7/27/2019 04651480

1/4

Future Trends of Substation Automation System by

Applying IEC 61850M.Vadiati, M. Abbas Ghorbani

NirooResearch Institute (NRI)*

mvadiati@nri.ac.ir

A. R. Ebrahimi, M. Arshia

Tehran Regional Electric Company (TREC)

a-ebrahimi@trec.co.ir

* This research has been supported by Tehran regional electric company (TREC) Deputy managing director for development and project"

Abstract- Substation automation systems (SAS) consist ofintelligent electronic devices (IEDs) and the communicationnetworks between them, for implementing control, protectionand monitoring tasks in power system. Rectitude of this systemdepends on integrity and interoperability of its components,especially in the case of applying various IEDs from differentmanufacturer of substation automation system and it is possibleby flexible and common protocol in various manufacturersIEDs. For this purpose and in order to interoperability betweendifferent manufacturers IEDs, international standard IEC 61850has been prepared. In this paper the advantages and effects of

applying IEC 61850 on SAS performance have been studied andthe future modern SAS have been compared to conventionalsubstation automation system.

Key words: Substation automation system (SAS), IEC 61850,Intelligent Electronic Device(IED), Control and Protection

I. INTRODUCTIONIn Substation Automation System (SAS), the accurate

functionality of system depends on integrity and

interoperability of IEDs from different manufacturers. In

management arguments, cooperation means to get better

results from a team work in comparison with separate

individuals. In other words, team efficiency is more than

single and separate performances. At high voltage

substations, team works flourish when cooperation of control

and automation devices from various manufacturers seems to

be necessary. But, the equipment that communicate with

various protocols and inaccessibility of common protocol

avoid coordination. Since introduction of substation

automation systems up to recent years, each manufacturer

uses his own protocol such as LON, Profibus, EFIP and etc.

However, IEC 60870-5-103 is provided to communicate

among digital protection devices regardless theirmanufacturers based on master-slave model. But,

accessibility of this standard limited due to advancement of

control and protection devices as well as data increment and

traffic. Therefore, to achieve high speed data transfer rate,

reduce traffic and facilitate communication among various

manufacturers IEDs, a flexible-adaptable standard protocol

for substations protection, control and monitoring seems to be

necessary. For the first time in 2002, IEC committee tried to

collect and edit a comprehensive standard for substation

automation system according to above requirements. This

goal accomplished in 2006.

In this paper, substation automation system components

performance has been studied based on IEC61850. and

functionality improvement of SAS has been compared to

conventional SAS.

II. IEC 61850 FEAUTURE AND SPECIFICATIONIEC61850 provides cooperation among various control and

protection equipment.

Main features of IEC 61850 are as follows:

Interoperability by various manufacturers IEDs asan integrated system

High data transfer among IEDs considering peer topeer communication model instead of master-slavecommunication model in recent protocols.

Data definition based on advanced object-orientedmodel which contains whole data specifications

instead of single-oriented model with each datadefinition by numeric addresses.

Supporting functionality of devices to provide bettercommunication.

Communication extend ability and data integrity Providing integrated communication system. Providing robust management of substation

automation system.

III. VERTICAL COMMUNICATION BASED ON IEC 61850The SCADA application of the network is performed by a

local or remote operator. The data communication for the

SCADA (Supervisory Control and Data Acquisition)

application, which is related to human operation, is directed

vertically, i.e. from a higher hierarchical control level down

to a lower one for commands of any kind from the operators

place or reverse for binary indications like breakers or

isolators position, measurands from instrument transformers

and other sensors, events, alarms.

This vertical communication between bay level and station

level, is implemented based on client-server model. IEDs in

7/27/2019 04651480

2/4

the bay level act as servers which send data to station or

remote control center. Data are sent due to client request or

automatically to the high level by server. Client is usually an

operator work station that can send control command to

servers for operation of switch gears. In a client-server

communication, client control data exchange and client-

server communication is very flexible due to data

exchanging.Client-server model can allow the implementation of

multiple clients comparing a mater-slave model. Client-server

communication is based on seven layer stack, therefore it is

very reliable, but transfer rate is very slow. Thus, client-

server communication is not suited for critical times transfer

those require fast transmission rate. However, they are

suitable for 1 second response time.

IV. HORIZENTAL COMMUNICATION BASED ON IEC 61850Data transmission shall be very fast for several automated

functions, which are located within the same bay or in

different bays. There are some examples as follows: data transferring between line protection and

autorecloser

data interchange within bays for breaker failure data transferring between bays for interlocking

These functions are independent of human operation and

must be very fast (i.e. mS) due to their security level. For this

data type, client-server model is very slow due to several

perfect layers application. If functions information is located

in different IEDs, copper wiring with auxiliary relays and

contacts or serial network must be used for fast transferring.

The data exchange is performed by horizontal communication

network between IEDs.For the exchange of this data type, IEDs are connected as a

serial network and based on peer to peer communication

model using GOOSE (Generic Object Oriented Substation

Event) message with high speed communication. The

GOOSE message is sent as a multicast message over the

communication network as is shown in Fig 1.

Fig. 1: IEDs Communication based on GOOSE messages

V. PROCESS CONNECTION BASED ON IEC 61850Substation automation system must connect to process for

data exchange between SAS and high voltage equipments.

These data are as follows:

Current and voltage waveforms Switchgear status Control commands

Data exchange may be performed by copper wiring orserial communication network. According to IEC 61850, for

voltage and current waveforms exchange, a service is defined

for sampled value transmission. All other data exchanges are

using either client-server model for non-critical times transfer

data (e.g. SCADA application) or GOOSE message for

critical times transfer data such as sending trip signal from

protection relays to circuit breaker.

VI. SAS CONFIGURATION BASED ON IEC 61850IEC 61850 not only specifies the method of the data

transfer, but also defines as well the process data of the

servers. For this purpose, IEC 61850 uses object-oriented

method and logical node (LN) as core objects. A logical node

is a functional grouping of data and represents the smallest

function, which may be implemented independently in

devices. For example, XCBR contains all data of circuit

breaker and PTOC contains all data of timed over current

protection. Each logical node contains data and all the data

include attributes.

VII.SUBSTATION CONFIGURATION LANGUAGE BASED ONIEC 61850

Substation Configuration description Language must beaccording to IEC 61850 to configure IED equipments in

substations. This language describes data model and

communication service based on IEC 61580-7-X. According

to specification of this language based on IEC 61850-6, the

task is coordinating between different and exchanging

between SCL files. SCL files are used to exchange data

between different equipments from different manufacturers.

SCL files are classified considering their tasks as follows:

IED Capability Description (ICD): this file definesdata exchange from IED configuration tool to thesystem configuration tool. This file describes generalcapabilities of IED and must have IED descriptioncomponent. Moreover, this file should includerequired data to describe logical node and is requiredfor general system configuration that should bepresented by manufacturer.

System Specification Description (SSD): this filedefines data exchange from a system specification

tool to the system configuration tool and describessubstation single diagram and the required logicalnodes. This file should have substation descriptionpart and required data types and logical nodesdescriptions. Function assignment is determined by

7/27/2019 04651480

3/4

this file. This file replaced with old signal list andsignal list data are placed in logical nodes data.

Substation Configuration Description (SCD): thisfile defines data exchange from system configurationtool to IED configuration tools and contains allIEDs, a communication configuration section and asubstation description section.

Each system configuration tool requires ICD andSSD files for all system equipments. The outputs of

these tools are SCD files that shall be kept as projectdocumentation for future maintenance andmodifications.

Configured IED Description (CID): this file definesdata exchange from the IED configuration tool to the

IED. The communication section contains thecurrent address of the IED. The substation sectionrelated to this IED may be present and then shall

have name values assigned according to the projectspecific names. It is an SCD file, possibly strippeddown to what the concerned IED shall know.

VIII. THE DIFFERENCE BETWEEN CONVENTIONAL ANDFUTURE SAS STRUCTURE

A. Conventional SAS structureA typical conventional SAS structure is shown in Fig. 2

includes as follows:

Intelligent electronic devices (IEDs) for all functions Parallel hardwired connection between IEDs and

primary equipment

Serial communication of the IEDs to the station unitand station HMI with proprietary protocols forcontrol (e.g. LON, SPA, Profibus, etc.), DNP 3

(mainly USA), IEC 60870-5-103 or other protocolsfor protection equipment.

Serial communication between gateway to networkcontrol centre (NCC)

IEDs include protection units, control units,combined protection and control units.

Functions are typically allocated to bay level equipment for

protection, bay control, disturbance recording, general data

acquisition, and time synchronization. Functions are typically

allocated to station level equipment for communication to

remote NCC and bay equipment, station level HMI, event and

alarm handling, monitoring, data evaluation and archiving,

and status supervision.B. Future SAS structure

The typical structure of future substation automation

system based on IEC 61850 is shown in Fig. 3 and includes

the followings:

Intelligent electronic devices (IEDs) for all functions Serial communication between IEDs and the primary

equipment by sensors and actuators based on IEC61850-9-1 and IEC 61850-9-2 protocols.

Fig 2: Typical structure of conventional SAS

Fig 3: Typical structure of future modern SAS

Serial communication between IEDs and the stationunit and station HMI based on IEC 61850-8-1

protocol Serial communication between gateway and the

network control centre (NCC)

Functions are allocated to bay level and station level

equipment.

Bay level equipment includes:

Protection Control Disturbance recorders Data acquisition in general

Station level equipment includes:

Communication to remote NCC Communication to feeder level Station level HMI Event and alarm handling Monitoring Data evaluation and archiving Status supervision Time synchronization

IEC 61850-8-1

IEC 61850-9-1 and 9-2

7/27/2019 04651480

4/4

IX. FUNCTIONAL COMPARISON BETWEEN CONVENTIONALAND FUTURE SAS

In this research different technologies of SAS in the past

and improved performance of SAS by applying IEC 61850

have been studied. This part shows an overview of

conventional functionality and the expected functionality in

the future with the IEC 61850 bus as specified in Table I

where there is :A: Conventional SAS

B: Future SAS

-: Function not fulfilled

(x): Function fulfilled with limitations / manufacturers

specific solutions

x: Function fulfilled

X. CONCLUSIONStandard IEC 61850, which all automation manufacturers

are forced to perform its rules, enables substation automation

system designers to reduce design duration time and errors. If

a company desires to work with SAS system to cooperate

with various manufacturers IEDs, interoperability of

equipment and functions as well as integration is expected.

IEC61850 provides these requirements and improves the

quality of engineering tools, measured values and

management construction. IEC61850 is proper for all the

local communications and presents comprehensive method

for substation protection and automation by serial

communication, Although, this is not guaranteeing the same

qualities of the systems. However, commissioning procedure

and function quality are chosen freely by the manufacturers.

ACKNOWLEDGMENT

M. Vadiati thanks to Mr. Farzalizadeh, Mr. Shariati and

Mr. Rassaie for their great support and useful comments.

REFERENCES

[1] K.P.Brand, M.Janssen The specification of IEC 61850 basedSubstation Automation Systems, Paper presented at theDistribuTECH

2005, San Diego, January 25-27.[2] CIGRE SC B5, WG11, The introduction of IEC 61850 and its impact

on protection and automation within substations, work started in 2003,report to be scheduled for 2005/2006

[3] Gwan-Su Kim, Hong-Hee Lee, A Study on IEC 61850 BasedCommunication for Intelligent Electronic Devices, InformationalTechnologies IEEE 2005.

[4] IEC 61850, "Communication networks and systems in substations"

all parts,www.iec.ch, 2002-2005..[5] F. Crispino, C. A, Villacorta C., P0. R. P. Oliveha, J. A. Jardini,L. C.

Magrini, An Experiment Using an Object-Oriented Standard - IEC 61850 to integrate IEDs Systems in Substations, 2004 IEEWPES

Transmission & Distribution Conference II Exposition Latin America .[6] Mesmaeker, I.; Brand, K.; Brunner, Ch, How to use IEC 61850 in

protection and automation,Electra, No.222, October 2005.[7] I van De mesmaeker, P.rietmann.k. Brand, P.Reinhardt, Practical

consideration in applying IEC 61850 for protection and substationautomation systems, GCC power 2005 conference & Exhibition ,

November 2005.

TABLE IFUNCTIONAL COMPARISON BETWEEN CONVENTIONAL AND FUTURE SAS

Function Functionality A B Comment

Protection

Fundamental protection

functionsx x

Upload disturbance

record files from

protection units

x x

Interoperability control

and protection unitsx x

Enhanced

interoperability

between protection

units

- x

For example,

multicast state

change essages

so that all

devices know

the status of the

other devices.

Remote configuration x

Control

Basic control functions x x

Enhanced control

functionsx x

Station level control

functionsx x

Interoperability

between control and

protection units

Interoperability of

control units

- x

Permits multi-vendor

interoperability

, and allows

distributed

functionality.

Interchangeability of

station units- (x) Future trend

Metering

Integration of metering

data equipment and

data into SAS for

billing purposes

Metering is a

completely

separate

system.

Connect kWh meter to

non- conventional

sensors

- x

Permits use of

single

instrumenttransformer.

Monitoring

protectionand control

equipment

Basic monitoring

functionsx x

Enhanced monitoring

functions(x) x

Monitoring

switchgearequipment

Monitoring of

equipment(x) x

Analysis and

Diagnostics

Provide meaningful

information of

secondary equipment

(x) x

Automatic disturbance

record upload and

analysis

(x) x

Support formaintenance,

operation,and

restoration

Automatically generatemaintenance alarms

(x) x

Automatic switching

programs(x) x

Automatic power

restoration programs(x) x

Integration of

nonconventional

sensors (e.g., CT, VT)

(x) x

Integration of

nonconventional

actuators (e.g., for

breakers, isolators)

(x) x