Improved Protection and Control Testing utilizing IEC 61850

Authors: Benton Vandiver III, and Bharadwaj Vasudevan, ABB, USA

SCADA Tests: The SCD file which was used to build the communication mapping between the IEDs also contains portions of data mapping required for the SCADA communication. This means SCADA testing can be done in parallel with the relay testing. The same GOOSE messages and SVs that were simulated for the IED testing, can also be simulated to test the SCADA points.
Conversely, on the IED side, the testing tools can be used to act as a SCADA and all the SCADA controls can be tested before deploying the actual SCADA at the substation. The test plan can be automated to test each operational scenario and every data point required for the SCADA system. (Figure 6).

Troubleshooting in a Digital Substation environment
The data model in IEC 61850 has all the information pertaining to the current state of every function modeled within an IED. Many of today’s modern relay test sets, make it possible to obtain the current state of any function in an IED. In the standard, it’s called the ‘Behavior of the logical node.’ Consider the scenario mentioned under functional testing above. An IED can be put into test mode by a test set without any physical isolation or modifications. It’s also equally necessary to validate before starting any test to physically check if the ‘behavior’ of the function has changed. Positive feedback can be used to verify that an IED is in the correct test or simulation mode before proceeding with the detailed test plan.
Every message engineered using IEC 61850 has a quality information bit associated with it. There are methods and/or tools within the test software that can verify this quality bit according to the standard’s definition and provide visual cues to diagnose the actual validity of the data. This way the testing personnel can focus on the real application problems rather than interpreting bits and bytes to their actual meanings.

Typical Use Case
Consider a typical 138/13.8kV substation. Assume it has 5 feeders. Each feeder will have a breaker controller, feeder protection, plus transformer protection and overall bus protection for the substation. Typically, it would take about 3 days to test and commission the whole substation using traditional secondary injection methods. In the overall time spent for testing these protection panels, a third of it is spent on preparation. This involves choosing the right sources to be isolated for testing, isolating the correct trips/interlocks and connecting the right cables to the test set. In a digital substation, most of the preliminary work can be done even before arriving at the site. The SCD file for the substation can be used for the test plan preparation which will provide information on what SV streams need to be simulated and what functions are to be tested and what GOOSE messages need to be monitored. Another one-third portion of the time is spent on running the actual tests which include all the functional and scheme tests. With the techniques mentioned above for conducting the scheme and SCADA test, it is possible to reduce this time by half. The final one-third of the time is spent on troubleshooting and documentation. By automating test plans to document the results and by using all the techniques mentioned above for troubleshooting, it is possible to document every step of the test plan with detailed checks and feedbacks from all the IEDs and complete all the tests in half the time required traditionally.

Conclusion
The intent of this article was to clear some initial misconceptions around the standard that usually lingers with first-time users. Most of the existing accepted processes used for testing and commissioning a typical substation can be easily adapted for a digital substation. By using automated test scripts, the whole test plan can be automated, and a report can be prepared and published much faster than through a traditional test procedure. Only a few tools have been showcased in this paper to help with troubleshooting. the standard itself has evolved over the last few years and has provided a lot of new features like the LGOS, LSVS, and LTRK to online monitor GOOSE, SV streams and all the MMS based services respectively. There are also logical nodes available today to monitor the error statistics of the IED and switch communication ports which help with communication supervision for any network topology. There are many tools available today which utilize the built-in features from the standard and provide the users with options to test, commission, diagnose and maintain a digital substation. For details and the latest information on this subject, please refer to Brochure 760 (March 2019) developed by the CIGRE working group B5.53 who investigated and reported on the state of the art related to test strategies for protection, automation and control functions in a fully digital substation based on IEC 61850 applications. To fully utilize the benefits of the standard, strong importance must be given to the engineering of the digital substation and resulting SCD file using a standard conformant system engineering tool. Today the standard provides enough conformance guidelines to verify tool compliance. Enough has not been said about the benefits of IEC 61850 and in this article, we attempt to highlight the usability of the standard itself. It’s a proven global standard that can benefit any utility design.

Biographies:

Benton Vandiver III received a BSEE from the University of Houston in 1979. He is currently the Technical Sales Engineer for ABB in the South & Central Regions located in Houston, TX. A registered Professional Engineer in TX, he is also an IEEE senior member, PSRCC member, PSCCC member and Vice-chair of the P0- Protocols and Communication Architecture Subcommittee, and IEEE-SA member. He has been in the power industry for 40 years and worked previously with Houston Lighting & Power, Multilin Corp., and OMICRON electronics. He has authored, co-authored, and presented over 100 technical papers and published numerous industry articles.

Bharadwaj Vasudevan graduated from North Carolina State University with a master’s degree in power systems and joined ABB as an Application Engineer for Protection, Control and Auotomation systems. He started his career in power systems with Areva T&D India Ltd. He has worked on various EHV substation de-sign projects throughout India.Currently he is working out of New Jersey as the Regional Technical Manager (ABB Power Grids – Grid Automation) for North East US. In the last 6 years he has been invloved in numerous IEC 61850 projects accross the United States.

BeijingSifang June 2016