Increase Of Renewable Energy Sources Research Articles

THE EFFECTS OF RENEWABLE ENERGY SOURCES ON THE STRUCTURE OF THE TURKISH ELECTRICITY MARKET

The structure of the electrical power system in Turkey has undergone rapid change and transitioned into a free market. With this development, the tendency to employ renewable energy sources (RES) has increased. In this study, both the Turkish electricity market and the renewable energy incentive structure, and the effects of RES on the electrical market have been investigated. A 10 buses power system with both traditional and renewable generator units has been considered. In this system, five different scenarios have been constructed and simulated using the PowerWorld program. Marginal prices, voltage amplitudes, voltage angles of buses and the total costs have been examined using optimal power flow (OPF). In particular, for scenarios where there was a load increase and a transmission line was disconnected, significant changes were observed in electricity prices, the voltage amplitude and the voltage angle. With the increase of RES in the electricity market, a price increase was observed in the initial stage. However, as the volume of RES gets larger, the rate of increase was observed to slow down and almost reach its previous state. Generator electricity costs have decreased and profits have increased even though retail prices have increased. The generators with increased profits have been observed to use RES. Keywords: Turkish Electricity Market, Renewable Energy Sources, Bus Marginal Price, Voltage Amplitude, Voltage Angle. JEL Classifications: Q40, Q41, L94, C61 DOI: https://doi.org/10.32479/ijeep.8896

Resource Adequacy Methodologies in the European framework – how to take flexibilities into account in future modelling of resource adequacy?

The drastic increase of renewable energy sources in combination with the fade-out of big thermal units leads to an increase in the amount of flexibilities for the European electricity system. Since a huge amount of flexibilities are located in the distribution system area, the potential and proper amount for modelling is challenging to catch. Transmission system operators (TSOs) need to establish a way to retrieve this data to carry out analysis to determine their level of security of supply. Probabilistic resource adequacy assessments serve as a basis to terminate those levels and try to answer the question of sufficient generation can be provided every hour of the year to cover future demand. Within this study, some general introduction to Resource Adequacy Assessments within Europe is provided. Special focus is drawn to the implementation of flexibilities by the use of a new database supporting future flexibilities. Since probabilistic resource adequacy assessments constantly develop, an assessment of adding stepwise amounts of demand-side response (DSR) to the Austrian system is performed. DSR aims to increase or decrease demand by shifting peak values to time intervals when this would be beneficial to system operation using stimulation through market pricing signals.

Wind energy integration: Variability analysis and power system impact assessment

The progressive increase of renewable energy sources (RES) share during past decade strongly reflects on power system operating conditions. Romania is the South Eastern European country with the largest RES generating capacity. This paper proposes a novel method for assessing the impact on national power systems operation of integrating high shares of RES. Specifically, the method addresses first a variability analysis of RES production, based on historical records over 10 years for the Romanian power system. Wind energy is selected as the RES with the widest confidence interval, thus generating the largest power output fluctuations. Further, different simulation scenarios are defined in terms of variable wind energy share. The values obtained are integrated in a scaled simplified model, implemented in PSS/E. The impact of generating sets based on wind energy employment on voltage magnitude and transient time is assessed in fault conditions. Considering that the simulation scenarios defined comprise variable wind energy generation shares, this study emphasizes the impact of its dynamics on power systems. Simulation results highlight the negative influence of increasing wind energy share on the analyzed quantities. The outcomes of this research can suggest a particular analysis approach useful in studying power systems operation.

OVERVIEW OF SOLAR ENERGY CONVERSION IN TURKEY

According to global energy statistics, the amount of energy consumed increased from 8557 Million Tons of Equivalent oil (mtep) in 1990 to 13509 mtep in 2016. Research has shown that life span of 200 years of coal, 40 years of oil and 60 years of natural gas. Therefore, it is foreseen that fossil fuels will not be able to respond to the increase in energy needs and will fall behind energy consumption. because of this reason, it has been considere important to search for new energy sources to prevent future energy crises. Today, it can be said that this searching mostly focuses on renewable energy sources. Research suggests that renewable energy will constitute approximately 40% of total energy in the future. Although the importance of hydroelectric and wind energy from renewable energy sources has been understood much earlier, it is seen that the importance of solar energy has been realized in recent years. It is estimated that the highest increase in renewable energy sources between 2012 and 2040 in electricity generation will be in solar energy. Based on the years 2010 and 2018, while in 2010 was obtained 40,871 MW energy from the solar and 180,854 MW energy from the wind, but in 2018 was obtained 485,826 MW energy from the solar and 563,726 MW energy from the wind. According to these results, the energy obtained from the solar has increased approximately 12 times in the last nine years, while the energy obtained from the wind has increased approximately 4 times.

Wind Energy Projects and Species Protection Law: A Comparative Analysis of the Application of EU Law in Five Member States

Wind farms and their associated transmission infrastructure can have negative impact on biodiversity. Offshore wind farms, for example, can pose threats to animals like harbor porpoises and migrating birds and onshore wind farms and transmission grids may harm birds and bats.In this article we analyse how European Union species protection law is transposed and applied to decision-making on wind energy projects in five member states, namely Denmark, Germany, the Netherlands, Belgium and the United Kingdom. The analysis aims to understands the differences in the interpretation and application of national species protection law, point out deficiencies, and make recommendations, partly based on learning from best practices. Though transposition in national law is almost identical, implementation practice in these states varies substantially. The question in raised whether the legal regime, as currently applied, can be improved to serve the aims of a considerable increase of renewable energy sources whilst simultaneously protecting biodiversity.

Comparative Analysis of the Energy Sector Development Trends and Forecast of Final Energy Demand in the Baltic States

The paper provides a comparative analysis of economic growth in Estonia, Latvia and Lithuania and discusses differences in development of the main sectors during the period 2000–2016. Based on detailed analysis of energy sector development, the driving factors influencing changes in primary energy consumption in each country and in the Baltic region are discovered. Increase of renewable energy sources (RES) consumption in the Baltic region over this period by 73.6% is emphasized. The paper presents valuable insights from analysis of trends in final energy consumption by sectors of the national economies, branches of the manufacturing sector, and by energy carriers. Long-term relationships between economic growth and final energy consumption are established. An econometric model was applied to predict final energy demand in the Baltic States for the 2020 horizon. It is emphasized that growing activities in the manufacturing and transport sectors will cause increase of final energy demand in all three countries. Based on detailed analysis of greenhouse gas (GHG) emissions trends some positive shifts are shown and the necessity of new policies in the transport sector and agriculture is identified. Changes of emission intensity indicators are examined and a potential for decoupling of carbon dioxide (CO2) emissions from economic growth in Estonia is indicated.

A Methodology for Determination and Definition of Key Performance Indicators for Smart Grids Development in Island Energy Systems

There is a growing interest over the last decades in the field of autonomous island grids that is driven mainly by climate reasons. The common objective among the members of the European Union (EU) is the increase of Renewable Energy Sources (RES) penetration in the energy mixture, as well as turning the grid into a smart grid. Consequently, more and more state-of-the-art solutions are being proposed for the electricity generation and the optimization of the energy system management, taking advantage of innovations in all energy related sectors. The evaluation of all available solutions requires quantitative assessment, through the adoption of representative Key Performance Indicators (KPIs) for the projects that are related to smart grid development in isolated energy systems, providing the relevant stakeholders with a useful comparison among the proposed solutions. The evaluation approach that is described in this paper emphasizes the role of the various stakeholder groups who face the proposed solutions by different points of view. Apart from the domains of interest that are also observed in previous approaches, the proposed list also contains a set of legal KPIs, since the regulatory framework can either represent a serious barrier or grant a strong incentive for the implementation of state-of-the-art energy technology and grid management solutions in different countries.

Distributed Optimal Load Frequency Control with Non-Passive Dynamics

Motivated by an increase of renewable energy sources, we propose a distributed optimal load frequency control scheme achieving frequency regulation and economic dispatch. Based on an energy function of the power network, we derive an incremental passivity property for a well-known nonlinear structure preserving network model, differentiating between generator and load buses. Exploiting this property, we design distributed controllers that adjust the power generation. Notably, we explicitly include the turbine-governor dynamics, where first-order and the widely used second-order dynamics are analyzed in a unifying way. Due to the non-passive nature of the second-order turbine-governor dynamics, incorporating them is challenging, and we develop a suitable dissipation inequality for the interconnected generator and turbine-governor. This allows us to include the generator side more realistically in the stability analysis of optimal load frequency control than was previously possible.

Durability of technologies in the keeping of ZEB’s performances

Durability is an important aspect that has not to be neglected in ZEB design. The requirements for buildings energy needs reduction and increase of renewable energy sources stimulated designers to integrate technologies in an efficient way. This ambitious goal must meet the capacity of the technical solutions to guarantee their performances over the years. The durability of materials and technologies is a topic that warrants further analyses in order to assess the proper efficiencies and the expected lifetime of a ZEB. Typically the energy balance of a ZEB is calculated by considering the annual energy flows or rarely the whole life cycle. The most used approaches consider constant performance of materials and technical elements over the lifespan. However, the performance loss of a single element can cause an imbalance in the behavior of a ZEB, for which persists a thin balance between inlet and outlet flows. The paper provides a critical point of view on this issue paying attention on the following technical solutions implemented in a case study for which the current scientific literature provides analysis on the degradation during their lifetime: glazing systems, VIPs, PV panels and GSHPs.

A Virtual Synchronous Generator Control Strategy for VSC-MTDC Systems

With the rapid increase of renewable energy sources and power electronic converters in the power system, the inertia of the power system is declined and the stability problem is more serious than ever before. In this paper, a virtual synchronous generator (VSG) control strategy is proposed to enable the voltage-source converter-based multiterminal high-voltage direct current (VSC-MTDC) system to damp the low-frequency oscillation modes. Both rotational inertia part and governor part are modeled in the VSG controller. The $V^2-P-\omega$ characteristic is developed based on the $V^2-P$ droop control to emulate the action of the speed governor when the frequency of ac grid deviates from the nominal value. The virtual inertia part is used to emulate the inertia response of the synchronous generator. The communication between VSC stations is unnecessary with the autonomous power allocation ability of the $V^2-P-\omega$ characteristic. Modal analysis is utilized to test the system stability and optimize the controller parameters. Two test systems which include offshore wind farms, VSC-MTDC systems, and onshore power grids are built in the DIgSIENT/PowerFactory. The simulation results verify the effectiveness of the proposed VSG strategy.

Do people really want renewable energy? Who wants renewable energy?: Discrete choice model of reference-dependent preference in South Korea

Renewable energy is gaining more attention than before in terms of tackling climate change and ensuring the public safety. The South Korean (hereafter, Korean) government has announced various policies to expand renewable energy sources and reduce the share of nuclear and coal-fired power. Since the energy sources are directly related to the lives of people, it is important to identify the public's acceptability of changes in the energy mix. Therefore, the purpose of this study is to analyze public preferences for changes in the shares of energy sources. For estimation of preference, this study used a mixed logit model that reflects the reference point to consider the relative shares of the energy sources and the relative level of attributes. In addition, this study used a hierarchical Bayesian logit model to examine whether the public characteristics result in any preference difference on the electricity service attributes. The results show that the Korean public's acceptability is high for renewable energy source expansion policy. Based on the analysis, this study found that the respondent's level of education had a significant effect on the preference for increase of renewable energy sources.

Heuristic optimisation for automated distribution system planning in network integration studies

Network integration studies try to assess the impact of future developments, such as the increase of Renewable Energy Sources or the introduction of Smart Grid Technologies, on large-scale network areas. Goals can be to support strategic alignment in the regulatory framework or to adapt the network planning principles of Distribution System Operators. This study outlines an approach for the automated distribution system planning that can calculate network reconfiguration, reinforcement and extension plans in a fully automated fashion. This allows the estimation of the expected cost in massive probabilistic simulations of large numbers of real networks and constitutes a core component of a framework for large-scale network integration studies. Exemplary case study results are presented that were performed in cooperation with different major distribution system operators. The case studies cover the estimation of expected network reinforcement costs, technical and economical assessment of smart grid technologies and structural network optimisation.

Impact of Considering 110 kV Grid Structures on the Congestion Management in the German Transmission Grid

The structural changes in the European energy system lead to an increase of renewable energy sources that are primarily connected to the distribution grid. Hence the stationary analysis of the transmission grid and the regionalization of generation capacities are strongly influenced by subordinate grid structures. To quantify the impact on the congestion management in the German transmission grid, a 110 kV grid model is derived using publicly available data delivered by Open Street Map and integrated into an existing model of the European transmission grid. Power flow and redispatch simulations are performed for three different regionalization methods and grid configurations. The results show a significant impact of the 110 kV system and prove an overestimation of power flows in the transmission grid when neglecting subordinate grids. Thus, the redispatch volume in Germany to dissolve bottlenecks in case of N-1 contingencies decreases by 38 % when considering the 110 kV grid.

Wind speed forecasting model for northern-western region of India using decision tree and multilayer perceptron neural network approach

Power production by wind energy with the increase in renewable energy sources, plays an important role in India due to its critical location. In this paper, using the input variables like latitude, longitude, cooling design temperature, relative humidity, air temperature, atmospheric pressure, daily solar radiation – horizontal, Earth temperature amplitude, Earth temperature, heating degree-days, cooling degree-days, elevation, heating design temperature, frost days at site, monthly wind power density and air density, wind speed is predicted by multilayer perceptron in 17 cities of India. The varying number of hidden neurons helps in calculation of accurate forecasting. It is found that prediction accuracy is highest for six hidden neurons in training and testing phase which is 99.14% and 96.116%, respectively.

Variability and correlation of renewable energy sources in the Portuguese electrical system

The lack of predictability in the output of solar, wind, and small hydroelectric power plants aggravates the problem of consistently matching supply with demand on electric grids. In this paper, a database of renewable power injection, at 15-minute intervals during 2010–2014, into the Portuguese electric transmission system is analysed to characterize the variability and other patterns of renewable energy injection into the system. The system, operated by REN (Redes Energéticas Nacionais), received 20–28% of its electricity from the three renewable energy sources (RES) mentioned, with wind contributing about 90% of that amount. A strong complementarity (smoothing effect) between wind and PV was found, with correlation factors of −0.92 and −0.83 for typical summer and winter days, respectively. The correlation factors for different time scales decrease from annual totals (−0.88) to hourly totals (−0.24), as expected. The results suggest that lower wind power years correspond to sunnier ones. Moreover, the reserve regulation costs appear to decrease when the installed capacity of the three considered RES increase.

Life Cycle Cost Analysis for BESS Optimal Sizing

The increase of renewable energy sources (RES) installations all over the world during the past decades leads to a more sustainable energy scenario, however some drawbacks still persists and hinder the complete replacement of traditional fossil fuels. One of the main challenging issue is related to the intermittent production that generates serious problem in the power grids operations. Battery energy storage systems (BESS) represent one of the most promising technology which can help to overcome this issue, revolutionizing the way in which electrical power grids are designed and operate. The main aspects of these devices are related to the grid energy management, increasing the host capacity of RES, the system reliability and the users’ self-consumption. However, even energy storage systems present several pitfalls. They should be correctly maintained over the lifetime and they cannot be completely recycled at the end of their life, in addition, maintenance, decommissioning and disposal costs represent a significant share of the total cost. So as to consider these aspects in a holistic model the present work proposes a life cycle cost (LCC) model, which take into account all the most relevant cost components during the entire operation of the system.

Voltage and frequency control strategies of hybrid AC/DC microgrid: a review

Microgrids have become an attractive option for distributed generation (DG) with increase in renewable energy sources (RES) and storage systems. The existence of both AC and DC microgrids has led to a new concept of hybrid AC/DC microgrid which consists of both AC and DC grids tied by an interlinking converter (ILC). Such hybrid AC/DC microgrid has the advantages of both AC and DC with increased efficiency and less cost since the conversion between AC and DC is reduced. The management of power in such a grid becomes important for voltage and frequency control. Different voltage and frequency control strategies have been successfully implemented within AC and DC grids, but the control of hybrid microgrid requires further attention with focus on ILC. This study presents an overview of various control schemes used for voltage and frequency regulation in standalone and transition mode operation of hybrid microgrid. A detailed study on hybrid grid structure is presented with different modes of operation. Various ILC strategies based on droop and communication-based control are presented. Based on the analysis, some recommendations are presented for future research.

Sensitivity Analysis for the Power Quality Indices of Standalone PV Systems

Standalone photovoltaic systems is a key technology for the increase of renewable energy sources share in electricity production worldwide. The power quality of those systems plays a fundamental role in avoiding volatile power supply. This calls for a concrete design in order to meet power quality specifications. In this context, a methodology has been developed in a previous work, in order to set the values of the parameters that optimize the power quality indices of the system. In this paper, an extensive sensitivity analysis is performed regarding the influence of the optimized parameters variation on the power quality indices. Throughout the outcomes of the sensitivity analysis a more insightful view of the system performance under the deviations of system parameters is revealed, which in combination with the aforementioned optimal design strategy becomes an essential tool that ensures high power quality level. The theoretical outcomes are validated by experimental results, highlighting the effectiveness of the proposed design strategy.

Modeling of optimal energy flows for systems with close integration of sea water desalination and renewable energy sources: Case study for Jordan

This paper presents a new approach for modeling energy flows in complex energy systems with parallel supply of fresh water and electricity. Such systems consist of renewable energy sources (RES), desalination plant, conventional power plants and the residual brine storage which is used as energy storage. The presented method is treating energy vectors in the system as control variables to provide the optimal solution in terms of the lowest critical excess of electricity production (CEEP) and highest possible share of RES in the supply mix. The optimal solution for supplying the demands for fresh water and electricity is always found within the framework of model constraints which are derived from the physical limitations of the system. The presented method enables the optimization of energy flows for a larger period of time. This increases the role of energy storage when higher integration of RES in the supply mix. The method is tested on a hypothetical case of Jordan for different levels of installed wind and PV capacities, as well as different sizes of the brine storage. Results show that increasing the optimization horizon from one hour to 24h can reduce the CEEP by 80% and allow the increase of RES in the supply mix by more than 5% without violating the CEEP threshold limit of 5%. The activity of the energy (brine) storage is crucial for achieving this goal.

Development and Characterization of a Dithionite / Air Fuel Cell

With the increase of renewable energy sources in an electrical network, the need for energy storage increases. Depending on the application, there are different ways to store electrical energy. For electrochemical energy storage options exist in the form of batteries, redox flow batteries and fuel cells coupled with electrolysis. The longer the storage time, the lower the cost of energy storage medium must be in order to be competitive with other technologies. Batteries and redox flow batteries use reversible electrochemical reactions, fuel cells do not normally what makes specially adapted electrolysers required. Wherever possible, simple and rapid electrochemical reactions for the reversal of the reactions are required, as for example are found in the redox couple H2/2H+. The reactions of organic redox couples of DMFC and DEFC can be electrochemically not reversed. Another way could be combinations of anodes of dissolved ions with an oxygen cathode, thereby “burning” the salt solutions which results in direct ion liquid fuel cells. A representative is the vanadium / oxygen fuel cell in which divalent vanadium ions are oxidized to trivalent at the anode by means of oxygen at the cathode [1]. The reactions can be reversed by vanadium / water electrolysis in the same cell as a reversible fuel cell (redox flow battery) [2, 3] or externally with a separate electrolysis cell [4]. Here we would like to report a work in which we have built and studied an alkaline fuel cell with the inexpensive redox couple dithionite / sulfite. Anode: S2O4 2- + 4 OH- -> 2 SO3 2- + 2 H2O + 2 e- E0= -0.294 V Cathode: O2 + 2 H2O + 4 e- -> 4 OH- E0= +1.227 V Cell: 2 S2O4 2- + O2 + 4 OH- -> 4 SO3 2- + 2 H2O E = 1.530 V As with the VOFC the reactions in a separate or the same cell may be reversed, and thus serve as an energy storage. For investigating the feasibility of such a cell a carbon-based anode and a platinum catalyst cathode for the ORR was used. The investigations were carried out by means of polarization curves, discharge tests and impedance spectroscopy using the cell voltage and the half-cell potentials and showed a maximum power density of 2 mW/cm² at room temperature. Under these conditions the oxidation of dithionite at carbon was much slower than the ORR. With a 0.85 M Na2S2O4the cell reached 12.4% energy efficiency and an energy density of 8.6 Wh/L. 1 C. Menictas, M. Skyllas-Kazacos, Journal of Applied Electrochemistry 2011, 41, 1223–1232. 2 S. S. Hosseiny, M. Saakes, M. Wessling, Electrochemistry Communications 2011, 13, 751–754. 3 J. grosse Austing, C. Nunes Kirchner, E.-M. Hammer, L. Komsiyska, G. Wittstock, Journal of Power Sources 2015, 273, 1163–1170. 4 J. Noack, T. Roth, M. Hihn, J. Tuebke, The 7th International Green Energy Conference & The DNL 1st Conference on Clean Energy, Dalian, China, 2012 Figure 1