Vasco Delgado-Gomes
, Jos
e A. Oliveira-Lima
, Jo
ao F. Martins
and Celson Lima
CTS - Uninova, Dep. Eng. Electrot
ecnica, Faculdade de Ci
encias e Tecnologia,
Universidade Nova de Lisboa, Caparica, Portugal
Instituto de Ci
encias e Geoci
encias, Universidade Federal do Oeste do Par
a, Santar
em, Brasil
DPWS, IEC 61850, Power Distribution, Energy Storage, Power System Management, Networked Control
Efficient energy storage in distributed energy systems depends on the operation of a set of coordinated devices
spread around the power system. These include not only storage devices, but also production and consump-
tion devices. Usually these devices encompass some communication skills and are able to be operated by
energy management systems, regarding the status of the power system. However, despite this interaction
readiness, most of these devices rely on non-standard communication protocols and some interoperability
issues still remain. This paper presents an innovative plug & play approach for the integration of energy stor-
age devices, supported by a standard-based and service-oriented software infrastructure entitled NEtworked
MOnitoring & COntrol, Diagnostic for Electrical Distribution (NEMO). This approach adopts the Interna-
tional Electrotechnical Commission’s 61850 (IEC 61850) semantic information model and the Devices Profile
for Web Services (DPWS) specific communication service mapping, to perform a seamless device integration
and communication of energy storage devices.
Energy industry has recently witnessed a growing in-
terest and study on the smart grid concept. It is quite
clear that the energy crisis has brought two interlinked
actors to the stage, namely Information and Com-
munication Technology (ICT) and Renewable Energy
Sources (RES), triggering the development of smart
tools for efficient energy monitoring and controlling,
namely Energy Management Systems (EMSs), and
advanced distributed energy systems with communi-
cation and electronic processing capable devices.
Major manufacturers are concentrating their ef-
forts on the development of interoperable Intelli-
gent Electronic Devices (IEDs) and applications, with
smart features and remote access. However, cur-
rent systems and platforms rely mostly on private
or access restricted communication protocols and do
not target legacy or multiple vendor installations, nor
even ad-hoc systems.
Recently, energy storage, and its management re-
garding a holistic view of the power system has be-
come a major research topic. In order to ensure the
correct diagnosis and operation of the energy stor-
age devices spread around the energy system, exist-
ing energy management systems must able to prop-
erly take acquaintance of the status of each of its play-
ers, and perform the adequate operations. This will
improve not only the coordination of multiple storage
devices (Lim and Nayar, 2010; Mendis et al., 2010)
but also the coordination of storage devices with pro-
duction (Figueiredo and Martins, 2010), protective
(Lima et al., 2012) and consumption devices.
Therefore, it is imperative that energy storage de-
vices are adequately monitored and operated to guar-
antee grid stability. Moreover, they can contribute
with relevant information for the operational decision
The NEMO system, raised from the identified
need at the energy sector for adequate complex dis-
tributed systems management and further described
in (Lima et al., 2011a), aims to enable the seamless
integration and communication of every device (re-
lated with distributed energy systems) plugged into
the grid, despite its manufacturer or communication
capabilities, using communication standards such as
Delgado-Gomes V., Oliveira-Lima J., Martins J. and Lima C..
DOI: 10.5220/0003952600330038
In Proceedings of the 1st International Conference on Smart Grids and Green IT Systems (SMARTGREENS-2012), pages 33-38
ISBN: 978-989-8565-09-9
2012 SCITEPRESS (Science and Technology Publications, Lda.)
IEC 61850 and DPWS (Driscoll and Mensch, 2009).
This paper focuses on the development of a plug
& play environment for the integration and operation
of energy storage devices, using NEMO architecture.
The next sections describe the several stages regard-
ing device specification and communication, and the
respective implementation, using the IEC 61850 data
model allied to the DPWS service mapping, for the
integration and operation of energy storage devices.
2.1 Conceptual Vision
NEMO targets the development of a software infras-
tructure to help managing and controlling (from the
energy efficiency perspective) complex energy sys-
tems where renewable sources are used in the produc-
tion, distribution, and consumption of energy (Lima
et al., 2011b).
The conceptual vision guiding NEMO is that net-
works of energy-related devices can be operated with
the help of a (distributed) software infrastructure
based on service oriented paradigm and standards.
Any instance of NEMO can use both new and
legacy IEDs, which are required to have a minimum
level of “intelligence” in order to be virtualised. In
other words, they have to provide a software-enabled
communication channel to be used in a communica-
tion process.
Two networks, namely energy and software net-
works compose each so-called NEMO system. The
former is composed by systems and devices, which
produce, distribute and consume energy. The is later
used to monitor and control the energy network.
Two basic issues are addressed: IEDs recognition
and communication with them. NEMO strategy to
overcome them relies on two main pillars, namely
Service-Oriented Architecture (SOA) and Standards.
On the one hand, SOA architectural guidelines are
followed for handling all IEDs as “service providers”
and rely on DPWS profile for communication with
and among those IEDs. On the other hand, IEDs are
modeled, configured, and characterized into the Sys-
tem using the IEC 61850 standard. The role of both
DPWS and IEC 61850 are described in detail in the
next section.
The NEMO software network, shown in
figure 1, relies on five main components,
namely: NEMO-Kernel (NEMO-K), NEMO-
Figure 1: The main components of NEMO Software Net-
Connector (NEMO-C), and IEDs.
IEDs are at the nearest level regarding the devices
and through them, commands are sent to the devices
or data is gathered from them.
On the opposite side, there is the NEMO-K, which
is the supervisor of the operation of Software Net-
work. NEMO-K manages the services that can be
provided by the system to the rest of the world. These
services are named External Services, implemented
as Web Services.
NEMO-B supports the interaction between the
NEMO-K and all devices that are connected in the
software network. Finally, NEMO-C is a wrapper that
allows both integration and virtualization of IEDs into
a given NEMO system.
Each of these components is further explained in
(Lima et al., 2011a), and together they are essential
for supporting the described conceptual approach.
2.2 Standard-based Approach
IEC 61850 is a worldwide-accepted standard for han-
dling communication within substations. It integrates
an information model, the so-called Abstract Com-
munication Service Interface (ACSI), for substation
description and the Substation Configuration Lan-
guage (SCL), used to describe the ACSI information
ACSI allows describing an energy system and its
respective components in a standard manner, indepen-
dently from the respective individual manufacturers
and with high level of detail. NEMO takes advantage
of the intrinsic ACSI ability of virtualizing IEDs, by
decomposing their respective physical properties and
functionalities into a data model (Lima et al., 2011b).
IED virtualization using the ACSI data model is fur-
ther detailed in (Lima et al., 2011a).
Each standard compliant IED carries an XML-
based SCL file, where the entire respective ACSI in-
formation is stored.
The physical features of each device may be en-
abled and disabled, or its information may be re-
quested or changed, through the invocation ACSI ser-
Figure 2: ACSI services invocation.
A shown in figure 2, two main ACSI service types
are considered by NEMO: GetDataValues and Set-
DataValues. While the former is invoked for monitor-
ing operations, when knowledge about the state of a
physical feature is required, the later allows the phys-
ical control of a given device, replacing the older data
attribute value by a new one.
Both require a reference that points to the required
Data Attribute (DA) path with which the service is
to be invoked. This reference is given by a Func-
tional Constrained Data Attribute (FCDA) which in-
cludes, among others, the Logical Device (LD), Logi-
cal Node (LN), Data Object (DO), and DA that univo-
cally characterise the physical operation (monitoring
or control) to be performed (Lima et al., 2011a).
DPWS, the Web Service standard promoted by
OASIS, was chosen to support the operation of the
channel and really allow a seamlessly communica-
tion among all members of the network, support-
ing the inter-devices communication (C
andido et al.,
2009b; Driscoll and Mensch, 2009). Web Services
are the preferred mechanism for SOA implementation
(Ribeiro et al., 2008; C
andido et al., 2009a) and the
application of Web Services at device level will im-
prove the operation of the system as well as the devel-
opment process (Jammes and Smit, 2005). The ser-
vice mapping between ACSI and DPWS allows sup-
porting higher level heterogeneous platforms.
Similar to the Specific Communication Service
Mapping (SCSM) based on Manufacturing Mes-
sage Specification (MMS), described in IEC 61850
(Commission, 2003), NEMO uses a SCSM based
on DPWS. The aforementioned ACSI Services -
GetDataValues(FCDA) and SetDataValues(FCDA,
DataAttributeValue) - are identified and mapped
into the GetIEC(FCDA) and PutIEC(FCDA,
new value) Web Services (NEMO Internal Services),
respectively. Therefore, each Web Service will be
able to interact with single or multiple low level
device physical features, through the invocation of
NEMO Internal Services, each of them identified by
its ACSI path.
Additionally to the services specified by the
IEC 61850 data model, and in order to provide ad-
vanced features to the substation automation sys-
tem not considered by the standard, NEMO defines
a NEMO Communication Service Interface (NCSI)
(Lima et al., 2011b). NCSI incorporates two NEMO
Internal Services: GetNonIEC(NemoIS) and Put-
NonIEC(NemoIS, new value). These additional
NEMO Services allow the integration and request of
non-compliant services.
Since the majority of the IEDs do not understand
DPWS, they usually need a mediator to make a bridge
between DPWS and ACSI. This translation process is
also performed by the NEMO-C who is responsible
for offering device’s features in the form of Web Ser-
vices, performing all the necessary mapping between
the device’s ACSI and DPWS. This process is further
described in (Lima et al., 2011b).
An instance of NEMO System was implemented and
evaluated in an experimental scenario, that covers the
whole energy process (Lima et al., 2011a). For the
sake of clarity, only the production and storage parts
are explored and detailed here, which include:
A set of photovoltaic panels, with a total installed
capacity of 0.6 kW.
A wind turbine with an installed capacity of 2 kW.
A hydrogen fuel cell, installed capacity of 1.2 kW.
An Active Front End (AFE) converter, attached to
a set of batteries.
A electric vehicle are though to be integrated in
order to store part of the electric energy generated, or
too provide energy when the RES production is insuf-
ficient (figure 3).
Figure 3: Energy Storage Devices Scenario.
The implemented fuel cell, photovoltaic panels,
wind generator and the AFE do not comply with
DPWS and IEC 61850 standards. For interacting with
the devices, a proprietary communication protocol is
required. For a better control of the fuel cell, its
NEMO-C interacts with the fuel cell itself and the re-
spective inverter (Hydro Boy). The interaction with
the fuel cell and the inverter is performed through a
RS-232 channel, using both proprietary communica-
tion protocols. Fuel cell is always sending packages,
so an initial synchronization is needed, while to in-
teraction with the Hydro Boy is made by an event re-
The interaction with the AFE converter is per-
formed through the USS Protocol, also by a RS-232
channel, reading and writing values. Several tests
were executed in order to test the integration of the
devices. Table 1 describes some of the executed tests.
As previously described, the scope of this work is to
develop a plug & play approach for remotely monitor-
ing and operating energy storage devices and, there-
fore, only the storage part of the experimental setup
will be detailed. The production and consumption
parts are further detailed in (Lima et al., 2011b; Lima
et al., 2011a).
In figure 4 it is possible to behold how the
NEMO-C of the fuel cell is implemented. As de-
scribed in previous section the NEMO-C of the fuel
cell is connected to two IEDs, interacting with each
one in its specific communication protocol.
Figure 4: Fuel Cell Communication.
The interaction with AFE converter is made
through a RS-232 connection, as shown in figure 5.
Figure 5: AFE Converter Communication.
As aforementioned, NEMO-C is responsible for
the integration and virtualization of IEDs into the
NEMO System, providing additional features through
Web Services and enabling the interaction between
NEMO System and the physical devices. Three
different types of mappings are performed by the
1. Between DPWS and IEC 61850, to allow the
invocation of ACSI services using DPWS Web
Services to both IEC 61850 compliant and non-
compliant devices.
2. Between IEC 61850 and the IED’s manufac-
turer communication protocol, to guarantee that
IEC 61850 non-compliant devices understand
ACSI services.
3. Between DPWS and the IED’s manufacturers
communication protocol, to allow the invocation
of services not contemplated by the IEC 61850.
NEMO-C receives the DPWS service invocations
of NEMO-K and through internal the mappings, it
will be capable of performing the requested opera-
tions in the device. Regarding the energy storage
area, and for the purpose of this work, there are two
NEMO-Cs implemented: one virtualizing the fuel cell
and one connected into the AFE converter.
The interaction between the NEMO-C and the fuel
cell is made through a RS-232 converter. Equal con-
verter is used to interact with Hydro Boy. Two dif-
ferent libraries are needed to interact with the de-
vices: RXTX is a native library which provides se-
rial and parallel communication for the Java Develop-
ment Toolkit (JDK); YasdiMaster is a Dynamic Link
Library (DLL) which allows communication with Hy-
dro Boy via the proprietary protocol.
The connection with the AFE is performed
through a RS-232 connector. The proprietary commu-
nication protocol to interact with the AFE converter
is the USS Protocol. USS Protocol defines an ac-
cess technique acordint to the master-slave principle
for communication via a serial bus.
Both fuel cell and AFE are fully functional with
all the possible services mapped to non-ACSI or to
ACSI services. Examples of ACSI compliant services
and of non-ACSI compliant services currently imple-
mented in the fuel cell and AFE are shown in Table 2
and Table 3, respectively.
Lets consider that the NEMO-K requests an invo-
cation of a non-ACSI service, for instance, a moni-
toring operation regarding a fuel cell hydrogen con-
centration. This operation starts with the invocation
of the GetNonIEC Web Service having NEMO ser-
vice identifier parameter with the value Hydrogen-
Concentration (Table 3). This Web Service request
will be received in the NEMO.IS component, and
since it is identified as non-compliant service, it is
Table 1: Executed Tests for Integration Assessment.
FuelCell HidroBoy AFE
Read Air Temperature Read Mode Read Language Voltage
Read Stack Current Read Storage Read AFE current
Read Purge Cell Voltage Read Frq Dif Max Read Reactive Power
Read/Write DC Vtg Str Read Hardware Version Read/Write Operating Mode
Read Hydrogen Pressure Read Time Stop Read/Write Vd(set) Factor
Table 2: Examples of ACSIs services currently implemented.
NEMO Internal Service
LdInst LnClass LnInst DoName DaName Fc
HidroBoy SB MMXN 1 Vol mag MX DC Vtg Str
FuelCell FC STMP 1 Tmp mag MX Stack Temperature
FuelCell FC STMP 2 Tmp mag MX Air Temperature
FuelCell FC MMXN 2 Vol mag MX Purge Cell Voltage
AFE AF MMXN 1 Vol mag MX Vd(act)
AFE AF MMXU 1 Hz mag MX Line Frequency
AFE AF AVCO 1 LocSta ctlNum MX Access Level
Table 3: Non-ACSIs services currently implemented.
IEDs Type of Service NEMO Service Identificer Input Units Output Units
HydroBoy Get SerialNumber n/A n/A
HydroBoy GetPut EnOp n/A n/A
FuelCell Get HydrogenPressure n/A barg
FuelCell Get HydrogenConcentration n/A %
AFE Put OperatingStatus () n/A n/A
AFE GetPut LineVolts () V V
forwarded to NEMO.IS.to.NonACSI, where its ac-
complishment is verified. If NEMO-C is able to ex-
ecute the requested service, this is dispatched to the
NonACSI.to.IED component, which will perform the
requested operation through the Communicator com-
ponent, according to the NEMO-C internal mapping.
Otherwise the service will be denied.
Lets consider now an IEC 61850 compliant moni-
toring operation, regarding the Air Temperature of
the environment where the fuel cell is located. A
GetIEC service is invoked (ACSI compliant), in-
troducing the reference STMP.Tmp.mag[MX] to the
FCDA parameter (Table 2). NEMO-K invokes the
NEMO.IS, and this time the request is dispatched to
the NEMO.IS.to.ACSI component, which verifies if
the FCDA is correct, i.e., if it is defined in the IED’s
SCL file. If this is verified and the IED is IEC 61850
compliant, the operation is performed according to
the IEC 61850 protocol. Otherwise, if the IED is
not IEC 61850 compliant, the ACSI.wrapper com-
ponent acts and the service is performed according to
the FCDA internal mapping.
The intermittency characteristic of RES must be mit-
igate, for attaining a higher energy efficient manage-
ment. A holistic view regarding the continuous and
remotely management of energy storage devices is,
therefore, a must. By integrating two communica-
tion standards and a standard data model, NEMO pro-
vides the seamless integration and interoperability of
energy storage devices, required for a real effective
operational architecture for the integration of energy
storage devices.
As future work, new devices as super-capacitors
are planed to be integrated, as well as the study of the
effects in the electric power network of different con-
trol functions, where all the production devices will
be managed to fulfil the demands.
Some studies to measure the delay added by the
Web Services layer in RS-232 communications have
to be performed. In a small system like the one de-
scribed it may not be a problem, but in a large scale
system this have to be taken into account.
The mapping between the DPWS Eventing feature
(Driscoll and Mensch, 2009) and the Report ACSI
service (Commission, 2003), is planned to be devel-
oped, in order to have a more efficient monitoring op-
eration. With this features the devices will be able to
inform the NEMO-K, about a system malfunction or
a overrated value.
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