Areva T&D is engaged in a huge project to refurbish and improve the electrical distribution network of western Algeria. The g89 million project reflects the complexity of the work, which involves refurbishing over 600 substations spread out over an area of 26 000 km2.
Algerian state utility Sonelgaz runs both the transmission and the distribution network of Algeria. The grid comprises over 200 000 km of lines, with accompanying high and medium voltage substations. In recent years, the company upgraded its high voltage transmission network, introducing SCADA and dispatching technology in order to control the grid centrally.
The effect of such upgrading has been fewer blackouts and quicker isolation of faults in the system, resulting in a much more reliable service to customers. Sonelgaz, aided by a loan from the Islamic Development Bank, is rapidly advancing on introducing the same kind of technology in the medium voltage distribution network.
Figure 1. The city of Oran, home to the main control centre of the project
The utility has divided the country’s distribution network into four zones: Algiers, Oran, Constantine and the southern zone. The Algiers zone has been partly upgraded and Oran, for which Areva T&D is the contractor, is now well underway. The two other zones are due to be upgraded in the near future.
The Oran project will link 621 distribution substations with four new telecontrol centres: a main control centre in Oran and three secondary control centres in Tlemcen, Sidi Bel Abbes and Mascara. Under the turnkey contract, Areva T&D, formerly the Transmission and Distribution sector of Alstom, is providing all the necessary hardware, software and electrical telecommunications equipment for creating a telecontrolled distribution network. This includes building and equiping the four new control centres, constructing the telecommunications network and refurbishing 621 substations.
The whole project is to be completed within a timeframe of 27 months and with no loss of power during the refurbishment work. These exacting requirements demand a strict and precise way of working, in which Areva T&D has considerable experience.
The company first began working on the project in 2000, preparing the technical bid according to Sonelgaz’s specifications. This was submitted, and in July 2001 Areva T&D was then chosen to be among the last three to bid for the contract. In October 2001, it was selected to carry out the contract and the detailed discussions on exact costs began. The final contract was signed in February and the project came into force in July 2002.
At this point, the commercial team working on the project began the handover to the team that would carry out the project work. The pilot team was put in place to manage the contract and the relationship with the customer and coordinate teams in charge of telecommunications, electrical works, control-command and SCADA. The Electrical Distribution Systems business within Areva T&D is in charge of the project, as it is the business that specialises in distribution projects management.
The teams, the perimeters of their work and how interactions between each team and the client would be handled was established early on in the process. This was crucial, as once work begins, there is no time for errors or oversights.
Areva T&D has established a project office in Algeria. The office serves not only as a central base for the management of the project with the usual phone/office facilities but also as a legal office, necessary for the import of products or the hiring of subcontractors and local staff.
Figure 2. Old switchgear is replaced by the new Fluokit switchgear produced by Areva T&D.
At the heart of the new electrical distribution system is the SCADA system. Areva T&D is installing four control centres, each equipped with SCADA. Essentially, each control centre consists of a large room in the offices of Sonelgaz where a computer system is installed that receives status information from all over the distribution grid.
The SCADA system contains the powerful software for distribution management, e-terradistribution, created by Areva T&D and used in applications all over the world. The system installed allows Sonelgaz to surpervise and control the status of the network from the control centres. Other functions undertaken by the system include fault identification, load-restoring procedures, load-flow calculations, management of work orders and management of information received from customer calls, in addition to an interface with a geographical information system.
The SCADA system communicates with the distribution infrastructure through a telecommunications network. For the project, Areva T&D is installing a radio-based telecommunications solution.
The telecoms system is organized on four levels. The most powerful link is the high-capacity “backbone” that ensures communications between the four control centres, consisting of 7 GHz digital microwave links.
The next level consists of four medium capacity links at 2.4 GHz, based around the four control centres. This network is used for communications between the control centres and the Remote Terminal Units (RTUs) situated in the larger substations. In addition, it is used by Sonelgaz for communications with clients and to communicate with its maintenance staff working in the field via mobile telephones.
A 450 MHz “tetra” system is used for the Sonelgaz office telephone systems and for communications with the smaller substations. Another radio network at 420 MHz is used to relay information from clients’ electricity meters directly to the control centres.
Physically, the telecommunications equipment to make the system work is being installed at the top of pylonssituated in predetermined locations throughout the region. The team carried out a survey of the area to work out how many pylons would be needed to provide total coverage of the area, how high they would need to be and where they would need to be situated. Once decided, they needed to test the soil in each location to establish the depths of the foundations for each pylon. A total of 108 pylons fitted with the appropriate telecoms equipment are being installed in the project.
Figure 3. Areva T&D is refurbishing a total of 621 substations in the Algerian BCC Oran project
So that the distribution equipment can communicate with the new SCADA system, all the region’s distribution substations are being refurbished. The work extends beyond the installation of communication equipment and encompasses a complete refurbishment and upgrade of electrical systems. There are 45 high voltage (HV)/medium voltage (MV) and MV/MV substations and 585 MV/low voltage (LV) substations to be refurbished.
In each of the 45 HV/MV or MV/MV substations, Areva T&D is installing new switchgear, either PIX or DNF7 brands produced by Areva, depending on the substation ratings. These substations are then fitted with RTU, Areva’s MiCOM S10. The MiCOM S10 is a computer that controls all the functions of the substation and can be remotely interrogated and controlled via a telecoms link from the appropriate control centre.
In the 585 MV/LV substations, Areva T&D is installing M24 or M36 switchgear and an ITI, which is a micro version of an RTU. Some 315 of these substations will be telecontrolled from the control centre and 270 of these will have telesignalling capabilities, that is, they will not be directly controlled but will transmit system information to the control centre.
Sonelgaz also wants to have automatic metering installed at some of its larger customers’ sites, so Areva T&D is installing electronic meters at 380 sites, which relay information to the control centre on the amount of electricity consumed by each customer.
The team is also installing 335 pole-mounted switches around the distribution network. These allow Sonelgaz, in the event of a fault, to disconnect lines on the network directly from the control centre.
Areva T&D is charged with carrying out this work without significant disruption to the network. As it takes several days or weeks to refurbish each substation – depending on the size – the team is using mobile back-up substations, which are connected to assure the electricity supply while work is carried out. As soon as the mobile substation is connected, the team will disconnect the substation, take out the switchgear, disconnect the transformer, carry out any general repair work such as reconcreting and painting, install the new switchgear, cabling and other equipment, reconnect the transformer and test that everything works.
Sonelgaz is present for both disconnection and reconnection, and the utility commissions each refurbished substation.
The project is due to finish in November 2004, at which time Areva T&D will hand over the system to Sonelgaz. The final handover will take place two years later, and between times Areva T&D will work with Sonelgaz to ensure that the system performs exactly as expected.