PMU-based informational support of power system control tasks

Up-to-date wide area measurement systems (WAMS) based on phasor measurement units (PMU) appeared at the very end of the 20th century. Under present-day conditions, WAMS serve as the basis for information-measuring systems, which significantly improve power system control and operation. In practice, WAMS are mostly used for power system stability control and transient monitoring and visualization. This paper discusses the new opportunities for power system control quality improvement, resulting from PMU application for power system steady-state parameters' assessment. Firstly, better control is provided by online equivalent circuit parameters' identification using PMU measurement data and taking into account FACTS and other shunt and series compensation equipment. Secondly, the paper addresses the problems of "nodal" identification, which have taken on great importance recently due to the intensive development of small-scaled distributed generation. Based on PMU measurements of nodal voltages and incident transmission lines' electric currents, one can obtain online steady-state load characteristics, which can be used for dispatch control applications. Moreover, PMUs provide superaccelerated power flow calculations, which are of crucial importance for emergency automation, adjusted for prior operation. Such principles of emergency automation consist of the quick determination of control actions, aimed at power system stability maintenance in cases of any programmed faults' occurrence. It is known that such control is carried out by means of power flow calculations based on remote metering data. The proposed application and allocation of PMUs in the power system by means of combinatorial matrix transformation to triangle form give the possibility to perform accelerated node-voltage analysis without equivalent circuit simplification. All the calculations are verified using IEEE test networks. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Investigation of the infusion solutions of different qualitative composition influence on the dynamics of neuron specific enolase activity in patients with acute ischemic stroke

At the moment, the question remains insufficiently studied what kind of infusion fluids or their combination should be preferred in patients with acute ischemic stroke (AIS) to provide intensive care. Purpose. To investigate the dynamics of neuron-specific enolase (NSE) against the background of the iso-osmolar 0.9 % NaCl solution, colloid iso-osmolar fluid HES 130, colloid hyperosmolar fluid HAES-LX-5 % and hyperosmolar fluid mannitol application in AIS. Materials and methods. The study included 32 patients with AIS. As the studied solutions were used: colloid hyperosmolar HAES-LX-5 % (Gekoton), colloid iso-osmolar hydroxyethyl crystal 6 % 130/04 (HES 130), hyperosmolar mannitol 15 %, and iso-osmolar 0.9 % NaCl. The control group consisted of patients receiving only 0.9 % NaCl, the comparison groups – the patients receiving 0.9 % NaCl + HES 130 or 0.9 % NaCl + HAES-LX-5 %, or 0.9 % NaCl + mannitol. NSE activity was used as a marker of cerebral ischemia at the corresponding time (the 1st, 4th and 7th days). Results. An increase in NSE (P < 0.05) was observed in the 0.9 % NaCl group at the 7th day of stroke. A similar dynamics of NSE elevation was in the group with mannitol (P < 0.05), as well as in the control group. A 17.3 % decrease in the NSE activity was noted in the application of HES 130 at the end of observation relative to the 1st day. The NSE activity decreased by 34.6 % (P < 0.05) on the 7th day in comparison with the 1st day in the HAES-LX-5 % group and was significantly less than in the control group, groups of HES 130 and mannitol – on average 2.88 times and 30.3 %, 39.8 %, respectively. Conclusions. The use of 0.9 % NaCl or 0.9 % NaCl + mannitol within 7 days in patients with AIS in addition to basic therapy was accompanied by an increase in NSE. Infusion of 0.9 % NaCl + HES 130 or 0.9 % NaCl + HAES-LX-5 % was accompanied by a decrease in NSE activity at the 7th day of treatment, herewith the HAES-LX-5 % group showed the best dynamics of NSE activity decreasing (P < 0.05)

Післяопераційне знеболення у травматологічних хворих з ендопротезуванням кульшового суглоба

Дослідження проводилися у двох групах хворих (n = 82), оперованих під спинномозковою анестезією (СА) в стандартному виконанні. Дизайн передбачав створення двох рандомізованих груп пацієнтів: досліджувана група складає 42 хворих з ендопротезуванням кульшового суглоба, що підлягали оперативному втручанню, яким у комплекс терапії було включено препарат декскетопрофен за схемою: 1­ше введення в дозі 50 мг декскетопрофен внутрішньом’язово за 40 хв до оперативного втручання; 2­ге введення в тій же дозі (50 мг в/м) через 8 год від 1­го введення і 3­тє – в тій же дозі (50 мг в/м) через 8 год від 2­го введення. Добова доза лікарського засобу не перевищувала 150 мг/добу згідно з інструкцією до лікарського засобу. Група порівняння (група “Контроль”) складала 40 пацієнтів з аналогічними нозологіями та оперативними втручаннями з боку опорно­рухової системи. Пацієнти отримували стандартну терапію без планового застосування препарату декскетопрофен. Виявлено, що застосування декскетопрофену в плановому порядку у складі мультимодальної аналгезії в післяопераційному періоді у травматологічних хворих дозволяє досягти більш якісного знеболювання порівняно з аналгезією “за потребою” опіатами чи іншими НПЗЗ

Assessment of infusion therapy impact on the dynamics of endothelin-1 in patients with acute ischemic stroke

The impact of infusion solutions on endothelial damage correction in acute ischemic stroke (AIS) remains an insufficiently studied. Purpose. To investigate the dynamics of endothelin-1 as one of the main markers of vasoconstriction and endothelial dysfunction (ED) with the use of 0.9 % NaCl, HES 130, HAES-LX-5 % and mannitol in patients with AIS. Materials and methods. The study included 32 patients with AIS. As the investigated solutions were used: colloid hyperosmolar HAES-LX-5 % (Gecoton), colloid isoosmolar hydroxyethylstarch 6% 130/04 (HES 130), hyperosmolar mannitol 15 %, isoosmolar 0.9 % NaCl. The control group consisted of patients who received only 0.9 % NaCl, comparison group patients received 0.9% NaCl + HES 130 or 0.9 % NaCl + HAES-LX-5 %, or 0.9 % NaCl + mannitol. The level of endothelin-1 (EN-1) served as a vasoconstriction marker of ED at a fixed time (days 1, 4 and 7). Results. Infusion therapy with only 0.9 % NaCl negatively affected the level of EN-1, since its level was 3.17 times increased on the 7th day of observation in comparison with the 4th day (P 0.05) at the end of observation in comparison with mannitol and 0.9 % NaCl groups, which showed a paradoxical increase in its level at the 7th day of infusion. Conclusions. The dynamics of EN-1 level as the main vasoconstrictor marker of ED were negative in the group of patients with 0.9 % NaCl and mannitol: its level was 3.17 and 3.48 times increased in the 0.9 % NaCl and mannitol groups (P < 0,05), respectively, on day 7 compared to day 4 of observation. Intensive therapy with HAES-LX-5 % and HES 130 had a better depressing effect on an increase in EN-1 level than other solutions

SILICON MONOCRYSTALS FOR ALTERNATIVE ENERGY

This paper considers features of the formation and microstructure revealing of profound n- and p-type silicon monocrystals. Influence of hole and electron conductivity in semiconductors on the pattern of anodic etching is determined. Correlation among silicon microstructure, dislocation density and minority carriers’ lifetime has been studied. Influence of impurity diffusion from the surface into the space of the crystal on electrical properties’ changes of the semiconductor is shown

Comparison of Mathematical Methods for Compensating a Current Signal Under Current Transformers Saturation Conditions

Current measurements from electromagnetic current transformers are essential for the construction of secondary circuit systems, including for protection systems. Magnetic core of these transformers are at risk of saturation, as a result of which maloperation of protection algorithms can possibly occur. The paper considers methods for recovering a current signal in the saturation mode of current transformers. The advantages and disadvantages of methods for detecting the occurrence of current transformers core saturation are described. A comparative analysis of mathematical methods for recovering a current signal is given, their approbation was carried out, and the most promising of them was revealed. The stability and sensitivity of recovery methods were tested by adding white noise to the measured signal and taking into account the initial flux density (remanent magnetization) in the current transformers core. Their comparison is given on the basis of angular, magnitude, and total errors at a given simulation interval. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was supported in part by the International Cooperation Project of National Natural Science Foundation of China under Grant 41761144079, in part by the Strategic Priority Research Program of the Chinese Academy of Sciences, in part by the Pan-Third Pole Environment Study for a Green Silk Road under Grant XDA20060303, in part by the K. C.Wong Education Foundation under Grant GJTD-2020-14, in part by the CAS PIFI Fellowship under Grant 2021PC0002, in part by the Xinjiang Tianchi Hundred Talents Program under Grant Y848041, in part by the CAS Interdisciplinary Innovation Team under Grant JCTD-2019-20, in part by the project of the Research Center of Ecology and Environment in Central Asia under Grant Y934031, and in part by the Regional Collaborative Innovation Project of Xinjiang Uygur Autonomous Regions under Grant 2020E01010

Power Flows and Losses Calculation in Radial Networks by Representing the Network Topology in the Hierarchical Structure Form

This paper proposes a structured hierarchical-multilevel approach to calculating the power flows and losses of electricity in radial electrical networks with different nominal voltages at given loads and voltages of the power source. The researched electrical networks are characterized by high dimensionality, dynamism of development, but also insufficient completeness and reliability of state information. The approach is based on the representation of the initial network graph in the form of a hierarchical-multilevel structure, divided into two stages with rated voltages Unom ≤ 35 kV and Unom ≥ 35 kV, and using the traditional (manual) engineering two-stage method, where the calculation is performed in a sequence from bottom to top (stage 1) and from top to bottom (stage 2), moving along the structure of the network. The application of the above approach makes it possible to obtain an algorithm for implementation on a computer, which is characterized by universality (for an arbitrary configuration and complexity of the network), high performance and low requirements for the computer memory. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was supported in part by the International Cooperation Project of National Natural Science Foundation of China under Grant 41761144079, in part by the Strategic Priority Research Program of the Chinese Academy of Sciences, in part by the Pan-Third Pole Environment Study for a Green Silk Road under Grant XDA20060303, in part by the K. C. Wong Education Foundation under Grant GJTD-2020-14, in part by the Research Fund for International Scientists of National Natural Science Foundation of China under Grant 42150410393, in part by the CAS PIFI Fellowship under Grant 2021PC0002, in part by the Xinjiang Tianchi Hundred Talents Program under Grant Y848041, in part by the CAS Interdisciplinary Innovation Team under Grant JCTD-2019-20, in part by the project of the Research Center of Ecology and Environment in Central Asia under Grant Y934031, and in part by the Regional Collaborative Innovation Project of Xinjiang Uygur Autonomous Regions under Grant 2020E01010

Обгрунтування використання декскетопрофену для знеболення в ранньому післяопераційному періоді в онкохірургії

Дослідження проведені у 64 пацієнтів (16,4 ± 1,2 років), прооперованих з приводу пухлин заочеревинного простору (44 пацієнти, 69 %), пухлин яєчника (20 пацієнтів, 31 %). Дослідження проводилися у двох групах хворих (n = 64), знеболення морфіном у дозі 10 мг (НА, 34 пацієнтів) у стандартному виконанні та декскетопрофен («Кейвер») (ДА, 30 пацієнтів) за схемою: 1-ше введення в дозі 50 мг «Кейверу» внутрішньом’язово за 40 хв до оперативного втручання, 2-ге введення в тій же дозі (50 мг в/м) через 8 год від 1-го введення і 3-тє – в тій же дозі (50 мг в/м) через 8 год від 2-го введення. Добова доза лікарського засобу не перевищувала 150 мг/добу. Використання декскетопрофену дозволяє значно знизити потребу в опіоїдах, а їх комбінування може відновити аналгетичний потенціал останніх. Різні механізми дії даних препаратів дозволяють призначати їх у комбінації і в малих дозуваннях з метою досягнення значного аналгетичного ефекту. Призначення декскетопрофену дозволяє значно знизити прояви синдрому абдомінальної гіпертензії та покращить кровоплин у магістральних судинах черевної порожнини за даними ультразвукового дослідження. Ключов