ICD - IED Capability Description
What is an ICD file?
ICD File (IEC 61850)
IED Capability Description (ICD) files are a specific type of Substation Configuration Language (SCL) file, containing a generic description of the whole capability range of a given device, including the functions and objects it can support.
The ICD file is usually supplied by the developer/manufacturer.
How SCL files are Used
The engineer imports the ICD file of each device to the System Configuration Tool (SCT) to build the Substation Configuration Description (SCD) for the substation design. The SCD includes the capabilities of all devices required for the designed system.
The designer/tool can also be used to export an Instantiated IED Description (IID) file from the SCD. The IID can be seen as a subset of the ICD in terms of functions and objects, but it also includes configuration information related to the system design (such as reports and GOOSE subscriptions).
An IED Configuration Tool/ Designer (ICT) can use the IID along with device specific information (which could include mapping information) to create a Configured IED Description (CID) file to tell the device how to configure itself. As such, IED engineers usually user a designer/tool to produce CID files using IID imports.
CID vs ICD vs IID vs SCD — SCL File Types
IED Capability Description (ICD)
The ICD file is supplied by the manufacturer and defines the complete capability range of an IED. The file contains a single IED section and can optionally also provide the communication and substation sections.
Configured IED Description (CID)
CID files can be considered SCD files stripped down to the sections that are relevant to the IED, connecting IED configuration tool (ICT) and the IED. It contains everything from the SCD file the IED needs in order to be configured, as for example the dataset definition behind a GOOSE message the IED shall receive.
Instantiated IED Description (IID)
The IID file defines the configuration of an IED for a specific project, providing a data exchange format to connect the IED configurator and the system configurator. It contains an IED section, the communication section (including parameters), the IED’s data type templates, and, optionally, a substation section with the binding of functions (LogicalNodes) to the single line diagram.
System Specification Description (SSD)
The SSD file contains the complete specification of the substation automation system, including the single line diagram for the substation and its functionalities (logical nodes). The SSD requires to define the substation part, data type templates and logical node types but does not require the IED section
Substation Configuration Description (SCD)
The SCD file describes the entire substation in detail, inculding the communication, IED and data type template sections. As such, SCD files integrate both ICD and SSD files
System Exchange Description (SED)
The SED file can be considered a subset of an SCD file with additional engineering rights for each IED and ownership of all SCL data. It is used to exchange system configurations between different projects, describing the interfaces of one project to be used by another project.
What is IEC 61850?
The IEC 61850 standard was a response to the growing need for higher and deeper levels of control and automation in electrical grids. With steadily increasing numbers of devices, device types and data points, further accelerated by digitization, as well as the integration of new, often geographically distributed and heteregenous, generation sources, it became evident that future demands could not be met with the technological limits of serial protocols like Modbus.
In order to guarantee interoperability in the face of rapid technological development and product innovation in the industry, the IEC 61850 standard not only defines various communication protocols and interfaces, but also provides specifications concerning the substation modelling, configuration language and data models. For this reason, IEC 61850 is commonly referred to as “not just a protocol” and often called a data model or framework instead.
The scope of the standard allows to map the standardized data models and services onto serveral communication protocols and thus transfer the data via Ethernet using different protocols for different requirements and applications, as for example TCP/IP-based protocols for clients/server communications. For this reason, despite its initial focus on substation automation, the flexibility of IEC 61850 has spread its use to other applications, such as the integration of distributed energy resources (DERs) into the power system or the communication between intelligent devices in Building Management Systems (BMS).
The IEC 61850 standard distinguishes itself through the following elements:
Abstract Communication Service Interface (ACSI)
The ACSI (defined in IEC 61850–7‑2) describes the functions and services for the interaction between IEDs in the system. Examples of IEC 61850 services include the transmission of files, reading of data or assignition of values. The ACSI can be mapped onto various protocols, including MMS or web services.
System Design and Structure
The functions of the IEC 61850 standard are the often-heard logical nodes, which can simply contain device descriptions but usually represent a real physical device like switches, sensors or IEDs, and its entire range of functionalies.
IEC 61850 Protocol Suite
The IEC 61850 standard defines several different protocols for different purposes in substations and other facilities/ utilities.
The standard defines the low-level (process bus) client/server based GOOSE/GSSE (Generic Object Oriented Substation Events) protocol to transmit event data across networks at very high speeds. This enables to new possibilities for advanced substation automation and protection functions and schemes.
It also defines the more complex MMS (manufacturing message specification) protocol for communications between servers and clients. It provides a set of functions that allows the client to obtain the data model of the server, read or modify individual values, or even delete entries as well as to transfer files.
The last two protocols displayed on the chart comprise the Sampled Values (SV) protocol for the transmission of digitized instantaneous values of power system quantities, mainly primary currents and voltages and time synchronization protocols such as SNTP over UDP/IP.
IEC 61850 Protocol Suite
The GOOSE (Generic Object Oriented Substation Event) protocol is a communication model defined by the IEC 61850 standard, which uses fast and reliable mechanisms to group any format of data (status, value) into a data set and transmit it through electrical networks within a time period of 4 milliseconds.
It is most commonly used for data exchanges between IEDs (IED – Intelligent Electronic Device) in electrical substations over Ethernet.
IEC 61850 MMS (Manufacturing Message Specification) is a client/server based protocol for communications between IEDs (IED – Intelligent Electronic Device) and higher level entities (such as RTUs and SCADAs) over Ethernet that is part of the IEC 61850 standard for communication technology in substations.
It is mapped onto TCP/IP and allows to access the server through its IP address in order to write/read data and exchange files.
The IEC 61850 standard for substation automation specifies a standardized Substation Configuration Language (SCL) to transfer device descriptions and communication parameters amongst different vendors/ manufacturers.
SCL files define several capability subsets for the IED to instantiate its capabilities.
The IED Capability Description (ICD) file is a specific type of SCL file, which are the configuration files defined by the IEC 61850 standard for modern substation automation.
It is usually supplied by manufacturers and defines the full capability range of an IED.
Logical nodes (abstract data objects) are the main elements of the virtual object-oriented IEC 61850 model, which consists of standardized data and data attributes.
They can represent switches in the grid, sensors, communication interfaces, or simply contain descriptions of devices.
IEC 61850 ICD & iGrid
iGrid T&D has a special commitement to interoperability and IEC 61850 in particular. For this reason, iGrid has developed the state-of-the-art “iConfICD” tool facilitate the configuration of IEC 61850 RTUs, SCADAs, I/O Extension Units and other devices for IEC 61850 projects.
All iGrid devices and software solutions support the IEC 61850 sstandard.
iConfICD is a state-of-the-art ICD design tool for the creation of ICD and CID files and the configuration and modelling of IEC 61850 servers.
The tool can be used to set up any device supporting IEC 61850 communication. It allows to create all of the standard’s Logical Devices and Logical Nodes, as well as to select the corresponding Data Objects, while strictly following the guidelines of the IEC 61850 edition 2 standard. With the integrated iEdit tool, expert professionals can also manually access and modify SCL files without restrictions.
iRTU – With I/Os for Direct Data Acquisition
iGW‑S Substation Gateway
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