ANALYTICAL REVIEW OF FILTER-COMPENSATING DEVICES (FCD) OF THE HIGHER HARMONIC COMPONENTS OF VOLTAGE AND CURRENT

Применение в электроприводах механизмов городского хозяйства систем, включающих пару «преобразователь частоты – асинхронный электродвигатель», неизбежно приводит к ухудшению качества напряжения питания в результате увеличения уровня высших гармонических составляющих. Наличие последних влечет за собой повышение действующих значений напряжения и тока, что в свою очередь приводит к срабатыванию защит, отключению потребителей и ухудшению энергетических показателей работы энергосистем. Целью данной работы является обзор и анализ функционирования применяемых в настоящее время фильтрокомпенсирующих устройств (ФКУ) для снижения влияния на сети высших гармонических составляющих. Рассмотрены случаи применения линеаторов, пассивных «R-L-C» фильтров, схем 12-ти и 18-ти пульсных выпрямителей, а также параллельных активных фильтров (ПАФ) комплексного действия, обеспечивающих не только коррекцию формы кривых тока и напряжения, но и компенсацию реактивной мощности. Установлено, что для улучшения качества напряжения в сетях 0,4 кВ необходимо применение специальных фильтрокомпенсирующих устройств, выбор типа и мощности которых должен производиться для каждого конкретного случая индивидуально, исходя из условий получения оптимальных технико-экономических показателей.The use in electric drives of municipal services systems, including a couple of “frequency converter - asynchronous induction motor”, will inevitably lead to a deterioration in the quality of the supply voltage by increasing the level of the higher harmonic components. The presence of them leads to an increase in operating voltage and current, which in turn leads to an atuatuion of the protection, blackouts and poor in energy performance of power systems. The aim of the article is to make a review and analyze the functioning of the currently used filter-compensating devices (FCD) to reduce the impact on the network of higher harmonic components. We analyze line application, passive «RLC» filter, circuits 12 and 18-pulse rectifier and parallel active filter (PAF) integrated action to ensure not only the correction of the shapes of the current and voltage, and compensation of reactive power. It was found that to improve the quality of voltage of 0.4 kV networks it requires the use of special filter-devices, the choice of type and capacity which should be carried out for each case individually, based on the conditions for obtaining optimum technical and economic indicators

COSMOGRAIL: Measuring Time Delays of Gravitationally Lensed Quasars to Constrain Cosmology

COSMOGRAIL is a long-term programme for the photometric monitoring of gravitationally lensed quasars. It makes use of several medium-size telescopes to derive long and well-sampled light curves of lensed quasars, in order to measure the time delays between the quasar images. These delays directly relate to the Hubble constant H0, without any need for secondary distance calibrations. COSMOGRAIL was initiated in 2004, and has now secured almost a decade of data, resulting in cosmological constraints that are very complementary to other cosmological probes

The Stellar Abundances and Galactic Evolution Survey (SAGES). I. General Description and the First Data Release (DR1)

The Stellar Abundances and Galactic Evolution Survey (SAGES) of the northern sky is a specifically designed multiband photometric survey aiming to provide reliable stellar parameters with accuracy comparable to those from low-resolution optical spectra. It was carried out with the 2.3 m Bok telescope of Steward Observatory and three other telescopes. The observations in the u _s and v _s passband produced over 36,092 frames of images in total, covering a sky area of ∼9960 deg ^2 . The median survey completenesses of all observing fields for the two bands are u _s = 20.4 mag and v _s = 20.3 mag, respectively, while the limiting magnitudes with signal-to-noise ratio of 100 are u _s ∼ 17 mag and v _s ∼ 18 mag, correspondingly. We combined our catalog with the data release 1 (DR1) of the first Panoramic Survey Telescope And Rapid Response System (Pan-STARRS, PS1) catalog, and obtained a total of 48,553,987 sources that have at least one photometric measurement in each of the SAGES u _s and v _s and PS1 grizy passbands. This is the DR1 of SAGES, released in this paper. We compared our gri point-source photometry with those of PS1 and found an rms scatter of ∼2% difference between PS1 and SAGES for the same band. We estimated an internal photometric precision of SAGES to be of the order of ∼1%. Astrometric precision is better than 0.″2 based on comparison with DR1 of the Gaia mission. In this paper, we also describe the final end-user database, and provide some science applications