By Mr. Philippe Morin, MSc, CEng, MIET, MIEEE Executive Chairman, Public Utilities Corporation, Republic of Seychelles and Mr. Suresh Vishwakarma, IEng, MIET, MBA, Principal Engineer Public Utilities Corporation, Republic of Seychelles

Seychelles is one of the world’s most beautiful archipelago located 4^O South of the equator in the western part of the Indian Ocean, North of Madagascar and 1593 Kms east of Mombassa, Kenya. Seychelles has no equal simply because of the purity of its islands and is commonly known as “Paradise on Earth” or the “Pearl of the Indian Ocean”. There are 115 islands in the entire archipelago out of which habitation is limited to only 10 islands. Majority of the total 455 sq km of land area is conserved as national parks and reserves. The capital city of Seychelles is Victoria which is on the main Island – Mahe.

IMPORTANCE OF SEYCHELLES

The case of Seychelles is particularly important and sensitive because of the existence of exotic plant and animal species, which are unique to the island, namely the giant Coco-de-Mer palm which lives for a 1000 years and is found nowhere else in the world. The above gift of nature has naturally bestowed upon its dwellers the responsibility of ensuring its everlasting beauty of green hillsides, clear seawater and sparkling white sand, which will continue to lure tourist all over the world and enrich its economy. With its unique flora and fauna, it is one of the most environmentally conscious countries on earth, with eco-tourism as one its key exports.

FRAGILE ECO SYSTEM

Intended to protect the beautiful but fragile eco system, the majority of the nation’s land is conserved as National Parks and Reserves. There have been major efforts by Government & NGOs to conserve the precious natural treasures and the country is a signatory to various International Conventions, such as Basel, MARPOL, IFCS, and PIC etc.

HISTORY OF ELECTRICITY IN SEYCHELLES

The history of electricity in Seychelles began long ago in year 1925 with the formation of a small private company – the Societe Cooperative d’Electricite Ltd.

In year 1926, power station at Huteau Lane in the capital city Victoria (Mahe) was constructed. Upon installing necessary plant and equipment, the Societe Co-operative supplied DC electricity generated by a 30 kW dynamo to private houses on Mahe. Electricity was available daily only from 6:00 pm to 6:00 am.

By the year 1940, Huteau Lane power station had an installed capacity of 300 kW, DC. The station operated from dusk to dawn with little growth in electrical power demand until 1960.

In year 1960, a Government utility company – Seychelles Electricity Corporation Limited was formed.

The Huteau Lane power station was upgraded to accommodate AC generators and in year 1961 a full 24 hours supply was available to 613 consumers.

By year 1970, the Huteau lane Power station acquired installed capacity of 3,380 kW and generation & distribution voltage was 6,600 Volts.

Construction of new power station began at New Port in the year 1971 and was operational in the year 1972 with installed capacity of 7.5 MW. Capacity of this power station was increased by installing new generator sets in 1978,1980,1986,1990 and 1998. Present available capacity is 16 MW.

In the year 1986, a government owned corporate body – Public Utilities Corporation (PUC) was formed subsequent to the merger of two previous parastatals, namely the Seychelles Water Authority and Seychelles Electricity Corporation Limited. PUC is responsible for providing the islands of Seychelles with electricity, water and sewerage services.

Construction of another modern power station began in 1999 at Roche Caiman that became operational in the year 2000 with installed capacity of 43.5 MW. Huteau Lane Power Station became non-operational upon commissioning of the Roche Caiman Power Station. The sets operate on Fuel Oil and waste heat is recovered for fuel treatment and purification of lubricating oil.

Available generating capacity on Mahe is 60 MW and the peak demand is 38MW.

Independent generation started at Praslin in the year 1981 with initial generating capacity of 2 MW. Capacity of this power station was increased by installing new generator sets in 1990, 1996 and 2003. Operation of the sets is on Diesel Fuel. Present available capacity is 12 MW and peak demand is 5.5MW.

Owing to its considerably small land area, limited electricity demand, remote location, restricted resources and being an environmentally sensitive nation, the most feasible and environmentally compatible mode of electricity generation in Seychelles is through diesel generators. Other modes of generation e.g. Coal, hydro, nuclear are not commercially and environmentally feasible to this small island nation.

PUBLIC UTILITIES CORPORATION OF SEYCHELLES

PUC – Electricity Division comprises of two main sections: Generation and Transmission & Distribution. The Generation Section is responsible for safe and continuous production of electricity. There are 3 diesel-based generating stations based on Mahé and Praslin Islands. The Transmission & Distribution Section manages an integrated 33 kV / 11 kV distribution network on the island of Mahé and 11 kV network on Praslin and La Digue Islands. In addition, it provides an inspectorate service to the public to ensure that a high standard of electrical wiring is maintained in all installations.

The average annual growth rate in electricity demand for Mahe, Praslin and La Digue is approximately 5.2%. The recorded maximum electricity demand for Mahe is 38 MW, whilst that for Praslin and La Digue combined is 5.2 MW. Transmission of electrical power is achieved through the 33 kV network. This network transmits electrical power at a voltage of 33 kV from the Generating stations on Mahe to the 33/11 kV sub-stations at Anse Boileau and Huteau Lane. From there, the voltage is stepped down to the 11 kV required for distribution through 33 kV / 11 kV transformers.

The graph below indicates the growth of medium voltage network in Seychelles during past years. The current route length of overhead medium voltage network is 243.34 Kms whereas the length of underground medium voltage network is 125.7 Kms

The number of connected consumers at the end of 2006 was approximately 28 000 spread over 10 islands.

As indicated in the pie chart below, majority of the electricity customers are under domestic category. Only 10% of the customers are under industrial and commercial category.

The pie chart below indicating category wise consumption of electricity in the country indicates that industrial and commercial customers shares 42 % of the total electricity consumption.

T&D NETWORK CHALLENGES

There are several major constraints that the electric utility faces in upgrading or extending its network:

• Due to the geographical location and topography of the island, it is tough to extend network through remote areas, valleys and hills. Land area is limited and major portion is protected as natural reserve
• Environmental laws do not permit stringing wires or cables at quite a few places that may endanger the scenic beauty of islands
• The process of organizing all the required resources is fairly lengthy and onerous, since each and every item needs to be imported.

MAJOR ONGOING PROJECT: REINFORCEMENT OF T&D NETWORK IN SOUTH MAHE

The transmission system for South Mahe comprises of a single circuit 33 kV overhead line between Roche Caiman Power Station and Anse Boileau 33 /11 kV Sub-station. Electricity to entire south Mahe is distributed from Anse Boileau Sub-station.

In view of the upcoming infrastructure and continually increasing electricity demand, the existing 33 kV as well as 11 kV Distribution network in South Mahe has now been demanding continuous reinforcement and upgrading especially during past few years. During last ten years itself, apart from the extension of educational complex, many big hotels & tourism establishments have come up demanding for bulk supply of power in addition to the high index of system reliability. As per reports in addition to the various big housing projects, as many as 6 large tourism establishments shall be developed in next 5 years.

The existing maximum demand of 10 MW of South Mahe is likely to double in next 5 years. The existing system shall not be able to cater the upcoming demand since it is already operating beyond its rated capacity. The voltage profile at remote end is beyond the acceptable limits. Apart from reinforcement of 33 kV network, the existing 11 kV network of South Mahe also demands upgrading.

PROPOSED DESIGN FOR REINFORCEMENT OF T&D NETWORK

In the above scenario, it is required to build a new transmission and distribution network from Roche Caiman Power Station to Anse Boileau via East Coast and extension of the existing 33 kV network from Dugand to Port Launay via Port Glaud as soon as possible. The under-noted design is being implemented to reinforce and upgrade the existing 33 kV transmission and distribution network on Mahe Island.

• Installation of one 33 kV underground circuits using between Roche Caiman Power Station and Quatre Bornes with the provision of new 33 kV sub-stations at Providence Industrial estate, Seychelles International Airport, Anse Royale and Quatre Bornes. The work entails installation and commissioning of one 4.5 km of 33 kV, 3x1Cx240 mm² Aluminium underground cable network from Roche Caiman to Providence. Additionally one 11 kV, 3x1Cx150 mm² Aluminium XLPE cable network insulated to IEC standard would also be installed along the same route
• Installation of one 33 kV underground circuit between Quatre Bornes Sub-station and Anse Boileau substation with the provision of new 33 kV sub-stations at Takamaka, Baie Lazare, and Anse La Mouche and up gradation of Anse Boileau sub-station. The work entails installation and commissioning of 14.3 km of 33 kV, 3x1Cx240 mm² Aluminium underground cable from Quatre Borne Sub- Station to Anse Boileau Sub-Station passing through the proposed 33 kV sub-stations at Takamaka, Baie Lazare, and Anse La Mouche
• Installation of one 33 kV underground circuit between Roche Caiman Power Station and Turtle bay and then a dual circuit overhead network from Turtle bay to Anse Boileau substation to increase the power transfer capability and transmission network security in the event of breakdowns on the system. The overhead work entails the installation and commissioning of a dual circuit 6.5 km of overhead bare conductor network of 100 mm² AAAC from Turtle Bay to Anse Boileau
• Extension of the existing 33 kV overhead line from Dugand to Port Launay via Port Glaud. Overhead circuit from Dugand to Port Glaud and then Underground circuit from Port Glaud to Port Launay Sub-station. The overhead network entails the installation and commissioning of one 3.9 km of 33 kV overhead bare conductor network of 100 mm² AAAC from Dugand to Port Glaud. The underground work entails the installation and commissioning of one 2.4 km of 33kV, 3x1Cx240 mm² Aluminium underground cable network from Port Glaud to Port Launay
• Replacement of ageing equipment on existing 33 kV network to facilitate interface with the new system to the existing one. This involves replacement of existing Isolators, faulty Insulators, rusted conductor and damaged cross arms. Additional ground earth will also be provided wherever necessary
• Installing a new SCADA system at the generating station to monitor and control the existing and proposed transmission and distribution feeders.

EXISTING AND PROPOSED T&D NETWORK AT SOUTH MAHE

ADDITIONAL BENEFITS IN FURTHER REINFORCING OF 11 KV NETWORK IN SOUTH MAHE

Upon commissioning of new 33 / 11 kV Sub-stations at Takamaka, Baie Lazare, and Anse La Mouche and up gradation of Anse Boileau sub-station, it would be quite convenient to create new 11 kV feeders from various Sub- Stations to relieve load on existing feeders, particularly in those areas where developments are underway and electricity demand is going to increase.

CONCLUSION

The environmentally compatible Transmission & Distribution model that is being successfully implemented and practiced in Seychelles is a culmination of understanding of the intricate relationships between socio-economic development, technological advancements and environmental protection. Successful and effective establishment of equilibrium between environmental protection and electricity transmission & distribution development in the Seychelles could be very well taken as a universal blueprint especially for the tropical islands of the world with limited resource.