Search

The world’s attention has turned towards renewable energy due to escalating energy demands, declining fossil fuel reservoirs, greenhouse gas emissions, and the unreliability of conventional energy systems. The sun is the only renewable energy source that is available every day for a specific period of time. Solar photovoltaic (PV) technology is known for its direct conversion of sunlight into electricity using the photoelectric effect. However, due to the non-linear electrical characteristics, the power output of solar PV cells is bound to a lower value and can not produce the power of which it is capable. To extract the maximum possible power, the PV cell needs to be operated at its maximum power point (MPP) uninterruptedly under numerous weather conditions. Therefore, an electronic circuit driven by a set of rules known as an algorithm is utilized. To date, the flower pollination algorithm (FPA) is one of the most renowned maximum power point tracking (MPPT) algorithms due to its effective tracking ability at the local and global positions. After an in-depth analysis of the design, strengths, weaknesses, and opportunities of the FPA algorithm, we have proposed an additional filtration and distribution process named “Random walk” along with the ordering of solutions, to improve its efficiency and tracking time. The proposed structure named “Ordered FPA” has outperformed the renowned FPA algorithm under various weather conditions at all the standard benchmarks. Simulations are performed in MATLAB/Simulink.

An electrical energy is and would be one of the most important energy sectors. By accepting green resolutions to generate electricity, researchers are giving their best to get the most reliable and efficient way to generate electricity with renewables. As renewables are intermittent in nature healthy management system is very important. In this article, we have demonstrated 2-way energy and communication flow with peer-to-peer energy transfer. Users and utility connection is distinguished with the Smart Control Panel in the street, which empower small prosumer to participate in the market. To identify algorithm and system management, two cases are considered. Normal Gird operation and Faulty Grid. The result shows that systems have the potential to withstand for a quite long time to get supplied to the street even without taking electricity from the main grid. This system saves user rights to use electricity anytime in a day with a full load and including cost-saving phenomena.

The future power system must provide electricity that is reliable and affordable. To meet this goal, both the electricity grid and the existing control system must become smarter. In this paper, some of the major issues and challenges of smart grid’s development are discussed, and ongoing and future trends are presented with the aim to provide a reader with an insight on the relevant research topics, challenges and actual engineering tasks in smart grids. The focus areas of this review study are distributed generation, microgrids, smart meters’ deployment, energy storage technologies, and the role of smart loads in primary frequency response provision. The exploration of smart grid technologies and distributed generation systems has been accomplished, and a general comparison of the conventional grid and a future smart model is included. The issue of increasing penetration of renewable energy sources to the power system and posers related to the integration of distributed generation are also presented.

To reduce emissions worldwide, decarbonization has also affected for power engineering and its conventional methods of power generation, distribution, and transmission. This fact affects not only the production of power and supply itself, but also other parts related to it, namely systems for the protection of electricity generation facilities and the location of faults in distribution networks and transmission systems. Is this new technology of renewable energy sources (RES) mastered enough to be able to replace traditional methods of energy generation reliably and safely? If we can answer the previous question, we could proceed to the next phase of putting these technologies into practice, considering the actual state of distribution networks and transmission systems. The aim of the article will be to evaluate the current state of systems and production sources of electricity in the Slovak Republic and to provide a better insight and suggestions for rebuilding current networks on a smart grid. The proposals will also include models of some RES in the Matlab/Simulink software.

The effect of slurry mixing in an anaerobic digester on biogas production was intensively studied in the last few years. This subject is still debatable due to fact that this process involves three phases, solid-gas-liquid, along with the involvement of microbes during biochemical reactions, which are highly vulnerable to changes in hydrodynamic shear stresses and mixing conditions. Moreover, the complexity in the direction of optimization of mixing magnifies due to the implication of both fluid mechanics and biochemical engineering to study the effect of mixing in anaerobic digestion (AD). The effect of mixing on AD is explored using recent literature and theoretical analysis, concentrating on the multi-phase and multi-scale aspects of AD. The tools and methods available to experimentally quantify the function of mixing on both the global and local scales are summarized in this study. The major challenge for mixing in an anaerobic digester is to minimize dead zones and maintain uniform distribution of viscosity and shear at low mixing intensities without disrupting the microbial flocs and syntrophic relationships between the bacteria during the AD process. This study is a critical analysis of various techniques and approaches adopted by researchers to evaluate the effectiveness of mixing regimes and mixing equipment. Most studies describe biogas production performance and hydrodynamic characteristics of the digesters separately, but the evaluation of mixing requires interdisciplinary experts, which include mechanical engineers, microbiologists and hydrodynamic experts. Through this review, the readers will be guided through intensive literature regarding agitation, the best possible way to scrutinize the agitation problems and the approach to answering the question “why is the optimization of mixing in an anaerobic digester still a debatable subject?”.

This article aims to present some opportunities for improved solar energy utilization by raising the share of renewables in energy generation in the Visegrád Countries (Poland, Czech Republic, Slovakia, and Hungary). The analysis is based on the status of the renewable energy targets in the member countries and their future possibilities. This paper derives input through a thorough investigation of independent data, government policies, European Commission reports, and other data available online with free access. The analysis is processed by focusing on Hungary, as a country with various possible facets of solar energy demand and supply in the region. The assessment methodology is in the context of a geographical map, technical regression analysis, temperature distribution profiles, and the relative trends of solar potential in Hungary. The country currently has ten solar power plants with more than 10 MWp, and five remarkable plants under 10 MWp capacity spread over Hungary. The analysis on geographical aspects clubbed with technical and solar affecting parameters was carried out to harvest the sustainable potential of solar energy in the region. This study attempts to establish a relationship between the current and future prospects of solar energy in Hungary as a nation, and as part of the Visegrád countries, based on assessment for a sustainable future.

It is inevitable truth that Electric Energy become one of the most concern topic of a 21st century. Usage of fossil fuels in exhausting way made it vulnerable and it will last longer for just few years if it will be usage in same manner. However, concern is not just extinction of fossil fuel but also more on environmental pollution, increasing of global warming and which meant it to be needs to go for green, sustainable and reliable energetic world. Admitting the fact that rooftop solar and micro wind technology have warranted the self-dependency on electricity for the consumer at least for the few hours. However, these renewables come with major issues such as balancing the grid, frequency-voltage-current regulation and many more. In practical thinking, all system should have to be automated for most efficient use; hence, it has to be obeyed the IOE (Internet of Electricity) principle. For beneficial of both, consumer and Power operator we come up with the idea of “Smart Street”. We have present brief idea of Smart Street as landing information in this paper. This paper is more concentrated on “Algorithm Development of Smart Homes for Electric Power Flow in between smart homes and street grid power”. Street is consisting of Renewables, Energy Storage (Home and Street) and smart control panel.

This paper deals with the research of FACTS devices, specifically TCSC regulators. In the research, the NEPLAN program compiles a mathematical model of the TCSC system for the control of oscillations and the improvement of the dynamic stability of the transmission system. The TCSC element is implemented in the design in two places, namely in stations with generator outlets. The first outlet is the Mochovce nuclear power plant and the second on the outlet line of the Vojany thermal power plant. The height is mainly focused on reducing oscillations in short circuits. The result is the processing of dynamic stability data at a set short circuit with and without a TCSC device, as well as how this affects the CCT (Critical clearing time).

The occurrence of renewable energy sources (RES) in distribution systems has increased significantly in recent years, with this change in fundamental changes to the conventional concept of central energy production to local production and consumption. The integration of RES reduces transmission losses and increases the operational reliability of the distribution network, while new problems associated with this change arise, especially in systems of protected and localized failures in the networks. Distribution systems are traditionally associated with the radial topology of larger networks. The standard STN EN 60909 (33 3020) does not take into account the contributions of photovoltaic stations, while their impact takes into account the growing number and performance in distribution networks will be crucial for changes in the systems of protected equipment in the future.

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.

This paper deals with the impact of Photovoltaic Power Plants (PPP) on remote voltage control (DRN). Paper also considering the assessment of DRN quality as a change of delivered reactive power. The impact of PPP on DRN is modelled on Slovak power system model in program MODES. Results shows significant impact of RES on voltage stability.

The electromagnetic field (EMF) is known to influence functions of the nervous, cardiovascular and reproductive systems of many animals, including ticks. The aim of this study was to test the behavior of ticks in the presence of radio-frequency EMF. For testing, 160 adult male and 140 adult female unfed Ixodes ricinus ticks were used. Individuals were exposed to 900 MHz EMF in the Radiation–Shielded Tube (RST). Ticks were attracted to the irradiated area. This effect was significantly stronger for ticks infected with Rickettsia spp., suggesting that pathogens can alter the ticks’ response to environmental stimuli. These results lead to the question of whether man-made EMF may have an impact on I. ricinus activity and, as such, be a contributing factor to the ongoing changes in the distribution of the tick and its pathogens currently observed in Europe and elsewhere.

Paper deals dynamic calculations. It presents two cases for real black start tests and shows their dynamic simulation.

This paper deals with the analysis of the transient phenomena caused by the operation of the electric arc furnace in the 22 kV network, describes the causes of their origin and proposes the possibilities of their reduction with regard to the fulfillment of the quality of electric energy. In particular, it focuses on assessing the short-term flicker rate and the use of the STATCOM device to reduce it. The analysis and subsequent reducing of transient phenomena impact was realized by simulations using the Matlab / Simscape Power Systems tool. The obtained results were evaluated in accordance with the valid European standards and legislation of the Slovak Republic.

This paper deals with the impact of a low voltage smart grid on the distribution system. The last European directives 2014/94 / EU, 2009/28/EC and 2010/31 / EU, bring new problems to solve for distribution system operators. The existing networks of distribution systems are not prepared to fulfill these criterions. Paper shows results related with application of this new directives on existing distribution systems.

The world demands a smart and green future in every sector, which directly corresponds to increases in electrical energy demand one way or another. It is unfeasible to attain future energy demand with the present electrical infrastructure. That means more research and development is required. Future energy sources should be intermittent, and, in addition, the energy sector should be more inwards for distributed energy generation with demand side control. In such cases, the smartest and most autonomous system would be essential to deliver an adequate power supply with all electrical properties. A real-time monitoring and control system with a self-healing infrastructure is a forthcoming desideratum. By accepting these challenges, we have designed a smart street. The basic idea of the smart street is presented in this paper as a landing page, the paper is more focused on emphasizing information regarding the electrical energy flow algorithm for the household, street, and street battery storages. This algorithm is helpful for two-way energy flow and the automatic detection of islanding and the grid connection mode. It will be not only helpful for the users but to the utility as well.

One way of handling short-time short-circuits without causing equipment failure is the management of the reclose function integrated into smart switchboard which is described in this article. Due to the cost of the application, the optimal placement of such equipment must be well-planned. During the planning of the placement optimization of a low-voltage electricity network quality, the increase of the consumer supply security must be considered along with the best economic utilization. The research presented in this article aims to introduce a new special decision support methodology calculated with these variables. The management of smart switchboard (SSB) tool installation into low voltage (LV) network was investigated. The selection of the placement nodes is based on the complex investigation of the network characteristics. Investigation is performed by empiric analysis. This method can support the power companies to make the optimal decision. The presented new device can have outstanding importance for the electric industry and for further research as no testing results of such investigations have been published yet.

This article discusses the design of a power station earthing system using two methods that are compared to each other. The design was based on the software method using CYMGRID and the mathematical method based on IEEE 80-2000. The process in both methods is aimed at creating a grounding model, determining the overall resistance, overloading the cross-sections of the earthing switches and adhering to the limit values for the touch and step potential. The work compares these analyses and evaluates the differences in design and possible shortcomings, such as the possibility of over-dimensioning or underestimating the grounding system.

The paper deals with the evaluation of shielding effectiveness of different types of paints, which is recommended as a shielding. There is performed an experiment on the creation of a non-professional shielding paint that could be used as a substitute for the professional shielding paints, that are commonly available on the market. The measurement is performed in the frequency range 0.9 - 6 GHz.

The article deals with the research of devices used to improve the transient stability of the power system. It refers to current global electricity trends, leading to ever-increasing electricity transmission. This is due both to the increase in consumption and production of electricity, as well as to the creation of a single electricity market. Recently, there is an increasing problem of the operation of renewable resources with unpredictable production, which also often contributes to the creation of unplanned transit flows and to the deterioration of system stability.

The submitted paper deals with the analysis of the temperature field of selected electric power equipment. In the introduction there are described theoretical knowledge of thermodynamics, such as heat generation, influence of temperature increasing and heat transfer mechanisms. In the next sections, there are presented the results of simulations of temperature field distribution of selected electric power equipment using the ANSYS tool.

This article deals with the issue of creating a network analyzer of the power quality using the open-source platform in the form of the Raspberry Pi microcomputer. This paper presents a proposal design of a measurement circuit for recording the AC voltage up to 1500 V and a subsequent analysis of the measured data.

Paper deals with short circuit calculations. It compares results of three different tools for short circuit currents calculation.

This paper deals with evaluation of shielding effectiveness by measurement in anechoic chamber for combination of shielding paint with building materials. The material used for the experiment was polystyrene POLYFORM with thickness 5 cm, shielding paint YSHIELD HSF 64, water and building glue BauKleber, class C1T. The measurement was performed in the frequency range from 1 GHz to 9 GHz with step 50 MHz

The increased demand for power transfer in combination with environmental and economic issues which set constraints to building new lines, force the implementation of new technologies into the existing system in order to improve its power capability. This paper investigates the use of specific FACTS devices and WAMS systems to maximize total transfer capability generally defined as the maximum power transfer transaction in Central-East-Europe power system. Optimal allocation and control of these devices will be very important for TSO or other power market regulators. Effectiveness, optimal allocation and utilization of phasor measurement units (PMUs) for different types of FACTS devices designed for power flow control and increasing transfer capacity were investigated. Paper also compares the economic aspects of these devices.

This paper deals with modelling of a photovoltaic power plant in combination with a battery energy storage system and their cooperation in order to better renewable energy utilization at local level. In this paper, the model of grid on a hybrid system that is formed by the battery energy storage system, a photovoltaic power plant, a utility grid and a small commercial load is proposed. Battery energy storage system based on lithium ion technology is connected by a DC-DC bidirectional power converter to the DC bus together with a photovoltaic power plant. Avltage source converter is used for conversion of DC to AC power. Utility grid and commercial load are connected to the AC side. Modeling of a hybrid system and simulation of the system’s behaviour during a random day of the year was performed in Matlab/Simulink environment employing SimPowerSystems toolbox. The results show the cooperation of the battery energy storage system and the photovoltaic power plant using system control in order to satisfy load requirements.

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.

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.

This article deals with sizing of hybrid renewable sources applications that are suitable in remote areas where grid connection is unavailable or connection to grid is expensive. Depending on the size of installed capacity of each photovoltaic, wind power and small water power plant, such a system can be used to power small systems with hundreds watts consumption and also can be used to supply entire villages where the connected load has a power in the order of up to megawatts. All depends on the installed performance of different sources, types and sizes of the storage device and the equipment, to be an island power system. Such hybrid renewable sources systems are strongly dependent on the weather conditions of the site of their construction. The present paper is about a small grid-off system that powers a small single house. This house is modelled as family house with a two-membered family. The system consists of a photovoltaic cell field, a wind turbine, a small hydroelectric power plant, and a battery bank as a cumulating source. This system is designed to power a whole daily consumption load without electricity outages.

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.

This article deals with the analysis of a day-ahead generation diagram in specific part of a power network with renewable energy sources. As a renewable energy source a photovoltaic power plant was chosen. Input data for a day-ahead analysis was obtained from the database of previous measurement that was realised on the existing configuration in off-grid network at the department of authors. The simulation network was created in Matlab/Simscape Power System environment that consisted of rotating generators (for regulation of generated power due to fluctuated power generation from photovoltaic sources) and photovoltaic power plant of variable energy generation and loads. The results refer to a necessity to consider the previous measured data of the weather for prediction of future expectation of a day-ahead load diagram.

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.

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.

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.

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.

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.