Zsolt Čonka

Impact of renewable energy sources on stability of EWIS transmision system

This paper describes the impact of renewable energy sources on stability of EWIS transmission system. EWIS is modeled in simulation program MODES. This model consist of 25 control areas, and includes photovoltaic power plants with 18, 7 GW of installed capacity and wind power plants with 15, 9 GW. This article examines the effectiveness of support services in Slovak power system.

Influence of photovoltaic power plants on the power system to the prediction for year 2020

This paper discusses the influence of growing amount of electrical energy produced in photovoltaic (PV) power plants to power system stability, according prognosis of PV growth for year 2020. A few different scenarios were created according to PV development outlook documents listed in references. The simulations were performed in MODES on the continental Europe power system model which was upgraded to adapt to the grid topology predicted for year 2020.

The implementation of an ideal photovoltaic module in Matlab/Simulink using simpowersystems toolbox

This paper deals with creating a mathematical model of ideal photovoltaic module. The performance of the model is demonstrated with output characteristics which also show the effect of changes in temperature and solar radiation on the output parameters of cell, module, and field. The model is realized in Matlab/Simulink environment due to frequently using and complexity of this software.

Benchmarking the reliability of medium-voltage lines

Abstract This paper discusses the problem of reliability of the Polish medium voltage power lines. It presents the benchmarking of power lines and values of SAIDI. The probability density distribution of the medium voltage lines length as well as selected indicators of the MV power lines reliability, being operated by the distribution companies under test, are also introduced. The analysis is based on the actual MV lines and uses the nonparametric method of kernel density estimation.

Analysis of the impact of nonlinear distortion in voltage and current curves on the errors of electric energy metering devices

This article deals with the problems of electricity metering under non-sinusoidal loads that consume non-sinusoidal currents from network and/or generate distortions into the network. The equations for determination of estimated values of active and reactive electric energy under the presence of higher harmonics are deduced. It is shown and experimentally confirmed that the meters of active and reactive power have unaccounted inaccuracies, which can exceed allowable metrological ranges. Frequency characteristics of some meters, used in the power grids of the Slovak Republic, are received, and they confirm the conducted theoretical studying.

Solution of transient phenomena during the connection of the photovoltaic power plants

This paper deals with the solution of transient phenomena during the connection of the photovoltaic power plants. There was investigated the impact of the failure of current protection for renewable energy sources during the network disconnection. There was verified the possibility of network operation during the islanding operation. Failure of network protection represents the significant hazard for employees of distribution system operator so it is necessary to solve the accurate current and voltage values during the connection of particular renewable energy sources.

Experimental observation of interaction between radiofrequency electromagnetic field and blood tissue

The exposition of biological and technical systems to electromagnetic radiation has increased with the rapid development of wireless data transfer. Recent studies are incrementally aiming at electromagnetic compatibility between electromagnetic radiation sources and biological and technical systems. No source of electromagnetic radiation should affect operation of other technical systems and endanger biological systems. Studies show that biological organism reacts to electromagnetic fields. This paper is focused on experimental observation of interaction between electromagnetic radiation and biological samples in the form of blood preparations. Results of interaction of radiofrequency electromagnetic radiation produced by mobile phone and biological tissue are presented. Samples of animal blood were used. The first part is focused at actual research in the world. In the second part there is presented workplace setup for exposing biological tissues to non-ionizing electromagnetic field. Results of this exposure are presented in the end.

Measuring of real value of short-circuit power in island operation condition

This paper deals with the problematic of the actual short-circuit power determination in real conditions. Presented principle of a real value of short-circuit power determination in arbitrary node of the power system is based on the measurement of one cycle RMS voltage and current changes. Described should be useful for determination of short-circuit power in the nodes electrically far enough from any synchronous machines (mainly from a generators of big power plants), in which the subtransient and transient effects of synchronous machines can be neglected. The comparison of the maximum short-circuit power computed according to the IEC 60909-0 standard and the actual short-circuit power obtained from the measurement of RMS voltage and current changes in the island operation of a small network is presented in this paper.

Increasing Net Transfer Capacity (NTC) by UPFC in Central East Europe power system

Most important issue in electricity markets is the maximizing of Net Transfer Capacity (NTC). This paper presents an approach for the placement of one Unified Power Flow Controller (UPFC) in interconnected power systems to increase NTC. Detailed analysis is presented for Slovak - Czech and Slovak - Hungary interconnection in Central East Europe network. Simulation results with and without UPFC are used to analysis the impacts of UPFC on the NTC between Slovakia - Czech Republic and Slovakia - Hungary.

UPFC influence to transient stability of power system

Large-scale power systems operation is faced with many challenges. One of many criteria, which should be fulfilled are stability criteria. Interconnecting separated power systems into interconnected network results in large system complexity, and therefore mixed influences from one power system to another part. Also, new devices are introduced to improve power system performance, like FACTS devices. Main goal of this paper is to examine influence of one of these devices to power system stability.