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This paper presents possibilities to increase the efficiency of three-phase squirrel cage induction motors. The necessary legislative requirements are stated in the first part of the paper, which are basically the main reason for efficiency increasing. After that a theoretical basis and explanation of the design for efficiency increasing follow. The final part presents the results of measurements...
This paper describes the analysis of power generating units and their implementation, these are located within the technological centre in Ostrava-Vitkovice. Further issues concerned in this paper deal with digital simulation using computer model created using the EMTP — ATP software to evaluate particular process courses that may occur on the power inverter installed in the technological centre....
This paper deals with analysis of induction motor fed by non-harmonic voltage source. The losses are determined based on direct method for analysis of motor efficiency. The method is presented for fractional losses analysis with consideration harmonics generated by PMW. The introduced method earmarks the fundamental harmonic components of electrical magnitudes for comparison purposes of different...
The basic formulas for analytical determination of the earthing system resistance are given by the European standard EN 50522:2010 [1] in its annex J. As these formulas are rather vague about how to determine the earthing system resistance for more complicated shapes of earthing systems consisting of more basic earthing electrodes (e.g. strip, rod, ring), this formulas are cited in the Czech Republic's...
The approach of this paper it is about voltage conformity delivered to the final customer, on electricity distribution networks. Have obtained physical and electrical characteristics information from the network coming from the database of the electricity company. The study presents the process of voltages estimation in primary and secondary circuits wich estimation of indicators of voltage violation...
The paper deals with an analysis of features of on-off controllers. It was assumed that the control quality can be described by three distinctive indexes: the period, the amplitude and the mean value of the controlled signal in the steady state. The on-off controller with positive hysteresis was a basic form of the controller that was analyzed. To eliminate the disadvantages of this basic form the...
Progress in efficiency improvement has been main a matter in grid tie inverters. The employment of multilevel inverters in energy conversion promises a better power quality and lower switching losses than ordinary two-level inverters even in low voltage grid. This paper presents the implementation of several control schemes (Vector Oriented Control, Hysteresis Control) and modulation techniques (Pulse-width...
The purpose of this work is to find the values of the electric parameters of synchronous and induction machines in order to validate the electrical interactions between an induction generator and a synchronous generator. The two generators will be connected in two ways: i) isolated to the common bus and ii) jointly connected to the common bus in permanent regime, subject to non-linear load. The results...
In this article, authors developed a model for one particular example of microgrid and considered possibilities to integrate solar panels and power storage into existing grid with diesel generator. The choice of configuration is described and power Quasi-Dynamic simulations are performed for the verification of the model. This paper mainly focuses on reliability issues and considers probability of...
Presented article discusses the impact of electromagnetic radiation on dielectric properties of magnetic fluids based on transformer oil ITO 100. For measurements and evaluation of the samples we used the PDC analysis. The measurements were performed in two variants, specifically when individual samples were irradiated and were not irradiated with the external magnetic field. To minimize undesired...
The paper deals with the power loss distribution along the arc heater with intensively blasted electric arc and compares the measured power loss of individual parts of the arc heater and power loss computed using a simple model of the electric arc. In previous works, the authors have presented the simple model of electric arc burning in the arc heater channel. Measured integral quantities obtained...
This work is focused on monthly electricity demand prediction, which is necessary for the maintenance planning in power systems as well as for negotiation forward contracts. In the proposed approach patterns of the load time series are defined, which unify input and output data and filter out the trend. Relationships between inputs and outputs simplified due to patterns are modeled using nonparametric...
The future in electric power supplying is characterized by huge deployment of AC and DC distributed generations (DG). The main requirement was caused by the maximum use of local energy resources in countries with advanced technologies with good cost flows, into the usable energy forms. Huge possibility has especially photovoltaic generation together with accumulation systems or with others local power...
This paper presents a method how to simulate overhead DC network transmission losses that are estimated by a variable location of an electric vehicle regarding to an invariable location of a traction substation. Electric public transport infrastructure is one of the major electrical energy consumers. Electrical energy amount which is acquired due to overhead line voltage drop and current flowing through...
Night charging and fast charging are currently the two most common systems for charging electric buses. Despite the fact that numerous trial installations were started, neither of these two systems has obtained unqualified approval of the users. The alternative is to charge vehicles in motion (the so-called In Motion Charging), which combines the advantages of trolleybus transport and of electric...
This paper describes the design and prototyping process of outer rotor permanent magnet generator meant for the use in small scale wind turbines. The initial design of the machine is presented. Main issues and phenomena, affecting the generator design, such as cogging torque and its reduction possibilities, selection and demagnetization risk assessment of permanent magnets, machine losses and thermal...
This paper aim to analyze the action of the wind on photovoltaic panels installed on the roof of the building through computational simulation, considering different intensity of wind subjected to the installation. The intensity and direction of the flow combined with the photovoltaic panel inclination are strong factors for the occurrence of pressures that could cause accidents and damage that require...
The paper is focused on the possibilities of Mat-power toolkit within the phenomenon of delayed current zero occurrence. The analysis of delayed current zero and its effects are introduced along with the most important parameters playing the key role in the topic. Paper contains the Z-bus matrix evaluation within the Matpower toolkit and joints it with the DC components' generation and the danger...
This paper describes the Failure Mode and Effects Analysis (FMEA) focusing on tertiary side of (E)HV/HV/MV transformers and MV self-consumption subsystem of the Czech transmission power system. The goal of this FMEA is a) to identify all possible failure modes, which can occur in the examined system; b) to determine the impact of each failure mode on upstream (E)HV/HV system (referred to as FMEA I...
In connection with the development of infrastructure for electric vehicles (EVs) is in this article presented complex mathematical analysis of operation fast charging station (FChS) with integrated battery and by promoting of photovoltaic (PV) system. The goal of presented simulation of operating conditions was to demonstrate possibilities (advantages and disadvantages) of integrated batteries during...
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