Feasibility study on power feeding system for scientific cable network ARENA

Kenichi Asakawa, Jun Muramatsu and Yuichi Shirasaki

Abstract:

IEEE OES (Institute of Electrical and Electronics Engineers Oceanic Engineering Society) Japan Chapter organized a committee on the underwater cable-network for scientific seafloor monitoring. The committee has proposed a versatile scientific submarine cable network of next generation and showed the technical possibility. The outline of the proposed scientific cable network will be presented in the accompanied paper. In this paper, power feeding system for ARENA will be presented.

For the power feeding system, three method were proposed and compared, that is, (a) constant current (CC) power feeding system, (b) constant voltage (CV) power feeding system, and (c) hybrid system that comprise constant voltage feeding subsystem and constant current feeding subsystem.

The CC power feeding system has many advantages such as (a) robust against cable failures, (b) easy to locate cable fault points, (c) the electric power circuit in the underwater repeaters are simple and easy to be isolated from sea ground. However it is not easy to divide a constant current into two constant current to provide electric power to mesh-like cable network of ARENA. We have proposed a concept of a new current to current converter to overcome this disadvantage.

In case of CV power feeding system, it is easy to provide electric power to mesh-like cable network, but it is not robust against cable failures and it is not easy to locate and detach fault cable portions.

In case of hybrid system, it has both advantages of the two system, but it also has both disadvantages of the two system.

The outline and the comparison of the above three power feeding systems will be presented.

The NEPTUNE Power System: Desin from Fundamentals

Harold Kirkham, Philip Lancaster, Chen-Ching Liu, Mohamed El-Sharkawi and Bruce Howe

Abstract:

This paper describes the process and recounts the decisions that have been made in the design of the NEPTUNE power system. The design process has consisted of a number of top-level decisions based on trade-off studies, followed by a number of more detailed developments based on fundamental considerations of the system needs. The trade-offs included the choice of ac or dc , the choice of a series-connected system vs a parallel one, and the choice of voltage furnished to the user. The system will use a parallel 10-kV dc scheme to deliver power at 400 V to the user. Altogether, around 100 kW can be delivered to the load distributed along the underwater cable, and up to 10 kW can be obtained at any one science node. At the level of fundamental issues, power system operation and protection have been the most challenging, aimed at establishing an appropriate degree of reliability for the network. The controllability and observability of the power system depend on the availability of communication between the power system and the shore stations, and such communication cannot be guaranteed. In the design process, several commonplace assumptions of power engineering have been re-examined and abandoned.