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[email protected]
Testing of IEC 61850 Compliant Smart Grid Devices: A Malaysian
Experience
1M.I. RIDWAN,
1N.S. MISWAN,
1M.N. NORAN,
1M.S.M. SHOKRI,
2H.N. AWANG,
2A. MUSA
1TNB RESEARCH SDN BHD
2TENAGA NASIONAL BERHAD
MALAYSIA
AORC Technical meeting 2014C4-1093
http : //www.cigre.org
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SUMMARY
One of the important aspects to ensure the success of a Smart
Grid implementation is the ability of
the devices and systems in a Smart Grid domain to be able to
seamlessly communicate and exchange
information with each other. This aspect, which is also referred
as interoperability, is crucial for the
execution of functions that are defined in a Smart Grid domain,
regardless whether it is a distributed or
centralized function. To ensure interoperability is implemented
successfully in a Smart Grid domain, it
is imperative for power utilities to acquire know-now on the
relevant open standard based Smart Grid
technologies that can ensure interoperability without fail.
Smart Grid solutions with proprietary
technology may pose significant long term risks to utilities,
such as expensive replacement of devices
and system extension due to over dependency to single vendor ,
low flexibility to define new
requirements and susceptible to technology obsolescence from the
single vendor.
Interoperability in a Smart Grid domain is crucial to ensure the
seamless information exchange
between devices and systems in the domain to execute their
intended functions. Standardization bodies
such as the Institute of Electrical and Electronic Engineers
(IEEE), International Electrotechnical
Committee (IEC) and National Institute of Standards and
Technology (NIST) have published
standards, guideline and roadmaps suggesting on the technologies
that can enable seamless
interoperability between devices and systems in a Smart Grid
domain. For communications related to
power system and electrical substations in Smart Grid domain,
IEC 61850 standard has been
recognized as the open standard that enables interoperability
through its standardized data models and
communication services. These data models and communication
services are mapped to the
mainstream Ethernet technology, which has allowed IEC 61850 to
be future proof regardless of the
advancements of communication technology.
As the public electric utility company in Malaysia, Tenaga
Nasional Berhad (TNB) believes that the
integration of solutions from different vendors using open
standard is the way forward and has the
promising potential to provide substantial cost savings in the
near future. TNB has identified the IEC
61850 standard as the key enabler standard for this purpose and
has included the standard as a part of
the long term technology implementation plan under the TNB
Technology Road Map (TRM). To
ensure the successful implementation of IEC 61850 standard in a
Smart Grid domain, TNB has
embarked in several initiatives, which are also defined in TNB
TRM. The initiatives include the
development of an IEC 61850 laboratory, new product acceptance
process for IEC 61850 compliant
devices and in-house software applications for IEC 61850
substations. These initiatives are vital for
TNB not only to pave the path to realize TRM vision, but also to
obtain in-depth understanding
regarding IEC 61850 and to develop in-house expertise on the
subject. Although IEC 61850 promises
interoperability, it is imperative for users to understand the
detailed methodologies and know-how
specified in IEC 61850 to successfully achieve interoperability
during the implementation stage. This
paper will discuss TNBs experience on the interoperability
testing of IEC 61850 compliant devices
and highlights some of the findings which were observed during
the execution of the initiatives above.
KEYWORDS
IEC 61850, Intelligent Electronic Devices (IEDs),
Interoperability, Smart Grid, Substation Configuration Language
(SCL), Substation Information Management System (SIMS),
Substation
Protection, Automation and Control System (SPACS), System
Verification and Simulation (SVS)
Laboratory
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1. Introduction
Interoperability in a Smart Grid domain is crucial to ensure the
seamless information exchange
between devices and systems in the domain to execute their
intended functions. Standardization bodies
such as the Institute of Electrical and Electronic Engineers
(IEEE), International Electrotechnical
Committee (IEC) and National Institute of Standards and
Technology (NIST) have published
standards, guideline and roadmaps suggesting on the technologies
that can enable seamless
interoperability between devices and systems in a Smart Grid
domain [1,2,3]. For communications
related to power system and electrical substations in Smart Grid
domain, IEC 61850 has been
recognized as the open standard that enables interoperability
through its standardized data models and
communication services [4]. These data models and communication
services are mapped to the
mainstream Ethernet technology, which has allowed IEC 61850 to
be future proof regardless of the
advancements of communication technology [5].
Realizing the benefits that can be exploited from the
implementation of IEC 61850 standard, Tenaga
Nasional Berhad (TNB), a public electric utility company in
Malaysia has recognized IEC 61850 as
the key enabler standard in the long term technology
implementation plan which is called Technology
Road Map (TRM). TRM defines Smart and Intelligent Electricity
Delivery System as TNBs own
definition of Smart Grid. The vision of TRM is to achieve the
Smart and Intelligent Electricity
Delivery System by the year 2020, which smart substation based
on IEC 61850 standard has been
identified as one of the major contributors for TNB to achieve
the vision [6]. The overview of TNB
TRM is illustrated in Fig. 1 below.
Fig. 1. TNB Technology Roadmap Destinations and Enabling
Technology
Under TRM, a cluster of technologies have been identified to
achieve the vision of Smart and
Intelligent Electricity Delivery System by the year 2020. The
vision is to develop smart substations
equipped with integrated Substation Protection, Automation and
Control System (SPACS), which is
TNBs term for SAS. Realizing the capabilities and potential
benefits of IEC 61850, the standard has
been identified as the key enabler standard and foundation for
the technologies. Fig. 2 highlights the
cluster of technologies in TRM.
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Fig. 2. Clusters of Technology under TRM with IEC 61850 Standard
as the Enabler
With IEC 61850, TNB expects to achieve the following goals:
1. Integration of SPACS with IEDs from different vendors, or
multi-vendor solution. This is to reduce the risk of common cause
of failure and failure modes of IEDs from the same vendor
2. Standardized and self descriptive data models which
explicitly defines the functions in power system domain. Such
feature will simplify the engineering and configuration of
SPACS.
3. Seamless exchange of information between multi-vendor devices
using standardized communication services.
4. Vendor independent engineering and maintenance tools to ease
the training and change management process of end users in
maintaining SPACS.
To ensure that the above expectations are met, it is imperative
for TNB to have the facility, tools and
procedure to:
1. Test IEC 61850 compliant devices and systems to ensure the
functions are actually available and within the required
performance criteria
2. Confirm the interoperability of the devices in utilizing IEC
61850 data models and communication services for information
exchange
3. Identify and rectify potential issues before the devices are
implemented in TNB system 4. Understand the specific implementation
of IEC 61850 by vendors due to the open nature of the
standard
Hence, in July 2007, the Engineering Department of TNB
Transmission Division has appointed
TNB Research Sdn Bhd (TNBR), a wholly owned subsidiary of TNB,
to carry out a 3 year R&D
program called Research and Development of Substation Automation
System based on IEC 61850
for Optimal Substation Design in TNB. As part of the research
program deliverables, an in-house
research and testing laboratory which is the System Verification
and Simulation (SVS) Laboratory has
been developed. The laboratory is equipped with IEC 61850
compliant IEDs and system which
simulates the communication of secondary equipment as per actual
substation. The overview of the
SVS Laboratory is shown in Fig. 3.
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Fig. 3. SVS Laboratory in TNB Research Sdn Bhd
The next section will discuss on the overall design,
communication architecture and capabilities of
the SVS Laboratory.
2. TNB IEC 61850 System Verification and Simulation (SVS)
Laboratory
SVS laboratory is designed to replicate a typical configuration
of 132kV Air Insulated Substation
(AIS). The configuration follows a double bus-bar configuration
with two over headline bays, one bus
coupler bay, two HV transformer bays and two MV transformer
bays. Each bay is assigned with 2
protection IEDs with duplicated functions of Main 1 and Main 2
together with 1 control IED. The
IEDs are connected to a dedicated Ethernet Switch for each bay
using star topology through RJ45
cables. The Ethernet Switches between bays are connected using
fiber optic cables that form a ring
topology network. The ring topology provides n-1 redundancy of
the network connection through the
Rapid Spanning Tree Protocol (RSTP). This configuration has
allowed the SVS laboratory to emulate
IEC 61850 station bus communication architecture as in the
actual substations. Fig. 4 illustrates the
physical communication architecture of the laboratory.
Fig. 4. Physical Communication Architecture for SVS
Laboratory
While the physical communication architecture describes the
physical connection between devices,
the information flow of the SVS laboratory is described by the
logical communication architecture.
IEC 61850 services such as Manufacturer Messaging Specification
(MMS) and Generic Object
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Oriented Substation Event (GOOSE) are implemented for
client-server and server-server
communication. Fig. 5 describes the logical communication
architecture in SVS Laboratory.
Fig. 5. Logical Communication Architecture for SVS
Laboratory
As shown in Fig. 5, IEDs in SVS laboratory are engineered and
configured to exchange information
between each other in order to execute various substation
functions. The detailed functions are
described in Table I. TABLE I
SUMMARY OF COMMUNICATION SERVICES AND INFORMATION FLOW IN SVS
LABORATORY IN FIG. 5
Symbol Descriptions
MMS message exchange between IEDs (server) and client
applications
GOOSE (Trip & blocking) message exchange between Protection
IEDs within bay
GOOSE (Interlocking) message between protection IEDs to Control
IED within bay
GOOSE message between one protection IED to another protection
IED within the same bay or adjacent bay
GOOSE (Inter-trip) message between Transformer
HV protection IEDs and Transformer MV protection IED
GOOSE (Interlocking Live Transfer) message between Bus Coupler
Control IED and rest of bay Control IED within same voltage
level
IEC 60870-5-104 message exchange between Switchgear Simulator
Remote Terminal Unit (RTU)
and Human Machine Interface (HMI)
To prove the interoperability using IEC 61850 standard, SVS
laboratory applies the multi-vendor
concept where IEDs from 3 different vendors were installed and
configured to communicate and
exchange information based on IEC 61850 data models and
communication services as per described
in Table I. The IEDs were successfully configured and
interoperability using IEC 61850 has been
achieved in SVS laboratory. The detailed information of the IEDs
and other devices installed in the
SVS laboratory is described in Table II.
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TABLE II
DEVICES IN SVS LAB
Equipment Manufacturer/
Models
Protection IED Protection 1: NR-PCS 931, PCS 9611, PCS 978
Protection 2 : GE Multilin-L90, F35, T60
Control IED NR-PCS 9705
Automatic Voltage regulator IED Maschinenfabrik Reinhausen
(MR)-Tapcon 260
Managed Ethernet Switch RuggedCom-RS 900
Time Server Tekron TCG 02-E
Switchgear Simulator Xenon HMI server
Brodersen-RTU 232 with auxiliary relay contacts
Incontrol Tech-iTec 680 touch-screen based monitor
Secondary Testing Equipment Omicron-CMC 256plus with
CMIRIG-B
The software applications that are used in the SVS laboratory
are divided into two categories, which
are the proprietary or hardware based applications and
independent applications. The list of software
applications is shown in Table III. TABLE III
SOFTWARE APPLICATIONS IN SVS LABORATORY
Proprietary software Independent software
IED configuration tools-PCS PC and Visual SCD for NARI IEDs and
Enervista for GE Multilin IEDs.
Client-Server and peer to peer communication
applications-Omicron IED Scout
Secondary testing application- Test Universe for Omicron
256plus
Third party IEC 61850 System Configuration Tool-HELINKS STS
Network Monitoring and Management-RuggedNMS for RuggedCom
Ethernet switches
Network Protocol Analyzer-MMS Ethereal and Wireshark
HMI design-STRATON HMI Design Tool
As mentioned earlier, one of the main functions of the SVS
laboratory is to serve as the platform to
test and verify IEC 61850 compliant devices before they are
deployed in TNB system. This is
facilitated under TNB product acceptance process where the IEC
61850 features of a device, typically
IED, are meticulously tested and verified against TNB IEC 61850
requirement. The next section
elaborates the implementation of the product acceptance process
and highlights some findings related
to interoperability during the tests.
3. TNB Product Acceptance Process
Starting from September 2013, the SVS laboratory has been
utilized for TNB product acceptance
process for IEC 61850 compliant devices, which mostly are IEDs.
The significance of having an
internal IEC 61850 product acceptance process is although most
IEC 61850 compliant devices have
been tested at independent test laboratories, there is no
guarantee that that the devices can interoperate
when assembled together in a system. This is mainly because the
tests conducted at independent test
laboratories are IEC 61850 conformance tests, which focuses on
the IEC 61850 functionalities of the
devices [7]. Hence, there is a need for TNB to establish a
platform to be able to verify the
interoperability aspect of the devices before they are installed
in actual substations. Using the existing
IEDs, communication network and testing tool in SVS laboratory,
the test setup for the product
acceptance process is shown in Fig. 6.
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Ethernet Switching Local Area Network
TIME SERVER
GPS
CLIENT
DEVICE UNDER TEST(DUT)
NETWORK ANALYSER
GOOSE SIMULATOR
SECONDARY INJECTION TEST
SET
SWITCHGEAR SIMULATOR
IED CONFIGURATION
TOOLS
SCL CHECKER
SCLFILES
CONFIG.FILES
SYSTEM CONFIGURATION
TOOL
IED CONFIGURATION
TOOLSSCD FILE
IRIG-B Time Bus
Control
Statuses
VoltageCurrent
Binary Output
Binary Input
REFERENCE INTELLIGENT ELECTRONIC
DEVICE (RIED)
Fig. 6. Test Setup for TNB Product Acceptance Process
Even with constraints on tools, such as the unavailability of
established IEC 61850 protocol
analyzer and traffic generator, SVS laboratory is still able to
conduct significant amount of test to
verify the IEC 61850 features and capabilities of an IED in
ensuring its compliance to the standard
and TNB requirement. Table IV highlights the test cases which
are tested in the test procedure. TABLE IV
TEST CASES IN TNB IEC 61850 INTEROPERABILITY AND VERIFICATION
TEST PROCEDURE
DOCUMENT AND VERSION CONTROL
1. DUT IEC 61850 Document Verification 2. DUT IEC 61850
Compliance with TNB Requirement
CONFIGURATION FILE
1. .icd File Schema Confirmation 2. .icd File General Content
Verification
DATA MODEL
1. Logical Node (LN) Mandatory Objects Verification 2. Logical
Node (LN) Mandatory Data Objects/Data Attributes Verification
ASSOCIATION MODEL TEST
1. Client Associations Test 2. Lost Connection Detection Test 3.
Startup After Power Interruption Test
SERVER MODEL TEST
1. Quality Bits for Analog Value Test 2. Quality Bits for Status
Value Test
DATASET MODEL TEST
Maximum Number of Dataset Elements Test REPORT MODEL TEST
1. Self Descriptions Of Report Control Block (RCB) 2. RCB
Trigger Options 3. RCB Optional Fields 4. BRCB Association Test 5.
URCB Association 6. Buffering Events 7. Purge Buffered Events 8.
Segmented Report
SELF DESCRIPTIONS OF GOOSE CONTROL BLOCK (GoCB) TEST
CONTROL MODEL TEST
1. Direct Control With Normal Security 2. Select Before Operate
(SBO) - Positive Response Test 3. Select Before Operate (SBO) -
Negative Response Test
IRIG-B TIME SYNCHRONIZATION TEST
SNTP TIME SYNCHRONIZATION TEST
DUT GOOSE COMMUNICATION LATENCY PERFORMANCE AND TEST MODE
FEATURE TEST
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1. Secondary Injection Test (SIT) And Device Under Test (DUT)
Test 2. Reference Intelligent Electronic Device (RIED) And Device
Under Test (DUT) Test 3. Goose in Test Mode Test
CLIENT and DEVICE UNDER TEST (DUT) TEST
FILE TRANSFER TEST
As of January 2014, 12 IED models for 4 different vendors has
been tested and approved to be
deployed in TNB. However, regardless of the IEDs having
certified as IEC 61850 compliant, issues
related to IEC 61850 functional and interoperability are still
observed. Some of the issues are [8]:
1. The performance of GOOSE message for protection tripping was
not as fast as declared. This will impact the performance of
protection function if GOOSE is used for tripping. Fortunately, TNB
only specifies that GOOSE message is to be used for non-time
critical functions such as
interlocking for the time being.
2. IED tested or device under test (DUT) could not interoperate
with some IEDs in SVS laboratory despite of exhaustive engineering
and configuration effort. This has raised the
question of the degree of interoperability of the DUT.
3. Capability declaration of DUT in its IEC 61850 documents did
not match with the actual capability of the DUT, such as inability
of sending buffered reporting after connection failure is
normalized, although the DUTs were from the same vendor but
different model. These are
shown in Fig. 5 and Fig.6. Some DUT also showed missing data
object and data attributes
although they were declared supported in the documents.
Fig. 7. Vendor X Model A-Buffered reports were not sent after
connection failure is normalized
Fig. 8. Vendor X Model B-buffered reports were sent after
connection failure is normalized
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4. Certain DUT configuration tools were not able to parse
Substation Configuration Language
(SCL) file generated using third party engineering tool. This
will restrict the engineering process as users need to fully rely
on vendor proprietary for engineering and configuration of
IEC 61850.
5. Unexplained error message generated by DUT was observed
during the test for control function. The control command was
successful but the latest status was not updated to the IEC
61850
client simulator. This is illustrated in Fig. 9. Vendor has yet
to provide an explanation on this phenomena
Fig. 9. Unexplained No-error error observed in Vendor Y DUT when
performing control function
6. Significant deviation of DUT timestamp was also observed
although the DUT were
synchronized using external IRIG-B time synchronization
protocol. The vendor highlighted that it was due to the event
sorting method implemented in the DUT that has caused the delay
in time stamping
The above observations have shown that the importance of having
an in-house testing facility and
methodology to test IEC 61850 compliant devices before they are
installed in the system. This is to
ensure that the implementation of IEC 61850 will not pose
unnecessary risk to the system, in
particularly SPACS. Although the issues may look trivial, if
they were not discovered and rectified
earlier, there is high probability that they may affect other
critical substation functions that may
jeopardize the reliability and availability of TNB transmission
network when deployed.
Apart from testing works, the SVS laboratory is also utilize as
research and development platform
for TNB to further explore advanced functionalities that can be
achieved from IEC 61850 and Smart
Grid domains. The next section will discuss on TNBs vision to
develop in-house software
applications for the operation and maintenance of IEC 61850
compliant substation and systems.
4. Development of IEC 61850 Substation Intelligent Management
System (SIMS) in-
house software applications
The SIMS initiative is intended to develop in-house software
applications that can be utilized as
operation, maintenance and monitoring tools for IEC 61850 based
substations. Unlike commercial off-
the-shelf tools, in-house developed tools are independent from
any patent or contract restrictions from
vendors. Hence, there will be no cost impact to TNB in fully
utilizing or make any changes to the
tools. Furthermore, these tools are independent from IED vendors
hence associated issues related to
IEC 61850 interoperability can be minimized. The overview of
SIMS platform is shown in Fig. 10 [9].
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Fig. 10. TNB IEC 61850 SIMS platform
The key elements in the SIMS platform are the software
applications which are intended for various
operation, maintenance, monitoring and analytic purposes. In
total there are 16 applications which
were developed under SIMS using National Instruments
LabViewTM
programming software. Some
notable applications are:
1. Communication Network Management (NetView) 2. Fault and
Disturbance Analysis Viewer (FastView) 3. Substation Asset
Monitoring (SAM) 4. GOOSE Message Viewer (GOOSEVIEW)
The snapshots on some of the applications above are shown in
Fig. 11 and Fig. 12.
Fig. 11. SIMS NetView Application
Fig. 12. Publisher-Subscriber Matrix for SIMS GOOSEVIEW
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The main challenge during SIMS development was the design of IEC
61850 Communication Stack
as TNB has decided not to use any commercially available stacks
to avoid any potential restriction in
further developing and implementing the applications in the
future. The IEC 61850 Communication
Stack is the heart of all the 16 applications and the SIMS
initiative is currently still on-going to further
improve and enhance the stack.
Conclusion
The initiatives implemented by TNB has allowed the utility to
have better insight in achieving
interoperability using IEC 61850 which is vital to ensure the
successful Smart Grid implementation. It
is also believed an in-depth understanding regarding the key
enablers of interoperability should be the
main focus for utilities before embarking in any Smart Grid
initiatives. This is to avoid unnecessary
cost implications and technical issues that may hinder the Smart
Grid implementation.
References
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