Utilization of the voltage rate to localization of harmonic sources in a power system
The paper proposes the new approach to determine which side, the utility or the customer is dominant harmonic source in a power system. At the beginning, review of existing approaches to localization of harmonic sources is given. Then, the theoretical background of the new approach is presented. The used criterion of localization of harmonic sources in a power system is based on examining the voltage ratio, which is defined in the paper. The results of investigation of sensibility of this ratio to the errors burdening quantities used for its calculation are analyzed. The practical conclusions are given. It is underlined that the presented approach has better properties than existing ones.
A new method for identification of main harmonic source based on the superposition and critical impedance methods
In this paper, a new method for identification of dominant source of harmonic generation in PCC bus is presented. In the proposed method, using superposition along with the concept of critical impedance method, new indices are defined and a novel algorithm is presented. In this algorithm, unlike the critical impedance method, there is no need to exact value of customer side harmonic impedances. Also, it is unlikely that the proposed algorithm leads to incorrect identification of the dominant source, even when the contribution of both sides is close to each other. The analysis is verified by running simulations on the modified IEEE 13-bus industrial distribution system.
Effect of a new inhibitor of cholesterol biosynthesis (AY 9944) on serum and tissue sterols in the rat.
AY 9944 is a novel inhibitor of cholesterol biosynthesis which appears to act on the Delta 7-reductase enzyme, interfering with the conversion of 7-dehydrocholesterol to cholesterol. In all tissues studied, with the exception of the lens, there was a reduction in cholesterol and a marked accumulation of 7-dehydrocholesterol. Isotope studies showed a reduced uptake of acetate into cholesterol, and an increased uptake into 7-dehydrocholesterol, in various tissues in vivo and by skin samples in vitro. There was no apparent accumulation of lanosterol or of the methostenols in the rat skin.