Next-Generation Protection System over Ethernet

In recent years, progress in the development of communication network technology has been very rapid and Ethernet can now be applied to provide the backbone for wide area communication networks. Within this framework a Next Generation Network (NGN) that fuses mobile and fixed communication service interfaces is considered for the integration of a variety of data traffic types. This type of technology is commonly called 'Carrier-class Ethernet', and seems likely to become dominant in NGN networks. In addition, Carrier-class Ethernet enables consideration of the application of Ethernet technology to current differential protection. This presentation describes the global shift to NGN and the trend towards the application of Ethernet technology to protection and control. The presentation also describes the communication technologies currently utilised by conventional current differential protection. The presenter summarizes PDH/SDH/SONET communication technologies and the current methods used by current differential relays to achieve sampling timing synchronisation, for example using a 64kHz synchronisation clock / GPS sampling synchronisation. The presentation also discusses configuration of the next generation protection system over Ethernet. The presenter relates his experience in connecting to a legacy relay system using an X.21 Converter.He reports on the performance of the data communications and the influence of sampling synchronisation on the test results. It is important to consider the application of existing current differential relays to Ethernet, thereby supporting the utility in the transition from legacy communication networks to the Ethernet. To achieve this, the presenter considers the insertion of a converter between the legacy relay and the Ethernet network, to which standards for pseudo-wire conversion such as IETF RFC3985 can be applied. The presenter identifies the critical issues and discusses solutions to the problems experienced in applying Direct Ethernet communications. For example,he suggests a solution to the problem of establishing and maintaining synchronisation between relays. The presentation describes methods of sampling synchronisation such as high-accuracy time control functions including Precision Time Protocol (PTP - IEEE 1588) and the test results of the prototype system using a Layer-2 SW, from which it becomes apparent that the use of Direct Ethernet communications in the application of current differential protection is fully realisable within the near future. This presentation describes the extension of IEC 61850 and relates an implementation in an actual application based on experience gained from the prototype system. Finally, the presenter summarizes the review of substation communications and discusses the potential for applying differential protection over the Ethernet. The extension of the techniques to Wide Area Differential Protection and Stability Control Systems are suggested for the future. The presentation anticipates the advancement of protective performance and describes the ambitions to resolve the outstanding issues in the application of this technology.