Overview of IEC 61850
July, 2010
Maciej Goraj
maciejgoraj@ruggedcom.com
1
Agenda
1. Evolution of Protection and Control Systems
2. Overview of IEC 61850 Standard
3. Key Benefits of IEC 61850
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Evolution of Protection and
Control Systems
3
Typical Substation Diagram
Sub Sub
Transmission Transmission
Line No. 1 Line No. 2 • Information provided to SCADA via
communication channels -
Automatically:
IED 1
LN 1 IED 3
TB 1
IED 2
LN 2 – Metering
– Alarm Status
IED 13
BUS 1
– Breaker Status
Tie Breaker – Commands to Operate Breakers
– Lockout Status
Power
• Information required by Engineering
IED 4
TX 1
Transformers IED 5
TX 1
or Maintenance – Accessed by
authorized personnel on demand:
– Protection & Control Status
IED 12
TB 2 – Oscillography Files
IED 14
BUS 2
– Sequence of Event Reports
– Access to view or change setpoints
IED 6 IED 7 IED 8 IED 9 IED 10 IED 11
FDR 1 FDR 2 FDR 3 FDR 4 FDR 5 FDR 6
• New Requirements of IEC61850:
– Peer to Peer Messages (GOOSE)
Feeder Breakers
– Digital I/Os
Total: At least 50 multi-core cables from the – Transfer Trips
HV equipment to the Control Building
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Substation Network - Past
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Conventional Wiring in Electrical Substations
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Conventional Substation P&C System
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Conventional Substation Control Panel
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Substation Network - Present
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Present Substation P&C System
Still a lot of copper wiring !
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Substation Network - Future
Station Bus
IEC61850
Process Bus
IEC61850
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The Future – Digital Switchyard
All digital Ethernet based
IEC 61850 Communications
in the Switchyard
Merging Units and IEDs at
direct proximity to
High Voltage equipment
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Modern Substation Automation HMI
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Overview of IEC 61850 Standard
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What is IEC 61850 ?
• IEC 61850 is NOT just a communication protocol
• It is a suite of multiple protocols
• It is an application focused communication architecture
• It is one of the key building blocks for the Smart Grid
IEC 61850 standard defines complete communication
architecture in Electrical Power Systems
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IEC 61850 Key Features
• Uses the strengths of the OSI 7 layer communication model
• Standardized data models for electrical applications
• Defines Data Types and Communication Services
• Models devices, functions, processes and architectures
• Describes Engineering and Configuration Process
• Provides examples of typical applications in electrical substations
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IEC 61850 Key Features
• The data is organized in devices in a standardized way
• The devices are “self-descriptive”,
– either online (MMS protocol) or offline (SCL language)
• IEDs not only provide the data itself but also the information about
data types used, its structure and complete naming.
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Parts of IEC 61850 Standard Edition I
Basic principles Part 1
Glossary Part 2
General Requirements Part 3
System and project management Part 4
Communication requirements Part 5
Substation Configuration Language (SCL) Part 6
Basic Communication Structure Part 7
Sampled Measured Values
Part 9-1
Mapping to (serial)
Part 8 MMS and
Ethernet Sampled Measured Values
Part 9-2
(ethernet)
Conformance testing Part 10
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Data Models and Services
• IEC 61850 Part 7-3 defines a base set of data types for describing objects
• IEC 61850 Part 7-4 defines a set of Objects (Logical Nodes)
• IEC 61850 Part 7-2 defines a set of Services to manipulate and access
those objects. Services are well defined procedures on how information is
exchanged.
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Application Modelling According to IEC 61850
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IEC 61850 is Application Oriented
• DNP3.0, IEC-60870-5, Modbus, etc. are industrial generic use
protocols and are not application oriented
• In generic industrial protocols we talk about “points” or
“addresses” without knowledge what data is behind it
• IEC 61850 is an application oriented architecture, it introduces
meaningful semantics
• IEC 61850 defines application specific data like PTOC
(Protection Time Overcurrent) logical node or XCBR (Circuit
Breaker) logical node, etc.
• Example of semantic: Position of the breaker XCBR1$ST$Pos$stVal
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Data Mapping Examples
Position of breaker at 345kV feeder #1:
– Modbus: register 0x1C1A, bit 3
– DNP 3.0: object 1.1, point #26
– IEC 61850: XCBR1$ST$Pos$stVal
Operate the circuit breaker at 345kV feeder #1:
– Modbus: register 0x251A, bits 0, 1
– DNP 3.0: object 12.1, point #10
– IEC 61850: XCBR1$CO$Pos
Phase A voltage for the 345kV feeder #1:
– Modbus: register 0xB5C7, 4 bytes
– DNP 3.0: object 30.1, point #23
– IEC 61850: MMXU1$MX$PhV$phsA$instCVal
Line frequency for the 345kV feeder #1:
– Modbus: register 0xCC02, 4 bytes
– DNP 3.0: object 30.1, point #27
– IEC 61850: MMXU1$MX$Hz$nstMag
Data inside the IED
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IEC 61850 Data Mapping Models Application
Position of breaker - XCBR1$ST$Pos$stVal
…………
Control of circuit breaker - XCBR1$CO$Pos
…………
Sum of Switched Amperes - XCBR1$MX$SumSwARs
XCBR:
• Logical Node Circuit Breaker
• A group of data describing the Breaker
• Data is grouped based on functionality
Data inside the IED • IEC 61850 models the application
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Logical Node
• Standardizes which elements of specific functions related to power
system should be contained in substation devices
• A Logical Node is an abstract model of a real device or function
• A Logical Node is a collection of data that is grouped taking into
account its functionality
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Communication Services in IEC 61850
• GetDataValues/SetDataValues
• Unbuffered Reports
• Buffered Reports
• Control Operations
• Logging
• Time Synchronization
• File Transfer
• Substitution
• GOOSE
• Sampled Values
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SCL – Substation Configuration Language
• Description language for communication in electrical substations
• Defined in IEC 61850-6
• Based on XML language
• Defines common file format and allows formal description of:
– Substation automation system and the switchyard and the relation between them
– Communications parameters
– IED configuration
• Makes an efficient engineering process of a substation
• Eases the integration process of devices from multiple vendors
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Engineering process using SCL
ICD Files
from
ICD- other SSD-
IEDs vendors
Files File
System Specification Tool
specifies single-line diagram,
make bindings of IEC 61850
Logical Nodes to physical IEDs.
IED Configuration Tools
generate ICD files
System Configuration Tool
configures communication network
parameters, configure GOOSE’s and
Reports.
SCD
File
Station Station Controller Configuration Tool
Controller parses ICD files or SCD IEDs
CID File
IED Configuration Tools import or
SCD file and extract from it info
parame-
relevant to its IED
ter file
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IEC 61850 Architecture
Level 3 – Dispatch Center
Future use of IEC 61850:
• Substation-to-Substation
• Substation-to-Dispatch Center
Corporate WAN
• Synchrophasors over 61850
Router
Level 2 – Substation HMI SCADA Gateway 61850 Station Bus
SAS Client-Server, GOOSE
Level 1 – Bays
IEDs
61850 Process Bus
Level 0 – Switchyard Sampled Values, GOOSE
Intelligent Sensors, I/Os
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Station Bus and Process Bus
• Station bus
– Communication between IEDs and master stations
– Data polled by Master from IEDs or asynchronously sent by IEDs
– Inter IED data exchange through multi-cast GOOSE messages
• Process bus
– Communication between plant equipment (intelligent switchgear,
Instrument transformers) and IEDs
– Exchange of sampled values (digitized measurements)
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Communication Schemes in IEC 61850
• Client-Server communication
– Information exchange like fault record, event record, measurement values, etc.
– Data size much greater, can run into kB or MB
– Uses the full services of the OSI model (MMS over TCP), reliable data transfer
– Not time critical data
• GOOSE messages
– Time critical data eg. trip, block, interlock, etc.
– Initiation of data transfer only on occurrence of the event.
– Compensated by multicasting (repeated transmission)
• Sampled Values
– Time critical data – sampled values of current / voltage signals from non-
conventional instrument transformers or IEDs
– Continuous stream of data, rate determined by the sampling frequency of the data
– Data size depends on the resolution of the sample
– Not reliable data transfer (like Goose messages)
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GOOSE Usage for Interlocking & Tripping
GOOSE messages Conventional Hardwired
IEDs interconnected via interconnections
Ethernet network
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IEC 61850 GOOSE
• Device to multi-device communication
• Layer 2 Multicast message
• Fast transmission of substation events, blocking, permissive signals, etc.
• Also transmission of analog values (voltage, frequency, etc.)
• Limited to LAN segment, for transmitting over router tunneling is needed
• Event driven transmission sent on change of state
• Periodic heartbeat messages to enable detection of device or link failure
• Reliability effected through message retransmission scheme
• Uses VLAN ID and priority tagging
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GOOSE Example – False Bus Differential
VT
Substation without dedicated Busbar protection
Distance
Protection
CT
3. Transformer relay receives the message
HV
that feeder had seen the fault. It is a
“Block” message preventing tripping the
CT whole busbar.
Trafo
Prot
2. Feeder IED sees the fault and
CT immediately sends a GOOSE message
MV
VT
Fdr Fdr
CT CT
Prot Prot
1. A fault occurs
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Process Bus Overview
IEC 61850-9-2
• Digitization of CTs/PTs and connection of Intelligent Switchgear
• Merging Units – electronic interfaces to measured values from switchyard
• Defines communications service mapping of Sampled Values
• SV messages encapsulated in Ethernet and sent via Layer 2 Multicast
• Does not define types of data and number of elements in SV message
• The streams of sampled values generated by Merging Units must be
synchronized in time
• The required time synchronization accuracy is few microseconds as IEDs
are using sampled values for protection
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Process Bus Overview
IEC 61850-9-2 LE (Lite Edition)
• Is an “Implementation Agreement” to facilitate interoperability
• Is maintained by UCA, not by IEC. Is a defacto standard.
• Specifies fixed message format, fixed Data Set with:
– 4xVoltages & 4xCurrents
• Specifies two sampling rates:
– 80 samples/cycle and 256 samples/cycle
• Specifies types of Ethernet connectors and physical layer:
– 100Base-FX with ST, 100Base-FX with MTRJ, 100Base-TX with RJ45
• Specifies 1PPS as synchronization mechanism
• Future revision of IEC 61850-9-2 most probably will add IEEE 1588 time
synchronization and more Ethernet connector types and physical layers
IEEE 1588 time synchronization will replace 1PPS
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Key Benefits of IEC 61850
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Key Benefits of IEC 61850
• Increases flexibility
• by connecting protection, control, measurement and monitoring devices to common
Ethernet network within substation
• Reduces copper wiring
• through GOOSE messaging that enables fast and reliable applications like
interlocking, distributed bay tripping, breaker failure, etc.
• Reduces total installation cost
• by enabling Process Bus with electronic CT/VTs and intelligent switchgear and by
replacing conventional copper wiring by Ethernet digital communications
• Eases system engineering and integration process
• through graphical configuration tools based on SCL language – XML common file
format designed for exchange of configuration information.
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Key Benefits of IEC 61850
• Improves application performance and security
• through fast Ethernet communications and redundancy (IEC 61850 Edition II)
• Provides easy way of implementing typical applications
• due to standardized naming conventions
• Saves time and money in setup & commissioning
• because of object-oriented structure and high-level services that enable self-
description of devices and automatic data discovery.
• Minimizes costs of technological obsolescence
• because of a global acceptance and adoption and future-proof concept of
abstract services as well as independence of mapping to protocols
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Where IEC 61850 is currently used
• Transmission substations
• Distribution substations
• Distribution automation
• Power plants
• Wind farms
• Railway traction substations
• Substations in industrial plants and big
infrastructure:
• Aluminum
• Oil&Gas
• Mines
• Airports
• Other
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Questions?
40
