Computationally efficient composite transmission expansion planning: A Pareto optimal approach for techno-economic solution

•For fast reliability evaluation, DC approximation based non-iterative DNS/GNS calculation procedure is demonstrated.•Integration of the different sensitivity factors has been proposed to reduce the computational effort.•Islanding detection scheme is incorporated with severe probabilistic N-2 along with N-1 deterministic contingency analysis.•A techno-economic composite TEP methodology for updating the capacity of new/existing transmission lines is presented.•Optimal generation capacity to minimize the investment is proposed to mitigate market power (flatness of buses price).