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In view of the world's energy scenario, it is important to seek exploration of alternative resources of energy. In Brazil there is great availability of biomass that isn't exploited, as in the food industry. The soybean processing industry has production losses that increase the availability of waste and consequently emitting methane gas into the atmosphere. The use of such waste for clean energy...
This paper deals with power semiconductor converter technology used for coupling the hydrogen-based technologies like electrolyzers and fuel cells with different types of the accumulators. The current control methods for two-phase buck-boost converter are further presented in this paper. The function of the coupling converter has been proven in both directions of current/power flow in the experimental...
Predictive maintenance of high voltage devices is a major issue for all power providers, due to costs and complexity. This article provides some theoretical and experimental principles which can be useful for all maintenance operations performed on high voltage switching devices and some simple methods applicable for assessing the status of all their contacts. Some of the aspects described here are...
Island operation possibility plays nowadays an important role in the view of preserving a part of the power system working during close-to-blackout emergency states such as collapsing power system divided in to smaller parts. Unfortunately following paper shows that not all regulation tools available for the transmission system operator (TSO) which are secured by the national grid code might be used...
The process of insulation coordination of power systems is conditioned by a number of factors, among which the improvement of methods of surge analyses occupy a special position. The use of statistical procedures in coordination of insulation of overhead power lines requires knowing statistical distributions of surges and reliability of their parameters. Establishing the type of distribution and the...
Natural oils are divided into vegetable and mineral oils. Compared with vegetable oils, the mineral oils show better dielectric properties, however, they are rather dangerous for the living environment and their flammability is higher. The vegetable oils are composed of natural ester molecules with a triacylglycerol structure. The mineral oils are a mixture of hydrocarbons produced from crude oil...
Any failure of a power transformer can result in serious consequences for a power system. Bushing failures, mechanically damaged windings or deterioration of solid insulation may cause unexpected power line cut-offs and financial losses to a company. Faulty operation of the on-load tap changer (OLTC) caused by increased contact resistance, contact misalignment or broken drive mechanism also reduces...
This paper is focused on the description of phenomenon called "floating water bridge" and several experiments in our high voltage laboratory which are joined with this phenomenon. Water bridges bring some new knowledge in chemistry, electrochemistry, lighting technology and high voltage field. In this paper we will be dedicated space for describing the properties of water bridges in the...
This paper is a contribution to solid air exhale analysis, regarding to outer insulation design. It describes the method of exhale collection, their composition measurement and their chemical analysis. Further proposals are made in conclusion for solid exhale analysis.
The paper discusses the impact of microgeneration on the energy quality in a low-voltage (LV) network. Expressions are formulated for obtaining voltage deviations and fluctuations caused by microgeneration sources. Simulations are carried out to predict the impact of microgeneration on voltage drops in nodes of low-voltage lines.
The paper focuses on the charging of LiFePO batteries with big output voltage. This voltage is necessary to feed a frequency inverter circuit with approx. output of 7.5 kW. This is a part of the solution applied during the Pre-seed project solved in the past at VSB — TUO Ostrava. Due to the unavailability of standard chargers, we provide a solution based on the Siemens 6RA80 controlled rectifier.
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