Earlier in the year, Areva T&D won a contract to build a high voltage, gas insulated substation at Al Dhaid in the United Arab Emirates (UAE). The project is significant as it forms part of a plan to interconnect the electricity grids of all the Emirates.

Grid interconnection is a priority for the UAE for all the usual reasons. Interconnection with other grids provides the possibility of sharing resources and improving the provision of electricity to users throughout the region. One authority can import electricity from another as needed, giving the authorities more flexibility in supplying the fast-growing industrial and commercial Emirates with an increased reliability of electricity supply.

In March 2004, Areva T&D won a contract to build a high voltage, gas insulated substation at Al Dhaid which will form part of a plan to interconnect the electricity grids of all the Emirates. Notably, the project also lays the basis for the UAE’s interconnection with the Gulf Cooperation Council comprised of Saudi Arabia, Oman, Kuwait, Qatar and Bahrain. The size of the contract, worth A70 million, reflects the complexity of the project and the amount of high-voltage equipment needed to make the UAE grid interconnection a reality.

The contract was awarded by the UAE’s Ministry of Electricity and Water (MEW), and will interconnect the five UAE electricity authorities, namely the Abu Dhabi Water and Electricity Authority (ADWEA), the Dubai Water and Electricity Authority (DEWA), the Sharjah Water and Electricity Authority (SEWA), the Federal Water and Electricity Authority (FEWA) and the Union Water and Electricity Company (UWEC).


Gas insulated substation manufacturing at the Aix-Les-Bains workshop in France.
Click here to enlarge image

The financing of the project will be broken down with SEWA paying ten per cent of the total costs, ADWEA, FEWA and UWEC each paying 20 per cent and DEWA paying 30 per cent.

Project overview

The UAE interconnection project comprises seven projects throughout the UAE carried out by different companies.

These include the extension of ADWEA’s 400 kV Taweelah substation; the extension of DEWA’s 400 kV H substation; the extension of the Sajja 220 kV substation of SEWA; the construction of the Emirates’ monitoring centre and telecommunications networks, and two projects for 400 kV and 220 kV overhead lines. Gas insulated substation manufacturing at the Aix-Les-Bains workshop in France.

The core of the project is the interconnection substation, which is being built from scratch in the heart of the UAE, not far from the town of Al Dhaid in the Emirate of Sharjah. The substation will be connected to the SEWA network by a 220 kV overhead line; the UWEC network by a 400 kV line to the DEWA network by a 400kV line; which in turn will connect to the ADWEA network by a 400 kV line. The substation is situated in the FEWA grid and connects to an existing 132 kV switchyard nearby.

The MEW employed EDF, the French national utility, as a consultant on the project to establish the scope and technical Gas insulated substation manufacturing at the Aix-Les-Bains workshop in France

The UAE interconnection project comprises seven projects throughout the UAE specifications. As with all such large projects, the initial stages involve the precise definition of the scope and the exact specifications of all the equipment required.

For the Al Dhaid project the role of Areva T&D is one of manufacturer, system designer, installer and project and logistics manager all rolled into one. The main equipment will be manufactured and delivered from several Areva T&D factories and a host of other equipment will be sourced and delivered to the site.

Altogether six different factories/units of Areva T&D are involved in the project. The heart of the substation is the gas-insulated switchgear. The French factory at Aix-les-Bains will design and manufacture ten bays of T155 400 kV gas-insulated switchgear and ten bays of 220 kV B105 gas-insulated switchgear both with spring operated mechanisms. The company’s T155 and B105 models are built with single-phase design welded-aluminium alloy enclosures and feature interrupting chambers in SF6 gas used to isolate and to interrupt the arc in the main chamber.

The French transformer factory at Saint-Ouen, which specializes in the manufacturing of large and special transformer applications, will supply two 500 MVA and two 300 MVA power autotransformers.Their function will be to interconnect the 400 kV line with the 220 kV high voltage electrical networks and the 220 kV line with the 132 kV networks, respectively.

From the booking of the order through to the shipment of the equipment to the Al Dhaid site, approximately 12 months will be necessary to carry out design studies, to purchase the necessary material, to manufacture the tailor-made autotransformers and to perform testing in Areva T&D’s special extra high-voltage factory (EHV) laboratory.

Once fully erected at the site, the largest autotransformers will weigh approximately 450 tons each and will occupy a floor surface of about 200 m2.

The transformers are designed for outdoor use and can withstand the extreme weather conditions inherent to the region i.e. very high temperatures with important variations and sand storms.

Because of their dimensions, the autotransformers will be shipped to site in sub-assembly parts where they will be carefully erected. The largest shipping part will weigh approximately 240 tons. Thanks to the Saint-Ouen factory’s own loading facilities located along the Seine River, the transformers will be easily and safely transported by barge up to the nearest sea harbour.

MEW’s operation and maintenance staff will be trained by Areva T&D specialists in the company’s factories in France and on the Al Dhaid site installation.

The French factory at Lattes will produce the substation’s control system, Space 2000, designed to optimize the substation’s assets, minimize its life-cycle costs and maximize existing investments. The Space 2000 system covers bays and substation interlocking, advanced automation functions, operator interface, supervisory functions such as historical reports, alarms and events handling, primary equipment advance monitoring and Scada interface.

Two 3-phase 220 kV air-insulated surge arresters will also be manufactured and supplied by the factory in Villeurbanne near Lyon. Areva T&D’s zinc oxide (ZnO) surge arresters without spark gaps are perfectly suitable for outdoor use and can be used for special applications ranging from power transformers, capacitor banks, static compensators and filters to protect the equipment from atmospheric and internal over-voltages.


Preparing a three-phase transformer for testing and shipment.
Click here to enlarge image

null

Project execution

The overall organization of the project, from design through to final commissioning, is being carried out by the specialist systems unit based in Levallois and Saint Priest, near Paris and Lyon in France. The unit will organize the shipping of all the equipment to be sent in sub-assembly parts to the Al Dhaid site, representing a total volume of 10 000 m3 and 2900 tons. The systems unit will also organize the civil works at the site, including provision of generators and the installation of ventilation, air conditioning, fire detection, protection systems and all necessary purchasing. Approximately seven or eight Areva T&D engineers will be on site to supervise the erection of the substation and carry out a series of pre-commissioning tests on the equipment.

The project will be finalized in just 22 months and will be broken down into three phases, each lasting approximately seven months. The first phase will consist of engineering studies. The second phase will concentrate on the manufacturing and shipping of equipment and the last phase will focus on civil works, commissioning and testing.

From the preliminary stages of the project until its completion, Areva T&D will interface with a total of five authorities, ADWEA, DEWA, SEWA, FEWA and UWEC, each with their own standards and requirements. The challenge for the company is to provide its customers with a technical solution, which blends all these different needs. This requires broad and expert knowledge of electrical transmission and distribution and an understanding of country-specific standards and norms.