access icon openaccess Improved high-speed de-excitation system for brushless synchronous machines tested on a 20 MVA hydro-generator

Synchronous machines with brushless excitation have the disadvantage that the field winding is not accessible for the de-excitation of the machine. This means that, despite the proper operation of the protection system, the slow de-excitation time constant may produce severe damage in the event of an internal short circuit. A high-speed de-excitation system for these machines was developed, and this study presents the continuation of a previously published study. This study presents the design by computer simulation and the results of the first commissioning of this de-excitation system in a commercial 20 MVA hydro-generator. The de-excitation is achieved by inserting resistance in the field circuit, obtaining a dynamic response similar to that achieved in machines with static excitation. In this case, a non-linear discharge resistor was used, making the dynamic response even better.

Inspec keywords: brushless machines; hydroelectric generators; dynamic response; synchronous generators

Other keywords: high-speed de-excitation system; apparent power 20 MVA; field winding; field circuit; computer simulation; hydrogenerator; brushless excitation; static excitation; nonlinear discharge resistor; brushless synchronous machines; dynamic response

Subjects: Hydroelectric power stations and plants; Synchronous machines

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