A general presentation on IEC 61850 application to substation automation.
Describes Data Semantics, communication services and the substation configuration language
1. IEC 61850 Data & Service
Model and SCL
Alidu Abubakari
Researcher, KEPCO Research Institute (KEPRI)
Power Transmission Lab
2. Introduction
īą Electric power networks are responsible for the transport of energy from
generation sites to end consumers
īą The nodes in such networks are called substations and take over the
voltage transformation and also energy routing.
īą Substations are controlled by the
Substation Automation system (SAS)
which is composed of
īą all the electronic equipment that
continuously
īļ monitor,
īļ control and
īļ protect
the high voltage equipment so as to avoids
unplanned network outages
3. Intelligent Electronic Device
īą Microprocessorâbased controllers of power
system equipmentâ e.g. circuit breaker,
protective relayâĻ
īą Receive digitalized data from sensors and
power
equipment
īą 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
âĸ Protocols
âĸ Data models
âĸ Abstract service
definitions
IEC 60870-5
âĸ A communication profile for sending basic
telecontrol
messages between two systems
âĸ Based on permanent directly connected data
circuits
6. Why Standards Are Needed ?
īą Interoperability and Integration
â No standard for data representation or how
devices should look and behave to network
applications
īą Intuitive device and data modeling and naming
naming
â Hierarchical and structured, rather than plain
plain formatted
īą Fast and convenient communication
īą Lower cost for installation, configuration and
configuration and maintenance
Interoperability Concept
7. IEC 61850 Substation Architecture
īą 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).
īą Process bus connects the IEDs to the traditional dumb devices (merge units, etc.) and
8. Core Components of IEC 61850
īą An object model describing the information available from the
different primary equipment and from the substation
automation functions
â Abstract definitions of services, data and Common Data
Class, independent of underlying protocols
īą A specification of the communication between the IEDs
of the substation automation system.
â Maps the services to actual protocols
īą A configuration language
â Exchange configuration information
9. IEC 61850 Standards
īą Part 6-1: Substation
Configuration Language (SCL)
īą Part 7-2: Abstract
Communications Service Interface
(ACSI) and
base types
īą Part 7-3: Common Data Classes
(CDC)
īą Part 7-4: Logical Nodes
īą Part 8-1: Specific
Communications Service Mappings
(SCSM) -
MMS & Ethernet
īą 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
īąObviously, when developing such a
system it is necessary to create a
model of a general substation with all
of its components and functions.
īąThen it is necessary to stipulate the
exact form of communication that is
allowed and supported by the system.
īąThis describes exactly the challenges
addressed by the IEC61850 standard
īąThis data model consists of a number
of logical nodes, which are the key
objects in the model of the IEC61850
standard.
īąA logical node can have a number of
data objects attached to it, and each
13. Anatomy of an IEC 61850-8-1 Object Name
âĸ For instance, suppose that you have a logical device named âRelay1â
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
īąLN : A named grouping of data and associated services that is logically
related to some power system function.
15. Logical Nodes Information Categories
īą Common logical node information
â Information independent from the dedicated function represented by the LN, e.g., mode, health, name plate,
name plate, ...
īą Status information
â Information representing either the status of the process or of the function allocated to the LN, e.g., switch
switch type, switch operating capability
īą Settings
â Information needed for the function of a logical node, e.g., first, second, and third reclose time
īą Measured values
â Analogue data measured from the process or calculated in the functions like currents, voltages, power, etc.,
power, etc., e.g., total active
â power, total reactive power, frequency
īą Controls
â Data, which are changed by commands like switchgear state (ON/OFF), resettable counters, e.g., position,
position, block opening
īą 88 pre-defined logical nodes and extensible
16. Common Data Classes (CDC)
âĸ Defines structure for common types that are used to describe
DATA
objects.
âĸ CDC are complex objects built on predefined simple base types
organized into functional constraints (FC)
âĸ Examples:
âĸ Single point status (SPS) â on/off
âĸ Double point status (DPS) â on/off/transient
âĸ Double point controllable (DPC) â state can be changed via controls
17. Functional Constraints
âĸ There are many data attributes in an object like a breaker that have
related use:
īļControl, configuration, measurement, reporting, etc.
âĸ Functional Constraints (FC) is a property of a data attribute that
characterizes the specific use of the attribute.
âĸ 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 engineerâs 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
īąNone timing critical message transmitting
īąUsed for configuration, maintenance, logâĻ
īąThree basic components
īļA set of objects
īļA set of services to manipulate and access those objects
īļA base set of data types for describing objects
23. Basic Information Models
īą SERVER
īļ Represents the external visible behavior of a (physical)
(physical) device
īļ Communicate with a client
īļ Send information to peer devices
īą LOGICAL-DEVICE (LD)
īļ Contains the information produced and consumed by a
by a group of domain-specific application functions,
functions, which are defined as LOGICAL-NODEs
īą LOGICAL-NODE (LN)
īļ Contains the information produced and consumed by a
by a domain specific application function
īą DATA
īļ Status and meta-information of object it presents in
in substation
īļ Provide means to specify typed information
24. Basic Information Models
īą DATA-SET
īļ The grouping of data and data attributes
īļ A view of DATA
īą SETTING-GROUP
īļ How to switch from one set of setting values to
another one
īļ How to edit setting groups
īą REPORT and LOG
īļ Describe the conditions for generating reports and
logs based on parameters set by the client
īļ Reports may be sent immediately or deferred
īļ Logs can be queried for later retrieval
īą Generic Substation Event (GSE) control block
(GSSE/GOOSE)
īļ Supports a fast and reliable system-wide
distribution of input and output data values
īą Sampled Values Transmission control block
īļ Fast and cyclic transfer of samples
25. Basic Information Models
īą Control
īļ Provide client mechanisms to control the DATA related
related to external devices, control outputs, or other
other internal functions
īą Substitution
īļ Support replacement of a process value (measurement
(measurement of analogue values or status values) by
by another value
īą Get/Set
īļ Retrieve or write particular Data Attribute Values
īą Dir/Definition
īļ Retrieve Object References and definitions of all sub-
sub-objects.
26. Basic Information Models
īą Association
īļ How the communication between the various
types of devices is achieved
īļ Two-party and Multicast
īļ Access Control
īą Time Synchronization
īļ Provide the UTC synchronized time to devices
and system
īą File Transfer
īļ 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
īŽ tripping of circuit breakers: short
information that needs to be transmitted
with a low probability of loss within a few
milliseconds
īŽ 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
īą Two-Party-Application-Association (TPAA)
ī A bi-directional connection-oriented information
information exchange Reliable and end-to-end
end flow control
īą Multicast-Application-Association (MCAA)
ī A unidirectional information exchange
ī Between one source (publisher) and one or many
destinations (subscriber)
ī The subscriber shall be able to detect loss and duplication
of information received
ī The receiver shall notify the loss of information to its user
and shall discard duplicated information
30. Service model
âĸ 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.
âĸ In order to request a service in a server, an application must first
establish a valid two-party application association (TPAA)
31. âĸ 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 âlogs inâ 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
īą Used for fast transmission of substation events, such as commands,
alarms, indications, as messages
īą A single GOOSE message sent by an IED can be received several
receivers
īą Take advantage of Ethernet and supports real-time behavior
īą Examples:
īļTripping of switchgear
īļProviding position status of interlocking
35. Mapping To Real Communication
Systems
īąIEC 61850 is just a high level description of substation automation
īļUse MMS to implement IEC61850
īļMap each IEC 61850 object to a MMS object
īļMap each IEC 61850 service to a MMS operation
īļAll but GOOSE messages and transmission of sampled values
are mapped to MMS protocol stack
37. Sampled Measured Values
īą A method for transmitting sampled
measurements from transducers such as
CTs, VTs, and digital I/O.
īą Enables sharing of I/O signals among
IEDs
īą Supports 2 transmission methods:
īļMulticast service (MSVC) over Ethernet
īļUnicast (point-to-point) service (USVC)
over serial links
38. SCL: Substation Configuration
Language
īą Purpose: interoperable exchange of communication system
configuration data between an IED configuration tool and a
configuration tool from different manufacturers.
īą A formal description of
â Relations between substation automation system and the
switchyard
â Relations of the switchyard structure to the SAS functions (logical
nodes) configured on the IEDs
39. Four different file types
īą System Specification Description (.ssd)
īļAllows users to describe the substation design and associated functional
description
īļDescribe the single line diagram of the substation
īą Substation Configuration Description (.scd)
īļConfiguration of the system
īļContains the substation description section, communication configuration
and the IEDs
īļIEDs in the SCD are no more in their default configuration and they
configured to operate with the SAS.
40. īą IED Capability Description (.icd)
īļDefault functionality of an IED in substation
īļDescribes the capabilities of an IED
īļBefore configuration, the IED name in this file is TEMPLATE
īļContains different logical node Types
īąConfigured IED Description (.cid)
īļContains substation specific names, values and address instead of the
the default one in the ICD
41. Information Flow in the Configuration Process
âĸ First Step is to define function
specification via substation one-
line-diagram
âĸ This enters into a system
specification tool which provides
SSD files as output
âĸ System designers selects an
appropriate IEC 61850 compliant
IED
âĸ The ICD file of the IED and the SSD
became input to the system
configurator
âĸ The output of the system
configurator is the SCD file
42. The SCL Section
âĸ Header --> identifies the configuration
âĸ Substation --> identifies connections
electrical function
âĸ Communication --> identifies the
and subnets
âĸ IED --> identifies device functions and
setting
âĸ Data Types Templates --> to
other sections
43. Conclusion
īą Due to its complexity and the assumed domain-specific knowledge,
the IEC 61850 standard is difficult for people to understand and
implement.
īą 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.