Introduction
In the framework of KM3NeT project (an European project funded under the FP6) devoted to the study of a future "Neutrino Telescope" to be located deep underwater in the Mediterranean sea, we are considering the technical solutions for the transmission of the power required by the off-shore detector from the on-shore laboratory.
The detector will be located in a deep-sea site (3 possible locations can be indicated here at 2500m, 3500m or 5000m depths) at a distance from the shore that can range between 50km and 100km.
We are considering a DC power transmission by a monopolar system with seawater as return conductor. The connection then, between the underwater equipment and the on-shore laboratory, will be assured by a Main Electro-Optical Cable (MEOC) capable to transmit DC current up to a maximum intensity of 10A, allowing a maximum voltage of 10kV.
The power transmission system will be made by two parts:
- on-shore Power Feeding Equipment (PFE): it converts the local available utility power to the medium voltage DC for distribution to the seafloor equipment via the MEOC;
- off-shore DC/DC power converter system: it converts the high voltage to a DC value compatible with the needs of the detector. The converter, that we envisage, has an input of up to 10kV and an output of 400V at a maximum of 25A. The entire power converter will be located on the Sea Bottom (at the depths indicated above) and should be housed in a pressure and corrosion resistant vessel. The thermal equilibrium with the outside environment (?14°C) should be ensured.
The power required by the off-shore equipment varies according to the different detector components and layouts that we are envisaging.
On-shore Power Feeding Equipment technical Characteristics
|
A |
B |
| Power level [kW] |
50 |
100 |
| Local available AC power utility |
400V/3-phase |
400V/3-phase |
| Output DC Voltage level |
50V - 10kV |
50V - 10kV |
| Output DC Current intensity [A] |
5 |
10 |
| Maximum Current [A] |
10 |
10 |
| Efficiency |
>85% |
>85% |
| Ripple |
<1Vrms |
<1Vrms |
Off-shore DC/DC converter technical Characteristics
|
A and B |
| DC Power level [kW] |
8-12 |
| DC Vout at 5.7-10kV input [V] |
400 |
| Output switch off at |
5.2kV input |
| Slow control on from |
4.5kV input |
| Over-current switch off time for I >100A |
30 μs |
| Efficiency at full load |
>90% |
| Undershoot, overshoot at 10-90% of output load |
1.5Vpp |
| Monitor |
Iout, Iin, Uin, Uout |
| Lifetime |
25 yr |
| External ambient temperature [°C] |
13.8-14.0 |
| External Pressure [Bar] |
300-600 |
Manufacturer List
- ALCATEL Submarine Network
Centre de Villarceaux, Nozay
91625 La Ville du Bois Cedex
France
- Danfisik A/S
Mollehaven 31
DK 4040 Jyllinge
Denmark
- Bruker Biospin S.A.
rue de l° Industrie 67166
Wissenbourg Cedex
France
