  This paper presents a techno-economic optimisation tool to study how the
power system expansion decisions can be taken in a more economical and
efficient way, by minimising the consequent costs of network reinforcement and
reconfiguration. Analyses are performed to investigate how the network
reinforcement and reconfiguration should be planned, within a time horizon of
several years, by continuously keeping the network feasibility and ability to
satisfy the load. The main contribution of this study is the inclusion of key
features within the mathematical model to enhance the investment decision
making process. A representative maintenance cost of existing cables and
apparatus is included, to analyse the influence of the historical performance
of the electric items on the investment decisions. A multihorizon methodology
is developed to take into account the long term variation of the demand,
combined with the long term variation of cables maintenance costs. Moreover,
technological learning coefficients are considered, to take into account the
investment costs reductions that arise when an investment in network
restructuring and/or reconfiguration is repeated throughout the years. Finally,
construction time constraints are included to find a proper investment
scheduling that allows a feasible power flow, also during the years required to
build a new connection or restructure an existing one. This study is also
providing recommendations for future research directions within the power
system reliability field. The analyses show the important and urgent need of
proper methodologies for a better definition of cables projected maintenance
costs and learning coefficients dedicated to network restructuring,
reconfiguration and expansion.
