Masahiro Kurono

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.

Transient state of polarization in optical ground wire caused by lightning and impulse current

This paper describes a transient state of polarization in an optical ground wire (OPGW) theoretically, experimentally and with field measurements in lightning conditions, which is considered one of the fastest phenomena of polarization fluctuations in the natural environment. These characteristics will be required for optical coherent communication for utilities in future and for application to sensing of lightning with OPGW.

Field measurements and a study of transient state of polarization produced in OPGW by lightning

This paper describes field measurements of the transient state of polarization in an OPGW (Optical Ground Wire) caused by lightning. The polarization state and the polarization diversity characteristics of coherent communication under normal conditions are also discussed. Transient fluctuations of the polarization state were detected 51 times in two half months. These data were identified as due to lightning by comparing the time records with the data of LLS (Lightning Location System) and the records of power line trips. By analyzing waveforms of polarization states, it has been found that the rise time is 0.04 to 0.2 ms, which is consistent with the time-to-crest of the lightning current. The tail of the wave has decaying oscillations of 2 to 5 kHz with durations of 2 to 5 msec. The largest case of polarization shift is 165 degrees, which means that the polarization changes to almost the opposite state. By estimating the locations of lightning by LLS, we were able to confirm that polarization fluctuations are caused by lightning strikes within the range of 60 km from the observed OPGW.

A Proposal of IP-based Computer Network Architecture for Facility Maintenance Information

Abstract – In this paper, we propose IP-based computer network architecture for communications of facility maintenance information. This architecture enables realization of overlay network on the IP network to control the communications. We also examined a feasibility of the architecture with an experiment system. The result shows that the feasibility of the architecture is confirmed. Keywords : Facility maintenance, IP network, Network control, Network management 1. Introduction It is necessary for Japanese electric companies to operate electric apparatus until limit of their performance and life and maintain them with a broad view all over power system. Technologies for condition-based maintenance (CBM) are being researched and developed. It is expected various sensors are allocated in substations and power plants and sensor information is collected across wide area to check electric apparatus, repair them and formulate a maintenance plan in the future. It is effective to realize facility maintenance networks to collect and deliver the information with proof and stability for long time and utilize the information by compiling data in accordance with their usage. The networks are also required to be adaptive to plugging sensors in and out in accordance with secular variation of electric apparatus and collect and deliver their information. Japanese electric companies already have built wide area IP networks to transfer information for their business supporting systems. It is effective for utilizing their existing IP networks as foundation of the facility maintenance networks, which realizes facility maintenance systems. The IP networks enclose information for other application systems including business support systems. Controlling the communications for each application systems has activity on assuring the quality of the communications. It is required for satisfying requirement of the facility maintenance network to build communication control functions for the network. Therefore, Section 2 illustrates the outlines and problems of existing technologies to satisfy the requirements for the facility maintenance network. Section 3 follows by proposing architecture to control communications for facility maintenance information. Section 4, we also examined feasibility of the architecture with an experiment system and the result shows that the feasibility of the architecture is confirmed, before concluding in Section 5.

Consideration of IP Telephony Quality on the IEEE802.11a Wireless LAN

Recently, IP telephony services in wired network are started, and paid attention for its charge-free nature due to IP technology. On the other hand, the Hot-Spot service, which provides one to access the Internet at the public space such as cafe, using the IEEE wireless LAN has been evolved, and it is expected that the IP telephony service on the Hot-Spot network will be developed. However, the IP telephony quality on the IEEE802.11a wireless LAN has not been fully studied yet. In this paper, we discuss about the quality of IP telephony service on the IEEE802.11a wireless LAN from the aspect of R-value, and show ability to improve the IP telephony quality on the Hot-Spot network employing PLC function defined in the ITU-T Recommendation G.711 Appendix I.