61850-5©1EC:2001 16 57/526/CDV complete substation.Examples of such functions are station wide interlocking,automatic sequencers or busbar protection.These functions communicate mainly via the logical interface 8. Interface related station level functions Interface related station level functions are functions representing the interface of the SAS to the local station operator HMI (human machine interface),to a remote control center TCI (telecontrol interface)or to the remote engineering for monitoring and maintenance TMI (telemonitoring interface).These functions communicate via the logical interfaces 1 and 6 with the bay level and via the logical interface 7 and the remote control interface to the outside world. 4 ABBREVIATIONS HMI Human Machine Interface GOOSE Generic Object Oriented Substation Event GPS Global Positioning System(time source) IED Intelligent Electronic Device IF (Serial)Interface I/O Input and Output contacts or channels (depending on context) ISO International Standard Organization LAN Local Area Network LN Logical Node LC Logical Connection MMS Manufacturing Message Specification NCC Network Control Center OSI Open System Interconnection PC Physical Connection PD Physical Device PICOM Piece of Information for COMmunication SAS Substation Automation System TCI Telecontrol Interface(for example,to NCC) TMI Telemonitoring Interface(for example,to engineers workplace) 5 SUBSTATION AUTOMATION SYSTEM FUNCTIONS 5.1 Introduction The functions of a substation automation system (SAS)refer to tasks,which have to be performed in the substation.These are functions to control,monitor and protect the equipment of the substation and its feeders.In addition,there exist functions,which are needed to maintain the SAS,i.e.for system configuration,communication management or software management. 5.2 Logical allocation of functions and interfaces The functions of a substation automation system may be allocated logically on three different levels (station,bay/unit,or process).These levels are shown by the logical interpretation of Fig.2 together with the logical interfaces 1 to 10
61850-5 IEC:2001 57/526/CDV 16 complete substation. Examples of such functions are station wide interlocking, automatic sequencers or busbar protection. These functions communicate mainly via the logical interface 8. Interface related station level functions Interface related station level functions are functions representing the interface of the SAS to the local station operator HMI (human machine interface), to a remote control center TCI (telecontrol interface) or to the remote engineering for monitoring and maintenance TMI (telemonitoring interface). These functions communicate via the logical interfaces 1 and 6 with the bay level and via the logical interface 7 and the remote control interface to the outside world. 4 ABBREVIATIONS HMI Human Machine Interface GOOSE Generic Object Oriented Substation Event GPS Global Positioning System (time source) IED Intelligent Electronic Device IF (Serial) Interface I/O Input and Output contacts or channels (depending on context) ISO International Standard Organization LAN Local Area Network LN Logical Node LC Logical Connection MMS Manufacturing Message Specification NCC Network Control Center OSI Open System Interconnection PC Physical Connection PD Physical Device PICOM Piece of Information for COMmunication SAS Substation Automation System TCI Telecontrol Interface (for example, to NCC) TMI Telemonitoring Interface (for example, to engineers workplace) 5 SUBSTATION AUTOMATION SYSTEM FUNCTIONS 5.1 Introduction The functions of a substation automation system (SAS) refer to tasks, which have to be performed in the substation. These are functions to control, monitor and protect the equipment of the substation and its feeders. In addition, there exist functions, which are needed to maintain the SAS, i.e. for system configuration, communication management or software management. 5.2 Logical allocation of functions and interfaces The functions of a substation automation system may be allocated logically on three different levels (station, bay/unit, or process). These levels are shown by the logical interpretation of Fig.2 together with the logical interfaces 1 to 10.
61850-5©1EC:2001 17 57/526/CDV Process level functions are all functions interfacing to the process.These functions communicate via the logical interfaces 4 and 5 to the bay level. Bay level functions (see bay definition above)are functions using mainly the data of one bay and acting mainly on the primary equipment of one bay.These functions communicate via the logical interface 3 within the bay level and via the logical interfaces 4 and 5 to the process level,i.e.with any kind of remote l/Os or intelligent sensors and actuators.Interfaces 4 and 5 may be hardwired also but hardwired interfaces are outside the scope of 61850 There are two classes of station level functions: Process related station level functions are functions using the data of more than one bay or of the complete substation and acting on the primary equipment of more than one bay or of the complete substation.These functions communicate mainly via the logical interface 8. Interface related station level functions are functions representing the interface of the SAS to the local station operator HMI (human machine interface).to a remote control center TCI (telecontrol interface)or to the remote engineering for monitoring and maintenance TMI (telemonitoring interface).These functions communicate via the logical interfaces 1 and 6 with the bay level and via the logical interface 7 and the remote control interface to the outside world. NOTE:The interface 2 regarding remote protection(teleprotection)is outside the scope of this standard.Since the same kind of data is exchanged over this interface as within the substation,the future use of IEC 61850 is recommended. NOTE:The remote control interface to the network control center (IF10)is outside the scope of this standard.The related IEC standard is IEC 60570-5-101 /5-104.To reduce the efforts for the gateway to the NCC,a future alignment would be very convenient.Since between the control centers partly the same data are exchanged as between the substation and the NCC,a coordination with the related standard IEC 60870-6 (TASE2)is recommended.The standard should be used for a future seamless communication structure from the process level to the network control center.Since the use of interface 7 and the interface 10 may be overlapping,a co- ordination of the standards for both interfaces is recommended. Remote control (NCC) Technical Services 10 STATION LEVEL FCT.A FCT.B ⑧ 3 BAY/UNIT LEVEL PROT. CONTR. CONTR. PROT Remote Remote protection protection PROCESS LEVEL Process Interface Fig.2-Levels and logical interfaces in substation automation systems The meaning of the interfaces
61850-5 IEC:2001 57/526/CDV 17 Process level functions are all functions interfacing to the process. These functions communicate via the logical interfaces 4 and 5 to the bay level. Bay level functions (see bay definition above) are functions using mainly the data of one bay and acting mainly on the primary equipment of one bay. These functions communicate via the logical interface 3 within the bay level and via the logical interfaces 4 and 5 to the process level, i.e. with any kind of remote I/Os or intelligent sensors and actuators. Interfaces 4 and 5 may be hardwired also but hardwired interfaces are outside the scope of 61850. There are two classes of station level functions: Process related station level functions are functions using the data of more than one bay or of the complete substation and acting on the primary equipment of more than one bay or of the complete substation. These functions communicate mainly via the logical interface 8. Interface related station level functions are functions representing the interface of the SAS to the local station operator HMI (human machine interface), to a remote control center TCI (telecontrol interface) or to the remote engineering for monitoring and maintenance TMI (telemonitoring interface). These functions communicate via the logical interfaces 1 and 6 with the bay level and via the logical interface 7 and the remote control interface to the outside world. NOTE: The interface 2 regarding remote protection (teleprotection) is outside the scope of this standard. Since the same kind of data is exchanged over this interface as within the substation, the future use of IEC 61850 is recommended. NOTE: The remote control interface to the network control center (IF10) is outside the scope of this standard. The related IEC standard is IEC 60570-5-101 / 5-104. To reduce the efforts for the gateway to the NCC, a future alignment would be very convenient. Since between the control centers partly the same data are exchanged as between the substation and the NCC, a coordination with the related standard IEC 60870-6 (TASE2) is recommended. The standard should be used for a future seamless communication structure from the process level to the network control center. - Since the use of interface 7 and the interface 10 may be overlapping, a coordination of the standards for both interfaces is recommended. Fig. 2 - Levels and logical interfaces in substation automation systems The meaning of the interfaces Remote control (NCC) Technical Services CONTR. PROT. FCT. A FCT. B PROT. CONTR. Sensors Actuators Remote protection BAY/UNIT LEVEL STATION LEVEL PROCESS LEVEL HV Equipment Remote protection Process Interface 1,6 3 3 9 8 1,6 2 2 4,5 4,5 10 7
61850-5©1EC:2001 18 57/526/CDV IF1:protection-data exchange between bay and station level IF2:protection-data exchange between bay level and remote protection(outside the scope of this standard) IF3:data exchange within bay level IF4:CT and VT instantaneous data exchange (especially samples)between process and bay level IF5:control-data exchange between process and bay level IF6:control-data exchange between bay and station level IF7:data exchange between substation(level)and a remote engineer's workplace IF8:direct data exchange between the bays especially for fast functions like interlocking IF9:data exchange within station level IF10:control-data exchange between substation( (devices)and a remote control center (outside the scope of this standard) The devices of a substation automation system may be installed physically on different functional levels (station,bay,and process).This refers to the physical interpretation of Fig. 2. NOTE:The distribution of the functions in a communication environment may occur through the use of Wide Area Network,Local Area Network,and Process Bus technologies.The functions are not constrained to be deployed within/over any single communication technology. (1)Process level devices are typically remote l/Os,intelligent sensors and actuators (2)Bay level devices consist of control,protection or monitoring units per bay (3)Station level devices consist of the station computer with a database,the operator's workplace,interfaces for remote communication,etc. 5.3 The physical allocation of functions and interfaces Despite of the similarity of logical and physical levels there is no unique way for mapping the logical function structure to the physical device structure.The mapping is depending on availability and performance requirements,cost constraints,the state of the art in technology. etc. The station computer may act as client only with the basic functions HMI,TCI and TMI.All other station level functions may be distributed completely over the bay level devices.In this case the interface 8 is the backbone of the system.On the other side all station wide functions like interlocking etc.may reside in the station computer acting now both as client and server.In this case the interface 1 and 6 take over the complete functionality of interface 8.Many other solutions are possible. The bay level functions may be implemented in dedicated bay level devices (protection unit, control unit,without or with redundancy)or in combined protection and control units. If there are no serial interfaces 4 and 5,the process level functions are implemented in the bay level devices.The realization of the serial interfaces 4 and 5 may include remote 1/O devices only or intelligent sensors and actuators,which provide some bay level functionality on process level already. The logical interfaces may be implemented as dedicated physical interfaces (plugs).Two or more may be combined also into a single common physical interface.In addition,these interfaces may be combined and implemented into one or more physical LANs.The
61850-5 IEC:2001 57/526/CDV 18 IF1: protection-data exchange between bay and station level IF2: protection-data exchange between bay level and remote protection (outside the scope of this standard) IF3: data exchange within bay level IF4: CT and VT instantaneous data exchange (especially samples) between process and bay level IF5: control-data exchange between process and bay level IF6: control-data exchange between bay and station level IF7: data exchange between substation (level) and a remote engineer’s workplace IF8: direct data exchange between the bays especially for fast functions like interlocking IF9: data exchange within station level IF10: control-data exchange between substation (devices) and a remote control center (outside the scope of this standard) The devices of a substation automation system may be installed physically on different functional levels (station, bay, and process). This refers to the physical interpretation of Fig. 2. NOTE: The distribution of the functions in a communication environment may occur through the use of Wide Area Network, Local Area Network, and Process Bus technologies. The functions are not constrained to be deployed within/over any single communication technology. (1) Process level devices are typically remote I/Os, intelligent sensors and actuators (2) Bay level devices consist of control, protection or monitoring units per bay (3) Station level devices consist of the station computer with a database, the operator’s workplace, interfaces for remote communication, etc. 5.3 The physical allocation of functions and interfaces Despite of the similarity of logical and physical levels there is no unique way for mapping the logical function structure to the physical device structure. The mapping is depending on availability and performance requirements, cost constraints, the state of the art in technology, etc. The station computer may act as client only with the basic functions HMI, TCI and TMI. All other station level functions may be distributed completely over the bay level devices. In this case the interface 8 is the backbone of the system. On the other side all station wide functions like interlocking etc. may reside in the station computer acting now both as client and server. In this case the interface 1 and 6 take over the complete functionality of interface 8. Many other solutions are possible. The bay level functions may be implemented in dedicated bay level devices (protection unit, control unit, without or with redundancy) or in combined protection and control units. If there are no serial interfaces 4 and 5, the process level functions are implemented in the bay level devices. The realization of the serial interfaces 4 and 5 may include remote I/O devices only or intelligent sensors and actuators, which provide some bay level functionality on process level already. The logical interfaces may be implemented as dedicated physical interfaces (plugs). Two or more may be combined also into a single common physical interface. In addition, these interfaces may be combined and implemented into one or more physical LANs. The
61850-5©1EC:2001 19 571526/CDV requirements for these physical interfaces depend upon the allocation of function to levels and devices. 5.4 The role of interfaces Not all interfaces have to be present in any substation.This flexible approach covers both the retrofit of existing substations and the installation in new substations,today and tomorrow. The numbering of interfaces according to Fig.2 is helpful for the identification of the kind of interfaces needed in substations and for data flow calculations The interface numbers allow to define easily the two important LANs or bus systems:Very common,the interfaces 1,6,3,9,8 are combined to the station/interbay bus since it connects both the station level with the bay level and the different bays itself.The interfaces 4 and 5 are combined to the process bus,which connects the bay level with the process level and the different process level IEDs with each other.Very often,the process bus is restricted to one single bay only.If the process bus is extended to other bays it may take over the role of interface 8 also,at least for raw data. The interface 7 is dedicated for external communication with a remote monitoring center.It could be realized by a direct interface to the station/interbay bus also.The interface 2 dedicated to communication with a remote protection device and the interface 10 dedicated to remote control are outside the scope of this standard. According to the function allocation,the message types of clause 12 based on communication performance requirements may be assigned to the different interfaces.The free allocation of functions means that such an assignment may not be common for all substation automation systems 6 GOAL AND REQUIREMENTS 6.1 Interoperability The goal of the standard is to provide interoperability between the IEDs from different suppliers or,more precisely,between functions to be performed in a substation but residing in equipment(physical devices)from different suppliers.Interchangeability is outside the scope of this standard,but the objective of interchangeability will be supported following this standard Interoperability has the following levels for devices from different suppliers: (1)The devices shall be connectable to a common bus with a common protocol(syntax) (2)The devices shall understand the information provides by other devices(semantics) (3)The devices shall perform together a common or joint function Since there are no constraints regarding system structure and data exchange,some static and dynamic requirements shall be fulfilled to provide interoperability. 6.2 Static design requirements The goal of interoperability for any configuration results in the following requirements,which are not completely independent from each other: (1)The free allocation of functions to devices shall be supported by the communication
61850-5 IEC:2001 57/526/CDV 19 requirements for these physical interfaces depend upon the allocation of function to levels and devices. 5.4 The role of interfaces Not all interfaces have to be present in any substation. This flexible approach covers both the retrofit of existing substations and the installation in new substations, today and tomorrow. The numbering of interfaces according to Fig. 2 is helpful for the identification of the kind of interfaces needed in substations and for data flow calculations. The interface numbers allow to define easily the two important LANs or bus systems: Very common, the interfaces 1, 6, 3, 9, 8 are combined to the station/interbay bus since it connects both the station level with the bay level and the different bays itself. The interfaces 4 and 5 are combined to the process bus, which connects the bay level with the process level and the different process level IEDs with each other. Very often, the process bus is restricted to one single bay only. If the process bus is extended to other bays it may take over the role of interface 8 also, at least for raw data. The interface 7 is dedicated for external communication with a remote monitoring center. It could be realized by a direct interface to the station/interbay bus also. The interface 2 dedicated to communication with a remote protection device and the interface 10 dedicated to remote control are outside the scope of this standard. According to the function allocation, the message types of clause 12 based on communication performance requirements may be assigned to the different interfaces. The free allocation of functions means that such an assignment may not be common for all substation automation systems. 6 GOAL AND REQUIREMENTS 6.1 Interoperability The goal of the standard is to provide interoperability between the IEDs from different suppliers or, more precisely, between functions to be performed in a substation but residing in equipment (physical devices) from different suppliers. Interchangeability is outside the scope of this standard, but the objective of interchangeability will be supported following this standard. Interoperability has the following levels for devices from different suppliers: (1) The devices shall be connectable to a common bus with a common protocol (syntax) (2) The devices shall understand the information provides by other devices (semantics) (3) The devices shall perform together a common or joint function Since there are no constraints regarding system structure and data exchange, some static and dynamic requirements shall be fulfilled to provide interoperability. 6.2 Static design requirements The goal of interoperability for any configuration results in the following requirements, which are not completely independent from each other: (1) The free allocation of functions to devices shall be supported by the communication.
61850-5©1EC:2001 20 57/526/CDV (2)The functions of the substation automation system (SAS)and their communication behavior shall be described device independent. (3)The functions shall be described as far as necessary only to identify the information to be exchanged. (4)The interaction of device independent distributed functions shall be described by the logical interfaces in between.For implementation these logical interfaces may be freely allocated to physical interfaces or LANs. (5)The functions used today and their communication requirements are well known but the standard shall be open also for communication requirements arising from future functions. 6.3 Dynamic interaction requirements The goal of interoperability for any data exchange results in the following requirements,which are not completely independent from each other: (1)The standard shall define generic information to be communicated and generic communication behavior of the functions to support planned and future functional extensions of the substation automation system. (2)The information transfer data shall be defined with all related attributes(see PICOMs) (3)The exchanged data shall carry all attributes for a unambiguous understanding of the receiver (4)The acceptable overall transfer time of exchanged data shall be defined and guaranteed in any situation 6.4 Response behavior requirements Since interoperability is claimed for a proper running of functions also,the reaction of the application in the receiving node has to be considered. (1)The reaction of the receiving node has to fit into the overall requirement of the distributed function to be performed. (2)The basic behavior of the functions in any degraded case,i.e.in case of erroneous messages,lost data by communication interrupts,resource limitations,out of range data etc.has to be specified.This is important if the overall task cannot be closed successfully, e.g.if the remote node does not respond or react in a proper way. These requirements are local issues and,therefore.outside the scope of this communication standard.But the requirement left for this standard is the provision of proper quality attributes to be transferred with the data under consideration. 6.5 Approach to interoperability To approach interoperability,the functions to be performed in substations are identified in the following.The requirements for its data exchange shall be clearly defined.The interoperability for freely allocated and distributed functions implies a proper decomposition of functions in communicating entities.The requested mutual understanding of devices from different suppliers results in a proper data and communication service model (part 7).Last not least the mapping of this model to state-of-the-art communication stacks shall be defined unambiguously(parts 8 and 9)
61850-5 IEC:2001 57/526/CDV 20 (2) The functions of the substation automation system (SAS) and their communication behavior shall be described device independent. (3) The functions shall be described as far as necessary only to identify the information to be exchanged. (4) The interaction of device independent distributed functions shall be described by the logical interfaces in between. For implementation these logical interfaces may be freely allocated to physical interfaces or LANs. (5) The functions used today and their communication requirements are well known but the standard shall be open also for communication requirements arising from future functions. 6.3 Dynamic interaction requirements The goal of interoperability for any data exchange results in the following requirements, which are not completely independent from each other: (1) The standard shall define generic information to be communicated and generic communication behavior of the functions to support planned and future functional extensions of the substation automation system. (2) The information transfer data shall be defined with all related attributes (see PICOMs) (3) The exchanged data shall carry all attributes for a unambiguous understanding of the receiver (4) The acceptable overall transfer time of exchanged data shall be defined and guaranteed in any situation 6.4 Response behavior requirements Since interoperability is claimed for a proper running of functions also, the reaction of the application in the receiving node has to be considered. (1) The reaction of the receiving node has to fit into the overall requirement of the distributed function to be performed. (2) The basic behavior of the functions in any degraded case, i.e. in case of erroneous messages, lost data by communication interrupts, resource limitations, out of range data, etc. has to be specified. This is important if the overall task cannot be closed successfully, e.g. if the remote node does not respond or react in a proper way. These requirements are local issues and, therefore, outside the scope of this communication standard. But the requirement left for this standard is the provision of proper quality attributes to be transferred with the data under consideration. 6.5 Approach to interoperability To approach interoperability, the functions to be performed in substations are identified in the following. The requirements for its data exchange shall be clearly defined. The interoperability for freely allocated and distributed functions implies a proper decomposition of functions in communicating entities. The requested mutual understanding of devices from different suppliers results in a proper data and communication service model (part 7). Last not least, the mapping of this model to state-of-the-art communication stacks shall be defined unambiguously (parts 8 and 9).