A general presentation on IEC 61850 application to substation automation.
Describes Data Semantics, communication services and the substation configuration language
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IEC61850 tutorial
1. IEC 61850 Data & Service
Model and SCL
Alidu Abubakari
Researcher, KEPCO Research Institute (KEPRI)
Power Transmission Lab
2. Introduction
Electric power networks are responsible for the transport of energy from
generation sites to end consumers
The nodes in such networks are called substations and take over the
voltage transformation and also energy routing.
Substations are controlled by the
Substation Automation system (SAS)
which is composed of
all the electronic equipment that
continuously
monitor,
control and
protect
the high voltage equipment so as to avoids
unplanned network outages
3. Intelligent Electronic Device
Microprocessor–based controllers of power
system equipment– e.g. circuit breaker,
protective relay…
Receive digitalized data from sensors and
power
equipment
Issue control commands in case of anomalies
to
4. History of IEC 61850
ModBus
ModBus
IEC 60870-5
DNP 3.0
DNP 3.0
5. History of IEC 61850
UCA: Utility Communication
Architecture
• Protocols
• Data models
• Abstract service
definitions
IEC 60870-5
• A communication profile for sending basic
telecontrol
messages between two systems
• Based on permanent directly connected data
circuits
6. Why Standards Are Needed ?
Interoperability and Integration
– No standard for data representation or how
devices should look and behave to network
applications
Intuitive device and data modeling and naming
naming
– Hierarchical and structured, rather than plain
plain formatted
Fast and convenient communication
Lower cost for installation, configuration and
configuration and maintenance
Interoperability Concept
7. IEC 61850 Substation Architecture
Substation bus is realized as a medium bandwidth Ethernet network, which carries all
ACSI requests/responses and generic substation events messages(GSE, including GOOSE
and GSSE).
Process bus connects the IEDs to the traditional dumb devices (merge units, etc.) and
8. Core Components of IEC 61850
An object model describing the information available from the
different primary equipment and from the substation
automation functions
– Abstract definitions of services, data and Common Data
Class, independent of underlying protocols
A specification of the communication between the IEDs
of the substation automation system.
– Maps the services to actual protocols
A configuration language
– Exchange configuration information
9. IEC 61850 Standards
Part 6-1: Substation
Configuration Language (SCL)
Part 7-2: Abstract
Communications Service Interface
(ACSI) and
base types
Part 7-3: Common Data Classes
(CDC)
Part 7-4: Logical Nodes
Part 8-1: Specific
Communications Service Mappings
(SCSM) -
MMS & Ethernet
Part 9-2: SCSM - Sampled Values
over Ethernet
Basic principles Part 1
Glossary Part 2
General Requirements Part 3
System and project management Part 4
Communication requirements Part 5
Substation Automation System Configuration Part 6
Basic Communication Structure Part 7
Part 9
Sampled Measured Values
Part 8
Conformance testing Part 10
Mapping to Ethernet
Mapping to
MMS and
Ethernet
Primary Parts
10. Benefits of IEC 61850 Power Substation
IEC 61850
Protocol Integration/
Interoperability
Higher performance
messaging
for
inter-relay communications
support system evolution
Standardized naming
conventions
Free architecture
/free allocation of
function
self-describing devices &
automatic object
discovery
11. IEC 61850 Modeling Approach
Obviously, when developing such a
system it is necessary to create a
model of a general substation with all
of its components and functions.
Then it is necessary to stipulate the
exact form of communication that is
allowed and supported by the system.
This describes exactly the challenges
addressed by the IEC61850 standard
This data model consists of a number
of logical nodes, which are the key
objects in the model of the IEC61850
standard.
A logical node can have a number of
data objects attached to it, and each
13. Anatomy of an IEC 61850-8-1 Object Name
• For instance, suppose that you have a logical device named “Relay1”
consisting of a single circuit breaker logical node XCBR for which you want
to determine if the breaker is in the remote or local mode of operation. To
determine this you would read the object shown in Figure below.
14. Data Example of Logical Node
Common Data Class: Double
Points Control
LN : A named grouping of data and associated services that is logically
related to some power system function.
15. Logical Nodes Information Categories
Common logical node information
– Information independent from the dedicated function represented by the LN, e.g., mode, health, name plate,
name plate, ...
Status information
– Information representing either the status of the process or of the function allocated to the LN, e.g., switch
switch type, switch operating capability
Settings
– Information needed for the function of a logical node, e.g., first, second, and third reclose time
Measured values
– Analogue data measured from the process or calculated in the functions like currents, voltages, power, etc.,
power, etc., e.g., total active
– power, total reactive power, frequency
Controls
– Data, which are changed by commands like switchgear state (ON/OFF), resettable counters, e.g., position,
position, block opening
88 pre-defined logical nodes and extensible
16. Common Data Classes (CDC)
• Defines structure for common types that are used to describe
DATA
objects.
• CDC are complex objects built on predefined simple base types
organized into functional constraints (FC)
• Examples:
• Single point status (SPS) – on/off
• Double point status (DPS) – on/off/transient
• Double point controllable (DPC) – state can be changed via controls
17. Functional Constraints
• There are many data attributes in an object like a breaker that have
related use:
Control, configuration, measurement, reporting, etc.
• Functional Constraints (FC) is a property of a data attribute that
characterizes the specific use of the attribute.
• Useful to functionally organize data attributes to provide structure
and context.
19. Logical Node Class Example -XCBR
Attribute
Name
Type Functional
Constraint
Range Mandatory/
Optional
20. IEC 61850 Communication Scope
1. Protection-data exchange
between bay and station level
2. Protection-data exchange
between bay level and remote
protection
3. Data exchange within bay level
4. CT and VT instantaneous data
exchange between process and
bay levels
5. Control-data exchange between
process and bay level
21. IEC 61850 Communication Scope
6. Control-data exchange between bay
and station level
7. Data exchange between substation
and remote engineer’s workplace
8. Direct data exchange between the
bays especially for fast functions like
interlocking
9. Data exchange within station level
10. Control-data exchange between
substation (devices) and a remote
control center
22. ACSI: Abstract Communications Service
Interface
None timing critical message transmitting
Used for configuration, maintenance, log…
Three basic components
A set of objects
A set of services to manipulate and access those objects
A base set of data types for describing objects
23. Basic Information Models
SERVER
Represents the external visible behavior of a (physical)
(physical) device
Communicate with a client
Send information to peer devices
LOGICAL-DEVICE (LD)
Contains the information produced and consumed by a
by a group of domain-specific application functions,
functions, which are defined as LOGICAL-NODEs
LOGICAL-NODE (LN)
Contains the information produced and consumed by a
by a domain specific application function
DATA
Status and meta-information of object it presents in
in substation
Provide means to specify typed information
24. Basic Information Models
DATA-SET
The grouping of data and data attributes
A view of DATA
SETTING-GROUP
How to switch from one set of setting values to
another one
How to edit setting groups
REPORT and LOG
Describe the conditions for generating reports and
logs based on parameters set by the client
Reports may be sent immediately or deferred
Logs can be queried for later retrieval
Generic Substation Event (GSE) control block
(GSSE/GOOSE)
Supports a fast and reliable system-wide
distribution of input and output data values
Sampled Values Transmission control block
Fast and cyclic transfer of samples
25. Basic Information Models
Control
Provide client mechanisms to control the DATA related
related to external devices, control outputs, or other
other internal functions
Substitution
Support replacement of a process value (measurement
(measurement of analogue values or status values) by
by another value
Get/Set
Retrieve or write particular Data Attribute Values
Dir/Definition
Retrieve Object References and definitions of all sub-
sub-objects.
26. Basic Information Models
Association
How the communication between the various
types of devices is achieved
Two-party and Multicast
Access Control
Time Synchronization
Provide the UTC synchronized time to devices
and system
File Transfer
Defines the exchange of large data blocks such as
such as programs
28. Physical Device
ACSI Server
Data
Data
Physical Device
ACSI Client
Application
Data
Physical Device
ACSI Server
Data
Data
Application
Data
reports
req / rsp
Client / Server communication
Physical Device
Application
GOOSE Message
Sampled Values
multicast
Peer to peer communication;
time critical
Applications of "peer-to-peer" communication
tripping of circuit breakers: short
information that needs to be transmitted
with a low probability of loss within a few
milliseconds
transmission of sampled values from
instrumental transformers: high amount of
data, to be transmitted within a few
milliseconds, loss of data needs to be
detected
Communication concepts
29. Principle of TPAA and MCAA
Two-Party-Application-Association (TPAA)
A bi-directional connection-oriented information
information exchange Reliable and end-to-end
end flow control
Multicast-Application-Association (MCAA)
A unidirectional information exchange
Between one source (publisher) and one or many
destinations (subscriber)
The subscriber shall be able to detect loss and duplication
of information received
The receiver shall notify the loss of information to its user
and shall discard duplicated information
30. Service model
• Services provided by ACSI include querying object set,
getting/setting data values, controlling system objects, report
manipulation, log manipulation, and other services like file
upload/download.
• In order to request a service in a server, an application must first
establish a valid two-party application association (TPAA)
31. • A typical interaction procedure between an application A and a
server S goes as follows:
1. A establishes a TCP connection with S;
2. A “logs in” to S by requesting the Associate service from S,
providing authentication related information as parameters;
3. S validates the information provided by A and creates a TPAA
object, which provides a virtual view of S to A;
32. 4. A requests subsequent services while S processes the requests
and responses with appropriate responses defined in the IEC 61850
standard;
5. A issues a Release request to S;
6. S reclaims the TPAA of A and ends the session.
34. GOOSE: Generic Object Oriented Substation
Event
Used for fast transmission of substation events, such as commands,
alarms, indications, as messages
A single GOOSE message sent by an IED can be received several
receivers
Take advantage of Ethernet and supports real-time behavior
Examples:
Tripping of switchgear
Providing position status of interlocking
35. Mapping To Real Communication
Systems
IEC 61850 is just a high level description of substation automation
Use MMS to implement IEC61850
Map each IEC 61850 object to a MMS object
Map each IEC 61850 service to a MMS operation
All but GOOSE messages and transmission of sampled values
are mapped to MMS protocol stack
37. Sampled Measured Values
A method for transmitting sampled
measurements from transducers such as
CTs, VTs, and digital I/O.
Enables sharing of I/O signals among
IEDs
Supports 2 transmission methods:
Multicast service (MSVC) over Ethernet
Unicast (point-to-point) service (USVC)
over serial links
38. SCL: Substation Configuration
Language
Purpose: interoperable exchange of communication system
configuration data between an IED configuration tool and a
configuration tool from different manufacturers.
A formal description of
– Relations between substation automation system and the
switchyard
– Relations of the switchyard structure to the SAS functions (logical
nodes) configured on the IEDs
39. Four different file types
System Specification Description (.ssd)
Allows users to describe the substation design and associated functional
description
Describe the single line diagram of the substation
Substation Configuration Description (.scd)
Configuration of the system
Contains the substation description section, communication configuration
and the IEDs
IEDs in the SCD are no more in their default configuration and they
configured to operate with the SAS.
40. IED Capability Description (.icd)
Default functionality of an IED in substation
Describes the capabilities of an IED
Before configuration, the IED name in this file is TEMPLATE
Contains different logical node Types
Configured IED Description (.cid)
Contains substation specific names, values and address instead of the
the default one in the ICD
41. Information Flow in the Configuration Process
• First Step is to define function
specification via substation one-
line-diagram
• This enters into a system
specification tool which provides
SSD files as output
• System designers selects an
appropriate IEC 61850 compliant
IED
• The ICD file of the IED and the SSD
became input to the system
configurator
• The output of the system
configurator is the SCD file
42. The SCL Section
• Header --> identifies the configuration
• Substation --> identifies connections
electrical function
• Communication --> identifies the
and subnets
• IED --> identifies device functions and
setting
• Data Types Templates --> to
other sections
43. Conclusion
Due to its complexity and the assumed domain-specific knowledge,
the IEC 61850 standard is difficult for people to understand and
implement.
Although the IEC 61850 adopts an object-oriented approach,
implementers still need their own internal data representation or
take the advantage of a database system.