Analysis of Influence on the Grid of Input Part of Special Power Source 113 kW / 1 kA DC

This paper compares some variants of power circuit configurations for a special power DC source 110 V / 1 kA. The requirement for the source was to ensure minimum ripple of the output current and reduced EMC-disturbance generated from this DC-source to the supply network and to other surrounding equipments

Model Study of Cooperating Traction Substations at 25 kV Traction Catenary without Superior Power Distribution Control

OP VVV Electrical Engineering Technologies with High-Level of Embedded Intelligence CZ.02.1.01/0.0/0.0/18_069/0009855 and under project SGS-2021-021This paper describes the results of the model study for traction system 25 kV / 50 Hz, which is built on an advanced traction substation with a rail active balancer and phase shifting device. The first part of this paper is described traction substation topology with a description of its properties. The following section describes the operation of the traction system in terms of interconnection with the distribution power grid. The important requirements for the behavior and used equipment of advanced traction stations are explained in more details here. The last part of this paper presents the proposed concept of control of individual traction substations, while superior power distribution control is not available. Therefore, each traction substation must have its own independent control algorithms, its behavior properties are presented and documented in the results of simulation models. In order to be able to explain the whole issue well, the created model is simplified only to the control of two independent traction substations

Symmetrization Method of AC Traction Substation with Power Balancer

the project OP VVV Electrical Engineering Technologies with High-Level of Embedded Intelligence CZ.02.1.01/0.0/0.0/18_069/0009855, project SGS-2021-021The paper describes the symmetrization method of power converter used in topology of AC traction substation with power balancer. This topology provides the three-phase current symmetrization and the reactive power compensation for AC traction substation feeding 25 kV / 50 Hz traction catenary. The described symmetrization method is based on principles of the Steinmetz symmetrizing circuit. The main paper contribution is a derivation and description of the symmetrization equations, which are used for the control algorithm of multilevel semiconductor converters in a delta connected circuit

Dorsoventral variations in dark chilling effects on photosynthesis and stomatal function in Paspalum dilatatum leaves

The effects of dark chilling on the leaf-side-specific regulation of photosynthesis were characterized in the C4 grass Paspalum dilatatum. CO2- and light-response curves for photosynthesis and associated parameters were measured on whole leaves and on each leaf side independently under adaxial and abaxial illumination before and after plants were exposed to dark chilling for one or two consecutive nights. The stomata closed on the adaxial sides of the leaves under abaxial illumination and no CO2 uptake could be detected on this surface. However, high rates of whole leaf photosynthesis were still observed because CO2 assimilation rates were increased on the abaxial sides of the leaves under abaxial illumination. Under adaxial illumination both leaf surfaces contributed to the inhibition of whole leaf photosynthesis observed after one night of chilling. After two nights of chilling photosynthesis remained inhibited on the abaxial side of the leaf but the adaxial side had recovered, an effect related to increased maximal ribulose-1,5-bisphosphate carboxylation rates (Vcmax) and enhanced maximal electron transport rates (Jmax). Under abaxial illumination, whole leaf photosynthesis was decreased only after the second night of chilling. The chilling-dependent inhibition of photosynthesis was located largely on the abaxial side of the leaf and was related to decreased Vcmax and Jmax, but not to the maximal phosphoenolpyruvate carboxylase carboxylation rate (Vpmax). Each side of the leaf therefore exhibits a unique sensitivity to stress and recovery. Side-specific responses to stress are related to differences in the control of enzyme and photosynthetic electron transport activities

Uniform Selection as a Primary Force Reducing Population Genetic Differentiation of Cavitation Resistance across a Species Range

Background: Cavitation resistance to water stress-induced embolism determines plant survival during drought. This adaptive trait has been described as highly variable in a wide range of tree species, but little is known about the extent of genetic and phenotypic variability within species. This information is essential to our understanding of the evolutionary forces that have shaped this trait, and for evaluation of its inclusion in breeding programs. Methodology: We assessed cavitation resistance (P 50), growth and carbon isotope composition in six Pinus pinaster populations in a provenance and progeny trial. We estimated the heritability of cavitation resistance and compared the distribution of neutral markers (FST) and quantitative genetic differentiation (QST), for retrospective identification of the evolutionary forces acting on these traits. Results/Discussion: In contrast to growth and carbon isotope composition, no population differentiation was found for cavitation resistance. Heritability was higher than for the other traits, with a low additive genetic variance (h 2 ns = 0.4360.18, CVA = 4.4%). QST was significantly lower than FST, indicating uniform selection for P50, rather than genetic drift. Putativ