Alan Šala

Determination of Load Angle for Salient-pole Synchronous Machine

Determination of Load Angle for Salient-pole Synchronous Machine This paper presents two methods for load angle determination for salient-pole synchronous generator. The first method uses optical encoder to detect the rotor position. In some cases the end of the rotor shaft is not free to be used and mounting of an encoder is impossible. Therefore, the second method proposes estimation of the load angle based on the measured electrical values that have been already used in excitation control system of the synchronous generator. Estimation method uses corresponding voltage-current vector diagram and parameters of the synchronous generator, transformer and transmission lines. Both methods were experimentally verified on the digital control system and synchronous generator connected to power system. The estimation and measured results were compared. The accuracy of load angle estimation method depends on voltage and current measurement accuracy as well as generator, transformer and transmission line parameter accuracy. The estimation method gives satisfactory accuracy for load angles less than 120° el. Thus, it can be applied in excitation control system to provide stable work of synchronous generator in under-excitation operating area.

Bilateral direct comparison of Josephson array voltage standards of the PTB (Germany) and PEL (Croatia): Draft B report for EUROMET.EM-S28

A comparison of the 10 V Josephson array voltage standard of the Physikalisch-Technische Bundesanstalt (PTB), Germany, was made with that of the Primarni Elektromagnetski Laboratorij (PEL), Croatia, in April 2007. The results are in very good agreement and the measured overall relative combined standard uncertainty is better than 1 part in 1010. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).