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Badania eksperymentalne prostownika osiemnastopulsowego o mocy 150 kVA z opcjonalnym szeregowym energetycznym filtrem aktywnym

Mysiak P., Śleszyński W., Cichowski A., Wyrzykowski L., Kolan P.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

2016

Nr 50

67--70

W artykule przedstawiono system sterowania oraz wybrane wyniki badań eksperymentalnych przekształtnika AC / DC składającego się z osiemnastopulsowego diodowego prostownika na bazie dławików sprzężonych i szeregowego energetycznego filtra aktywnego. Przebadano i porównano trzy konfiguracje przekształtnika o mocy 150kVA: (1) osiemnastopulsowy prostownik bez dodatkowych elementów, (2) prostownik z dodatkowym dławikiem sieciowym oraz (3) prostownik zintegrowany z szeregowym filtrem aktywnym. Zastosowana metoda sterowania filtrem aktywnym znacznie zmniejsza zniekształcenia harmoniczne oraz asymetrię prądów sieci, co jest szczególnie korzystne w przypadku niskich obciążeń i nieidealnego napięcia zasilającego.

The paper presents the control system and selected results of experimental tests of the ac/dc power converter consisting of 18-pulse diode rectifier on the basis of coupled reactors and a serial active power filter. Three configurations of the 150kVA converter were tested experimentally and compared: 18-pulse diode rectifier with and without additional grid reactor and the rectifier integrated with the active power filter. The highest current harmonic distortion and asymmetry exists for individual operation of the rectifier. Connecting a supplementary grid reactor to a rectifier significantly reduces harmonic distortion and unbalance of the grid current, especially in the nominal load conditions. The 18-pulse diode rectifier integrated with S-APF outperforms other configurations in grid current balancing and harmonic suppression, which is particularly advantageous at low loads and non-ideal supply voltage. The integrated system has additional features like dc voltage regulation, low susceptibility to supply asymmetry and load changes.

Over 38 000 RR Lyrae Stars in the OGLE Galactic Bulge Fields

Soszyński I., Udalski A., Szymański M. K., Pietrukowicz P., Mróz P., Skowron J., Kozłowski S., Poleski R., Skowron D., Pietrzyński G., Wyrzykowski L., Ulaczyk K., Kubiak M.

Acta Astronomica

2014

Vol. 64, No. 3

177--196

We present the most comprehensive picture ever obtained of the central parts of the Milky Way probed with RR Lyr variable stars. This is a collection of 38 257 RR Lyr stars detected over 182 square degrees monitored photometrically by the Optical Gravitational Lensing Experiment (OGLE) in the most central regions of the Galactic bulge. The sample consists of 16 804 variables found and published by the OGLE collaboration in 2011 and 21 453 RR Lyr stars newly detected in the photometric databases of the fourth phase of the OGLE survey (OGLE-IV). 93% of the OGLE-IV variables were previously unknown. The total sample consists of 27 258 RRab, 10 825 RRc, and 174 RRd stars. We provide OGLE-IV I- and V-band light curves of the variables along with their basic parameters. About 300 RR Lyr stars in our collection are plausible members of 15 globular clusters. Among others, we found the first pulsating variables that may belong to the globular cluster Terzan 1 and the first RRd star in the globular cluster M54. Our survey also covers the center and outskirts of the Sagittarius Dwarf Spheroidal Galaxy enabling studies of the spatial distribution of the old stellar population from this galaxy. A group of double-mode RR Lyr stars with period ratios around 0.740 forms a stream in the sky that may be a relic of a cluster or a dwarf galaxy tidally disrupted by the Milky Way. Three of our RR Lyr stars experienced a pulsation mode switching from double-mode to single fundamental mode or vice versa. We also present the first known RRd stars with large-amplitude Blazhko effect.

The Optical Gravitational Lensing Experiment. OGLE-III Photometric Maps of the Large Magellanic Cloud

Udalski A., Soszyński I., Szymański M. K., Kubiak M., Pietrzyński G., Wyrzykowski L., Szewczyk O., Ulaczyk K., Poleski R.

Acta Astronomica

2008

Vol. 58, No. 2

89--102

We present the OGLE-III Photometric Maps of the Large Magellanic Cloud. They cover about 40 square degrees of the LMC and contain mean, calibrated VI photometry and astrometry of about 35 million stars observed during seven observing seasons of the third phase of the Optical Gravitational Lensing Experiment - OGLE-III. We discuss the quality of data and present color-magnitude diagrams of selected fields. The OGLE-III Photometric Maps of the LMC are available to the astronomical community from the OGLE Internet archive.