Eiji Ohba

Present and future ICT infrastructures for a smarter grid in Japan

This paper first provides a vision of a future power delivery and utilization grid in Japan, and reviews the present information and communication technology (ICT) infrastructure for existing power grids. Based on this vision and review, future ICT infrastructure to cope with the significant penetration of photovoltaic generation, legacy communication equipment and aged power assets is proposed for wide-area monitoring and emergency protection and control, demand area secure communications, and ad-hoc and plug-and-play sensing for maintenance. This will enable the renovation of ICT infrastructure for a future Japanese smarter grid.

Application of the IEC 61850 to communication in distribution automation and building energy management systems - Evaluation of the applicability of standard Logical Nodes and Data Objects

To realize smart grid technologies such as load control, load leveling and demand response and solve problems caused by connecting many DERs to a distribution network, a distribution automation system (DAS) and energy management system (EMS) are respectively essential components. The communication of these systems has generally been handled by proprietary or vendor-specific protocols to date. Conversely, in intra- and inter-substation communication, the IEC 61850 has started to gain acceptance in supervisory control communication, due to its interoperability supporting multi-vendor environments. If the IEC 61850 can be applied to communications in DAS and EMS, this is expected to reduce the maintenance and equipment costs of each system. To do so, we must first evaluate the applicability of the IEC 61850 from the perspective of Logical Nodes (LN) and Data Objects (DO), which are data models defined in IEC 61850. This paper focuses on the DAS and building EMS (BEMS) and provides the evolution. We choose BEMSs because we expect many EMSs to be installed in homes or buildings in the near future and anticipate that building energy management functions will include home energy management functions. This evaluation result shows that most data items appearing on such communications can be represented as standard LNs and DOs but several data items cannot be easily represented as the same.

XMPP-based energy management system architecture for communications systems

Generators and power storages for communication facilities for emergency use could get involved in realizing smart grids. Standard protocols of OpenADR 2.0b and IEC 61850 are used for communication to ensure the interoperability of smart grid. XMPP (Extensible Messaging and Presence Protocol) has promise to be applied to the transport layer of both of the standard protocols. In this paper, the authors examine the construction of a common communication platform based on XMPP.

Application of IEC 61850 to the communication of a large-scale photovoltaic power generation operation - Web service and conformance test -

We developed a SCADA server as a prototype to evaluate the applicability of IEC 61850 for the operation of large-scale photovoltaic (PV) generation systems. IEC 61850 and Web-service technology (IEC 61400-25-4) are applied to the data model and the server communication protocol. We also developed a test client for the conformance test, which was then executed. The result showed that the server conformed to IEC 61850 on the data model and protocol. Therefore, the applicability of IEC 61850 to the operation of a large-scale photovoltaic (PV) generation system is confirmed.

Proposal of Reliable and Real-Time Communication Method for SCADA on IP-Based Networks for Next Generation Electric Power Systems

In this paper, we propose a communication method with IP-based wide area networks for SCADA systems. This method controls communications between substations and a control center and can be implemented as a communication middleware. The method supports functions for UDP-based transmission, route control of double route transmission, retransmission control and priority control. The functions work cooperatively to assure reliable and real-time communications. We also examined the effectiveness of the method under circumstances where there are not only transmission delay and route breakdown in network but also information congestion in computer. The results show that the proposed method is more effective for assuring real-time and resilient feature than TCP-based communication method.

Reliability evaluation of power supply system for power utilities' communication system in Japan

This paper presents an unavilability evaluation method of power supply systems for power utility telecommunications and evaluation results using field data. Telecommunication systems in a power utility system have a numerical target of unavailability to be satisfied because they play an important role in power system protection relaying. Recently, switching-type equipment and VRLA batteries have been widely used in Japanese telecommunication power supply systems. To evaluate the unavailability of these systems, the authors developed an evaluation method for a typical configuration of power supply systems and evaluated their unavailability using field data obtained from a questionnaire to 10 power utility companies. As a result of this evaluation, they found that several configurations of the system did not satisfy the unavailability target and changing configuration or parameters are needed. This method can be used not only to confirm the configuration is proper or not but also the case the value of parameters change such as time capacity of engine generators and batteries, inspection intervals etc.