Interconnections between neighboring utilities are becoming increasingly vital for the implementation of an open energy trading market and to increase the reliability of power systems. The power utilities of the Arab countries in North Africa and the Middle East have made considerable investments in extending transmission system interconnections and power-transfer corridors at various voltage levels to facilitate the cross-border trading of electric power. Progressive development of interconnections, either between neighboring countries or within separate island power systems in one country, can be affected by the distances separating capital cities, power pools, population density and the Sahara Desert.
The interconnection between power systems benefits neighboring utilities. It takes advantage of the diversity factor or time difference of peak load periods on national systems, defers foreseeable investment in generating and operating costs, reduces the rate of system outages, enhances reserve margins and supply security, thus improving reliability. However, this is not always the case when the systems are geographically separated by large distances and are not designed with a meshed structure.
Libya's Power System
The General Electric Company of Libya (GECOL) is totally government owned and is responsible for the operation of the entire power sector in the country, supplying the electrical energy needs to the total population in Libya. With a population of 5.2 million, Libya is a 100% electrified country and has a current electricity consumption of 1900 kWh per capita. The county has a land area of 1.76 million sq km (679,540 sq miles), which is almost seven times the size of Great Britain, and forms part of the North African continent where less than 10% of the African population has an access to electricity supply.
The annual average consumption per capita in the Black Continent is around 500 kWh, which is considered relatively low compared to the world average of 2250 kWh. Chad, which borders Libya on the southern boundary, has a consumption of 15 kWh per capita, the lowest value in Africa and probably in the world.
The total installed capacity within the Arab countries is now 79,000 MW, with annual energy production of 276 TWh. The overall power demand is increasing at the rate of 7% per year, supplying a population that has an average consumption of 1400 kWh per capita.
The power system in Libya is constituted of four geographically well-dispersed, totally interconnected major island systems. The transmission system is supplied via 30 generating plants, mainly simple-cycle gas-turbine plants and steam units with some diesel generators located in rural areas of the Libyan Desert. The prime fuels used are natural gas, residual fuel oil and distillate. The transmission system comprises a huge length of transmission lines operating at various voltage levels:
The current transmission voltage is 220 kV, with a total circuit length 11,700 km (7313 miles).
The sub-transmission voltage level is 66 kV, with a total circuit length of 12,500 km (7813 miles).
The distribution networks use voltages of 30 kV and 11 kV.
With a load-growth rate averaging 8% per year, GECOL produced a master plan to upgrade the transmission system to 400 kV. The utility surveyed the first project in the program and awarded contracts for a 430-km (269-mile), 400-kV double-circuit transmission line. This line will connect Homs Power Plant — a Mediterranean coastal city close to the famous historical Greek city of Greater Lipts Magna — with the Man Made River Substation deep in the desert.
In the past five years, GECOL has commissioned five simple-cycle gas-turbine power plants, each equipped with four 165-MW gas turbines supplied by ABB. Four of the plants located on the Mediterranean coast are designed for future upgrading to combined-cycle operation.
As part of its generation-expansion plan, GECOL will construct two new power plants. A steam-thermal plant, which will be located at the Gulf of Sirt on the Mediterranean coast, has a planned capacity of 1400 MW (four 350-MW units). GECOL has not awarded the contracts for this plant.
GECOL awarded ENEL POWER the contract for the second power plant, West Mountain, located in the mountainous region in northwest Libya. Construction of this four 150-MW gas-turbine power plant is underway.
The GECOL infrastructure plan for upgrading the transmission system and increasing the installed generating capacity represents a large investment for the utility. The scheduled investment over the next five years is US$3.3 billion for generation and an additional US$1.8 billion for transmission system capacity.
North African Interconnectors
Libya is a large country that shares borders with six neighboring countries, four Arab states (Egypt, Sudan, Algeria and Tunisia) and two African states (Chad and Niger). Currently Libya is only electrically interconnected with Egypt at the east network boundary where energy has been exchanged through the tie line since the circuit was commissioned summer 1999. This interconnector was constructed as a double-circuit 220-kV line connecting Tobruk Substation in Libya, approximately 150 km (94 miles) inside the border, with Salum Substation in western Egypt. The 220-kV transmission line extends 165 km (103 miles) and is capable for the commercial trading of 200 MW in either direction. This line extends across the Egyptian desert another 350 km (219 miles) before it reaches areas of dense energy consumption and the load centers of the Mediterranean city of Alexandria. Therefore, the overall length of the transmission line is considered a 500-km (312.5-mile) circuit.
The power system of the Egyptian Electricity Authority (EEA) is interconnected on the eastern boundary of the country with the Jordanian system through a 500-kV circuit that links the two countries via overhead lines and a submarine cable crossing under the Bay of Aqaba in the Red Sea. Jordan is electrically interconnected with Syria, whereas Syria is about to be linked with the eastern boundary of the European grid (UCTE) via Turkey.
Tunisia and Algeria border Libya's western boundary, but until now, there has been no power-system interconnections between these two countries. However, the Tunisian and Algerian power grids are interconnected with two links, and Algeria is interconnected at its western border with Morocco, which is connected with Western Europe via Spain.
The 400-kV AC link with Spain, comprising transmission lines and a submarine cable under the Straits of Gibraltar, connects Mellousa Substation in Morocco with Pinar del Rey Substation in Spain. The “missing link” is the Libya-Tunisia interconnection, which will close the loop of the Mediterranean Basin countries when commissioned.
GECOL and the Tunisian utility STEG (The National Company of Electricity and Gas) awarded KCL of India the transmission line contracts to construct two 220-kV transmission lines that will connect the two power systems.
The first 220-kV circuit — The Coastal Line — is a double-circuit, single conductor (CROCUS/Redwing 412 sq mm [0.64 sq inches]) transmission line that will interconnect Abukamash Substation in Libya with Madneen and Abushama substations in Tunisia. This circuit, which has a route length of 380 km (236 miles), 26 km (16 miles) in Libya and 354 km (220 miles) in Tunisia, is currently in an advanced stage of construction as commissioning is scheduled for October 2002.
The second 220-kV circuit — The Sahara Line — is a single-circuit (CROCUS/Redwing 412 sq mm [0.64 sq inches]) transmission line that will connect Rouais Substation in Libya with Tataween Substation in Tunisia. The total length of this circuit is 298 km (185 miles) — 37 km (23 miles) in Libya and 261 km (162 miles) in Tunisia — and is scheduled to be commissioned by the turn of the year 2003.
ABB supplied and installed the equipment in the Libyan substations at Abukamash and Rouais when first commissioned. The utility awarded Siemens the contract to carry out the required modifications associated with the two interconnections, work that includes supervisory control and data acquisition (SCADA), remote thermal units (RTUs) and the protection equipment linked to the fiber-optic system.
The estimated cost of this major project is US$57 million, funded in part by local currency, the remainder in U.S. dollars.
The Arab Union of Producers, Transporters and Distributors of Electricity (AUPTDE), and Mediterranean Liaison Committee (MEDELEC) was restructured in 1991. During a meeting in Algeria in 1995, the Mediterranean countries of Northern Africa and South Europe formed EMATLIE, an expert group of seven electric utility chairmen from Spain, Morocco, Algeria, Tunisia, Libya, Italy and Egypt.
The group's main objectives are:
To exchange technical knowledge.
To consider the possibility of reinforcing the existing power grids.
To analyze the static and dynamic behavior of new interconnections.
To encourage and develop the energy market.
To establish suitable defence plans.
EMATLIE-established technical committees have conducted many studies and forecast huge benefits in terms of fuel cost savings as a result of the existing and planned links. A comparison between the operation of interconnected networks and separate power systems indicates that this benefit will be 4% per year, somewhat less than the benefits available to the southern European countries that are extensively interconnected.
Labib Daloub received a degree in electrical engineering from Malta University in 1979 and joined SOE, the electric utility of Libya, where his positions included generation, transmission planning, distribution and consultancy. After receiving the PhD from Bradford University in England, he returned to Libya and joined GECOL as a technical advisor.