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People talk about IEC 61850. Can you explain me what it is?
IEC 61850: A Protocol with Powerful Potential
IEC 61850? It’s an emerging protocol for Energy industry! Unlike earlier protocols, the technical approach makes it flexible and open to future requirement changes. It seems that it is slowly but surely becoming the international standard for power substation automation systems. At least more and more people will hear about it. The goal of this article is to help understand what is IEC 61850.
IEC 61850 standard defines the communication between devices in the substation and the system requirements which are related to this substation and those devices. In addition to purely defining communication protocols, the standard supports substation automation functions as well as their engineering.
There are over 50 protocols worldwide for substation automation. IEC 61850 is the only one that provides a standardized method of communications and integration. Its first goals is to support systems built from devices coming from multiple vendors. Those devices are named: Intelligent Electronic Devices (IEDs). They are networked together to perform protection, monitoring, automation, metering and control.
To achieve maximum benefit from this emerging protocol, it is essential to understand what it has to offer, how it is different from previous standards and what it provides to end users.
Capabilities
All these IEDs, inside a substation or even across an entire power network, are communicating in order to provide data gathering and setting capability as well as remote control. The fact that multiple IEDs are sharing data or control commands, results in new distribution protection, control and automation functions. This has the potential to supersede and eliminate much of the dedicated control wiring in a substation, plus costly special purpose communication channels between the stations and power network.
With IEC 61850’s standardization of data acquisition and description methods, integration efforts are reduced. This standardization enables the integration of the equipment and systems for controlling the electric power process into complete system solutions. This is necessary to support utilities’ processes. It ensures interoperability of equipment and systems by providing compatibility between interfaces, protocols and data models.
This protocol also meets utilities’ requirements for long-term system expandability. Not only does it enable utilities to combine products from a variety of manufacturers, but it also affords users long-term exchangeability of equipment to simplify parts stocking.
All of these factors contribute to time and cost savings as well as reducing the complexity of managing facilities.
This standard not only provides a device-to-device network, but it is also a station-to-station network. It transports important information from one substation to another, which is critical during power outages.
Differentiators
IEC 61580 is the only standard that meets the ever-increasing demand from utility companies worldwide for compatibility of an installed base of control equipment from multiple vendors.
Since the protocol is Ethernet based, it makes use of common and familiar tools and devices already present in utility business networks. This means each node on the network operates as a client to control the network and to talk to all the servers or slaves on the network. Since those slaves are typically IEDs that control the transformers and switchgear in the substations, they collect a lot of data that has to be read.
Unlike many other protocols, which do not have files and historical type transfer files, IEC 61850 enables files to be brought up from the IEDs to a Supervisory Control and Data Acquisition (SCADA) system to provide information on system activity. More importantly, it enables offline trending. Unlike online trending where update rates might be as long as a second, offline capabilities provide data in milliseconds so that it can be saved and brought up for review and comprehensive analysis.
To define the process data of servers (which provide data), IEC 61580 relies on object oriented programming, rather than traditional programming. Since object orientation emphasizes data, not procedure, it affords users ease of modification and flexibility in adapting to changes of his business needs. Code and data are merged into one “object.” So, all the information and functionality information resides in one place. A device “publishes” and sends information by multicasting, and only devices that are “subscribers” for this particular information receive this message.
End-user benefits
The standard provides users with the ability to know in advance and predict how data will be moved and identified between clients and services from any manufacturer. With this predictability, integration is simplified.
With the client/server architecture of IEC 61850, intelligence moves closer to the process and eliminates the bottlenecks of classic master/slave architecture. The client controls the data exchange making client/server communication very flexible in terms of the data to be transmitted.
The protocol speeds the time-critical exchanges of information. This way, it meets the safety requirements of several automated functions in a substation automation system.
The intended result is a seamless communication architecture for utilities. Since IEC 61850 has high impact on the investment and operation of power systems, the utilities and electrical energy substation on industrial sites, will actively consider the standard as well as the suppliers.
When implementing IEC 61850, it is imperative to work with suppliers who provide the high level of technical and application expertise that is critical to achieve optimal results. Supplier support ensures ease of configuration and commissioning, saves time, increases efficiency, provides faster return on investment and enables users to gain the advantages of the strengths of IEC 61850’s potential.
A complete set of standards
The IEC 61850 standard specifies a complete series of publications (which are available from the IEC organization – www.iec.ch) for "Communication networks and systems in substations" and “Communication networks and systems for automation of power utility.”
The 4 first parts of the standard are describing and specifying the environment, the vocabulary, the requirements, etc.
The first one (IEC/TR 61850-1) gives an introduction and overview, while the second part (IEC/TS 61850-2) contains the glossary of specific terms and definitions used by “Substation Automation Systems” specialists. The third part (IEC 61850-3) exposes the general requirements (in short, it specifically defines requirements for the communication between devices – IEDs – in the substation and the requirements of related system). Then, the fourth part (IEC 61850-4) focuses on requirements for system and project management process and for special supporting tools for engineering and testing.
The series of publications specifically comes to communications with part 5 to 9 of the series.
The fifth part (IEC 61850-5) standardizes the communication requirements for functions and device models. It applies to substation automation systems (standardizes the communication between the IEDs – such as protection devices, breakers, transformers, substation hosts, etc. – and the related system).
Part six (IEC 61850-6) relates to configuration description language for Communication in electrical substations related to IEDs. Let’s say that it specifies a file format for describing IED configurations and parameters related to communication, communication system configurations, etc. The purpose of this file is to ease exchanges between engineering tools from different manufacturers, in a compatible way. It is used together with part 5 and 7 of the series.
This seventh part is describing basic communication structure for substation and feeder equipment. It consists of multiple sections. First one (IEC 61850-7-1 ) defines principles and models (it provides an overview of the architecture for communication and interactions between substation devices; it also describes the relationships between other parts of the IEC 61850 series and defines how inter-operability is reached).
The second section of part 7 (IEC 61850-7-2) applies to the ACSI (Abstract Communication Service Interface) communication in substations and feeder applications. This “ACSI” describes 2 interfaces: one for communications between a client and a remote server; the other is for fast and reliable system-wide event distribution, and for transmission of sampled measured values.
Then comes the third section of part 7 (IEC 61850-7-3) which specifies common data classes (classes for status information, for measured information, for controllable status information, controllable analogue set point information, status settings, analogue settings) related to substation applications, and common attribute types used in these data classes. It is applicable to the description of device models and functions (of substations and feeder equipment).
The fourth section of part 7 (IEC 61850-7-4) specifies compatible logical node classes and data classes (information model of devices and functions related to substation applications). It stipulates in particular the compatible “logical node” names and “data” names for communication between devices.
Two additional sections in part 7 are respectively (IEC 61850-7-410) specifying the additional common data classes, logical nodes and data objects required for the use of the standard in a hydropower plant, and (IEC 61850-7-420) defining the information models to be used in the exchange of information with distributed energy resources (dispersed generation and dispersed storage devices: reciprocating engines, fuel cells, micro-turbines, photovoltaics, combined heat and power, and energy storage); it utilizes existing IEC 61850-7-4 logical nodes where possible, but also defines additional logical nodes where needed.
Part eight of the standard, with a single section (IEC 61850-8-1), specifies Specific Communication Service Mapping (SCSM). It deals with Mappings to MMS (ISO 9506-1 and ISO 9506-2) and to ISO/IEC 8802-3. In a few words, it specifies a method for exchanging time-critical and non-time-critical data through local-area networks by mapping ACSI to MMS (Manufacturing Message Specification - ISO 9506-1 and -2) and ISO/IEC 8802-3 (IEEE 802.3) Ethernet frames. (The use of MMS services and protocol allows provisions for supporting both centralized and distributed architectures; this standard includes the exchange of real-time data indications, control operations, and report notification.)
Part nine also deals with SCSM. Its first section (IEC 61850-9-1) focuses on sampled values over serial unidirectional multidrop point to point link. In short, it lays down the specific communication service mappings for the communication between bays/cabinets and process level, in accordance with IEC 60044-8 (electronic current transformers, for use with electrical measuring instruments and electrical protective devices).
The second section of part nine (IEC 61850-9-2) deals with sampled values over ISO/IEC 8802-3. It defines the SCSM for the transmission of sampled values according to the abstract specification in IEC 61850-7-2. The mapping mixes direct access to an ISO/IEC 8802-3 link for the transmission of the samples in combination with IEC 61850-8-1.
Finally, part ten (IEC 61850-10) Specifies standard techniques for testing the conformance (of devices and implementations) with the standard.
In addition, three more International Standards are associated to IEC 61850. A first one (IEC 62271-3) is for providing compliance with the IEC 61850 series, to existing high-voltage switchgear and controlgear; it specifies equipment for digital communication with other parts of the substation (and its impact on testing).
A second one (IEC/TS 62351-1) is an introduction to the remaining parts of the IEC 62351 series (data and communication security, for power system control and associated communications); it undertakes the development of standards for security of communication protocols series such as IEC 60870-5, IEC 60870-6, IEC 61850, IEC 61970 (application program interfaces for energy management systems), and IEC 61968 (system interfaces for distribution management in electric utilities).
To conclude, a third one (IEC/TS 62351-6) specifies messages, procedures, and algorithms for securing the operation of all protocols based on or derived from the standard IEC 61850 (applies to at least those protocols of IEC 61850-8-1, IEC 61850-9-2 and IEC 61850-6).
Applications
Definitely, this standard has been defined by and for the Energy (electricity) industry.
###
GOOSE and GSSE
Two acronyms are related to IEC 61850 standards in the literature: “GOOSE” and “GSSE.” Let’s try here to demystify the magic of those acronyms.
“GOOSE” stands for “Generic Object Oriented Substation Events.” Both Status and Value data is grouped into a dataset (object) and transmitted within a time period. The aim is to replace the conventional hardwired logic necessary for intra-relay coordination with substation bus communications. When detecting an event, the IED(s) use a multi-cast transmission to notify devices which have registered to use the data. The performance requirements are stringent (no more than 4 ms is allowed to elapse from the time an event occurs to the time of message transmission).
“GSSE” stands for “Generic Substation State Events.” Only Status data can be exchanged through GSSE. It uses a status list (in fact, it is a string of bits) rather than a dataset. GSSE messages are transmitted over MMS. They need more time for transmission and processing in comparison with GOOSE messages.
IEC 61850 standard defines the communication between devices in the substation and the system requirements which are related to this substation and those devices. In addition to purely defining communication protocols, the standard supports substation automation functions as well as their engineering.
There are over 50 protocols worldwide for substation automation. IEC 61850 is the only one that provides a standardized method of communications and integration. Its first goals is to support systems built from devices coming from multiple vendors. Those devices are named: Intelligent Electronic Devices (IEDs). They are networked together to perform protection, monitoring, automation, metering and control.
To achieve maximum benefit from this emerging protocol, it is essential to understand what it has to offer, how it is different from previous standards and what it provides to end users.
Capabilities
All these IEDs, inside a substation or even across an entire power network, are communicating in order to provide data gathering and setting capability as well as remote control. The fact that multiple IEDs are sharing data or control commands, results in new distribution protection, control and automation functions. This has the potential to supersede and eliminate much of the dedicated control wiring in a substation, plus costly special purpose communication channels between the stations and power network.
With IEC 61850’s standardization of data acquisition and description methods, integration efforts are reduced. This standardization enables the integration of the equipment and systems for controlling the electric power process into complete system solutions. This is necessary to support utilities’ processes. It ensures interoperability of equipment and systems by providing compatibility between interfaces, protocols and data models.
This protocol also meets utilities’ requirements for long-term system expandability. Not only does it enable utilities to combine products from a variety of manufacturers, but it also affords users long-term exchangeability of equipment to simplify parts stocking.
All of these factors contribute to time and cost savings as well as reducing the complexity of managing facilities.
This standard not only provides a device-to-device network, but it is also a station-to-station network. It transports important information from one substation to another, which is critical during power outages.
Differentiators
IEC 61580 is the only standard that meets the ever-increasing demand from utility companies worldwide for compatibility of an installed base of control equipment from multiple vendors.
Since the protocol is Ethernet based, it makes use of common and familiar tools and devices already present in utility business networks. This means each node on the network operates as a client to control the network and to talk to all the servers or slaves on the network. Since those slaves are typically IEDs that control the transformers and switchgear in the substations, they collect a lot of data that has to be read.
Unlike many other protocols, which do not have files and historical type transfer files, IEC 61850 enables files to be brought up from the IEDs to a Supervisory Control and Data Acquisition (SCADA) system to provide information on system activity. More importantly, it enables offline trending. Unlike online trending where update rates might be as long as a second, offline capabilities provide data in milliseconds so that it can be saved and brought up for review and comprehensive analysis.
To define the process data of servers (which provide data), IEC 61580 relies on object oriented programming, rather than traditional programming. Since object orientation emphasizes data, not procedure, it affords users ease of modification and flexibility in adapting to changes of his business needs. Code and data are merged into one “object.” So, all the information and functionality information resides in one place. A device “publishes” and sends information by multicasting, and only devices that are “subscribers” for this particular information receive this message.
End-user benefits
The standard provides users with the ability to know in advance and predict how data will be moved and identified between clients and services from any manufacturer. With this predictability, integration is simplified.
With the client/server architecture of IEC 61850, intelligence moves closer to the process and eliminates the bottlenecks of classic master/slave architecture. The client controls the data exchange making client/server communication very flexible in terms of the data to be transmitted.
The protocol speeds the time-critical exchanges of information. This way, it meets the safety requirements of several automated functions in a substation automation system.
The intended result is a seamless communication architecture for utilities. Since IEC 61850 has high impact on the investment and operation of power systems, the utilities and electrical energy substation on industrial sites, will actively consider the standard as well as the suppliers.
When implementing IEC 61850, it is imperative to work with suppliers who provide the high level of technical and application expertise that is critical to achieve optimal results. Supplier support ensures ease of configuration and commissioning, saves time, increases efficiency, provides faster return on investment and enables users to gain the advantages of the strengths of IEC 61850’s potential.
A complete set of standards
The IEC 61850 standard specifies a complete series of publications (which are available from the IEC organization – www.iec.ch) for "Communication networks and systems in substations" and “Communication networks and systems for automation of power utility.”
The 4 first parts of the standard are describing and specifying the environment, the vocabulary, the requirements, etc.
The first one (IEC/TR 61850-1) gives an introduction and overview, while the second part (IEC/TS 61850-2) contains the glossary of specific terms and definitions used by “Substation Automation Systems” specialists. The third part (IEC 61850-3) exposes the general requirements (in short, it specifically defines requirements for the communication between devices – IEDs – in the substation and the requirements of related system). Then, the fourth part (IEC 61850-4) focuses on requirements for system and project management process and for special supporting tools for engineering and testing.
The series of publications specifically comes to communications with part 5 to 9 of the series.
The fifth part (IEC 61850-5) standardizes the communication requirements for functions and device models. It applies to substation automation systems (standardizes the communication between the IEDs – such as protection devices, breakers, transformers, substation hosts, etc. – and the related system).
Part six (IEC 61850-6) relates to configuration description language for Communication in electrical substations related to IEDs. Let’s say that it specifies a file format for describing IED configurations and parameters related to communication, communication system configurations, etc. The purpose of this file is to ease exchanges between engineering tools from different manufacturers, in a compatible way. It is used together with part 5 and 7 of the series.
This seventh part is describing basic communication structure for substation and feeder equipment. It consists of multiple sections. First one (IEC 61850-7-1 ) defines principles and models (it provides an overview of the architecture for communication and interactions between substation devices; it also describes the relationships between other parts of the IEC 61850 series and defines how inter-operability is reached).
The second section of part 7 (IEC 61850-7-2) applies to the ACSI (Abstract Communication Service Interface) communication in substations and feeder applications. This “ACSI” describes 2 interfaces: one for communications between a client and a remote server; the other is for fast and reliable system-wide event distribution, and for transmission of sampled measured values.
Then comes the third section of part 7 (IEC 61850-7-3) which specifies common data classes (classes for status information, for measured information, for controllable status information, controllable analogue set point information, status settings, analogue settings) related to substation applications, and common attribute types used in these data classes. It is applicable to the description of device models and functions (of substations and feeder equipment).
The fourth section of part 7 (IEC 61850-7-4) specifies compatible logical node classes and data classes (information model of devices and functions related to substation applications). It stipulates in particular the compatible “logical node” names and “data” names for communication between devices.
Two additional sections in part 7 are respectively (IEC 61850-7-410) specifying the additional common data classes, logical nodes and data objects required for the use of the standard in a hydropower plant, and (IEC 61850-7-420) defining the information models to be used in the exchange of information with distributed energy resources (dispersed generation and dispersed storage devices: reciprocating engines, fuel cells, micro-turbines, photovoltaics, combined heat and power, and energy storage); it utilizes existing IEC 61850-7-4 logical nodes where possible, but also defines additional logical nodes where needed.
Part eight of the standard, with a single section (IEC 61850-8-1), specifies Specific Communication Service Mapping (SCSM). It deals with Mappings to MMS (ISO 9506-1 and ISO 9506-2) and to ISO/IEC 8802-3. In a few words, it specifies a method for exchanging time-critical and non-time-critical data through local-area networks by mapping ACSI to MMS (Manufacturing Message Specification - ISO 9506-1 and -2) and ISO/IEC 8802-3 (IEEE 802.3) Ethernet frames. (The use of MMS services and protocol allows provisions for supporting both centralized and distributed architectures; this standard includes the exchange of real-time data indications, control operations, and report notification.)
Part nine also deals with SCSM. Its first section (IEC 61850-9-1) focuses on sampled values over serial unidirectional multidrop point to point link. In short, it lays down the specific communication service mappings for the communication between bays/cabinets and process level, in accordance with IEC 60044-8 (electronic current transformers, for use with electrical measuring instruments and electrical protective devices).
The second section of part nine (IEC 61850-9-2) deals with sampled values over ISO/IEC 8802-3. It defines the SCSM for the transmission of sampled values according to the abstract specification in IEC 61850-7-2. The mapping mixes direct access to an ISO/IEC 8802-3 link for the transmission of the samples in combination with IEC 61850-8-1.
Finally, part ten (IEC 61850-10) Specifies standard techniques for testing the conformance (of devices and implementations) with the standard.
In addition, three more International Standards are associated to IEC 61850. A first one (IEC 62271-3) is for providing compliance with the IEC 61850 series, to existing high-voltage switchgear and controlgear; it specifies equipment for digital communication with other parts of the substation (and its impact on testing).
A second one (IEC/TS 62351-1) is an introduction to the remaining parts of the IEC 62351 series (data and communication security, for power system control and associated communications); it undertakes the development of standards for security of communication protocols series such as IEC 60870-5, IEC 60870-6, IEC 61850, IEC 61970 (application program interfaces for energy management systems), and IEC 61968 (system interfaces for distribution management in electric utilities).
To conclude, a third one (IEC/TS 62351-6) specifies messages, procedures, and algorithms for securing the operation of all protocols based on or derived from the standard IEC 61850 (applies to at least those protocols of IEC 61850-8-1, IEC 61850-9-2 and IEC 61850-6).
Applications
Definitely, this standard has been defined by and for the Energy (electricity) industry.
###
GOOSE and GSSE
Two acronyms are related to IEC 61850 standards in the literature: “GOOSE” and “GSSE.” Let’s try here to demystify the magic of those acronyms.
“GOOSE” stands for “Generic Object Oriented Substation Events.” Both Status and Value data is grouped into a dataset (object) and transmitted within a time period. The aim is to replace the conventional hardwired logic necessary for intra-relay coordination with substation bus communications. When detecting an event, the IED(s) use a multi-cast transmission to notify devices which have registered to use the data. The performance requirements are stringent (no more than 4 ms is allowed to elapse from the time an event occurs to the time of message transmission).
“GSSE” stands for “Generic Substation State Events.” Only Status data can be exchanged through GSSE. It uses a status list (in fact, it is a string of bits) rather than a dataset. GSSE messages are transmitted over MMS. They need more time for transmission and processing in comparison with GOOSE messages.
