According to the definition of [1], an ill-conditioned power system can be described as this system which, despite its solution does exists, it is not reachable using the standard Newton-Raphson technique and a flat start. They are ill-conditioned systems building by combining some available cases from Matpower's database (see file MATPOWER_Ill-conditioned_systems.txt for information). These systems have been used in some papers for validating novel Power-Flow techniques. [1] F. Milano, "Continuous Newton's Method for Power Flow Analysis," in IEEE Transactions on Power Systems, vol. 24, no. 1, pp. 50-57, Feb. 2009.

{"references": ["M. Tostado-V\u00e9liz, S. Kamel and F. Jurado, \"Comparison of various robust and efficient load-flow techniques based on Runge\u2013Kutta formulas,\" Electric Power Systems Research, vol. 174, Sept. 2019", "M. Tostado-V\u00e9liz, S. Kamel and F. Jurado, \"A powerful power-flow method based on Composite Newton-Cotes formula for ill-conditioned power systems,\" vol. 116, Mar. 2020"]}