18 Electrotechnical Systems
consists of the blocks that are equivalent, by their functions, to the program blocks
included in Simulink library. This library is diverse enough and expands constantly.
When the system model is elaborated, the developer “clicks and drags” the demanded
blocks from Simulink library into his model diagram and connects them according
to the system functional diagram.
Electrotechnical systems play an important place in our lives and have a wide
range of usage. Scientists and engineers are involved in their research and devel-
opment. Therefore, the development of investigation methods of these systems is
a very important task. In most cases, these systems turn out to be very difcult
for the full analysis of steady-state and transient processes, and a method of sim-
ulation proves to be the only possibility. A lot of elements and devices that form
an electrotechnical system have a complex intrinsic structure, and employment
of the standard Simulink blocks for their simulation turns out to be difcult and
demands from the staff, who are developing such systems, in-depth knowledge
about the device structure and the equations describing the processes proceed-
ing in it.
Therefore, models of more complicated blocks and devices are developed. The
set of SimPowerSystems™ blocks contains the models of the complex enough but
standard devices and units, whose elds of application are production, transmis-
sion, transformation, and utilization of the electric power, electrical drives, and
power electronics. SimPowerSystems operates in the Simulink environment. Since
Simulink uses MATLAB as the computational engine, the developer can use
MATLAB toolboxes and Simulink blocksets.
The rst step in simulation is development of the model scheme consisting
of the blocks of Simulink and SimPowerSystems. Under the block connection,
it is necessary to take into consideration the following. The inputs and out-
puts of Simulink blocks are denoted by “>.” The lines connecting them trans-
mit directional signals, as is usual for block diagrams. The inputs and outputs of
SimPowerSystems blocks are the electrical wires; they transfer electric energy in
both directions and are denoted as “◽.” The lines of these two kinds cannot be
connected with each other. The SimPowerSystems blocks that require interaction
with the Simulink blocks have special inputs and outputs for that purpose, which
are also denoted as “>.” Besides, there are the special blocks in SimPowerSystems
that convert quantities of SimPowerSystems in the signals that are accessible to
Simulink blocks and, conversely, convert Simulink signals into voltages and cur-
rents of SimPowerSystems.
After the blocks are connected, it is necessary to specify their parameters. For that
purpose, the block dialog box (or, the parameter window) opens, in which the block
parameters are entered according to block function. It is possible also to dene the
alphabetical symbols for the requested parameters and their numerical values to be
fed into the special program MATLAB (SP) with extension .m that is executed before
simulation. If the command sim(‘name Simulink program’) is executed at
the end of SP, the block parameters that are identied by their symbols are carried
to the corresponding blocks, and thereafter can be used without SP. For that purpose,
the command to be given for workspace storage is save <‘name’> where name
is the name under which the workspace is stored in the le with an extension mat.
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