Capacity withholding of GenCos in electricity markets using security-constrained generation maintenance scheduling.

• Modeling GenCos' CW in market equilibrium problem considering SCGMS. • Obtaining oligopolistic generation and maintenance schedules, consumption of loads, and nodal prices based on KKT conditions. • Capacity withholding analysis of GenCos using two novel indices WTI and RWLI. • Considering wealth transfer from loads to GenCos to model GenCos' CW impacts on electricity markets. • Introducing RWLI to model GenCos' CW by measuring loss of social welfare. The analysis of capacity withholding (CW) plays an important role in monitoring of the market power. One way of CW in oligopoly electricity markets is the strategic maintenance of generation companies. In this paper, a security-constrained generation maintenance scheduling is proposed using two sets of comparison indices to analyze the CW from the nodal and global points of view. The relative welfare loss index measures the market inefficiency in the form of social welfare loss relative to efficient markets, while the wealth transfer index enables the analysis of wealth transfer from customers to GenCos due to the CW. It is revealed that these indices identify the additional strategic leeway of GenCos due to the maintenance scheduling. Consequently, they can be used by the regulators and independent system operators for the evaluation of CW in the presence of GenCos' strategic maintenance. Focusing on changes in generation, nodal prices, and social welfare, the modified versions of IEEE 30 and 118-bus test systems are provided to demonstrate the robustness and effectiveness of the proposed indices. It is revealed that the price and welfare based measures detect the CW in the context of maintenance scheduling whereas the mere analysis of quantities is not sufficient. [ABSTRACT FROM AUTHOR]