The objective of this paper is to present the methodology, challenges and results of the transmission master plan of Oman 2014-2030. The main challenges affecting the planning of transmission investments are:

1. Fast growing demand (currently reaches about 10%),

2. High level of uncertainty due to unbundling (generation, transmission and distribution),

3. Peculiarity of the demand (high variation summer/winter, high participation of air conditioning to peak demand),

4. Limitation of place for extension of existing substations,

5. High concentration of demand creating high Short-Circuit Current (SCC) levels, and

6. Relatively strict planning criteria.

Tractebel Engineering and Oman Electricity Transmission Company have developed a methodology to optimize transmission investments in such an environment. It proposes the least cost development plan by first building a transmission network target structure (at 2030) that defines the long term vision of transmission, generation and

distribution companies and that tackles all technical issues. The combination of probabilistic and deterministic models is used to propose the optimal structure. A new 400kV backbone structure is developed. Then intermediate years’ structures (2018, 2020, and 2025) are built by phasing investment identified for the target structure.

Detailed static and dynamic analyses are used. Focus is given to limitation of SCC level, optimal location for compensation means and required investment in SVCs. The results of the transmission master plan are then illustrated focusing on impact of generation location, ways to limit SCC levels, benefits of optimal power flow for planning and operation of the system, impact of planning criteria, etc.