The increasing role of offshore wind power plants in the electricity generation mix in Turkey raises some critical grid operation issues. In this context, the grid code regulation concerning the penetration of large-scale offshore wind power plants into Turkey's power system has become a prominent factor in the development of a reliable grid operation. In this paper, a comprehensive benchmark for grid codes of the European countries that have large-scale offshore wind power plants and Turkey is performed by considering voltage regulation, frequency regulation, fault ride-through, and power quality features. The compatibility of the grid codes in terms of the minimum technical requirements is discussed to show the pros and cons. An elaborate assessment of the Turkish grid code reveals the technical properties that need to be improved. The rigorous state-of-the-art review indicates that active power control & frequency regulation, reactive power control & voltage regulation, and voltage ride-through capabilities should be clarified in detail for the Turkish grid code. With this background, various recommendations, key challenges, and future trends related to the improvement of technical requirements for the Turkish grid code for the integration of offshore wind power plants are highlighted to help researchers, plant owners, and system operators.
Offshore grids can play key roles in the transition of energy systems toward sustainability. Although they require extensive infrastructure investments, they allow for the exploitation of additional resources and may be important in providing for part of the increasing electricity demands driven by sector coupling. This paper quantifies the socioeconomic value of offshore grids and identifies their major drivers, performing energy system optimization in a model application of the northern–central European energy system and the North Sea offshore grid towards 2050. The increasing wake loss with the sizes of hub-connected wind farms is integrated in the modeling. We find that without sector coupling no offshore grid may develop, and that the higher the level of sector coupling, the higher the value of offshore grids. Therefore, it can be strongly stated that offshore grid infrastructure development should not be discussed as a separate political topic, but seen in connection to sector coupling.
Offshore energy hubs connect large amounts of offshore wind to a hub from where the generation can be transmitted to onshore, potentially linking to multiple surrounding countries. The benefits of such hubs, and the related meshed offshore grid to connect them, have been investigated in the North Sea. The system-wide impacts of offshore energy hubs in the Baltic Sea are less studied; however, the region is seeing increased interest in offshore wind development. This paper uses detailed offshore wind generation simulations and energy system optimisation to investigate the cost-effectiveness of offshore energy hubs in the Baltic Sea in different scenarios towards 2050. The results show that the largest deployment of offshore energy hubs occurs when the energy system is highly electrified. The strongest development of the offshore energy hubs occurs in the southern part of the Baltic Sea.
I Danmark har vi en god og lang tradition for en åben demokratisk debat om vores fremtidige energiforsyning.
Gennem årene har vi udviklet et godt fælles grundlag for, at en sådan debat er baseret på fakta om, hvad de enkelte teknologier kan i dag, samt en konsensus om fremtidige forventninger. Teknologikataloget, som løbende opdateres af Energistyrelsen og Energinet i en dialog med relevant faglig ekspertise, udgør en fælles ramme for denne forståelse.
I den senere tid har der været en debat om, hvorvidt atomkraft kan og bør være en del af den grønne omstilling af Danmarks energiforsyning eller ej. Debatten har indeholdt mange modsatrettede udsagn om blandt andet økonomien i atomkraft og dens evne til at være en del af det samlede fremtidige elsystem.
Det er forståeligt, at en sådan debat opstår i lyset af de nuværende klima- og energiforsyningsudfordringer, men det er en fordel for debatten, at den bliver så faktabaseret som muligt. Målet med vores notat er at bidrage til dette.
Vi har fundet frem, hvad vi kunne af relevante fakta om nyligt etablerede atomkraftværker i Europa samt forventninger til atomkraft i fremtiden baseret på data fra det Internationale Energiagentur. Disse fakta omhandler anlægsomkostninger, levetider, driftsomkostninger og byggetider.
På baggrund af en sådan viden samt tilsvarende data om eksisterende vedvarende energianlæg i Danmark i kombination med Teknologikatalogets forventninger til fremtiden har vi foretaget en direkte sammenligning af omkostningerne ved at producere el fra henholdsvis vind, sol og atomkraft.
Det er imidlertid svært direkte at sammenligne sol, vind og atomkraft. Atomkraft er kendetegnet ved kontinuert produktion i modsætning til den fluktuerende produktion fra vind og sol. Der er en umiddelbar relativ fordel ved kontinuert elproduktion. Men atomkraften har også nogle ulemper, hvad angår radioaktivt affald og sikkerhed. Den fluktuerende produktion fra vind og sol afføder et behov for kapacitet til at balancere systemet, når der ikke er forsyning fra vind og sol. Det kan fx være transmissionsnetskapacitet til at balancere over geografiske afstande, kapacitet i form af gasturbiner, der kan køre på grøn gas fra nettet i sådanne perioder og det kan være behov for kapacitet i form af elektrolyse til brintproduktion, så brinten produceres, når der er mest el i systemet.
For at kvantificere den økonomiske betydning af dette behov for ekstra kapacitet har vi foretaget energisystemanalyser og regnet på et fremtidigt dansk energisystem henholdsvis med og uden atomkraft. På den måde kan vi vurdere, hvordan atomkraft vil kunne påvirke det samlede energisystem og dets omkostninger.
Vi ser gerne en åben debat om de data, som vi fremlægger her. Derfor kalder vi også dette skrift for ’første version’, og er der noget, som skal korrigeres eller suppleres, så gør vi gerne det i en eventuelt revideret version.
Under alle omstændigheder håber vi, at notatet bidrager til at gøre debatten mere faktabaseret og transparent. Det er der brug for.
Recent times have seen a great interest on environmental issues and efficient, sustainable systems. This interest has required the employment of advanced composites for a myriad of industrial machines and innovative equipments. Among these applications, Flywheel Energy Storage Systems – FESS – represent a group of machines that are being re-invented through this process. Modeling composite flywheels has proven to be a complex task, which current Finite Element models fail to fulfill in a number of design contexts. This demand to model complex composite geometries and systems induced the proposition of new methods, aiming to capture the various physical effects existing in the problem. In the present contribution, the authors consider that it is viable to model the dynamic behavior of a Flywheel Energy Storage System via an adapted Carrera Unified Formulation, both in terms of accuracy and computational cost, for practical applications. The present work presents and explores a Carrera Unified Formulation model with extended capabilities dedicated to rotordynamics applications. The differences from standard Finite Elements models are presented, evidencing advantages and drawbacks of the proposed methodology over more traditional approaches. A case study is then presented, modeled, and the results are compared with those stemming from established formulations.
The estimation of the thrust deduction fraction is generally conducted in ideal weather conditions. However, the presence of waves considerably alters the magnitude of this propulsive coefficient. The increased load of the propeller could be the main cause for the variation of the thrust deduction fraction in realistic operating conditions. In this work, load-varying self-propulsion model-scale numerical simulations in calm water conditions for the same ship speed are performed to investigate the influence of the propeller loading on the thrust deduction fraction. The single screw model-scale KVLCC2 tanker is selected as the case study. The results reveal a non-linear inverse correlation between the thrust deduction fraction and the propeller loading. A comparison with model-testing conducted on the KVLCC2 tanker in regular head waves suggests that the propeller loading is the main factor influencing the magnitude of the thrust deduction fraction in waves for the considered case vessel.
The cybersecurity landscape is evolving, driven by a reinforcing feedback loop of increasingly sophisticated attacks and defences. Threat actors, long benefitting from the asymmetrical “attacker’s advantage” of focused targeting, have now matured their organizational structures to facilitate tactical information sharing, technique specialization, the establishment of markets for buying and selling exploit and vulnerability information, and providing training on how to circumvent detection and defence systems.
Taking concrete steps towards a carbon-free society, the Danish Parliament has recently approved the establishment of the world's first two offshore energy hubs on Bornholm and on an artificial island in the North Sea. Being the two first-of-their-kind projects, several aspects related to the inclusion of these “energy islands” in the current market setup are still under discussion. To this end, this paper presents a first large-scale impact analysis of offshore hubs on the whole European power system and electricity market. Our study shows that energy hubs in the North Sea contribute to increase social welfare in Europe. However, when considering the impact on each country, benefits are not shared equally. To help the development of such projects, we focus on the identification of the challenges arising from the hubs. From a market perspective, we show how exporting countries are affected by the lower electricity prices and we point at heterogeneous consequences induced by new transmission capacity installed in the North Sea. From a system point of view, we show how the large amount of wind energy stresses conventional generators, which are required to become more flexible, and national grids, which cannot always accommodate large imports from the hubs.
In this paper, the impacts of large-scale OWPPs penetration on the Turkish power system are addressed. The grid compliance analyzes for the large-scale OWPP integration are carried out by using the grid connection criteria defined in the Turkish grid code. PV and QV curves are obtained to assess the effect of OWPP on the static voltage stability limit. Eight scenarios are conducted to analyze the effect of the OWPP on the static and dynamic characteristics of the power grid. To observe the large-scale OWPP impact on the voltage and frequency stability, transient events such as the outage of conventional power plants and three-phase to ground faults are applied. The results of the voltage and frequency stability analysis reveal that the Turkish grid remains stable after the integration of an 1800 MW OWPP. Furthermore, the Turkish system remains stable even in the event of an outage of the international transmission lines to Bulgaria and Greece.
The results of load-varying self-propulsion model-scale experiments in calm water and regular deep-water following regular waves are presented. Open water tests were also performed at different propeller rotational speeds to evaluate the impact of the Reynolds number on the propeller thrust and torque. A model-scale fishing trawler was selected as the case study. Two ship speeds were considered. The open water curves showed a minimal influence of the Reynolds number on the thrust coefficient. However, the torque coefficient decreased with the increase of the Reynolds number. A good linear relationship between the tow force and the propeller thrust was detected in following waves and calm water conditions. The effective wake fraction increased in following waves compared to calm water conditions. The amplitude of the effective wake fraction decreased with the increase of the ship speed. A small influence of the ship motions and wave–particle velocities was reported on the thrust deduction fraction. The hull, relative rotative, propeller, and propulsive efficiency increased compared to calm water. The propulsive characteristics were estimated by considering the wave added resistance and the propulsive coefficients equal to their calm water values. Compared to the propulsive characteristics computed with the propulsive coefficients measured in waves, the propulsive efficiency was underestimated by about 2%–5%.