Plenz, Maik

One of the crucial steps for a successful integration of electric bus fleets into the existing electric power systems is the active and intelligent usage of their flexibility. This is important not only for reducing the eventual negative effects on the power grid but also for reducing energy and infrastructure costs. The first step in the optimal usage of flexibility is its quantification, which al-lows the maximum provision of flexibility without any negative effects for the fleet operation. This paper explores the available flexibility of large‐scale electric bus fleets with a concept of centralized and unidirectional depot charging. An assessment of available positive and negative flexibility was conducted based on the data from two real bus depots in the city of Hamburg, Germany. The analysis shows the biggest flexibility potential was in the period from 16:00 h to 24:00 h, and the smallest one was in the periods from 08:00 h to 16:00 h, as well as from 02:00 h to 08:00 h. The paper also gives an overview of the possible markets for flexibility commercialization in Germany, which can provide an additional economic benefit for the fleet operators. A further analysis of the impact of parameters such as the timeline (working day or weekend), charging concept, ambient temperature, and electrical preconditioning provides an additional understanding of available flexibility.

The high importance of demand-side management for the stability of future smart grids came into focus years ago and is today undisputed among a wide spectrum of energy market participants, and within the research community. The increasing development of communication infrastructure, in tandem with the rising transparency of power grids, supports the efforts for deploying demand-side management applications. While it is then accepted that demand-side management will yield positive contributions, it remains challenging to identify, communicate, and access available flexibility to the flexibility managers. The knowledge about the system potential is essential to determine impacts of control and adjustment signals, and employ temporarily required demand-side flexibility to ensure power grid stability. The aim of this article is to introduce a methodology to determine and communicate local flexibility potential of end-user energy systems to flexibility managers for short-term access. The presented approach achieves a reliable calculation of flexibility, a standardized data aggregation, and a secure communication. With integration into an existing system architecture, the general applicability is outlined with a use case scenario for one end-user energy system. The approach yields a transparent short-term flexibility potential within the flexibility operator system.

To capture reliable information about the existing flexibility potential of electric vehicles forecasts of charging processes are required in order to allow of utilization and management of available flexibility. Measurements of vehicles from different manufacturers show a heterogeneous behaviour of charging characteristics and charging characteristic switching points when connected to 11 kW charging stations. This paper analyzes the relationship between vehicle-specific easy to identify parameters and the charging characteristics. The proposed generic model is able to capture different charging characteristics with only a small set of parameters, to generate vehicle-specific forecast profiles.

Many bus operators worldwide have started with the electrification of their fleets. Analysis of the total cost of ownership is an often-used tool in this process allowing the bus operators to compare different technologies, find the cost optimum composition of their fleet and make strategic decisions. This paper provides a unique combination of analyzing the total cost of ownership for two electric bus depots depending on the impact of route and charging scheduling. Two different approaches to both route and charging scheduling were analyzed enabling a quantification of their effect on the total costs. As the analysis shows, the optimized scheduling can have a significant effect on the costs, emphasizing the importance of intelligent management systems for the future electric bus depots. Additionally, this paper provides a sensitivity analysis investigating the effects of diesel and electricity prices, CO2 tax and prices for electric buses on the total cost of ownership and on the break-even point compared to the conventional fleets. The analysis was conducted using real timetables from two existing bus depots in the City of Hamburg in Germany.

The high importance of Demand-Side-Management for the stability of future smart grids is consensus among a wide spectrum of energy market participants and within the research community. While it is accepted that Demand-Side-Management will yield positive contributions, it remains challenging to identify, access, and communicate available flexibilities to the flexibility managers in order to determine impacts and choose temporarily required demand-side flexibility to ensure system stability. In this paper we introduce a methodology to determine and communicate local flexibility potential of end-users to flexibility managers for short-term access. The presented approach achieves a reliable calculation of flexibility, a standardized low bandwidth data aggregation, and communication. With the integration into an existing system architecture the general applicability is outlined with a one end-user use case. The approach yields a transparent short-term flexibility potential within the flexibility manager system.

Die fortlaufenden, regulatorischen Eingriffe der Bundesregierung im Bereich erneuerbarer Energien führen zu einem hohen Anteil an Windkraft und Photovoltaikanlagen im elektrischen Energieversorgungssystem. Neben einer bevorzugten Einspeisung der erneuerbaren Energien erfolgt aktuell und zukünftig ein Rückbau oder die Stilllegung konventioneller Kraftwerke, wie Atom- und Kohlekraftwerke. Als quantitativer Bewertungsparameter zur Abschätzung der potenziellen Konsequenzen wird die Kurzschlussimpedanz verwendet, die aus den Kurzschlussströmen ableitbar ist. Die Kurzschlussimpedanz dient beispielsweise zur Bewertung der Aufnahmekapazität der Netzanschlusspunkte, der Sicherstellung der Versorgungsqualität und der Reduktion der Netzrückwirkungen. Die Impedanz eines Netzverknüpfungspunktes einer Anlage berechnet sich aus Netzkurzschlussleistung und der Netznennspannung. Somit ist die Netzkurzschlussleistung ein wesentlicher Parameter der Netzbewertung, der sich durch die Energiewende verändert. Betrachtet wird in diesem Beitrag der Anfangs-Kurzschlusswechselstrom, der die Grundlage für die rechnerische Größe der Netzkurzschlussleistung ist. Dieser Beitrag analysiert den Einfluss der Veränderung der Kurzschlussströme auf die Niederspannung (NS) unter Verwendung von Referenznetzen der Nieder- und Mittelspannungsebene (MS), szenariobasierten Simulationen und vereinfachten Modellen für erneuerbare Energieanlagen. Gleichzeitig werden bisherige Forschungsergebnisse auf Tendenzen untersucht, die die Veränderungen der Kurzschlussströme und den Einfluss von EE-Anlagen analysieren. Die Ergebnisse der Simulationen zeigen, dass die Kurzschlussströme trotz der Abschaltung von Großkraftwerken, die bisher durch Synchrongeneratoren den größten Anteil am Netzkurzschlussstrom lieferten, nicht in relevantem Maße abnehmen.