Martínez Ramos, José LuisBarragán-Villarejo, ManuelCasado Machado, Francisco2025-03-252025-03-252024-12-12Casado Machado, F. (2024). Reduced Referece Frame for AC Systems. (Tesis Doctoral Inédita). Universidad de Sevilla, Sevilla.https://hdl.handle.net/11441/170808The importance of something as fundamental to the electrical engineering as the reference frame used is seldom appreciated. The use of the Park coordinate transformation or the dq reference frame for the analysis of electrical machines, the decomposition into symmetrical sequence components using the Fortescue transformation for the study of asymmetrical short circuits, and the use of the Clarke transformation for the control of power converters are good examples where the use of an appropriate reference system is crucial. However, the above-mentioned classical reference frames manifest their weaknesses when used to analyse and control power in unbalanced three-phase four-wire systems with presence of zero-sequence symmetrical component. For these cases, a third component inevitably appears which complicates the analysis substantially, as well as altering the calculation of instantaneous power in three-phase four-wire versus three-phase three-wire. In particular, the computations related to the control of reactive power. With the aim of addressing these issues, this thesis proposes to use a reference frame, called the Reduced Reference Frame, which adapts to unbalance using only two components. This reduction to two coordinates allows generalisation and simplifies the calculation of power even when the zero-sequence symmetrical component is present. To achieve this, the Reduced Reference Frame is based on the geometric properties that arise from the space vector representation of voltages and currents, specifically in the locus described by those space vectors along time. The Reduced Reference Frame has made other important contributions such as the geometrically based classification for unbalance, the decomposition of an unbalanced system into two rotating sequences, and the extension of the Reduced Reference Frame to multi-phase systems with any number of phases.application/pdf115 p.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccess