The IEC 61850 Standard – Communication Networks and Automation Systems from an Electrical Engineering Point of View Yulian Rangelov, Nikolay Nikolaev and Milena Ivanova Department “Electric Power Engineering” Technical University of Varna Varna, Bulgaria
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[email protected] Abstract — The standard IEC61850 is presented, considering its implementation and application as a platform, from the point of view of electrical engineers rather than software and electronic engineers. This is important since electrical engineers are the staff responsible for the design, construction, operation and maintenance of the electrical substations. Keywords— substation; communications; automation; scada
I. INTRODUCTION On a global scale, the energy sector is geographically divided by two main standardization models - IEC (International Electrotechnical Commission) and ANSI (American National Standards Institute) [1]. Very often, this is an obstacle for the development of technologies in the field of power system automation.
II. OVERVIEW ON THE DIFFERENT IEC 61850 PARTS As mentioned above, the standard consists of many parts. The relation between them is clarified in fig. 1. Parts 1 and 2 give basic introduction to the ideas, principles, concepts and the glossary to the standard. Parts 8 and 9 focus on the mapping between the abstract data classes and services to the communication protocols and give specifications of the serial unidirectional communication and samples values transmission [13-15]. Part 10 is dedicated to the conformance testing of the client-server communication and the engineering tools [16]. The other parts are more relevant to electrical engineers and will be explained in the following subsections.
In 2004, the IEC61850 was issued as a global standard for the control and protection systems of switchgears for medium and high voltage. It covers both the IEC and ANSI standardization models [2]. The new standard ensures: •
Unified standard for all substations and power plants;
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Application of common format for description of substations and making the design approach easier;
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Defining the main services required for data transmission using different communication protocols;
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Interoperability manufacturers.
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IEC61850 provides standardized work-frame for integration of the specific communication requirements for substations, functional characteristics, structure of the data packages in the devices, unifying the names of data packages, how applications interact with and control the devices, and conduct standardized tests. The standard IECE61850 is structured in 10 parts on about 1200 pages [1]. The Bulgarian Institute for Standardization have harmonized only few parts of it.
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Fig. 1. General structure of IEC 61850
A. Part 3: General Requirements This part focuses on the construction, design and environment conditions of the intelligent electronic devices (IEDs) [3].
B. Part 4: System and Project Management This part of the standard defines a system for project management of utility automation systems (UAS), including substation automation systems (SAS) [4]. The UAS usually operates in an environment which typically includes the following (see fig. 2): •
Telecommunication environment: network control centers, subordinate systems, teleprotection;
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Human as local operator;
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Process environment: switchgear, power transformers and auxiliary equipment.
requirements. The responsibility is distributed among several engineers: • Engineer responsible for the project requirements; • Engineer responsible for the system architecture, based on the project requirements; • Equipment vendors; • System integrators – engineers who ensure the interoperability of the different UAS components and the process environment; • IEDs parametrization engineer; • Commissioning engineer. C. Part 5: Communication Requirements for Functions and Device Models The fifth part is focused mainly on the SAS [5]. It standardizes the communication between IEDs and the requirements which should be met. Being part of the SAS, the IEDs should be able to perform at least one or more functions, which are categorized as either protection, control, measurement etc. The different functions are standardized. The functions could be split into independent pieces which perform specific actions and could be used in more than one function. These pieces are called Logical Nodes (LN). The LNs contain the pieces of information which need to be communicated (PICOM) between the different functions and IDEs. The relation between LNs, physical devices (PD) and functions (F) is depicted in fig. 3. The LN are connected by logical connections (LC) and the physical devices by physical connections (PC). The figure shows that one function can encompass LNs from different PDs and that one PD can have
Fig. 2. Environment of the utility automation system
In terms of UAS, the “process” is used to denote the process of generation, transmission and distribution of electrical energy. IEDs are the main components of the UAS and could be: • For the telecommunication environment: gateways, converters, telecommunication part of RTUs, teleprotection; • For human-machine interface (HMI): gateways; personal computers; workstations, other IEDs with embedded HMI; • For the process environment: bay control units, relay protection, the process part of RTUs, measurement devices, autonomous controllers, sensors, numerical interfaces of switchgears, power and instrument transformers. The engineering process defines the conditions for the design and the configuration of a particular power plant or substation, based on the operation logic and the customer’s
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Fig. 3. Logical nodes, functions and physical devices
Fig. 4. Topology of substation automation system
many LNs. The functions are divided in three levels: station, bay/unit or process (see fig. 4). The process functions interface to the process itself, i.e. sampled values gathering, switchgear position monitoring and control, and others. The bay/unit level consists of the protection and control functions acting mainly on the primary equipment of their own bay. There are two types of station level functions: (i) functions related to the process, which use information from more than one bay and being able to act upon all of them; (ii) functions providing interface to the station operator or a remote control center. The numbers in a circle from fig. 4 denote the different interfaces between the levels: (1, 2) protection data; (4) analogue data; (5, 6) control data; (7) data exchange between substation level and remote engineer’s workplace; (3, 7, 8, 9) data exchange; (10, 11) control data exchange. Interfaces 2 and 11 are not within the scope of IEC 61850. D. Part 6: Configuration Description Language for Communication in Electrical Substations Related to IEDs This part of the standard defines an object-oriented, XML based language for automation system configuration, named System Configuration description Language (SCL) [6]. A configuration file typically starts with the description of the primary electrical circuit equipment and their interconnections. After that, the LN, the functions and the communication between them are defined. The SCL code also contains the configuration of each specific IED and from that perspective every IEC 61850 compatible device should be capable to be configured with an SCL code. The following file types are defined: ICD – IED capability description; IID – instantiated IED description; SSD – system specification description; SCD
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– system configuration description; CID – configured IED description; SED – system exchange description. Clause 10 of this part explains the functionality of the software tools needed for system specification and configuration. E. Part 7: Basic communication structure The main architecture which IEC 61850 adopts is the division of the data definition and the processes by creating data objects and processes which are independent from any protocols [7-12]. Therefore, the particular definitions allow the organization of the data objects and the processes in terms of any protocol which is capable to meet their requirements. Part 7-1 defines the modelling methods, the communication principles and the information models which are used in the next subparts. Part 7-2 standardizes an abstract communication service interface between client and remote server or between publishing device and subscribed devices (for sampled values transmission). Part 7-3 defines common data classes used to describe equipment models and functions for substations. Part 7-4 refines the models by introducing compatible LNs for the substation equipment and data classes. It contains detailed information for the used alphabetical designation of LNs (relay protection equipment, registering devices, regulators, tap changers, instrument transformers). Also, the rules for the application of LNs and their associated information are refined. The LNs are grouped according to the functions they relate. The name of the group starts with a specific letter: (A) for automatic control; (C) supervisory
control; (P) protection; (X) switchgear, (M) metering and measurement; and others. III. CONCLUSIONS The IEC61850 is internationally accepted and gives clear direction during the process of very intense automation of substations and power plants. The standard is very exhaustive and is dedicated to wide range of engineering areas – electric power, communications and software. For electrical engineers to be able to understand it, they need to gain same qualification in the field of communications. To greater extent, this would increase their ability to design and maintain entirely or partly the automated electric power plants and substations.
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ACKNOWLEDGMENT The research presented in this paper is a result of a project in Technical University of Varna as part of its research activities funded by the Bulgarian State.
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REFERENCES [1] [2]
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Kirrmann, H. Introduction to the IEC 61850 electrical utility communication standard, ABBCH-RD, 2012. L van der Zel, Guidelines for Implementing Substation Automation Using IEC61850, the International Power System Information Modeling Standard, Technical Report, 2004. IEC 61850-3:2014. Communication networks and systems for power utility automation – Part 3: General requirements IEC 61850-4:2011. Communication networks and systems for power utility automation – Part 4: System and project management IEC 61850-5:2013. Communication networks and systems in substations – Part 5: Communication requirements for functions and device models
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IEC 61850-6:2010. Communication networks and systems for power utility automation – Part 6: Configuration language for communication in electrical substations related to IEDs IEC 61850-7-1:2011. Communication networks and systems for power utility automation – Part 7-1: Basic communication structure - Principles and models IEC 61850-7-2:2010. Communication networks and systems for power utility automation – Part 7-2: Basic communication structure - Abstract communication service interface (ACSI) IEC 61850-7-3:2011. Communication networks and systems for power utility automation – Part 7-3: Basic communication structure - Common Data Classes - Ed.2 IEC 61850-7-4:2010. Communication networks and systems for power utility automation – Part 7-4: Basic communication structure Compatible logical node classes and data classes IEC 61850-7-410:2012. Communication networks and systems for power utility automation - Part 7-410: Basic communication structure Hydroelectric power plants - Communication for monitoring and control IEC 61850-7-420:2009. Communication networks and systems for power utility automation – Part 7-420: Basic communication structure Distributed energy resources logical nodes IEC 61850-8-1:2011. Communication networks and systems for power utility automation – Part 8-1: Mappings to Specific communication service mapping (SCSM) - Mappings to MMS (ISO 9506-1 and ISO 9506-2) and to ISO/IEC 8802-3 IEC 61850-9-1:2003. Communication networks and systems in substations – Part 8-1: Specific communication service mapping (SCSM) - Sampled values over serial unidirectional multidrop point to point link IEC 61850-9-2:2011. Communication networks and systems for power utility automation - Part 9-2: Specific communication service mapping (SCSM) - Sampled values over ISO/IEC 8802-3 IEC 61850-10:2006. Communication networks and systems in substations – Part 10: Conformance testing
