IEEE Electrification Magazine - March 2015 - 26

solutions and prototypes for hardware and software modules related to those applications.
Since the 1950s, the evolution of power systems has
evolved toward the deployment of long, interconnected
transmission networks fed by large conventional generators (mostly thermal or hydro), which would serve to deliver
power to the consumers. In this case, power system operation is pretty straightforward, given the reconfiguration
capability of the transmission grid coupled with the large
inertia of central generators. As a consequence, most of
these systems are characterized by high reliability and good
quality of service. At the end of the 20th century, renewable
power penetration, specifically, wind generation and solar
PV, began increasing due mostly to environmental pressure.
However, the variable nature of power from renewable
sources stressed the power system
operation, while in large systems
where renewable penetration levels
are still quite low, no significant problems were encountered.
In the case of smaller isolated
(noninterconnected) or islanded
power systems, the operation can
often be very challenging because of
the small inertia of the spinning
machines together with the limited
control and lack of flexibility of most
grid assets, in particular, the generating units. Also, in the case of remote
power systems, specifically in
islands, economic concerns are particularly important. Power production costs are usually very high as
they depend on fuel transportation.
This led to the option of increasing renewable generation
in this type of system. Since the power produced by such
renewable sources has a variable nature, not only can frequency stability problems occur in weak grids but also
voltage fluctuations may significantly deteriorate the
quality of service. Consequently, the operation of these
systems can be severely compromised since most conventional generation units (usually thermal and hydro) are
not able to cope with such power variability. Even in situations where enough conventional spinning reserve exists,
the automatic frequency control of these units may not be
robust enough given the slow response of the mechanical
power output of these machines.
On the other hand, in recent years, there has been significant technological progress in terms of control capability of
grid assets (of generators, controllable loads such as EVs, and
energy storage systems) as a result of a development in
power electronics. These advances allow overcoming some of
the technical problems that may arise in operating isolated
power systems in terms of fast frequency and voltage control
response by supporting and improving the robustness of
operation. Some of these advanced control solutions include

installing energy storage systems such as flywheels or batteries, enhancing the capability of renewable generation to
participate in grid operation, and exploiting the potential of
new emergent technologies such as EVs.
In this article, several studies that have been performed
for some of the Portuguese islands are described that
involved the simulation of the impact of introducing new
control solutions in these isolated systems as well as the
assessment of the benefits that the deployment of new technologies and more advanced control strategies may bring.
Portugal has two main groups of islands: the Madeira
Archipelago and the Azores Archipelago (see Figure 1).
Madeira is located in the North Atlantic Ocean, near
Morocco, about 1,000 km from the Portuguese continental
coast. The archipelago is one of the two autonomous
regions of Portugal and includes the
islands of Madeira, Porto Santo, and
Desertas. These islands are famous
as year-round resorts visited by
many tourists, in particular, in the
main Madeira Island, where there is
a large harbor that receives a considerable number of cruise ships.
Azores is the other autonomous
region of Portugal, composed of several
volcanic islands situated in the North
Atlantic, right on the Atlantic Ridge,
located about 1,350 km west of continental Portugal and about 900 km
northwest of Madeira. There are nine
major islands and an islet cluster
divided into three main groups: Flores
and Corvo to the west; Graciosa, Terceira, São Jorge, Pico, and Faial in the
center; and São Miguel, Santa Maria, and the Formigas Reef
to the east. The Azores islands extend more than 600 km in
the northwest-southeast direction. The Azores rely on agriculture, dairy farming, livestock ranching, fishing, and tourism, which is starting to become the major service activity in
the region. Smart charging schemes are identified to manage
the demand from EVs according to network limitations and
in close coordination with the presence of renewable generation. The benefits from an EV contribution to improve the
grid stability are also addressed through the definition of
strategies for EV participation in primary frequency control.
To support the development of innovative technological
solutions for this type of power system, a laboratory setup
based on scaled test systems is described in the "Proof of
Concept of New Management Solutions for Autonomous
Power Systems: Laboratory Setup" section. This enables the
testing of solutions and prototypes, both for hardware and
software modules related to applications for autonomous
power systems. Acting as a complementary verification to
simulation-based studies, the laboratory provides the necessary conditions for a proof of concept of new management solutions for electric grids, in scenarios characterized

Economic and
environmental
pressure has led
to an increasing
renewable power
penetration,
particularly in wind
generation and
solar photovoltaics.

I E E E E l e c t r i f i c ati o n M agaz ine / March 2015

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