6309_ConfigurationPerformance_YB_20080417 Black Box Laser Pointer LES421A Configuration And Performance Of IEC 61850 For First Time Users

User Manual: Black Box Laser Pointer LES421A

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Configuration and Performance of IEC 61850

for First-Time Users – UNC Charlotte Senior

Design Project

Youssef Botza, Matthew Shaw, Peter Allen, Mike Staunton, and Dr. Robert Cox,

University of North Carolina at Charlotte

Michael Boughman, Casey Roberts, and William Rominger, Schweitzer Engineering Laboratories, Inc.

Abstract—IEC 61850 was designed to be a substation IED

network and system communications standard rather than just

another communications protocol. The international standard

design allows for the interoperability of many different intelligent

electronic devices (IEDs). Using Ethernet, IEDs are networked

within a substation and across an entire power network. The

University of North Carolina Charlotte senior design group

applied the IEC 61850 standard to a substation integration

project that was first designed using traditional serial communi-

cations methods. The purpose of this project was to offer a

practical comparison between a system of protective relays

communicating protection schemes with serial communications

and hardwired contacts and another using IEC 61850 GOOSE

(Generic Object Oriented Substation Event) messages via

Ethernet. Because this project was an introduction to power

systems for most of the design team, the practical implementation

of incorporating IEC 61850 into a substation integration project

is presented at a beginner’s level.

I. NOMENCLATURE

The following list contains the definitions of abbreviations

that are used in this paper.

AX-S4 MMS IEC 61850 MMS Client Interface Software

COM Component Object Model

DCOM Distributed Component Object Model

DDE Dynamic Data Exchange

GOOSE Generic Object Oriented Substation Event

GUI Graphical User Interface

HMI Human-Machine Interface

IED Intelligent Electronic Device

LAN Local-Area Network

MMS Manufacturing Message Specification

MOE MMS Object Explorer

MTBF Mean Time Between Failures

OLE Object Linking and Embedding

OPC OLE for Process Control

RB Remote Bit

SCADA Supervisory Control and Data Acquisition

SER Sequential Events Recorder

SLC Software Logic Controller

TCP/IP Transmission Control Protocol/Internet

Protocol

WWMMELink Software Application Script That

Concatenates WWMMEItem1 and

WWMMEItem2

II. OVERVIEW OF IEC 61850

IEC 61850 was created to be an internationally standard-

ized method of communication and integration. The standard

is intended to allow IEDs from multiple manufacturers to be

networked to perform protection, monitoring, automation,

metering, and control. IEC 61850 supports all substation

automation functions and the engineering required for imple-

mentation. Unlike earlier standards, the technical approach of

IEC 61850 was premeditated to make it flexible and allow for

future improvements.

An effort to create a communications standard with global

appeal was initiated by an international IEC project group of

about 60 members. In 1995, they created Technical

Committee 57 to produce international standards in the field

of communications between the equipment and systems for

the electric power process, including telecontrol, teleprotec-

tion, and all other telecommunications to control the electric

power system. This committee began creating the communi-

cations standard IEC 61850. The objectives set for the

standard were:

• Develop a standard comprised of multiple protocols

for complete substation communication.

• Define basic services required to transfer data.

• Promote a high level of interoperability between

devices and systems from different manufacturers.

• Create a common method and format for modeling,

describing, and exposing data.

• Standardize configuration file structure and content to

simplify device configuration and methods for sharing

configuration parameters among devices and systems.

The IEC 61850 standard specifies the data transfer methods

and the server processes within the substation; this process is

based on a hierarchical data structure with an object-oriented

approach. The data objects are grouped by functional

constraints to allow information to be communicated with

high-efficiency data transfer. This standard also promotes

interoperability, where multiple IED manufacturers can

communicate over one or several standardized protocols.

Throughout the years, there have been many protocols used

within substations. These protocols are often proprietary with

custom communications links, which can make interopera-

bility between multiple manufacturers’ IEDs difficult. Using

IEC 61850 simplifies the interoperation of devices from

different manufacturers.

IEC 61850 differs from most previous communications

methods in its use of object models for device functions and

device components. These models define common data

formats, identifiers, and controls for substation and feeder

devices such as meters, switches, voltage regulators, and

protection relays. The models specify standardized and logical

groups of data for the most common device functions and

allow for significant manufacturer specialization.

III. PROJECT AND SYSTEM OVERVIEW

A student team from University of North Carolina

Charlotte conducted a senior design project that made a

practical comparison between a system of protection relays

using hardwired contacts and serial communications, and one

using IEC 61850 GOOSE messages via Ethernet. The project

system consisted of ten IEDs networked to provide protection,

monitoring, automation, metering, and control of two 138 kV

lines, a 138 kV ring bus, a 12.47 kV feeder, and a transformer.

The team provided a fully automated system with a rugged

computing platform and network switch that provided

SCADA and remote engineering control using LAN access.

The integration of the project resulted in pertinent IED

information displayed on an HMI with a GUI.

The group performed a comparison between IEC 61850

and the traditional methods of wiring microprocessor-based

protective relays. By designing and drafting a complete set of

drawings for each system, they were able to perform both

quantitative and qualitative comparisons against specified

acceptance criteria. The evaluation criteria included speed,

controls, usability, and reliability testing. Because the speed

with which information travels is critical to the performance

of a substation, the speed of IEC 61850 was compared to the

speed of traditional digital serial communications processor

controls and existing serial peer-to-peer communications.

A single-line schematic of this project is shown in Fig. 1. It

includes two lines, a radial feeder, a ring bus, a transformer,

four circuit breakers, and switchgear. The following protection

and monitoring devices are applied in the project’s power

system:

• Line distance protection

• Differential protection

• Transformer protection

• Bus differential protection

• Radial feeder overcurrent protection

• Communications processor

• Computing platform

IV. IMPLEMENTATION OF IEC 61850

Using the described system, pertinent IED information was

output to an HMI created with the Wonderware® software

application. The software runs on a substation-hardened

rugged computing platform with a touchscreen monitor-based

GUI. Using the information selected for the HMI and

associated timestamps at the IED level, the team tested the

speed difference between IEC 61850 communication and the

typical serial connections.

There are two methods of configuring Windows® software

applications to interact with the IEC 61850 protocol drivers

that also run on the Windows operating system on the rugged

computer. These two are DDE and OPC.

DDE offers an easy and flexible method of passing data

from one Windows application to another. Given that

AX-S4 MMS software (see Section IV.A for description of

the software) has the capability to communicate via DDE, this

method was a natural choice because Wonderware has mature

and often-used DDE interfaces as well. This eliminates the

need for a third-party protocol converter and reduces points of

failure. In addition, Microsoft Excel® can be programmed as a

DDE interface to mimic an HMI for testing controls and status

through IEC 61850.

The OPC communications method was based on the OLE,

COM, and DCOM technologies developed by Microsoft for

the Windows operating systems.

Feeder

Protection

Transformer

Protection

Bus Diff

Protection

Feeders

#14000 #13000 #12000 #11000

138 kV Ring Bus

Line and Diff

Protection

Line and Diff

Protection

1200/5

2000/5

Line 1Line 2

Fig. 1. One-Line Diagram

Fig. 2 represents the IEC 61850 process using the two

different communications methods—DDE and OPC. DDE

communication requires fewer individual pieces of software.

The design team selected Wonderware for HMI data and

control using DDE because the team was familiar with it. The

user can select either method for implementation.

IED IEDIED

Switch

AX-S4 MMS

(IEC 61850 Interface)

WWMME Link ReLab OPC

Console

Wonderware®

DDE OPC

ReLab SLC

ClearView

Server

ClearView

Fig. 2. DDE and OPC Control Implementation

A. AX-S4 MMS

AX-S4 MMS is the IEC 61850 interface that acts as a

client to collect data and perform controls and as a server to

provide data. It provides both DDE and OPC interfaces to the

IEC 61850 protocols based on MMS. AX-S4 MMS, with the

capability to communicate both DDE and OPC, provides

many integration options. The software is a server that links

clients such as Wonderware and Excel with MMS devices like

protective relays. AX-S4 MMS provides real-time data in

several ways. Data can be requested via a browser, similar to a

web browser that understands and displays values and

descriptions. One such browser is MMS Object Explorer

(MOE). The same data, or subsets of it, are collected via MMS

reports when data changes or at a fixed update rate to support

an HMI like Wonderware or Excel.

Starting MOE automatically initiates AX-S4 MMS and

other necessary software components to prepare the computer

to act as an MMS client. The MOE is the configuration viewer

of all the physical and logical devices available on the network

and visible to the AX-S4 MMS server. Once MOE is

configured with the device connection information, such as

network IP address, all available device information from each

IED can be viewed in the explorer window. This information

includes the IED’s physical and logical status and analog

values. Instantaneous and dead-band magnitude and angle

values are available for measured analog inputs such as

voltage and current. Instantaneous and dead-band values are

also available for calculated analog values such as watts, vars,

and frequency. Fig. 3 illustrates the ability to see the

individual frequency measurement for a line distance

protection relay. This window also identifies the device name

and DDE item information. The DDE item string information

serves as the data name for interface with software

applications.

Fig. 3. Starting AX-S4 MMS

The steps to add an IED to AX-S4 MMS are shown in

Fig. 4. From the Object Explorer window, select Tools >

AX-S4 MMS Configuration Utility. In the Utility window,

select Configuration > Network > Addressing.

Fig. 4. Adding an IED to AX-S4 MMS

The Network Addressing window will appear, as shown

in Fig. 5. Confirm that this window identifies Host Names

and select New > Next. From the IED Identifying window

you will “name” the relay. To avoid computing issues with

spaces or dashes, use the underscore character (_). Then select

Next. Select Yes to configure a TCP/IP network, and enter the

IP Address of your host, for example, 192.168.0.90.

Fig. 5. Network Addressing

After entering the IP address, select Next; then select Add

AR Name > Next. In this window, you will see the host name

that you added. Select Next; enter the same name for the

AR Name you are configuring and select Next > Next > Next

> Finish > Finish. At this point, you may close out of the

Network Addressing window and the Configuration Utility

window. Bring up the AX-S4 MMS window, and select Tools

> Reconfigure, as shown in Fig. 6.

Fig. 6. Reconfiguring AX-S4 MMS

This procedure will reconfigure AX-S4 MMS to accept the

new changes or additions to the configuration utility. Viewing

the MMS Object Explorer window, choose from the folder

list on the left side of the screen, right click on Physical

Devices, and select Add Nodes, as shown in Fig. 7.

Fig. 7. Adding Nodes and Updating

Adding the new IEDs through this window will update all

IEDs that have been added to the remote node listing. Select

OK to add the new nodes and complete this process.

From the MMS Object Explorer window, as shown in

Fig. 8, if the IEDs are online with the station LAN, relay

status can be polled, and AX-S4 MMS can implement

controls. The next set of instructions details the steps to test

the controls and status mechanisms using Microsoft Excel.

Fig. 8. Adding Polled Devices

Open a new Excel spreadsheet and start a new Visual

Basic® Editor. Copy the script provided in the appendix into

the Editor window and save. Then click on Button located in

the Forms toolbar and assign the macro script GetFrequency.

Another button can be assigned to a different macro script

SendOutput1.

Using any of the Excel button makers, select a function

name and cell for that button. The cell button will run that

particular function outlined in the Visual Basic script.

B. Wonderware

For this project, Wonderware InTouch® software was used

as an HMI to run the IEC 61850 application. Controls are

administered by issuing the DDE item from AX-S4 MMS

when a particular action is taken in Wonderware. Figs. 9

through 13 show how to set up a pushbutton to administer a

control, such as setting and resetting a remote bit in a relay.

To create a new window after starting a new application in

Wonderware, right click on Windows; then click on New, as

shown in Fig. 9.

Fig. 9. Creating New Window in Wonderware

This action will bring up the Window Properties box, as

shown in Fig. 10, where the appropriate window selections

and naming convention are chosen. The user can populate the

window as desired.

Fig. 10. Window Properties Screen

As seen in Fig. 11, a few simple pushbuttons and status

indicators are chosen. To label the pushbuttons, click on the T

in the toolbar, and place the cursor in the desired box to label

it appropriately. Text can also be typed in the window to label

other actions, like the LED status in the relay.

Fig. 11. Wonderware Draw Object Toolbar

The user must now configure the status indicators and

pushbuttons to operate as desired. As seen in Fig. 12, select

PB1, and choose Action under the Touch Pushbutton

column to configure this particular rectangle as a pushbutton.

In the same way, check Discrete under the Fill Color column

to configure the desired status indicators.

Fig. 12. Configuring Pushbuttons

Fig. 13 shows the field in which to enter the action script.

Fig. 13. Script Activated by Pushbutton

The following script sets a remote bit in the relay:

WWMMETopic = “AXS4MMS|Relay_2”;

WWMMEItem1 = “Read AR=Relay_2 Name=RBGGIO1

Domain=Relay_2CON DTDL={(ctlVal)Bool”;

WWMMEItem2 =

“,(origin){(orCat)Byte,(orIdent)OVstring64},(ctlNum)Ub

yte,(T)Utctime,(Test)Bool,(Check)BVstring2}

ADL=CO[SPCSO11[Oper]] Rate=2”;

SendControl = “1”;

DisableButtons = 1;

This script will run a small program WWMMELink that

concatenates WWMMEItem1 and WWMMEItem2 from the

Wonderware script. In Wonderware, every action, status, and

message has a tagname associated with it. This tagname

defines what type of action will be performed as well as where

it should be sent based on its “AccessName” and “Item.” The

item is where the control string would be entered. However, a

tagname item has an 80-character limit and the AX-S4 MMS

control string is more than 90 characters. In order to overcome

this obstacle, the AX-S4 MMS control string is divided into

two sections in the Wonderware script. Then the

WWMMELink program puts the two sections together and

sends the complete control string as required to AX-S4 MMS.

The WWMMELink also has the option to send a pulse, a one,

or a zero.

The WWMMELink proved to be an extremely valuable

tool to allow the HMI to communicate with the relays, making

retrieval of status from the relay much easier. Moreover, the

DDE item from AX-S4 MMS is placed into the item field for

that particular tagname. The following string represents an

item to retrieve frequency from a relay:

RELAY1_1MET/METMMXU1$MX$Hz$instMag

This item is just one example of polling data from a relay.

All other status and indication points are retrieved in this same

way. This item string can be traced in the MMS Object

Explorer that is a GUI for AX-S4 MMS.

Another method of real-time data retrieval is to bundle all

of the data that the HMI requires into a report within the IED.

Once the client, in this case AX-S4 MMS, establishes a

connection with the IED, the report will be sent any time data

change. This will reduce network traffic and assure timely

updates of changes. Both the polling and reporting methods

are frequently used for HMI GUIs, with designers balancing

their functional and performance differences.

V. TESTING

The group also designed and drafted a complete set of

drawings that include ac schematics, dc schematics, one-line

diagrams, communications diagrams, panel layouts, and

wiring diagrams. As mentioned earlier, these drawings

enabled the group to do a quantitative and qualitative compar-

ison between IEC 61850 and the traditional methods of wiring

microprocessor-based protective relays. The evaluation

criteria were speed, controls, usability, and reliability. The

speed with which information can travel is critical to the

performance of a substation. The speed of IEC 61850 was

compared to traditional digital serial communications

processor controls and existing serial peer-to-peer communi-

cations.

One of the IEC 61850 protocols is GOOSE, which is used

for substation events such as commands, alarms, and message

indicators. GOOSE messaging is a key component of

IEC 61850 and allows IEDs to effectively communicate to one

another to accomplish interlocking and integrated protection

schemes. A single GOOSE message that is sent by one IED

can be received and used by several other IEDs. GOOSE takes

advantage of the speed of Ethernet and supports real-time

messaging, which is crucial for accurate event recording.

GOOSE messages are transmitted periodically to increase the

probability of delivery, as well as every time the message

contents change.

A. Relay-to-Relay Communication

When considering how to test the speed of GOOSE

communication, the highest accuracy is required. The project

team decided to use the SER function available in the relays.

The SER data are timestamped to the millisecond.

Communications timing tests between the devices were

completed by analyzing different substation scenarios that are

commonly used in GOOSE messaging. Each test included the

following:

• Hardwired I/O

• Serial peer-to-peer communications protocol

• IEC 61850 GOOSE messaging

Fig. 14 shows the connections of the first test setup.

Relay

PORT 2

OUT02

OUT01

ALARM

IRIG-B

PORT 5

IN101PORT 2 PORT 5

Antenna 75'

PORT 1 PORT 2

ALARM

IRIG-B

OUT101

Legend

Coax

Copper

Ethernet

Serial

Satellite

Clock

Switch

Fig. 14. First Test Setup

The team assumed that the hardwired I/O would be the

fastest, because there was no communications processing time

in between the relays. However, as demonstrated by these and

other tests performed, the physical detection circuit time takes

longer than the communications message processing time to

verify that an element has changed state.

To accurately test all scenarios, each component of the test

must start from a single relay element to assure that they all

start at the same instant in time. To initiate the test, a

pushbutton on the front panel of Relay 1 was programmed to

set a logical latch function, PLT10, inside the relay.

PLT10SET := PUSHBUTTON10_PULSE AND NOT

PLT10 (Actuating the test button sets the logic bit if it is

not already set)

PLT10RESET := PB10_PULSE AND PLT10 (Actuating

the test button resets the logic bit if it is already set)

The latch was programmed to operate a contact output

(OUT101), a logic equation to transmit a serial peer-to-peer

output (TMB1A), and an IEC 61850 communications card

output (CCOUT01).

OUT101 = PLT10

TMB1A = PLT10

CCOUT01 = PLT10†

The initiating latch, the contact output, the serial peer-to-

peer message equation, and the IEC 61850 communications

card output were added to the SER trigger list so that all state

changes would be recorded.

SER1 = PLT10,PLT10,Asserted,Deasserted,N

SER2 = OUT101,OUT101,Asserted,Deasserted,N

SER3 = TMB1A,TMB1A,Asserted,Deasserted,N

SER4 = CCOUT01,CCOUT01,Asserted,Deasserted,N

This information provides the exact time that the relay

asserted each output and the latch.

The contact output and the serial peer-to-peer message

output consistently assert at the same time and within the

same millisecond as the initiating latch along with the

IEC 61850 communications card output. This timing was

consistent each time the communication was tested. In the

receiving relay, elements representing the hardwired contact

input, serial peer-to-peer received message, and IEC 61850

communications card input were programmed into the SER

equation to record the relative time of receipt of the various

signals.

SER1 = IN101,IN101,Asserted,Deasserted,N

SER2 = CCIN001,CCIN001,Asserted,Deasserted,N

SER3 = RMB1A,RMB1A,Asserted,Deasserted,N

To test the speed of the serial peer-to-peer communi-

cations, the speed was set to its maximum of 38400 bps. The

results are shown in Table I.

† CCOUT01 is used because the relay will respond faster than if not using

a CCOUT equation. If the CCOUT equation is not used, the relay polls every

500 milliseconds instead of sending the message as soon as the latch changes

state. This could cause a delay of up to 800 milliseconds in the communica-

tions.

When sending a latched state of 1 with IEC 61850 GOOSE communi-

cation using a CCOUT in the dataset, the relay sends a pulse that asserts and

then deasserts the receiving relay, unlike the serial peer-to-peer and hardwired

schemes where the receiving relay gets asserted and stays asserted. However,

if the CCIN equation is used without the CCOUT, the receiving relay gets

asserted and stays asserted, just like the serial peer-to-peer and the hardwired

schemes.

TABLE I

COMPARISON AT 38400 BPS

38400 Time Difference

Start

LATCH10

Time

RMB1A

Received

Time

IN101

Received

Time

CCIN001

Received

Time

RMB1A IN101 CCIN001

25.637 25.641 25.645 25.641 0.004 0.008 0.004

54.291 54.295 54.3 54.295 0.004 0.009 0.004

47.291 47.295 47.3 47.295 0.004 0.009 0.004

4.393 4.395 4.402 4.395 0.002 0.009 0.005

38.545 38.552 38.554 38.550 0.007 0.009 0.005

23.72 23.725 23.729 23.724 0.005 0.009 0.005

54.795 54.8 54.804 54.799 0.005 0.009 0.005

22.497 22.5 22.501 22.504 0.003 0.009 0.005

54.297 54.3 54.306 54.3 0.003 0.009 0.005

29.074 29.081 29.078 29.081 0.007 0.009 0.005

8.775 8.779 8.783 8.779 0.004 0.008 0.004

43.2 43.204 43.208 43.204 0.004 0.008 0.004

11.827 11.831 11.835 11.831 0.004 0.008 0.004

39.227 39.231 39.235 39.231 0.004 0.008 0.004

10.152 10.156 10.16 10.157 0.004 0.008 0.004

39.729 39.733 39.737 39.733 0.004 0.008 0.004

10.004 10.008 10.012 10.01 0.004 0.008 0.004

38.254 38.258 38.262 38.26 0.004 0.008 0.004

12.306 12.308 12.315 12.312 0.002 0.009 0.004

2.931 2.933 2.94 2.937 0.002 0.009 0.004

Average (Seconds) 0.00400 0.00855 0.00435

At a data transfer rate of 38400 bps, serial peer-to-peer

communication and GOOSE IEC 61850 protocol have about

the same transmission time. Surprisingly, hardwired I/O is the

slowest of the three connections.

The serial peer-to-peer connection was also tested using a

channel speed of 19200 bps. With this change, the serial peer-

to-peer channel speed is 2 milliseconds slower than the

GOOSE messaging speed, as shown in Table II. The speed of

serial peer-to-peer communication is dependent on the data

transfer rate, where as IEC 61850 is not. This is another

advantage of using Ethernet-based communications.

TABLE II

COMPARISON AT 19200 BPS

19200 Time Difference

Start

LATCH10

Time

RMB1A

Received

Time

IN101

Received

Time

CCIN002

Received

Time

RMB1A IN101 CCIN001

35.905 35.911 35.913 35.909 0.006 0.008 0.004

11.432 11.438 11.44 11.436 0.006 0.008 0.004

45.732 45.738 45.74 45.736 0.006 0.008 0.004

14.457 14.461 14.465 14.461 0.004 0.008 0.004

50.459 50.465 50.467 50.463 0.006 0.008 0.004

21.259 21.265 21.267 21.263 0.006 0.008 0.004

49.134 49.142 49.142 49.138 0.008 0.008 0.004

10.686 10.69 10.695 10.690 0.004 0.009 0.004

40.613 40.62 40.622 40.618 0.007 0.009 0.005

10.013 10.02 10.022 10.018 0.007 0.009 0.005

Average (Seconds) 0.006 0.0083 0.0042

These tests show that both serial peer-to-peer and

IEC 61850 communications were faster than the hardwired

connection. However, when figuring in reliability, hardwire

I/O is still a good method of communication. If the Ethernet

switch failed, then all protection would be lost in the

IEC 61850 applications, proving that equipment reliability is

crucial for any communication standard.

IEC 61850 does present some advantages when compared

to the serial peer-to-peer protocol. First, the serial peer-to-peer

protocol allows only eight bits to be transmitted in each

direction and GOOSE messages can transmit up to

140 Boolean data elements. However, most interlocking and

protection schemes require the exchange of fewer than eight

bits from each IED. Second, though both can be deployed

directly between two peers using a single cable, it is more

useful to multicast the message to several peers with a

communications switch. For each message type, a

communications switch must be added with each IED

connected to it via a direct link to multicast messages to all

IEDs on the network. The serial switch for the peer-to-peer

serial message adds latency to the message transfer on the

order of 15 milliseconds at 19200 bps. Ethernet switches used

for GOOSE message multicast add a very small latency, less

than 0.2 milliseconds.

Fig. 15 shows the connections of a second test setup with

the serial message communications switch connecting all the

IEDs on the network.

Table III shows the test results with the serial message

communications switch integrated into the communications

scheme. As with the use of an Ethernet switch, the reliability

decreases when adding another device to the system; however,

the serial message communications switch is designed for the

mission critical purpose of multicasting protection data and

has a typical MTBF of about 300 years, contrasted with

Ethernet switches that at best have an MTBF of 23 years.

Further, the peer-to-peer protocol has features to check that

the channels are operational, verify their dependability, and

calculate channel availability. If any channel were to fail,

settings in the relay would activate an alarm. IEC 61850 has

no checking features or bits to set if the channel loses

communication.

When compared with direct relay-to-relay communication,

multicasting through the serial message communications

switch increases the delay; however, this delay is close to one

electrical cycle, which is fast enough for many protection

schemes.

Relay

Logic Processor

PORT 2

PORT 1 PORT 2

OUT02

OUT01

ALARM

IRIG-B

PORT 5

IN101PORT 2 PORT 5

Antenna 75'

Serial Message Switch

PORT 1 PORT 2

ALARM

IRIG-B

OUT101

Legend

Coax

Copper

Ethernet

Satellite

Clock

Fig. 15. Second Test Setup with Serial Message Switch

TABLE III

COMPARISON AT 19200 BPS WITH LOGIC PROCESSOR

19200 Time Difference

LATCH10 RMB1A RMB1A

22.872 22.887 0.015

12.699 12.714 0.015

39.576 39.591 0.015

1.326 1.343 0.017

29.151 29.168 0.017

49.001 49.016 0.015

6.353 6.368 0.015

25.878 25.893 0.015

41.553 41.566 0.013

19.228 19.241 0.013

Average (Seconds) 0.015

B. HMI Controls

Many substations have HMIs that allow the user to look at

a computer screen and have control over the entire substation

with the click of a button. HMIs usually have advanced

graphics with many status indicators and pushbuttons. The

user can have more control, safer operation, and faster

recovery times after outages. The cost of the HMI is justified

by facilitating work and analysis on the substation system.

Fig. 16 shows a setup of an HMI SCADA system with a

Wonderware application to test controls of the relays using

two different communications methods. One method

implements IEC 61850 and the other method applies serial

communication through a communications processor.

HMI

Ethernet Comm 1

Satellite

Clock

Relay

Communications Processor

PORT 2

PORT 1 PORT 2

OUT02

OUT01

ALARM

IRIG-B

PORT 5

PORT 2 PORT 5

Antenna 75'

Switch

PORT 1 PORT 2

ALARM

IRIG-B

Legend

Coax

Copper

Ethernet

Serial

PORT 14

PORT 3

Fig. 16. Third Test Setup

The basic setup of the two relays consisted of two different

internal IED logic bits referred to as remote bits—RB01 and

RB02. RB01 was sent through the Ethernet with IEC 61850.

RB02 was sent through a serial connection with a

communications processor as an intermediary between the

HMI and as many as 16 relays. Since the times were so

drastically different, the team could easily identify which was

quicker by observing the LEDs on the relay. The test results

were surprising again, as shown in Table IV.

TABLE IV

CONTROLS FROM PC TO RELAY VIA IEC 61850 VS. SERIAL

Serial (RB02) IEC 61850 (RB01) Difference

21.853 24.538 2.685

12.755 15.517 2.762

1.748 4.506 2.758

5.962 8.494 2.532

38.554 40.473 1.919

17.575 20.433 2.858

50.893 52.483 1.59

22.777 25.389 2.612

50.795 52.568 1.773

29.449 31.372 1.923

37.342 39.34 1.998

0.715 3.332 2.617

36.088 38.311 2.223

58.978 61.309 2.331

30.59 33.242 2.652

51.088 53.173 2.085

23.519 26.221 2.702

45.596 48.211 2.615

6.446 9.177 2.731

29.265 31.152 1.887

Average (Seconds) 2.36265

On average, IEC 61850 was almost 2.5 seconds slower

than communication through a serial connection with a

communications processor, as configured in Fig. 16. The

IEC 61850 speed is highly dependent on the script that is

written to send the controls to the AX-S4 MMS server. The

script was written with high consideration toward speed.

However, IEC 61850 significantly lagged the serial

communication due to the much larger message size and

therefore processing overhead.

VI. RELIABILITY

Reliability is always a major concern when adding

anything new to a power system. In these tests, IEC 61850

never missed a protection bit that was sent across the network.

This is not to say there is not one single point of failure. The

switch is a single point of failure, and IEC 61850 GOOSE

does not have an acknowledgement mechanism to confirm to

the publishing IED that the message was received. Instead, the

sending relay will send its bit via multicast messages that are

sent very rapidly at first, and then gradually slowing to a

rhythmic heartbeat update time. The frequent publication right

after the bit changes increases the likelihood that the

information will get through the network to each intended

user. In low-voltage distribution substations, it may be

feasible to only use a single, individual IEC 61850 system.

However, in high-voltage transmission systems, the non-

deterministic nature of IEC 61850 protocols suggest it may

still be prudent to use two parallel forms of protection

communications.

VII. CONCLUSION

The ability to draw a comprehensive conclusion on a new

standard of communications protocol is difficult after only one

project. However, IEC 61850 can be compared to serial

communications within a substation as follows:

• Few software applications that support the protocols

exist, and those that do are less mature than their serial

counterparts.

• Fewer integration software tools exist.

• The nature of multiple protocols in one standard and

the use of Ethernet offer more versatility.

The controls from the HMI were a major roadblock in the

completion of the project. Initially, the design group decided

to use OPC as a medium to transmit and receive data.

Receiving data was quite easy; however, trying to implement

controls through a protocol converter proved to be difficult at

best, and in the end unattainable for this team. This issue was

overcome by the following:

• Communicating with DDE directly to AX-S4 MMS.

• Creating an HMI with Excel software.

• Learning Visual Basic script.

• Eliminating Wonderware limitations with Visual

Basic programming.

Although the bulk of the code could be copied into each

HMI script, the code used to transmit data packets over

Ethernet was unique for each relay and each type of control

issued.

The performance of IEC 61850 was not an issue. The

ability for companies to implement systems communicating

IEC 61850 protocols with less engineering effort than

previous methods will be most crucial to its success. Apply

the following to decrease implementation time:

• Software to automate integration.

• Tools to read configuration files and format data to

use the IEC 61850 nomenclature and constructs.

• Clients and servers, such as AX-S4 MMS, tightly

integrated into HMIs and other software applications.

Controlling a system through an HMI with IEC 61850 can

be as easy as integrating a new relay into the system.

However, a simple and cost-effective option is to forgo the

HMI, implement controls through the relay pushbuttons, and

use only the IEC 61850 GOOSE protocol for peer-to-peer

communication. In addition, the speed of GOOSE messaging

proved to be as quick and reliable as any protocol available

today. The ability to utilize TCP/IP protocol is the next logical

step for future integration projects, providing quick and easy

updates through remote terminal units for engineers to receive

updates over any LAN.

VIII. APPENDIX

The script provided here retrieves the status and sends

control to the relays using IEC 61850 through DDE communi-

cation.

‘This script is created to assert RB10 to ‘1’ and then

deassert RB10 to ‘0’ using Excel.

Sub SendOutput1() ‘starting the function

channel_5 = DDEInitiate(“AXS4MMS”, “Relay_1”)

‘setting a channel (any name) to initiate a DDE

communication from Excel to AXS4MMS Relay_1

Application.Worksheets(“Sheet1”).Activate

‘Activating Sheet1 of the Excel application

result = DDERequest(channel_5, “Read AR=Relay_1

Name=RBGGIO1 Domain=Relay_1CON

DTDL={(ctlVal)Bool,(origin){(orCat)Byte,(orIdent)OVst

ring64},(ctlNum)Ubyte,(T)Utctime,(Test)Bool,(Check)B

Vstring2} ADL=CO[SPCSO10[Oper]] Rate=2”)

‘Setting an array called ‘result’(any name) to the

requested data from AXS4MMS through the established

communications channel using “Read + the DDE item

string corresponding to the desired Oper”

Range(“A20:A26”) = result

‘Setting ‘result’ which contains the values of (ctlVal,

orCat, orIdent, ctlNum, T, Test, Check) to Cells in Excel

(for example from A20 to A26)

[A20] = 1 ‘Setting the value of cell A20 to 1

corresponding to ctlVal

[A25] = 0 ‘Setting the value of cell A25 to 0

corresponding to Test because it needs to be a (1 or 0)

instead of (True or False)

DDEPoke channel_5, “Write AR=Relay_1

Name=RBGGIO1 Domain=Relay_1CON

DTDL={(ctlVal)Bool,(origin){(orCat)Byte,(orIdent)OVst

ring64},(ctlNum)Ubyte,(T)Utctime,(Test)Bool,(Check)B

Vstring2} ADL=CO[SPCSO10[Oper]] Rate=2”,

Range(“A20:A26”)

‘Sending a poke command (write) to AXS4MMS

through the set channel, using “Write + the DDE item

string corresponding to the desired Oper”. The values sent

are the ones stored in the corresponding Excel cells A20

to A26. Basically setting RB10 to ‘1’

[A20] = 0 ‘Resetting the value of cell A20 to 0

corresponding to ctlVal (this step is optional, it is just to

reset RB10 to ‘0’)

DDEPoke channel_5, “Write AR=Relay_1

Name=RBGGIO1 Domain=Relay_1CON

DTDL={(ctlVal)Bool,(origin){(orCat)Byte,(orIdent)OVst

ring64},(ctlNum)Ubyte,(T)Utctime,(Test)Bool,(Check)B

Vstring2} ADL=CO[SPCSO10[Oper]] Rate=2”,

Range(“A20:A26”)

‘Sending a poke command (write) to AXS4MMS

through the set channel, using the same DDE item string

to reset RB10 to ‘0’

DDETerminate channel_5 ‘Terminating the

communications channel.

End Sub

‘This script is created to assert RB11 to ‘1’ and then

deassert RB11 to ‘0’ using Excel

Sub SendOutput0()

channel_6 = DDEInitiate(“AXS4MMS”, “Relay_1”)

Application.Worksheets(“Sheet1”).Activate

result = DDERequest(channel_6, “Read AR=Relay_1

Name=RBGGIO1 Domain=Relay_1CON

DTDL={(ctlVal)Bool,(origin){(orCat)Byte,(orIdent)OVst

ring64},(ctlNum)Ubyte,(T)Utctime,(Test)Bool,(Check)B

Vstring2} ADL=CO[SPCSO11[Oper]] Rate=2”)

Range(“A27:A33”) = result

[A27] = 1

[A32] = 0

DDEPoke channel_6, “Write AR=Relay_1

Name=RBGGIO1 Domain=Relay_1CON

DTDL={(ctlVal)Bool,(origin){(orCat)Byte,(orIdent)O

Vstring64},(ctlNum)Ubyte,(T)Utctime,(Test)Bool,(Check

)BVstring2} ADL=CO[SPCSO11[Oper]] Rate=2”,

Range(“A27:A33”)

[A27] = 0

DDEPoke channel_6, “Write AR=Relay_1

Name=RBGGIO1 Domain=Relay_1CON

DTDL={(ctlVal)Bool,(origin){(orCat)Byte,(orIdent)OVst

ring64},(ctlNum)Ubyte,(T)Utctime,(Test)Bool,(Check)B

Vstring2} ADL=CO[SPCSO11[Oper]] Rate=2”,

Range(“A27:A33”)

DDETerminate channel_6

End Sub

‘This script is created to bring the value of frequency

from AXS4MMS using Excel

Sub GetFrequency() ‘starting the function

channel_3 = DDEInitiate(“AXS4MMS”, “Relay_1”)

‘Setting a channel (any name) to initiate a DDE

communication from Excel to AXS4MMS Relay_1

Application.Worksheets(“Sheet1”).Activate

‘Activating Sheet1 of the Excel application

fq = DDERequest(channel_3, “Read AR=Relay_1

Name=METMMXU1 Domain=Relay_1MET

DTDL=Float ADL=MX[Hz[instMag[f]]] Rate=2”)

‘Setting a variable called ‘fq’(any name) to the

requested data from AXS4MMS through the established

communications channel using “Read + the DDE item

string corresponding to the desired Oper”

Sheet1.Cells(14, 1) = fq

‘Setting ‘fq’ which contains the value of the frequency

to Cell in Excel (for example A14)

DDETerminate channel_3 ‘Terminating the

communications channel

End Sub’

IX. BIOGRAPHIES

Youssef Botza earned his BS in Electrical Engineering from the University of

North Carolina at Charlotte with honors, where he served as a treasurer for the

IEEE UNC Charlotte Chapter in 2006. Youssef joined Schweitzer

Engineering Laboratories, Inc. as an intern in 2006. In 2007, he was promoted

to an associate protection engineer in the systems and services division. His

responsibilities include design, development, testing, and commissioning of

substation control house systems.

Matthew Shaw holds an AS degree from Catawba Valley Community

College. Currently he attends the University of North Carolina Charlotte,

working toward a BS degree in electrical engineering. Matthew is an active

member of Tau Beta Pi Engineering Honor Society and serves as vice

president of the IEEE Student Chapter. Presently Matthew is working at

Schweitzer Engineering Laboratories, Inc. as an engineering intern, gaining

valuable knowledge in power systems and substation integration.

Peter Allen earned his BS in Electrical Engineering from the University of

North Carolina at Charlotte. In 2006, he was employed by Central Piedmont

Community College as an instructor in their Engineering Technology

department. In 2007, he joined Schweitzer Engineering Laboratories, Inc. as

an intern and was later hired as an associate automation engineer. Peter has

been a member of IEEE since 2005.

William Michael Staunton expects to complete his BS in Electrical

Engineering degree at the University of North Carolina Charlotte in the

summer of 2008. Since 2006, Michael has been an active member of the

North Carolina Society of Engineers. In 2007, he worked as an electrical

design intern at Automation Tooling Systems Carolina, Inc. Currently,

Michael is an intern at Schweitzer Engineering Laboratories, Inc. in the

Charlotte office, working with protection engineers to design and complete

substation protection solutions.

Dr. Robert Cox received his BS, MEng, and PhD degrees from Massachu-

setts Institute of Technology in 2001, 2002, and 2006. He is currently an

assistant professor of electrical and computer engineering at UNC Charlotte.

His research is focused on the design, analysis, and maintenance of electrical

actuators, power-electronic drives, analog instrumentation, and sensors.

Michael Boughman earned his BS in Electrical Engineering from the

University of North Carolina at Charlotte. In 1987, he was employed by Duke

Energy Company, where he worked as a technical specialist. At Duke Energy,

his responsibilities included substation integration/automation design and

implementation. In 1999, he joined Schweitzer Engineering Laboratories, Inc.

(SEL) as an integration application engineer. His responsibilities include

technical support, application assistance, and training for SEL customers.

Casey Roberts earned his BS in Electrical Engineering from the University

of North Carolina at Charlotte. In 2004, he was employed by Duke Power as

an intern in the Fossil/Hydro Generation division. At Duke, his

responsibilities included development of controls and HMI for the overall

plant distributed control system. In 2006, he joined Schweitzer Engineering

Laboratories, Inc. as an automation intern. As of 2007, he was promoted to an

associate automation engineer. His responsibilities include design,

development, testing, and commissioning of SCADA and HMI systems.

Casey has been a member of IEEE since 2007.

William Rominger earned his BS in Electrical Engineering from the North

Carolina State University. In 2003 he was employed by ABB as an intern in

the Protection and Control department. At ABB his responsibilities included

ac and dc schematic design and implementation. In 2006, he joined

Schweitzer Engineering Laboratories, Inc. as an associate protection engineer.

His responsibilities include design, settings calculations and implementation,

testing, commissioning, and customer training. William has been an IEEE

member since 2006.

Schweitzer Engineering Laboratories, Inc.

20080417 • TP6309-01

6309_ConfigurationPerformance_YB_20080417 Black Box Laser Pointer LES421A Configuration And Performance Of IEC 61850 For First Time Users

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