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Harmonic voltage compensation of the load connected to the point of common coupling (PCC) by using a series of active power filter (SAPF) based on a single phase cascaded multilevel inverter is proposed. The proposed multilevel inverter are presented in detail. The inverter has the ability of acting as a harmonic source when the reference is a non-sinusoidal signal. To achieve this, a simple control...
This paper is focused on challenges related to an increased quantity of distribution energy resources connected to the distribution network within the context of newly defined requirements ENTSO-E, follow-up European standards TS 50549 and codes of distribution system operators on regulation of voltage through control of the reactive power in terms of P-Q diagram. A high number of connected and operated...
Because of the financial savings and with respect for the environment, several efforts are made to replace AC voltage long distance transmission lines for DC voltage transmission lines. This may lead to increases of charging of insulation materials. The main aim of this paper is to describe the space charge accumulation in insulation material and its effect on local overloading of insulation material...
Automated parking system (APS) is a mechanical system designed to minimize the area and/or volume required for parking cars. It is a solution for areas with a minimum place to parking, especially in city center. Sometimes there are some APS which are equipped with charge station for E-vehicle. Respecting power consumption of APS and possible charging stations there should be a problem with supply...
The reduction of active power losses in transmission lines of modern power supply systems by solving the problem of reactive power compensation is an important task. The efficiency of the compensation depends on the choice of powers and placement of compensation units in nodes of a network. The task considered is the multi-objective and multi-factor optimization problem, and the time required to solve...
This paper deals with estimates of capacity between rails of the traction tracks. The determination of capacity was performed using software for numerical processing of electromagnetic fields: QField, COMSOL, together with the ATP program. The model comprised a traction section with the track clearance of 10 cm above the ground. The result then provides the estimate of capacity changes between rails...
This paper presents a speed control for a DC motor. Despite the unknown parameters of the plant to be controlled, these parameters are found using a system identification method. The methodology implemented in this study is known as parametric regression and is based on an optimization technique. This optimization, through its fitness function, allows to find the system characteristics in order to...
This article discusses application of photovoltaic panels thermal features into complex numerical model. Heating of the panels affects power output and efficiency. This process depends on weather conditions including fast variations of solar radiation. Typical models of PV systems do not speculate about these fast changes. Analysis and simulation of this transient phenomenon is result of this research...
This paper presents an induction motor drive using a method of direct torque and stator flux control. One disadvantage of the algorithm is a variable switching frequency of a voltage source inverter although it is used a constant period for the direct torque control processing in a digital signal controller. It is difficult to carry out a good filtration of the variable switching frequency; therefore...
The aim of this work is the evaluation of the data obtained from experimental PV solar system performance. 500 Wp PV system is installed on the roof of Faculty of Electrical Engineering and Information Technology of Slovak University of Technology in Bratislava, Slovakia. In addition the obtained results are compared with the PVGIS simulation. A brief summary of components and construction parts of...
This paper is focused on an analysis of mutual influence between the circuits of different voltage level located on the same pylon. The significant consequence of these mutual couplings between all conductors including earth wires is a voltage induced into conductors which results in current asymmetry not only during a specific operations but also during standard operations. In the case, that some...
In this paper, the thermal ageing of pressboard impregnated with two kinds of insulation liquids is studied by means of frequency domain spectroscopy which involves the measurement of real and imaginary part of complex permittivity as function of frequency. The magnetic nanofluid was composed by mineral transformer oil as carrier liquid, nanoparticles of magnetite and surfactant. The thermal aging...
The induction machine operated as generator can be a very valuable alternative to the synchronous machines. Mostly in applications with lower nominal power ratings. In this case it can be more cost effective. Disadvantageous is a fact that induction machine cannot generate a reactive power and even more it is a permanent consumer of the reactive power. This paper strives to analyze possible application...
Overvoltages are transferred through power transformers by electromagnetic couplings between windings. Their waveforms and maximal values depends on overvoltages shapes occurring in power systems and physical mechanisms in transformer windings. It is a need of coordination insulation studies to perform analysis of transferred overvoltages influence on insulation system of electrical power equipment...
This paper deals with system analysis and control design. There are many ways to design a proper controller for a specific system. Usually, a good knowledge of a system dynamics is required to do so. The paper is mainly focused on the analytical method called pole placement. This method was implemented to the graphical user interface Dynamic systems created in the development software LabVIEW.
During long-term operation of safety cables, it can happen quite easily that standard operation conditions are not fulfilled. This paper deals with the thermal shock and its impact on electrical parameters and sustainability of quality of coaxial cables. The aim of this paper is to compare thermo-chemical properties (measured by DSC) of dielectric material of tested coaxial cable and electrical measurement...
In electrical installations with photovoltaic sources of energy, earth fault current may comprise alternating current component and direct current component. The waveform shape of this earth fault current mainly depends on the point of the fault and the properties of a photovoltaic power electronics converter. The waveform shape of the current influences operation of protection devices, especially...
This work presents ensembles of general regression neural network for short-term electricity demand forecasting. Several types of ensembles are proposed which differ in the source of diversity of individual members. Diversity is generated using different subsets of training data, different subsets of features, randomly disrupted training data and randomly disrupted model parameters. Experimental study...
This article describes the basic modeling approach of the creation of a resistive heating model of the molybdenum sheet with use of the finite element simulation method. The aim of the model creation is the research of a suitable electrode material with respect to its electrical and thermal properties. The created model is compared to the measurement and adjust for the best possible accuracy. The...
With the growing concern about sustainable development and sustainable energy, there exists increasing pressure on energy-efficiency technologies to reduce energy use and greenhouse gas emissions. This paper discusses and analyzes on real regional data the potential of biomass in energy-efficiency issues, how to determine the volume of changes of heating from coal or natural gas to wood and the effects...
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