Transmission Expansion Planning Considering an Hourly Demand Curve

This paper discusses the impact that different approximations have on the Transmission Expansion Planning (TEP) problem. Due to the long decision horizons involved, the number of variables can make the problem intractable if approximations to the problem are not made. Furthermore, new emerging technologies and changes in the way we operate our systems are putting under scrutiny some of the approximations usually made to the problem. In this context, this paper evaluates the effect on investment and operational costs of including operational constraints of generators (ramping), transmission losses, and N-1 security constraints on the TEP problem. TEP is formulated as a mixed-integer linear program (MILP). We first validate our analysis using the Garver test system. Then, the importance of including the aforementioned constraints to TEP is tested with the 24-bus and 118-bus IEEE systems. Our results show that additional transmission capacity may be required to satisfy the flexibility requirements caused by net load ramps.