1 Mar 2002 – Alstom has signed a €23m turnkey contract to upgrade the power transmission network on the Caribbean island of Curacao in the Netherlands Antilles. The contract is with Aqualectra Curacao N.A., the island’s water and electricity utility.

Aqualectra needs to upgrade its existing network in order to be able to receive power from the new Build-Own-Operate Isla power plant, which is due to come into operation early next year.

The utility is planning to take 25 MW of the plant’s 160 MW output, which will allow it to close some of its existing outdated diesel power stations. It therefore needs its existing 30kV network to be upgraded to 66kV.

The turnkey project includes all necessary civil works, installation, tests and commissioning and is due to be completed within 14 months. The Transmission & Distribution (T&D) sector of Alstom will build one 66 kV SF6 gas-insulated switchgear substation with 11 bays, three 66kV/30kV substations comprising several 12kV and 30 kV gas-insulated bays and 66kV cable between the 66kV substation and the 66/30kV substations. The company will also supply eight power transformers (45 to 75 MVA), associated protection and control equipment and auxiliary equipment.

“This is an important project to assure the power supply of Curacao, which is essential for the future development of the country. Alstom will deliver an optimised solution with high-quality products,” said Kurt Hakansson, vice-president of the Transmission Projects Business within Alstom T&D.

Separately, Alstom has launched new protection relays for high-voltage transmission systems that use Global Positioning System (GPS) satellite timing to achieve superior performance in the field.

The MiCOM P545 and P546 are current differential relays, which detect faults by measuring the difference in current between two points on the power line or cable. In order to measure with accuracy, the relays use GPS to obtain the time, ensuring that all relays, wherever they are positioned, are communicating with each other synchronously. If faults are detected, the relays trigger a shutdown of the power line.

In addition, Alstom has announced that, thanks to a unique patented “fallback” technique, the MiCOM P545 and P546 relays are the first in the field that continue to protect the power line even if the GPS signal is lost. For example, the signal may be lost due to “jamming” of a satellite by the military or the disconnection of GPS receiver in any way. This fallback technique allows the relay to continue protecting the power line as normal and will only close down the line if further abnormalities are detected.

This GPS time tagging and the patented fallback techniques give the new relays significant advantages over existing relays, most beneficially where relays are operating over switched-routing communication networks.

When the telecommunications path for signals to and from relays is configured in SONET or SDH (synchronous digital hierarchy) rings, switched-routing occurs, i.e., the signal might use a different path to go and return, which may result in a time delay. Traditional relays assume that the time taken for sent and received signals is equal and therefore any delays caused by switched-routing may cause the relays to maloperate. The MiCOM P545 & P546, thanks to GPS time tagging, calculate this delay and incorporate it into their operation. This means that they are less likely to maloperate and cause an expensive shutdown of a power line.

The MiCOM P545 and P546 join the existing P541 to P544 range of line/cable protection relays, suitable for all voltage levels up to EHV transmission. Full scheme integral distance protection is also available as parallel main or back-up protection in case of communications channel failures.