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This paper provides a new methodology to compute a reduced but efficient set of candidate lines in a transmission expansion planning (TEP) context. Considering this reduced set of candidate lines should lead to similar investment decisions as if all the possible ac and dc candidate lines that could be installed in the network were considered. A first “hybrid” relaxed TEP problem is solved. Based on this initial solution, a new relaxed TEP problem is iteratively solved in which the dc load flow (DCLF) model is enforced to a certain extent in the partially expanded ac corridors. Once a convergence threshold has been reached, an upper bound of the number of candidate ac and dc lines to install in each corridor can be defined. This process results in a compact search space. Our algorithm has been implemented in General Algebraic Modeling Software (GAMS) and has been tested on a case study based on the European power system. The method produces very promising results and in the considered case study, leads to a very efficient investment. [ABSTRACT FROM AUTHOR]

The marginal value of transmission lines in the dispatch is widely used in the literature and has relevant practical applications related to planning the expansion of the transmission grid and computing the remuneration of merchant lines. This paper presents a general formulation of the marginal value of a line in the dispatch that highlights the dependence of this value on the link between line admittance and capacity. We discuss the value of a line according to marginal principles following a general approach and prove that only if the admittance of a line can be expressed as a linear function of its capacity, or when admittance and capacity can be deemed independent, is this value equal to the product of the difference between marginal electricity prices at both ends of the line and the flow through this line. Afterwards, we show that under a set of stylized conditions the remuneration of efficient network investments according to their marginal value in the dispatch should result in an exact recovery of their cost. Finally, we compute the marginal value of lines in a stylized, though representative, system for several relationships between line capacities and admittances to illustrate the theoretical results obtained. [ABSTRACT FROM PUBLISHER]

Parties to the Internal Electricity Market of the European Union (IEM) decided in 2001 to abolish the method of pan-caking of transmission tariffs for cross-border transactions that was originally in place. Instead, they have agreed to implement a system whereby national transmission tariffs provide access to the entire IEM. This system is supplemented by a scheme of inter-TSO payments. However, conflict may arise if the compensation that a country must pay another one is not in accordance with the electrical usage that the former is making of the grid of the latter. For instance, Inter TSO Compensation methods (ITC methods) implicitly allocate the cost of any existing or new transmission line. Therefore, the adoption of an inefficient method may be an obstacle for building some needed regional grid investments. Consequently, one should give careful consideration to the selection of the ITC method. This paper analyzes, both qualitatively and quantitatively, the implementation of the most relevant ITC methods that have been considered so far in the European debate. When assessing each method from a conceptual point of view, considerable attention is devoted to the critical examination of its main underlying assumptions. [ABSTRACT FROM AUTHOR]