ISSN 1805-3386

April 6, 2020


2016 No.4

Stability of Grid-Connected Inverter with LCL Filter

Pástor, M., Dudrik, J.

The paper analyses oscillations in a singlephase grid connected inverter with the LCL output filter. Passive and active damping techniques are designed and compared by simulations. The inverter is controlled by a proportional resonant controller.


Keywords: control, dc/ac converter, filtering


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3D Numerical Calculation of Electric Field Intensity under Overhead Power Line Using Catenary Shape of Conductors

Bendík, J., Cenký, M., Eleschová, Ž.

This article presents a superposition method in combination with the Coulomb’s law and the Method of image charges for calculation of the electric field distribution generated by high voltage overhead power lines above a flat surface in every dimension. Such calculations are required to ensure the operational safety of people exposed to the action of external electric field as well as to reduce the cost of people protection. The method provides options for calculation of the field around the wire of a general shape. This substantial improvement of the method could be applied to eliminate the usual error in the calculation created using approximation of catenary shape conductors by infinite straight conductors. The method has been extensively tested on a set of shapes with known analytical solutions. It has been shown that the numerical solution converges uniformly to the analytical solution and the accuracy depends only on the number of finite elements.


Keywords: electric field, FEM, power transmission line, charge


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Comparison of Reconfigurations Using Deterministic Approach for Global Assessment of Operational State in Power System

Cintula, B., Eleschová, Ž., Beláň, A., Janiga, P.

This article deals with the analysis of impact reconfiguration on the power system operational state. The stated analysis assess results of the simulated calculations of N-1 events with the aim to obtain a more complex view of the security criterion N-1 use in comparison with the current methods and procedures being in practice. Methodologies based on the deterministic approach arising from calculations of steady states with the global assessment of the power system operational states are presented. The article objective is to comprehensively compare the selected operational states especially different reconfiguration variants in a power system.


Keywords: security criterion N-1, deterministic approach, reconfiguration, global assessment, operational state, power system


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Impact of Asymmetry of Over-Head Power Line Parameters on Short-Circuit Currents

Eleschová, Ž., Ivanič, M.

This paper analyses the impact of asymmetry of over-head power line parameters on short circuit currents when three-phase fault and phase-to-ground fault occur. The calculation results with consideration of an asymmetry of the power line parameters are confronted with the calculation in accordance with the Slovak standard STN EN 60909 which does not consider asymmetry of equipment parameters in the power system. The calculation of short-circuit conditions was carried out for two types of 400 kV power line towers on which is a considerably different arrangement of phase conductors.


Keywords: over-head lines, power line parameters, asymmetry, short-circuit current


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Numerical Analysis and Experimental Verification of Eigenfrequencies of Overhead ACSR Conductor

Murín, J., Hrabovský, J., Gogola, R., Goga, V., Janíček, F.

This contribution deals with the modal analysis of ACSR conductor using the finite element method (FEM) and experimental measurements of eigenfrequencies. In numerical experiments for the modelling of the conductor the material properties of the chosen conductor crosssection are homogenized by the Representative Volume Element (RVE) method. The spatial modal analysis of the power line is carried out by means of our new 3D FGM beam finite element and by standard beam finite element of the commercial software ANSYS. Experimental measurements are also carried out for verification of the numerical calculation accuracy.


Keywords: ACSR conductor, finite element method, modal analysis, experimental measurements


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