A Complete Guide to the IEC 61850 Standard
The IEC 61850 standard began with the development of the EPRI Utility Communications Architecture (UCA), a 6-volume report completed in 1991. Those volumes spelled out the need for communication standards and a UCA protocol that used as its basis the Manufacturing Message Specification (MMS), an international standard (ISO 9506) dealing with a messaging system for transferring real-time process data and supervisory control information between networked devices and/or computer applications.
In the software marketplace under UCA, software data objects began to be developed – first for distribution automation, then later for substation automation. That effort was picked up by the IEC around 1995, and the IEC 61850 standard was born. Originally called “Communication Networks and Systems in Substation Automation,” the first set of object models called Generic Object Models for Substation and Feeder Equipment (GOMSFE) was developed and eventually morphed into the IEC 61850 standard.
IEC 61850 fits into an overall structure of the IEC related to smart grid activities. 61850 is structured after the Common Information Model (CIM) under the IEC. CIM is the general information model of utility-specific data and underlies the information structures of most, if not all, IEC utility standards.
Work on the standard is ongoing. The name of the standard was changed in 2010 to “IEC 61850 Ed 2 Communication Networks and Systems for Power Utility Automation.” Since that time, the standard has been extended to other applications like DER, (IEC 61850-7-420) and use of IEC 61850 for Distribution Feeder Automation System (IEC 61850-90-6) and Object Models for Photovoltaic, Storage and other DER inverters (IEC 61850-90-7).
Adoption of IEC 61850
Adoption of the standard has been slow in North America, but more robust in Europe, Mexico and Canada. QualityLogic interviewed several large substation equipment manufacturers, and most responses were similar:
“Adoption of IEC 61850 has been growing over the last few years. Outside of North America, IEC 61850 is considered a standard protocol and adoption of the 61850 standard has been significant.”
“Outside of North America, any device used within a substation must adhere to IEC 61850 protocols. In North America, adoption of the IEC61850 has been very limited but certainly growing. There are many utilities that are experimenting with 61850, but no significant installed base as yet. However, all utilities adding new projects do specify 61850 protocol as a key requirement to possibly be used in future system integrations.”
Although clearly not a scientific survey and not necessarily reaching a target audience of substation designers, QualityLogic conducted an informal survey of utilities attending the SEPA Utility Conference in Portland, OR on April 16th, 2013. In that survey, utilities were asked which standards they currently are encouraging or enforcing today and which standards they expect to encourage or enforce in the future. Only one utility checked off IEC 61850 as a standard they plan to encourage or enforce in the future.
However, 6 out of 16 or 38% of utilities checked off DNP3 as a standard they currently or plan to encourage or enforce in the future. As a result, we believe that DNP3 is still the standard of choice among US utilities. In spite of these unscientific results, we do see other signs that utilities are considering alternatives to DNP3 and IEC 61850 is starting to make inroads in US utilities.
IEC 61850 Substation Implementation Testing
A full installation of an IEC 61850 substation should include the following testing:
- System Testing
- Conformance Testing (IEC 61850 part-10)
- Operations Testing
- Functional Testing
- IED Conformance Testing
- SCL Conformance Testing
- IEC Protocol compliance of individual components
- Operations Testing Merging Units
- Operations Testing of Compliant IED
- Operations Testing of bay level distributed applications
- Operations Testing of substation level of distributed applications
- Factory Acceptance Testing
Test and Certification Tools and Programs
Testing and certification for conformance of IEC 61850 devices is challenging because IEC 61850 is not just one protocol – it is a suite of protocols that work together to form a very comprehensive system. The standard utilizes layering, structured data, one-to-one and one-to-many messaging, data discovery, and LAN-based time synchronization, which all create a challenging environment for testing groups. Interoperability testing is even more challenging and is currently done on a custom basis for each implementation design.
Information in the standard is layered both vertically and horizontally. Vertical layering follows the Open Systems Interconnect (OSI) model for communications functions. Horizontal layering is used for the logical nodes that scatter the functions found in a substation in different physical devices.
Layering in this manner means that testing IEC functionality must rely on automated testing tools for conformance because humans cannot interpret the information. This puts a lot of pressure on the system test designer to develop accurate conformance tests. IEC 61850 is therefore quite different from DNP3 from a test perspective because elements of a DNP3 system are visible for humans to read.
Data in IEC 61850 is structured into objects. For example, a data object called Voltage may contain other objects that provide a better description of the elements that make up voltage (such as quality, phase angle, magnitude and others).
In the standard, there are many required objects. However, in order to assure the standard may grow and change with industry changes, designers allow implementation of other objects in a standard way called “namespaces.” Namespaces allow IED vendors to create new functions. These data objects must adhere to the naming conventions defined in the standard, and developers must visibly mark these extensions to the standard. Also, there must be a new data object discovery mechanism in the device; it is clear the new functions are either an object or attribute and that these new functions can be evaluated to assure they behave as the vendor claims. This flexibility of the standard also creates significant challenges for testing to not only assure the standard objects function properly, but to also discover and test the new data objects in the device.
In order to support standard communications via SCADA, one-to-one messaging is implemented in the standard. This allows a typical poling system connected to an HMI to gather information, generally in the station bus. However, to create the fast messaging needed for relay functions a different messaging system is employed using the one-to-many or publish/subscribe system, generally this is employed in the station bus but could be extended in the future to the process bus. The IEC 61850 specification defines “test” modes for the one-to-many messages, but the market is still looking for testing tools that can provide this capability.
The IEC 61850 standard specifies three parallel data discovery mechanisms. These include the Substation Configuration Language (SCL), the Manufacturing Message Specification (MMS) self-description, and the Model Implementation Conformance Statement (MICS).
The SCL offers object model discovery and device configuration that can be customized for a test. Like objects, SCL also allows vendor-specific extensions to the SCL language. This can complicate conformance testing because all extensions need to be validated during testing.
In an IEC 61850 installation, there are client applications and server applications. Typically the server will be the IED while the client will be the HMI. A client may request from the server a directory of object definitions. Testing is complicated because server devices offer self-description in parallel with the SCL definition mechanism. These two mechanisms must be tested to make sure they match.
As part of an IEC 61850 implementation, vendors must provide a MICS. The MICS does not have an established format as yet. It is more of a contractual document. The testing organization must therefore code this document’s information into the test system to verify that the SCL, MMS and MICS directories match.
Time synchronization is still emerging in the standard. The specification utilizes the Simple Network Time Protocol (SNTP), however, many engineers require a more accurate, faster and more robust time syncing system for IED-to-IED communications and sequence of event recording. The current standard provides classes of time accuracy, but the SNTP has no such provisions. Most substation devices achieve the accuracy they need via the IRIG B standard. This is not incorporated into the IEC 61850 standard, but there is a move to use a similar IEC time standard and incorporate it into 61850.
The Utility Communications Architecture International Users’ Group (UCA Iug) Testing Committee manages issues surrounding Conformance testing. Part 10 of the standard requires labeling a device as “IEC 61850 conformant.” The UCA IUG Testing Committee’s mandate created a conformance test system to test compliance for all elements of 61850.
The UCA International Users Group (UCAIug) is a not-for-profit consortium of leading utility user and supplier companies dedicated to promoting the integration and interoperability of electric/gas/water utility systems through the use of international standards-based technology.
The UCAIug has established a Quality Assurance Program (QAP) for Product Testing and Test System Accreditation. This provides a benefit to UCAIug members by improving the cost effectiveness of the testing process. Companies may apply to be approved Test Centers but must provide their procedures, test results, and ISO 9000 certificates (or equivalent) to the UCAIug in order to prove they are working according to the QAP guidelines.
Any product Certificates issued by an Accredited/Recognized Test Center will show the conformance blocks tested with positive result, the unique identification of the product tested, test center version, test systems used, and the version of Technical Issues (Tissues) which have been resolved in the product.
Vendors who have received certificates participate in the Users Group Quality Assurance Program and are required to provide feedback on problems encountered in field implementation. The UCAIug does audits periodically to ensure that testers and vendors are complying with the UCAIug Testing Quality Assurance Program.
The testing committee has three major documents:
- Accreditation Program – specifying the conditions an organization must meet before it can claim to be a UCA IUG-recognized (accredited) IEC 61850 conformance tester.
- Quality Assurance Procedures — specifies the rules conformance testers must follow to make sure that any interoperability issues are discovered and prevented in future versions of the 61850 spec.
- Test Procedures — provides detailed step-by-step rules for conducting conformance tests. These rules require tests for normal operating conditions (positive tests) but also error conditions (negative tests).
UCA Iug conformance tests are comprised of three steps:
- Documentation Inspection — inspection of the documentation accompanying the conformance test application. This documentation requires the MICS, Protocol Implementation Conformance Statement (PICS), and other specifications.
- Static Testing — verification that the documentation support all mandatory features required by IEC 61850.
- Dynamic Testing – stimulating the device with simulated conditions and reviewing appropriate response in the device under test (DUT). This verifies that the device properly implements all the features claimed in its documentation. The probing includes both positive (valid message) tests and negative (invalid message) tests.
Authorized IEC 61850 Certification Test Labs
KEMA was the first authorized IEC 61850 Certification Lab and has developed both the test tools and procedures for certification. Recently, UCA has qualified additional IEC 61850 Certification Test Labs. Because each authorized test lab develops their own detailed test procedures and tools, we are concerned that differing interpretations of the UCA Test Specification will result in slightly different “certified” IEC 61850 products. This could result in new interoperability problems between vendors using different certification labs.
The list below provides the UCA Iug certified testing agencies:
- DNV KEMA Energy & Sustainability, with 2,300 experts in 30 countries, is committed to drive the global transition toward a safe, reliable, efficient and clean energy future. DNV KEMA provides world-class, innovative solutions in the fields of business and technical consultancy, testing, inspections and certification, risk management and verification. As objective and impartial knowledge-based company, they support organizations along the energy value chain. The company is a global thought leader in critical utility telecommunication infrastructures and data communication projects, and are the leading provider in IEC 61850 testing and certification, test tools, consultancy- and training services. DVA KEMA experts participate in international standardization bodies such as IEC and IEEE.
- GridClone is the company for IEC 61850 based test tools, simulators and support tools. Testing and simulation of IEC 61850 based IEDs and systems require advanced and flexible software tools. GridClone provides these software tools for both IEC 61850 Edition 1 and Edition 2. The company has many years of experience in developing software solutions, conformance testing and power engineering. Worldwide major UCA Level A test labs and manufacturers are using GridClone software solutions. Focused on the need to efficiently and effectively test IEC 61850 based implementations, the company offers customers user-friendly, high-quality and affordable solutions. Their experts actively participate in IEC working groups and the UCA iug Testing Subcommittee.
- OMICRON is an international company serving the electrical power industry with innovative testing and diagnostic solutions. The application of OMICRON products allows users to assess the condition of the primary and secondary equipment on their systems with complete confidence. Services offered in the area of consulting, commissioning, testing, diagnosis and training make the product range complete. Customers in more than 140 countries rely on the company’s ability to supply leading edge technology of excellent quality. Service centers on all continents provide a broad base of knowledge and extraordinary customer support. All of this together with their strong network of sales partners is what has made Omicron company a market leader in the electrical power industry.
- SISCO provides standards-based, real-time communications and integration solutions to end users and OEMs in the energy industry. The company specializes in the application of IEC 61850 and CIM to manage the complexity of electric power systems while building a flexible Smart Grid integration architecture that is robust and scalable. For those seeking turnkey solutions in Europe, SISCO has appointed AMA-SYSTEMS GMBH as sole partner and distributor. SISCO and AMA products include source code, off-the-shelf interfaces, device simulators, test software, remedial action systems, and special protection systems. Services available include use case and model consulting, systems integration, application development, training, support and maintenance.
- Triangle MicroWorks, Inc. provides software libraries and PC-based tools to help implement and maintain systems using industry-standard communication protocols such as IEC 61850 [including: -9-2 (Sampled Values); -7-410 (Hydro); -7-420 (DER); IEC 61400-25 (Wind); and GOOSE]. They also support IEC 60870-6 (TASE.2/ICCP); IEC 60870-5 (-101, -102, -103, & -104); DNP3; and Modbus. The company’s Protocol Test & Verification Tools make it easy to test, troubleshoot and configure communication protocols and devices. Their Software Libraries help equipment vendors cost-effectively implement communication protocols in any device. They also offer OPC Drivers/Translators, Protocol Gateways, Visualization Tools, Web-based Training, and Implementation Services.
- TÜV SÜD Embedded Systems offers consulting, testing, certification and training for Functional Safety and IT Security related topics. The main field of activities is a test laboratory: Intelligent devices can be checked for seamless communication and trustworthy data transfer in Smart Grids, as well as in automation control and communication systems (chemical, oil and gas industry).
- Xelasenergy. IEC 61850 standards are powerful and futureproof. NOW its implementation is also convenient, efficient, rapid, reliable and performant! With the company’s MMS, Goose and SV protocols and embedded server software portable on all OSS. But especially through their new CIM based convergent Client, offering WEB-GUI based control, its in-built dynamic mediation plug-in capability for legacy devices integration (e.g. RTUs) and protocol conversion. Protocols, servers, clients, simulators, conformance testing and mediation: Xelas offer the full smart basis of smart grid management supporting ALL defined operations and based on leading ICT technology. For substation, Wind, Hydro and DER.
- TÜV Rheinland is a global leader in independent inspection services. Its independent experts stand for quality and safety for people, the environment, and technology in nearly all aspects of life. To ensure the reliable activity and interoperability of intelligent electronic devices, TÜV Rheinland supports customers in conforming compliance with the global IEC 61850 standard for power utility automation. The company’s services for the IEC 61850 standard include:
- Conformance testing.
- Interoperability testing.
- Technical expertise in the field of intelligent power networks / devices (smart grid).
Thanks to their IEC 61850 conformance testing services, customers can be sure that their devices are suitable for integration into the smart grid. Testing for interoperability makes the exchange of data between various systems possible.
The table below provides a breakout of systems and services offered by several of the vendors for testing IEC61850 performance or conformance:
The IEC 61850 Standard provides a very robust communication system for utility substation management. It also provides an excellent foundation for extending similar communications to distributed energy resources. North American utilities are encouraged to continue examining the IEC 61850 standard for use in their utility as a very cost effective alternative for substation automation while opening the door to future growth in moving away from analog systems and hard-wiring to digital systems and optical wiring.
The challenge for testing organizations is to develop easy-to-use testing and certification tools and get them in the hands of utility engineers to make IEC 61850-based systems design and implementation the lowest cost and most reliable alternative for utility systems communications.