Modeling and design of a power thyristor-based industrial arc-flash quenching device

• Autor(a) principal: Fernando Venâncio Amaral
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/50766
• topic: Industrial power systems; Substation protection; Electrical safety; Arc-flash; Thyristors; Engenharia elétrica; Sistemas elétricos de potência; Subestações elétricas; Tiristores

Since arcing faults in power systems started being recognized as a hazard in the industry, solutions have been proposed to the mitigation of its effects on equipment and personnel. The most recent rely on a power electronics-based switch, composed by two antiparallel thyristors connected in series with a current-limiting impedance, that is immediately operated when an arcing fault is detected by a relay in a busbar of a switchgear or motor control center, quenching the arcing path in a time interval of the order of microseconds and practically annulling the incident energy. The design and / or specification of these elements is not a simple task, being dependent on many variables like the short-circuit power and ratio and the existing upstream protective devices. The main contribution of this dissertation is the proposal, development and test of a solution that handles this concern, in full voltage and current levels. Two specific points can be highlighted: (i) a theoretical study useful for the prediction of the ride through capability of power thyristors submitted to high single- and multi-cycle ac, power frequency current surges with different amplitudes among consecutive cycles, which is not a standard data sheet test condition that can be readily used; and (ii) the analysis and proposition of fundamental guidelines to the design of a current-limiting impedance so that the surge current through the electronic switch and the upstream power system is reduced still guaranteeing that the arcing fault is safely eliminated. Both (i) and (ii) are validated by simulation and experimentally. Contributions on the discrete-time modeling of an internal arcing fault are also given.