A STANDARD-BASED SOFTWARE INFRASTRUCTURE TO

SUPPORT ENERGY STORAGE IN DISTRIBUTED ENERGY

SYSTEMS

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

Keywords:

DPWS, IEC 61850, Power Distribution, Energy Storage, Power System Management, Networked Control

Systems.

Abstract:

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.

1 INTRODUCTION

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

process.

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..

A STANDARD-BASED SOFTWARE INFRASTRUCTURE TO SUPPORT ENERGY STORAGE IN DISTRIBUTED ENERGY SYSTEMS.

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 THE NEMO CONCEPTUAL

ARCHITECTURE

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-

Api (NEMO-A), NEMO-Bus (NEMO-B), NEMO-

Figure 1: The main components of NEMO Software Net-

work.

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

model.

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-

vices.

SMARTGREENS2012-1stInternationalConferenceonSmartGridsandGreenITSystems

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).

3 THE EXPERIMENTAL SETUP

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

ASTANDARD-BASEDSOFTWAREINFRASTRUCTURETOSUPPORTENERGYSTORAGEINDISTRIBUTED

ENERGYSYSTEMS

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-

quest.

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.

4 CURRENT IMPLEMENTATION

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

NEMO-C:

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

SMARTGREENS2012-1stInternationalConferenceonSmartGridsandGreenITSystems

Table 1: Executed Tests for Integration Assessment.

IEDs

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.

IEDs

FCDA

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.

5 CONCLUSIONS AND OPEN

POINTS

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

ASTANDARD-BASEDSOFTWAREINFRASTRUCTURETOSUPPORTENERGYSTORAGEINDISTRIBUTED

ENERGYSYSTEMS

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.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the collaboration

and support of Dr. Cheng Yonghua.

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