German Wind Energy Association

This paper investigates the impact of short-circuits on conductor temperature in the context of curative grid operation. While previous studies have often neglected this aspect or focused on transmission grids, this work addresses the specific conditions in high voltage distribution grids, where short-circuit behaviour and conductor configurations differ significantly. A simulation-based approach is used to determine the thermal response of conductors during short-circuits, and the results are validated through a measurement in an experimental setup. The study shows that the temperature rise caused by short-circuits depends on fault magnitude, duration, and conductor type. In many cases, this heating effect cannot be neglected. Curative grid operation relies on the fact that thermal limits, not the current rating, determine the maximum line loading. Due to thermal inertia, temporary higher current loading is possible. However, if the conductor is already preheated by a short-circuit, this must be taken into account. Therefore, the paper further analyzes the relationship between permissible higher loading and prefault loading, both with and without considering short-circuit heating. It is shown how short-circuit-induced thermal stress can significantly reduce the available headroom for curative operation. Nonetheless, curative strategies still offer considerable potential for increased grid operation compared to the preventive approach.

This paper presents a new time-series-based approach for the optimal planning of medium voltage (MV) distribution grids, which aims to increase the distribution grid capacity of the underground cables by considering the environmental conditions. This should enable an optimal integration of e-mobility and renewable energy sources (RES) into the existing grid structure and keep the necessary grid reinforcements as low as possible. For this purpose, the developed planning method determines permissible values for the current rating of a particular cable for each time point of the year. Then, these can be processed in the time-series-based grid planning in order to increase the utilization of the allowable distribution grid capacity by optimal utilization of the available grid infrastructure. Furthermore, a method for calculating the charging profiles of e-vehicles (EVs) connected to the substations, is also presented to investigate the influence of e-mobility to the loading of the grid. Finally, the effects of the use of the dynamic current ratings and the increase of e-mobility on the MV-grid are investigated.

This study presents a new time-series-based approach based on a dynamic curtailment for the planning of high-voltage distribution grids. The approach enables the optimal integration of renewable energies source (RES) into the existing grid structure and aims to keep the necessary network reinforcements as low as possible. For this purpose, the developed planning method uses a dynamic curtailment method and determines, based on the curtailment results, which lines need to be reinforced most appropriately. The aim of the presented simulation process is to reduce the curtailed energy of RES to a legally defined value and to keep it as low as possible. This enables the targeted identification of grid reinforcements and expansion measures through the developed method in time-series-based, probabilistic grid planning.

Von den ersten Windenergieanlagen im Hinterhof bis hin zu einem bedeutenden Wirtschaftsfaktor war es ein langer und sturmischer Weg. Noch sind nicht alle Fragen beantwortet und noch nicht alle Herausforderungen bewaltigt, die zu einer kompletten nicht-fossilen und nicht-atomaren Energiewelt fuhren. Der folgende Text gibt einen Uberblick uber den wirtschaftlichen, okologischen und sozialen Status der Branche der Erneuerbaren Energien, erlautert die rechtlichen Rahmenbedingungen und weist darauf hin, dass Energiewende nicht ohne Akzeptanz funktioniert. Im Mittelpunkt steht der Mensch.

This paper presents a new approach for a dynamic curtailment method for renewable energy sources that guarantees fulfilling of (n-1)-security criteria of the system. Therefore, it is applicable to high voltage distribution grids and has compliance to their planning guidelines. The proposed dynamic curtailment method specifically reduces the power feed-in of renewable energy sources up to a level, where no thermal constraint is exceeded in the (n-1)-state of the system. Based on AC distribution factors, a new formulation of line outage distribution factors is presented that is applicable for outages consisting of a single line or multiple segment lines. The proposed method is tested using a planning study of a real German high voltage distribution grid. The results show that any thermal loading limits are exceeded by using the dynamic curtailment approach. Therefore, a significant reduction of the grid reinforcement can be achieved by using a small amount of curtailed annual energy from renewable energy sources.

Unter dem Motto ein Verteilnetz nicht „bis zur letzten Kilowattstunde“ auszubauen wird das Modell zum Einspeisemanagement (Spitzenkappung) diskutiert. Hierbei werden Einspeiseanlagen zu Spitzeneinspeisung temporar, aber gezielt aus dem Netz genommen, um den erforderlichen Netzausbau zu reduzieren. Der Anlageneigner wird fur den Erlosausfall durch die Abregelung monetar kompensiert. Nach dem derzeitigen Verordnungsentwurf zur Anderung der Anreizregulierungsverordnung (ARegV) sollen diese Entschadigungszahlungen als volatile Kosten klassifiziert werden, welche zwar jahrlich auf den Verbraucher gewalzt werden, im Effizienzvergleich aber berucksichtigt werden. Dieser Artikel beleuchtet die Schwachstelle dieses Modells: Es werden zwar Anreize fur eine optimale Kombination aus Netzausbau und Spitzenkappung gesetzt, allerdings ist die Partizipationsbedingung empfindlich verletzt: Im Erwartungswert sind die Gewinne negativ, sodass Investoren keinen Anreiz haben in Verteilnetze zu investieren. Dieses Problem kann gelost werden, indem volatile Kosten zwar gewalzt werden, im Effizienzvergleich mit ihrem durchschnittlichen Niveau berucksichtigt werden.