November 2010, Volume 4, No.11 (Serial No.36)
Journal of Energy and Power Engineering, ISSN 1934-8975, USA
A Study on the Testing Procedures of IEC 61850 Based
Transformer Protective IED
N.H. Lee, B.T. Jang, Y.H. Kim, Y.H. An, J.Y. Han and E.B. Shim
Transmission & Distribution Lab of KEPCO Research Institute, 65 Munji-Ro, Yuseong-Gu, Daejeon, Rebublic of Korea
Received: May 03, 2010 / Accepted: August 05, 2010 / Published: November 30, 2010.
Abstract: Korea Electric Power Corporation in charge of the power IT project “Development of Prototype for Advanced Substation
Automation System based on the Digital Control Technology”, is performing the verification of performance of the substation
automation system based on IEC 61850. In order to verify a transformer protective IED that might be operating in substation
automation system, the new standardized document and procedures are required in the aspect of the utility like KEPCO. But there is
nothing to describe systematically how to verify IEC 61850 based IED in the system environment except an individual IED testing way.
This paper will present the substation automation system based ways and procedures to verify the protective function of the IED using
UML (Unified Modeling Language).
Key words: IED, conformance testing, IEC61850, substation automation, testing procedure.
1. Introduction
A protective relay, one of the main facilities
consisting of the substation, is now called
IED(Intelligent Electronic Device) owing to its own
communication function using the digital network and
IEC 61850 international standard. Korea Electric
Power Corporation in charge of the power IT project
“Development of Prototype for Advanced Substation
Automation System based on the Digital Control
Technology”, is performing the verification of
performance of the substation automation system based
on IEC 61850 [1-5]. A big difference of IEC 61850
based IEDs, comparing with other protective relays, is
to be able to send and receive information among
devices within the substation throughout the
communication network [6-8]. This means to need
more an advanced testing method than a conventional
way with hard-wired contacts. IEC 61850 part-10 has
Corresponding author: B.T. Jang, senior researcher,
research fields: power system protection, substation automation
system and IEC 61850 conformance test. E-mail:
tbjang@kepco.co.kr.
described the conformance test of IED communication
services but does not deal with the performance
verification of the system based IED. CIGRE B5.32 is
discussing a new testing method for IEC 61850 based
substation automation system applying to the UML
S/W design and analysis tool [2]. This study is for
establishment the testing procedures of an IEC 61850
based transformer protective IED and the paper
describes an example that applies the IED test to UML
based procedures.
2. Tr IED Testing Procedures
In order to verify a transformer protective IED
operating in the substation automation system, the new
standardized document and procedures are required in
the aspect of the utility like KEPCO. So this study has
completed to implement some diagrams for system
based functional test, which changed from UML using
as the S/W design and analysis tool. First of all, Use
cases are chosen with some actors to test this IED as the
preparation step. This study decided most of the use
cases with protection and communication function of
A Study on theTesting Procedures of IEC 61850 Based Transformer Protective IED
IED. After making a use case diagram describing the
relation among selected use cases, actors and process
facilities, functional implementation statement and use
case description for each use case will be implemented
to make other diagrams.
UML diagrams that this study suggested for the TR
IED testing procedures consist of a communication
diagram for communication relation between logical
nodes of the TR IED and substation process facilities, a
sequence diagram for communication flow and order
of logical nodes with PICOM (Piece of Information for
COMmunication) and a deployment diagram for
physical connection and program setting between the
testing tool and logical nodes. Finally, when
completing all of the diagrams for the TR IED test, IED
testing description of computer programming language
type will be implemented as shown in Fig. 1. This
paper describes the test procedures of main protective
function (current differential protection, 87) of the TR
IED as an example.
2.1 Use Case Diagram
In order to implement the testing procedures of the
transformer protective IED based on UML, first, Use
cases on its own protective functions should be
selected and then the use case diagram to describe the
relation between actors and process facilities of the
substation will be implemented. The number of use
cases of the transformer protective IED is eight cases
included the main protective function, which was
mentioned by the paper. The process facilities of the
substation are a transformer considered as a protection
object of the IED and primary/secondary circuit
breakers. And the actor in the use case diagram is only
a system operator.
2.2 IED Functional
Specification
Specification
and
UC
Table 1 shows IED functional specification to summarize IED testing related function, which is utilized as
a basic material of UML based testing procedures. This
59
Fig. 1 Flowing flow chart of the testing procedures based
on UML.
specification has a LN (logical node) list. In case of the
main protective function of the transformer protective
IED, there are TCTR for a current transformer, PTDF,
PIOC and PTRC for the protective function of the IED,
CALH for alarm, IHMI and XCBR for CB and IED
operation status. And the specification describes
individually post condition either of success or failure
to be able to use the evaluation criteria of the testing
procedure.
Table 2 shows Use Case specification with a basic
course and an alternative course. The basic course
describes normal operation of the transformer
protective IED. And another describes operation
sequence of the IED with its own LNs in case of the
fault occurrence.
2.3 Communication and Sequence Diagram
The communication diagram shown in Fig. 2
describes communicative message movement among
logical nodes of the transformer protective IED with
relation of process facilities according to the use case
specification instructed above. TCTR1 and TCTR2
connected to current transformers for transformer
protection make digital sampled value from raw
current data and transmit the value to PTDF and PIOC
as protective functions of the IED. After detecting
a fault in the transformer, PTDF and PIOC send a trip
A Study on theTesting Procedures of IEC 61850 Based Transformer Protective IED
60
Table 1
IED functional specification.
Code
Name
Description
Customer
Substation
primary user
secondary user
F1
Main protective function
Open all of the CBs by detecting any phase to phase or phase to earth fault occurred inner the transformer
Developer
23 kV/154 kV substation
154 kV/23 kV transformer
Trigger
Component/LN
Process equipments
Performance
Preconditions
Post condition on success
Post condition on failure
Table 2
Execute the main protective function triggered by any phase to phase or phase to earth fault occurred
inner the transformer
TCTR, PTDF, PIOC, PTRC, CALH, IHMI, XCBR
Transformer, primary/secondary CB
Operation within 40 ms at two times of the setting value
The transformer is operating with rated current
CB is opened and the transformer does not provide power to the load
Over current continues to flow through the transformer
Use case specification.
Basic course
Alternative
course
sequence
LN
description
1
TCTR1/TCTR2
Transmit Sampled current to PTDF/PIOC
2
PTDF/PIOC
No Fault detection
3
PTRC
No CB trip command
4
XCBR
No CB open signal
1
TCTR1/TCTR2
2
PIOC
3
PTDF
4
PTRC
5
XCBR1/XCBR2
6
IHMI
Transmit Sampled current to PTDF/PIOC
After detecting a fault, transmit CB trip command to PTRC, inform the fault and trip
operation(PIOC) to IHMI, and transmit fault alarm to CALH
Detect differential Fault current, transmit CB trip command to PTRC, inform the
fault type(PTDF, A/B/C) to IHMI, and transmit fault alarm to CALH
Transmit CB trip command to XCBR1, XCBR2
Open CBs and change status data of XCBR
Transmit operation alarm to CALH and operation information to IHMI, individually
Display status of CBs
Fig. 2 Communication diagram of the testing procedures
of the Tr IED.
command to PTRC and then PTRC transmits the logical
node trip message to CSWI in charge of control of the
IED. But it may be different according to the
communicative LNs configuration of a real IED. That
means it is possible for PTDF or PIOC to transmit a trip
message to XCBR directly. XCBR1 and XCBR2 have
both of the CBs opened simultaneously when they
receive the trip signal from CSWI or PTRC. While
operating the protective function of the IED, main LNs
such as PTDF and XCBR inform their own status and
operation to CALH and IHMI, which can display fault
type, IED status and alarm information.
UML based sequence diagram could be made by using the communication diagram and use case specification
A Study on theTesting Procedures of IEC 61850 Based Transformer Protective IED
61
Fig. 4 Deployment Diagram of the testing procedures of
the Tr IED.
Fig. 3 Sequence Diagram of the testing procedures of the
Tr IED.
mentioned above. Fig. 3 shows the sequence diagram
of the IED. This diagram describes communicative
sequence with a directional line among logical nodes.
The value (40 ms) on the left of the figure is time from
the start of fault occurrence to the sending time of trip
command and it means the performance time of the
IED.
2.4 Deployment Diagram
The deployment diagram shown in Fig. 4 can be
used for describing the relation between a testing
system and an IED based on the communication
diagram. A process simulator of the diagram can
simulate any facility operation of the IEC 61850 based
substation such as circuit breakers, CT and PT. A
network simulator can analyze various network
packets in the substation automation system including
one IED or more. Finally, an operator simulator is in
charge of the testing system operation, and can verdict
the test result. With this diagram, a test operator can
connect current output (Tctr1_out) of the process
simulator with the physical analogue input (the port
may be related to LNs such as TCTR) of the IED and
set the digital input module to be able to receive the
signal of the CB statue from the IED using hard-wired
cable.
2.5 IED Testing Description
The testing system configuration with a deployment
diagram, it is required testing description to operate the
testing system for the transformer protective IED. This
study referred to the computer programming language
type suggested by CIGRE B5.92 for the testing
description.
The testing description consists of six steps, which
are test connection, test setup, test start, test stop, test
disconnection and test verdict. First step, test
connection shows variable setting of CB status, timer,
operator, system communication for the IED test as the
configuration of the testing system. Test stop describes
initialization of the testing system such as current
output connected with TCTR of the IED. Test start of
the description is a step to measure the start time of the
timer, to make an internal fault of a transformer and to
operate the network simulator. Test stop describes to
record a number of network packets from protective
logical nodes such as PIOC and PTDF. Test
disconnection shows the release of the testing system
and measures the change time of CB status and the
received time of a trip command from the IED. Finally,
test verdict describes that an arbiter should decide the
test result as either success or failure with the
performance condition of The IED function mentioned
in the sequence diagram.
A Study on theTesting Procedures of IEC 61850 Based Transformer Protective IED
62
Table 3
Test setup of the testing description.
Step
contents
Command
1
Set primary current of a transformer to 0 [A]
Tctr1->SetACCurentOutput (0,0)
2
Set secondary current of a transformer to 0 [A]
Tctr2->SetACCurentOutput (0,0)
3
Initialize primary current for the test
Tctr1->StartCurrentOutput ()
4
Initialize secondary current for the test
Tctr2->StartCurrentOutput ()
5
Set the status of primary CB to On
Xcbr1_out->SetDigitalOutput (1)
6
Initialize the test system with setting value of primary CB
Xcbr1_out->StartDigitalOutput ()
7
Set the status of secondary CB to On
Xcbr2_out->SetDigitalOutput (1)
8
Initialize the test system with setting value of secondary CB
Xcbr2_out->StartDigitalOutput ()
9
Save all of the network packets from PIOC for 1 minute
PIOC1->GetMessbageSequence (1 min)
10
Save all of the network packets from PTDF for 1 minute
PTDF1->GetMessbageSequence (1 min)
Table 3 shows test setup of the testing description for
the IED use case.
References
[1]
3. Conclusions
This paper described the testing procedures of IEC
61850 based transformer protective IED. The study is
the first approach to be able to test not stand alone IED
but a system based IED. Now we are developing the
testing procedures for all of the IED applied to the
substation automation system and plan to extend human
machine interface and digital network. In the future, we
expect to implement the testing automation system
based on this kind of the testing procedures.
Acknowledgments
This work was supported by The Verification of
Performance of the Substation Automation System and
Its Field Test of the Korea Institute of Energy
Technology Evaluation and Planning(KETEP) grant
funded by the Korea Government Ministry of
Knowledge Economy.
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verification of performance of the substation automation
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substation- Part7-2: Basic communication structure for
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