IEEE Electrification Magazine - June 2015 - 63

1.1
Simulation
Sea Trial

1.05

Bus Voltage (p.u.)

Generator Voltage (p.u.)

1.1

0.95

0.9

Simulation
FAT
30

30.5

31
31.5
Time (s)

1.05

0.95

0.9

32.5

44
46
Time (s)

Figure 16. A diesel generator factory acceptance test (FAT) and sim-

Figure 18. A sea trial and simulation confrontation of the generator's

ulation confrontation, no-load voltage reference step variation.

parallel operation, voltage transient due to one generator disconnection.

representation of the system's physics usually needs to be
simplified to achieve reasonable simulation times and a low
computational load. In addition, when a mathematical model
is created, some less relevant phenomena are normally
ignored because they do not significantly affect the system's
behavior. Because of these facts, the simulation procedure
leads to results that do not perfectly match reality. Hence,
simulator tuning is mandatory and is done by means of
some parameters' variations. The aim of this procedure is to
reduce the differences between the simulation and reality as
much as reasonably possible.
The tuning and validation procedure can be realized
using some of the most common tests on the IPS's components that are normally done during the ship's construction. For example, the factory acceptance tests (FATs),
done by the electrical machine's producers before the
delivery, permit the tuning of the generators' and motors'
models. As an example, Figures 16 and 17 show the results
of a generator's model validation, which compares the
voltage and frequency responses of the real system and

the simulator when the same solicitations are applied.
Conversely, Figures 18 and 19 show the comparison
between the simulated and real variables, which is done
using the parallel operation test results carried out during
the sea trials. All of these simulations have been made
using a software simulator created assuming the previously stated simplification hypothesis (electromechanical
transient's simulation). Obviously, the tuning and validation procedures imply that the real system has already
been built, making the simulator less useful for the design
of the vessel since it can be validated only after the ship's
construction. Despite that, once validated, the software
can be effectively used for both new ships' design or for
testing modifications on the constructed ship.

Important Simulator Applications
A first relevant application of an IPS simulator is to help in
setting the generators' controllers. Indeed, it is possible to
try different values for the AVR's and SG's parameters,
applying the same loads and disturbances to the system,

1.01

1.005
Bus Frequency (p.u.)

Generator Frequency (p.u.)

1.01

1
0.995
0.99
0.985
0.98
Simulation
FAT

0.975
0.97
39

42
Time (s)

Figure 17. A diesel generator FAT and simulation confrontation,
active load step variation.

Simulation
Sea Trial

1
0.99
0.98
0.97
0.96
0.95

44
46
Time (s)

Figure 19. The sea trial and simulation confrontation of the generator's
parallel operation, frequency transient due to one generator disconnection.
IEEE Electrific ation Magazine / j une 2 0 1 5

Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2015