1 Towards formalized test specifications for IEC 61850 Christof Brandauer, Georg Panholzer Salzburg Research {firstname.lastname}@salzburgresearch.at Salzburg, Austria Stephan Pietsch Testing Technologies IST GmbH pietsch@testingtech.com Berlin, Germany Abstract This paper is concerned with testing in the context of IEC 61850. Currently, a paper and pen method is used to create prose descriptions of test cases in a table-based template. The test cases, while still remaining on an abstract level, could be significantly enhanced by adding more detail and making use of a (more) formal specification language. To this end we have studied other approaches to (conformance) testing, in particular TTCN-3 which is an open, standardized testing technology. In the paper it is demonstrated how existing UCAIug client tests are mapped to abstract TTCN-3 test cases. With the addition of SUT-specific adapters these test cases are then executed against a commercial IEC 61850 client implementation. Finally, we contrast this approach with an UML-based test development methodology. 1. Introduction The inter-dependent processes of data acquisition, communication and (often automated) control of the smart grid are highly complex and stringent requirements in terms of correctness, standard conformance, interoperability, performance, and security are imposed on the components involved. Testing must play a major role in meeting these requirements – not least because the electric grid is a (if not the topmost) critical infrastructure. Our studies on the current state of testing are focused on the multi-part standard IEC 61850. Its development started in 1994 with the goal of developing a comprehensive world-wide standard for the design and operation of substation automation. The main requirements were to advance beyond a growing set of proprietary, incompatible and non-comprehensive approaches to communication solutions in substation automation and to define a global standard that facilitates interoperability and integration. While the initial focus was on the electric substation, the standard has since been extended in several directions and is nowadays employed more broadly for general power utility automation tasks. Part 10 of IEC 61850 is dedicated to conformance and performance testing. A conformance test has to include documentation and version control (IEC 61850-4), configuration (IEC 61850-6), data model (IEC 61850-7-3 and -7-4) and mapping of ACSI models and services (IEC 61850-7-2). Moreover, the testing “ecosystem” is explained including how to certify a tester. Part 10 identifies the areas to be tested (e.g., association, reporting, etc.) and introduces 167 server test cases for the ACSI mapping, all of which are mandatory if supported by the system under test (SUT). The positive and negative test cases are briefly described. Based on this framework, the testing subgroup of the Utility Communication Architecture International user group (UCAIug) elaborated more detailed test procedures for servers as well as clients, performance of fast event distribution with Generic Object Oriented Substation Events (GOOSE) and extended server reports. As a common denominator, all these test cases are described in prose using the table template as required by IEC 61850-10. Figure 1 shows a simple client association test case. Such brief prose descriptions naturally leave a lot of room for interpretation and many aspects of the test, some of which have certainly been in mind by the test developers, are not present in the test cases. As an example, it is not specified how to verify that the association has indeed been established. Where are the Points of Observation and Control? What exactly are the criteria against which the expected Associate.response + reply has to be matched? Which protocol fields are required? Do some of them need to contain specific values? Which are irrelevant for the given test? It is obvious that the test cases, while still remaining on the abstract level, could be significantly enhanced and formalized. We have thus studied other approaches to conformance testing with a special focus on communication protocols.