Search

The aim of the research is to analyse the energy transition in the Visegrad Group countries, because they depend on the production of energy from the burning of fossil fuels, and transition is a huge challenge for them. The diversity of the energy transformation in the V4 countries was examined by using two qualitative methods, including literature analysis and comparative analysis. The timeframe of the study was set for the period from 2020 to 2030, as these years are crucial for the implementation of the European Green Deal Programme. Four diagnostic features were taken into account in the analysis: the share of RES in final energy consumption, reduction of CO2 emissions in the non-Emissions Trading System (ETS) sector, date of withdrawal of coal from the economy, and energy efficiency. The analysis shows that the V4 countries have different approaches and levels of energy transformation in their economies. Poland is in the most difficult situation, being the most dependent on the production of electricity from coal, as well as having the largest number of employees in the coal and around coal sector. The other countries of the group can base their transformation on nuclear energy, as each of them has at least four such power units. The increased use of biomass for energy and heat production is the most important stimulus for Renewable Energy Sources (RES) growth in the analysed countries. The ambivalent attitude of the political elite to unconventional sources in the four analysed countries significantly hinders the development of certain forms of green energy. However, it has been observed that an increasing proportion of the population, especially those living in regions of the country where there is no fossil fuel mining industry, has a positive attitude towards energy transformation. The study is the first that shows the state of involvement in the process of systemic change of the Visegrad Group countries. The results can serve as a starting point for understanding the reticence of this group of European countries towards the transformation phenomenon, as well as contributing to further research on the implementation of closed-circuit economies in the Visegrad Group countries. [ABSTRACT FROM AUTHOR]

Fundamental shifts in the structure and generation profile of electrical grids are occurring amidst increased demand for resilience. These two simultaneous trends create the need for new planning and operational practices for modern grids that account for the compounding uncertainties inherent in both resilience assessment and increasing contribution of variable inverter-based renewable energy sources. This work reviews the research work addressing the changing generation profile, state-of-the-art practices to address resilience, and research works at the intersection of these two topics in regards to electrical grids. The contribution of this work is to highlight the ongoing research in power system resilience and integration of variable inverter-based renewable energy sources in electrical grids, and to identify areas of current and further study at this intersection. Areas of research identified at this intersection include cyber-physical analysis of solar, wind, and distributed energy resources, microgrids, network evolution and observability, substation automation and self-healing, and probabilistic planning and operation methods. [ABSTRACT FROM AUTHOR]

The advent of renewable energy sources (RESs) has posed several technical challenges related to the operation of modern power systems. These can be classified into two main categories: (a) problems at the power system level, and (b) local problems at the distribution network (DN). To solve these issues, there is a strong need for the development of innovative control schemes that can be employed by converter-based network assets, e.g., battery energy storage (BES) systems and distributed RES. In this context, a unified control system (UCS) for the provision of ancillary services (ASs) by distributed RES-BES systems within a multi-services perspective is introduced in this paper. The proposed UCS comprises different algorithms to provide ASs related to voltage regulation, voltage unbalance mitigation and frequency support. The UCS is implemented in 3-phase, 4-leg converters (3Ph4LCs) to ensure the provision of ASs in unbalanced DNs. In addition, at the dc side of the 3Ph4LC a series dc–dc converter for BES support allows the implementation of the proposed UCS in weak DNs. The transient operational performance of the proposed UCS is evaluated by conducting time-domain simulations. • A unified control system for the provision of ancillary services is introduced. • It employs voltage regulation, voltage unbalance mitigation and frequency support. • The proposed algorithms are integrated into a 3-phase, 4-leg converter. • A power oscillation damping technique is introduced to improve PLL performance. • Time-domain simulation results verify the performance of the proposed control system. [ABSTRACT FROM AUTHOR]

To achieve the Paris Agreement 1.5 °C target, apart from the obligation for new buildings to be ZEBs, the existing building stock should be retrofitted as well, in order to improve their energy efficiency by using more efficient electromechanical energy systems and envelope materials, whereas RES should cover their energy needs. In this context, Energy Performance Certificates (EPCs) have been institutionalized to certify the energy behavior of buildings. Various types of buildings energy modeling tools and calculation methods have been proposed for EPCs procedures. This study focuses on the energy performance gap between dynamic and quasi steady-state simulation tools. The results from a comparative case study have shown remarkable discrepancies between dynamic and quasi-steady-state simulation processes, for the same building. Indeed, the quasi-steady-state simulation tool estimates 4.5% higher annual electricity consumption per conditioned area for the existing building and approximately 74% less energy savings for the retrofitted one, leading to an overestimation of 85% in CO 2 emissions prediction. Finally, compared to the analysis with the dynamic simulation tool, an increased retrofit cost, approximately by 19.7% (and thus 3 times higher payback period), is needed according to the results of the quasi-steady-state simulation tool, in order to achieve the same Energy classification. • Dynamic simulation tools are the key for accurate and reliable EPCs. • Quasi steady-state tools overestimate the energy consumption of buildings. • Quasi steady-state tools underestimate buildings energy classification. • Quasi steady-state tools perform poor PVs net metering consideration. • Dynamic simulation tools contribute to avoid overestimations in building retrofit. [ABSTRACT FROM AUTHOR]

Originally, ancillary services (ASs) were provided by large-scale power plants to ensure the secure and reliable operation of power systems. However, with the advent of renewable energy sources either in large-scale or as smaller distributed generation units, there is a strong need to revisit the structure and aim of traditional ASs and reconsider them under two main concepts; ASs provided to distribution networks (DNs), aiming to solve local issues at the distribution level, and ASs offered to transmission system (TS), targeting to solve issues having a wider impact on the power system. The former can be considered as DN-oriented ASs, while the latter as TS-oriented ASs. In this changing environment, the increasing installation of measuring infrastructure has created new sources of data, providing the opportunity to improve the performance of several ASs by applying measurement-based analysis. This review paper gives an insight into the most important DN- and TS-oriented ASs foreseen to apply in future power systems. Additionally, state-of-the-art on measurement-based analysis techniques that can be used to facilitate the provision of several ASs by providing in real-time critical information regarding system dynamic performance is presented. • Detailed review on future ancillary services (ASs) in transmission systems. • Detailed review on future ASs in distribution systems. • Overview of measurement-based techniques to facilitate the provision of ASs. • Discussion on future research areas regarding ASs provision. [ABSTRACT FROM AUTHOR]