Unit 08 - IEC 61850

8/12/2019 Unit 08 - IEC 61850

1/16

Unit 08 - Standard IEC 61850 - 1 -

Unit 08 - Standard IEC 61850 for substation automation and otherpower system applications [1]

Automation systems in the area of power systems are widely accepted today. They are mostly

based on many proprietary solutions or (de facto) standards not specifically designed for

substations. To meet todays and future requirements a new standard with an advanced

approach has been requested a few years ago. As a result of international projects the standard

IEC 61850 (Communication networks and systems in substations) has been created.

It is not sufficient to develop systems that only produce, transmit, or distribute electric power.

Fully automated remotely supervised systems that require little or no human intervention

seem to be ideal. Technologies bundled into the power system, therefore, has to include

protection and control equipment, as well as interfaces to supervisory control and data

acquisition (SCADA) of control centers. The standard covers a wide range of substation

applications. At the process level the new standard defines a unidirectional serial communication

interface connecting current (CT) and voltage transducers (VT) with digital output to electrical

metering and protection devices. This allows the exchange of synchronized phasor

measurements using GPS signals for synchronization. Another real-time requirement is met by

the GOOSE (Generic Object Oriented System Event) that defines the transmission of high

priority information like trip commands or interlocking information.

Additional applications that are necessary for a complete system may include:

- metering,

- protection and control,

- remote monitoring and fault diagnosis,

- automated dispatch and control,

- data retrieval,

- site optimization of electrical/thermal outputs,

- asset management, as well as

- condition monitoring and diagnosis.

The standard IEC 61850 will be used for many other application domains outside substations,

too. One is the deployment of wind power now the world's fastest-growing energy source.

8/12/2019 Unit 08 - IEC 61850

2/16


Globally, utility deregulation is expanding and requiring demands to integrate, consolidate and

disseminate real-time information quickly and accurately within all kinds of utility automation

systems from power plants to customer interfaces. Utilities and vendors spend an ever-

increasing amount for real-time information exchange; costs for data integration and

maintenance are exploding. Vendors of power systems have because of the fast growing

market or market deregulation very limited resources to implement and apply hundreds of

proprietary communication systems. In response to this situation, the IEC (International

Electrotechnical Commission) and IEEE have developed and published a suite of (draft)

international communication standards and a technical report.

The future electricity systems will thanks to a seamless realtime communication system be

smart at the top but smarter at the bottom, self-regulated by millions of communicating devices

connected to form feedback loops, and permanently aware of the world around them.

1. The challenge

Imagine if you didn't have common electric outlets and plugs in your house, and every time you

bought a new appliance, choose a new power provider, or installed a new micro-power system

like a fuel-cell, you had to wire up the appliance to the wires in your wall. And everybody's wires

in everybody's walls were different. And everybody's appliance wiring was different. That's really

the way it works today trying to integrate device data into applications and these devices into

power automation systems. Examples for device data are status, diagnostic information,

measurements, metering data, configuration, description, and control information. This situation

forces developers of application software and devices to write new drivers daily implementing

just new gateways!

Imagine your department has to implement the countless number of proprietary solutions! If you

think its not hard to do think again.

Todays power networks in various regions may realistically be considered to be the largest

machines in the world since their transmission lines connect all the electric generation,

distribution, and appliances on a continent or part of it. The electric industry is unique in its

critical real-time coordinated requirements.

8/12/2019 Unit 08 - IEC 61850

3/16


Many utilities are already faced the problem of islands of information based on proprietary

technologies today, each of which literally speaks its own language. The challenge is to integrate

all those existing and new information islands of current and new applications into a functioning

utility automation system (Figure 1). Control center for example need to know the overall

operating conditions (gross load, plant activity, etc.) but the corporate culture is often resistant to

telephone and fax communication, thus, information flow between facilities is limited. Utilities use

the standards as a bridge between power plants, substations, and the control center, and to

communicate within substations. They now have a broader perspective with more information on

overall operating conditions such as change of loads, power production schedules, and other

plant information.

Fig. 1: Islands of information

An answer to the challenge has been found in standards-based communication systems. To

show just how important standards- based communication systems are, consider the example of

a large electric utility. At present, this utility has more than 200 different protocols running on

intelligent devices within its distribution network! A well known vendor is proud of supporting

more than 100 different RTU protocols!

Utilities spend an ever-increasing amount for real-time information exchange; costs for data

integration and maintenance are exploding The costs of integration are not well documented.

Many companies do not keep specific records of the cost of integration. The cost is not limited to

installing new applications, customers explain. Many customers tell they believe that savings in

maintenance alone is the biggest opportunity for saving time and money for an enterprise. To

8/12/2019 Unit 08 - IEC 61850

4/16


reduce the risk of getting even worse in the future, the integration of more and more intelligent

devices into the enterprise applications (SCADA, real-time asset, machine diagnostics, ...) is a

real challenge for programmers and engineers.

One of the most interesting development in the field of realtime monitoring of power systems, is

the possibility of IEC 61850 to support synchronized phasor measurements using GPS satellite

for synchronization. Standard compliant measurement units could provide real-time

measurements of voltages and currents at substation and send these measurements to many

devices in real-time.

To summarize, the driving force behind the standardization is to effectively and efficiently

perform seamless device data integration and sharing information based on a rich, finegrained

data-stream about the state of the power world in any given instant. Every node in the network

would have to be awake, responsive, flexible, and most important interconnected with

everything else: A distributed energy web.

2. Power systems become decentralized

More than 750 million homes around the world do not have access to electricity, and small-scale

power generation could change this situation. Power supplies in the coming decades is therefore

likely to take on a decentralized structure. In developing and newly industrializing countries,

decentralized power supply systems will serve mainly to meet demand in rural areas, out of

existing primary sources, e.g. wind, hydro, solar etc., in an optimised mixture.

In industrialized countries, existing generation centers will be gradually supplemented by

decentralized and communicating units. Intelligent energy management, allowing generation

management, load management, billing management and in teractive communication on the part

of consumers, will be integrated in the network.

Starting with a forecast, generation management monitors optimised use of resources. The task

of load management is control and optimization of the load, including balancing against

generation capacity and costs. Loads that scarcely affect supply security can be connected and

disconnected according to generation process efficiency criteria. This enables an optimum to be

attained in terms of economizing on resources, protecting the environment and keeping costs

down.

8/12/2019 Unit 08 - IEC 61850

5/16


New generation possibilities to be applied will mainly be:

Wind mills: A new generation of wind power technology that significantly reduces the cost of

power generated by large wind farms. The technology also allows wind farms to be built

offshore.

Microturbines: These small, efficient and low-emission gas turbines provide electricity for

homes, commercial buildings, hospitals, and small factories. Their compact size and high

reliability make them suitable for small combined heat and power installations.

Fuel Cell Systems: Similar to batteries, fuel cells generate electricity through a chemical

reaction, and produce very low emissions. They are small enough for residential and small

commercial applications, making them ideal for use in areas without connections to existing

power grids.

Solar systems: Providing power by solar pannels.

Microgrids: A microgrid is created by connecting a local group of small power generators using

advanced sensoring, supervising, and control relaying on open communication systems.

All these systems and micro-systems have to be connected to the power grid and to the

underlying decentralized information grid.

3. Objectives of the IEC TC 57 standardization

IEC and IEEE provide standards to dramatically improve device data integration into the

information and automation technology, reducing engineering, commissioning, operation,

monitoring, diagnostics, and maintenance costs and increasing the agility of the whole life cycle

of utility automation systems. These standards differs from most previous utility protocols in its

use of object models that model most common real devices and device components. These

models define common data formats, identifiers, behavior, and controls, e.g., for substation and

feeder devices such as switches, voltage regulators, and relays.

The standards selected, e.g., Ethernet, TCP/IP, etc., make use of advanced IT solutions, the

reduced bandwidth costs and increased processor capabilities in the end devices to define and

carry metadata: more than 3,000 standardized names and type information which can be (re-

8/12/2019 Unit 08 - IEC 61850

6/16


)used by applications for on-line verification of the integration and configuration of databases

throughout the utility. This self-description significantly reduces the cost of data management,

and reduces system down times due to configuration errors.

Examples for measurement metadata are "unit", "offset", "scale", "dead band for reporting", and

description. This feature significantly reduces the cost of data integration, data management,

and reduces down time due to configuration errors.

The standard information models of real-world devices (e.g. switches, disconnectors,

transformer, measurement unit, ...) can be (re-)used by applications for self-description and

online verification. The standards improve device data integration into the information and

automation technology, reduce engineering, commissioning, operation, monitoring, diagnostics,

and maintenance costs.

The objective of the standard is to provide for seamless information integration across the utility

enterprise using off-the-shelf international standards to reduce costs in several phases of a

system life cycle (Figure 2). These standardized models allow for multivendor interoperability

and ease of integration.

Fig. 2: Seamless information integration based on IEC 61850/UCA

8/12/2019 Unit 08 - IEC 61850

7/16


UCA has been incorporated into the draft standard series IEC 61850 (Communication networks

and systems in substations) published by IEC TC 57 in March 2001. The first parts of IEC 61850

have been published as international standards end of 2001.

The object models are defined in terms of standardized types and services. These services

(such as reporting by exception and select before operate controls) are defined in abstract

terms, then mapped to messages in the underlying application layer protocol. The use of the

standardized service definitions above MMS allow for future-proofing, in that new innovations

in application layer protocols can be incorporated in the future without disturbing the object

model definitions.

The MMS protocol, developed by the manufacturing community, supports real-time control and

data acquisition. MMS defines a message structure supporting access to data, programs,

journals, events, and other constructs common to real-time devices. These messages may be

transported using many different underlying protocol stacks.

The standard is developed in an international co-operation with broad vendor and utility

participation. The primary target is the electrical substation automation (switchyards and

transformers in the medium and high voltage transport and distribution). Most major utilities and

system suppliers contribute to the development of the standard.

IEC 61850 is defined so that it fulfils the special requirements of substation automation but the

"specialties" are to a large extent isolated, making the better part of the standard generic. The

"specialties", e.g. the modeling of a high voltage breaker, are defined separately.

The general definitions of IEC 61850 can be applied in all areas where there is a need to

exchange any structured process information in real-time. The general exchange methods, like

direct access (read and write), reporting (spontaneous and cyclic; with change detection),

sequence of events (SOE), device event archives, control, and upload of the self-description ofthe device, are implemented in the general and commonly known ways.

The communication networks, that are independent of the information and exchange models,

are separated as well. This provides for the use of independent communication networks (e.g.

TCP/IP, Ethernet ... ) or simple point-to-point connections.

8/12/2019 Unit 08 - IEC 61850

8/16

8/12/2019 Unit 08 - IEC 61850

9/16


Measurement (rms, power, etc.)

Event and alarm handling

- Parameter

Data/disturbance records retrieval

Logging and archiving

- Local and distributed automation

Protection and busbar protection (remote phasors)

Protection adaptation

Interlocking

Local/distributed synchrocheck and synchronised switching

Sequences

Voltage control

Load shedding

The 10 Parts of the standard IEC 61850 are as listed in the following tables.

The following parts define how the IED behaves:

8/12/2019 Unit 08 - IEC 61850

10/16


Among these models, two are dedicated to the transmission of information with high priority:

GOOSE (Generic Object Oriented System Event) is used to model the transmission of high

priority information like trip commands or interlocking information. The model is based on cyclic

and high-priority transmission of status information. Information like a trip command is

transmitted spontaneously and then cyclically at increasing intervals.

SMV (Sampled Measured Value) is used to model the exchange of the sampled measured

values from current and voltage transducers to any IED that need the samples. The model is

based on an unconfirmed transmission of a set of sampled values. A counter is added to time

correlate samples from different sources and to detect the loss of a set of samples.

IEC 61850-9-1 defines a unidirectional serial communication interface connecting

current/voltage transducers with digital output to electrical metering and protection devices. The

goal of the standard is to support interoperability between such devices from different

manufacturers. With devices supporting this standard, the customer has the possibility to select

a current/ voltage transducer of one manufacturer and connect it to a protection device or a

meter of another manufacturer.

ABB and SIEMENS developed each a device called Merging Unit converting their own

proprietary signals from the current/voltage transducers (CT/VT) to messages according to IEC

61850-9-1 transmitted over Ethernet. Each message contains sampled values of currents and

voltages for the three phases and neutral. On the data sink side, ABB and SIEMENS developed

8/12/2019 Unit 08 - IEC 61850

11/16


each a distance protection relay, supporting the IEC 61850-9-1 messages as input signals. In

addition SIEMENS

developed a meter with the same interface. An overview of the five devices is given in Figure 4.

Each merging unit transmits synchronized samples with a transmission rate of 1000

messages/sec. Two sample rates - 1000 samples/sec and 4000 samples/sec - are supported. In

the case of 4000 samples/sec, four sets of samples are transmitted in one message.

Fig. 4: Devices with IEC 61850-9-1 interfaces

5. The new IEC standard 61400-25 for distributed (wind power) generation

The IEC Technical Committee 88 has set up a new project to develop a communication standard

for distributed generation (primary scope per TC 88: wind power plants) in 2001:

IEC 61400 Part 25 : Communications for monitoring and control of wind power plants

The first official working draft can be downloaded from:

http://www.scc-online.de/std/61400/current.html

This standard defines like IEC 61850 several levels: information ,

information description methods,

substation configuration method,

information exchange for monitoring and control systems

for wind power plants, and

communications profiles.
http://www.scc-online.de/std/61400/current.htmlhttp://www.scc-online.de/std/61400/current.html

8/12/2019 Unit 08 - IEC 61850

12/16


The information defined in this standard comprises mainly wind power plant specific information

like status, counters, measurands, and control information of various parts of a wind power plant,

e.g., turbine, generator, gear, rotor, and grid.

The object oriented information description methods allow precise and complete specification

of the information.

The information exchange provides:

real-time data access and retrieval,

controlling devices,

event/alarm reporting and logging,

self-description of devices,

data typing and discovery of data types, and

file transfer

The SCL (substation configuration language) describes all information exchanged in a

substation communication network.

Communication profiles as can be found in the IT world are applied. Especially the security

solutions available in the IT world (e.g., SSL and STL) can be used as provided off-theshelf.

6. Re-usability and device modelling

Describing device functionality by specifying the data (syntax and semantic) and the dynamic

behavior (state machines) of devices (as seem from remote) is one of the fundamental

challenges in the standardization. Many standardization groups have started defining different

views of domain-specific device types. The views are e.g.:

Engineering (in the context of a plant),

Commissioning,

Configuration,

Operation,

Asset management,

Maintenance,

De-commissioning

8/12/2019 Unit 08 - IEC 61850

13/16


Hardware and software, as well as communication networks are subject to frequent innovation.

Therefore, it is worth-while to standardize independent (abstract) interfaces for communication

networks and the access to the application objects.

The abstract objects (objects define the semantic of the device functions) will continuously be

used (with minor changes only). The object definitions will be enhanced in the future to meet

additional requirements, i.e. re-using the definitions specified in the past (see Figure 5).

Fig. 5: What is important to be standardised?

The most important objective of the device description is to define re-usable parts to be used for

specifying the data models and behavior of various types of industrial devices. Re-usability has

two aspects. First, re-use of a given functionality in many devices throughout an application

domain (we may call this: horizontal re-use). Second, re-use of a given function in the definition

of an enhanced or specialized function (we may call this: vertical re-use). The re-usability is a

crucial factor in reducing the costs of the overall system design, engineering, operation, and

maintenance. Support of re-usability is the key issue in the standardization!

The re-usable parts describe for example how a substation can be configured using the SCL

substation configuration language. A diagram as shown in Figure 6 maps to a XML file

representing the use of the classes.

Fig. 6: Application diagram

8/12/2019 Unit 08 - IEC 61850

14/16


The application of the SCL allows to

Fig. 7: Application of SCL (excerpt)

The real benefit of device modeling is the re-use of (common) definitions made in the past. This

is the daily practice. We are using common terms at work (key board, laser printer, office, ..) or

at home (kitchen, chair, wheel char, bath room, ...). Just misunderstandings are the result if

terms are not understood uniquely on both sides (sender and receiver). It is not only a matter to

define something completely more important is, to understand it uniquely. All technical

specifications in the area of distributed systems have to follow distinct rules for defining,

exchanging, and unique interpreting exchanged information.

Interpretation is quite easy if we can re-use common terms learned in the past. In our daily life

we re-use (instantiate) the term laser printer (more precise we re-use the class definition that is

associated with term laser printer) for a laser printer next to you laser printer in room 23 or we

may reuse the term for a special type of a laser printer: A4 laser printer in room 23.

Distributed systems should operate in the way they have been told to do. If they do not? This

may have many reasons. A major issue is, that independently developed devices may follow the

specification of their implementers but the implementers may have different interpretations of the

specification that describes the co-operation of the devices!

Devices will not operate in the way they should do, if the human beings (the implementers) do

not understand each other! Device models are collections of terms with associated semantics

and a description of the dynamical behavior.

8/12/2019 Unit 08 - IEC 61850

15/16


Usually models are abstract in the sense that they do describe only those aspects that are

visible to the remote user of a device. It is sufficient to know the external visible data and

behavior of the device (the WHAT). The concrete realization of the device, its internal interfaces

and programming language or operating system (the HOW) are not of interest for the view from

outside. To understand the concept of a virtual system, the following saying may help:

If it's there and you can see it It's REAL

If it's there and you can't see it It's TRANSPARENT

If it's not there and you can see it It's VIRTUAL

If it's not there and you can't see it It's GONE

7. Resume

Deregulation will place greater demands for information on utilities than they have experienced

before. IEC 61850, IEC 61400-25, and IEEEs UCA provide a timely, cost-effective, and

standardized solution to allow advanced IED functions and distributed systems to form the

foundation for next generation electric utility systems.

With the standard IEC 61850 intelligent protection relays and other real-time devices are

becoming more common. Utilities could take advantage of these new developments, and make

the power systems safer than before taking into account that all critical information (status and

measurements) is available (at any time and any where) when making control decisions.

The customers are in a position to save large sums of money and time. The vendors who

provide solutions that meet or exceed expectations will become very successful. This is an

exciting time in the industry with an inexorable move toward practical software components.

The most important issues are the models of the real device data and the rules (service

interface) how to access these data. On the other side it is obvious that an appropriate transport

mechanism (communication profiles), e.g., the TCP/IP or a point-to-point link, must be used to

exchange the messages between devices.

By providing a common communications protocol stack allow an utility and other industries to

plug and play equipment from different vendors. The specification of the uniquely tagged

semantic of the most important device model data leads to a tremendous cost reduction during

8/12/2019 Unit 08 - IEC 61850

16/16


engineering, commission ing, operation, asset management, and maintenance. The solution

provides plant and enterprise wide seamless integration.

A comprehensive free Demo Software and Tutorial for IEC 61850 / IEC 61400-25 / UCA /

MMS (with Web/XML support) executable on PCs (Win 95, 98, NT, 2000, XP) could be

downloaded from the following URL:

http://www.nettedautomation.com/solutions/demo/20020114/index.html

8. References

[1] Schwarz, K.: Standard IEC 61 850 for substation automation and other power system application.Power System and Communication Infrastructures for the future, Beijing, September 2002.

[2] Brunner, C.; Schubert, H.: The ABB - SIEMENS IEC 61850 interoperability projects, (January 2002)http://www.nettedautomation.com/solutions/uca/products/9-1/index.html

[3] IEEE Technical Report 1550 (1999): Utility Communications Architecture, UCA;

http://www.nettedautomation.com/standardization/IEEE_SCC36_UCA[4] IEC 60870-6-TASE.2: Telecontrol application service element 2 - Standards and committee drafts IEC

61850: Communication networks and systems in substations; http://www.scc-online.de/std/61850[5] Working Draft IEC 61400-25: Communications for monitoring and control of wind power plants;

http://www.scconline.de/std/61400[6] Becker, G.; Grtner, W.; Kimpel, T.; Link, V.; Mrz, W.; Schmitz, W.; Schwarz, K.: Open

Communication Platforms for Telecontrol Applications Benefits from the New Standard IEC 60870-6TASE.2 (ICCP), etz-Report 32, VDE-Verlag Berlin, 1999www.Nettedautomation.com/standardization/IEC_TC57/WG07/etz_report.html

[7] Comparison of IEC 60870-5-101 (-103, 104), DNP3, IEC 60870-6-TASE.2 with the new standard IEC61850 http://www.nettedautomation.com/news/n_51.html
http://www.nettedautomation.com/solutions/demo/20020114/index.htmlhttp://www.nettedautomation.com/solutions/uca/products/9-1/index.htmlhttp://www.nettedautomation.com/standardization/IEEE_SCC36_UCAhttp://www.scc-online.de/std/61850http://www.scconline.de/std/61400http://www.nettedautomation.com/standardization/IEC_TC57/WG07/etz_report.htmlhttp://www.nettedautomation.com/news/n_51.htmlhttp://www.nettedautomation.com/news/n_51.htmlhttp://www.nettedautomation.com/standardization/IEC_TC57/WG07/etz_report.htmlhttp://www.scconline.de/std/61400http://www.scc-online.de/std/61850http://www.nettedautomation.com/standardization/IEEE_SCC36_UCAhttp://www.nettedautomation.com/solutions/uca/products/9-1/index.htmlhttp://www.nettedautomation.com/solutions/demo/20020114/index.html

Unit 08 - IEC 61850

Documents

Transcript of Unit 08 - IEC 61850