provided by
other simulators specifically designed for power system simulations (i.e. PSCAD/
EMTDC).
As mentioned before, PSCAD/EMTDC has been used here to carry out the
transient analysis of FACTS and CPcontrollers. Therefore, in the following subsec-
tion we present a tutorial-like introduction to this digital tool in order to familiarize
the reader with it and thus, facilitate the understanding of models and analysis
presented in this chapter.

8.3Electromagnetic transient simulator PSCAD/EMTDC

PSCAD/EMTDC is a general-purpose time domain simulation tool for examining
the transient behaviour of electrical networks. Since it was first developed in 1976,
the EMTDC simulation program has constantly been evolving in its scope and
capabilities. PSCAD provides a flexible user interface to make use of EMTDC,
enabling an integrated visual environment that supports all aspects associated with
the simulation, including circuit assembly, run-time control, analysis and reporting
(Gole, Nayak et al., 1996; Manitoba, 1994).
The following list summarizes the main studies that can be conducted with
EMTDC:
. contingency studies of AC networks containing rotating machines, exciters, gov-
ernors, turbines, transformers, transmission lines and cables
. sub-synchronous resonance studies of networks with rotating machines, controls,
transmission lines and HVDC systems
. design and evaluation of filter performance and harmonic analysis
. control system design and co-ordination of HVDC, FACTS and CPcontrollers
. optimal design of controller parameters
. investigation of new circuits and control concepts.
PSCAD/EMTDC has a comprehensive palette of components. Circuits are built by
dragging and dropping the appropriate model block onto the drawing canvas, and
using drag and stretch wires to connect it to the circuit under construction. The
process of circuit construction is thus similar to that of drawing a schematic diagram
of the power circuit under study. The main components available in PSCAD/
EMTDC are as follows:
. resistors (R), inductors (L), capacitors (C)
. single-phase transformers, i.e. mutually coupled windings
. transmission lines and cables
. current and voltage sources
. switches and circuit breakers
. diodes, thyristors and GTOs