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In this paper, a novel adaptive stator-ground fault protection scheme based on third-harmonic differential voltages is implemented on a lab scale synchronous generator. The lab scale generator is used to emulate the fault characteristics of industrial generators along the stator windings. Simulations based on finite element analysis methods were used to design and tune the laboratory testbed. Experimental results prove the expected fault characteristics as well as fault detection capability of the adaptive stator-ground fault protection scheme. [ABSTRACT FROM AUTHOR]

The paper presents a new adaptive 100% stator ground protection for high-impedance-grounded (HIG) synchronous generators. This is done by first examining reliability, that is, dependability and security of the most prominent conventional 3rd-harmonic voltage schemes. Using field data from various capacity industrial generators, it is shown that the conventional 3rd-harmonic differential voltage scheme, while being dependable, lacks security. Using the same field data, it is shown that the new adaptive scheme is a highly secure and sensitive scheme. Moreover, the new adaptive scheme is a zero-setting scheme which does not require any setting calculations, 3rd-harmonic voltage testings, or additional hardware. [ABSTRACT FROM PUBLISHER]