Elektrische Energiesysteme

This paper serves as a quick guide for the selection process of contactless electrical sensors involved in unmanned aerial systemsbased gridmonitoring applications. Since the selection criteria for such sensors can be enormous and hence challenging, the major key points were elaborated after a thorough review of relevant work. The review presented in this paper, composedof seven current sensors and three voltage sensors topologies, is critically investigated. In terms of flexibility, complexity, sensitivity, and other performance indices, it is concluded that an “all-optical” dual voltage and current contactless sensor would represent an optimum choice to be employed within remote measuring applications. The mainrecommended feature of the suggested sensor is its ability to freely measure electrical quantities while being “relatively” far from the electrical transmission line, implying no need to be “clamped” all around it. By presenting an informative background for intelligent field sensing applications, this paper also suggests the future work relevant to the studied topic.

To increase the service life or durability of PEM fuel cells, no-load operation at open circuit voltage has to be avoided to reduce destructive electrochemical effects. This paper shows two approaches to realize a regulated base-load with a fuel cell protection unit for application in aircraft multi-powertrain-concepts. Firstly, a clocked MOSFET in the form of a chopper circuit, and secondly, a MOSFET in linear operation as current source. This contribution describes the design concept of both approaches and the validation of prototypes in a laboratory pHiL-environment. Both approaches are proven to be viable solutions, with the current source approach resulting in smoother operation.

The importance of electrifying buses in public transportation is increasing massively during the last few years. This owes to the health detrimental emissions of diesel buses and their effect on the climate changes. Correspondingly, the two transportation companies in Hamburg, the Hamburger Hochbahn AG and Verkehrsbetriebe Hamburg-Holstein GmbH (VHH), decided to electrify their bus depots. This ambitious goal is combined with many challenges concerning the design and operation of the charging infrastructure at the minimum costs. Among others also load management, grid impact, power quality. The aim of implementing the presented model is to search for possible usage of flexibility of electric bus depots in the energy market. This is realized by considering the bus depot as an aggregator of positive or negative flexibility. The offering of this flexibility is based on the predefined atypical grid usage in Germany. This enables electricity customers with an annual energy consumption of more than 100,000 kWh to save in grid fees for their load regulation in coordination with grid operators. Nevertheless, the operation of the bus depot has the highest priority in this study to guarantee the ability of buses to travel their routes. This paper analyses three different scenarios for atypical grid usage: the role of load management, the role of a second-life stationary battery and the combination of both cases. As a result, the required supplying periods and capacities of the stationary battery are calculated. Finally, a combined scenario between the supply from the stationary battery and the supply from the grid is presented.

The coupling of the three energy grids electric power, gas and heat, via sector coupling devices such as fuel cells or electrolyzers enables the increase of the share of renewable energies in consumption beyond the electricity sector. Correct modeling is crucial for the physically correct description of the behavior of fuel cells and effects on the energy grids, especially regarding transients caused by switching processes or during plant faults. In the paper presented here, the proton exchange membrane fuel cell is introduced as a component for its use in the “Extended Node Method”. It allows a suitable integration into the grid-based energy systems electricity, gas and heat based on node equations. For this purpose, the fuel cell is described as a multi-energy component. Also, for gas and heating grids, electrical analogies are used. The associated systems of equations are constructed in such a way that they can be applied to different topologies. Exemplary operating points are shown for a sample configuration. The results are partly compared with other calculation methods and software and discussed.

Impedance-based analysis methods enable a more specific and earlier foundation for assessing harmonic stability in decentralized converter-based power plants compared to the conventional compliance testing in the grid connection process. Essentially, they can be implemented as black-box model approaches without the necessity to disclose internal control models. Initially, only knowledge of the input impedances of the planned grid connection point and the planned PV system is required for application. For this purpose, the method of impedance spectroscopy for inverters has already been developed as a means to determine the effective impedance profile and the internal harmonic sources of inverters, allowing for the description of the frequency-dependent behavior of individual units. The time- and frequency-dependent grid impedance at the grid connection point (GCP) has also been successfully measured in several campaigns on medium and low-voltage grids. Through the coordinated application of both measurement methods, a predictive harmonic assessment is intended in the future, ensuring high planning reliability and grid quality even in grids with a high penetration of power electronics-coupled systems. This paper provides an overview of the current state of research on impedance-based stability criteria and presents measurement methods for practical implementation. Furthermore, it outlines remaining open questions until application in the field.

The evolving technologies regarding Unmanned Aerial Vehicles (UAVs) have led to their extended applicability in diverse domains, including surveillance, commerce, military, and smart electric grid monitoring. Modern UAV avionics enable precise aircraft operations through autonomous navigation, obstacle identification, and collision prevention. The structures of avionics are generally complex, and thorough hierarchies and intricate connections exist in between. For a comprehensive understanding of a UAV design, this paper aims to assess and critically review the purpose-classified electronics hardware inside UAVs, each with the corresponding performance metrics thoroughly analyzed. This review includes an exploration of different algorithms used for data processing, flight control, surveillance, navigation, protection, and communication. Consequently, this paper enriches the knowledge base of UAVs, offering an informative background on various UAV design processes, particularly those related to electric smart grid applications. As a future work recommendation, an actual relevant project is openly discussed.

This paper aims to design the fundamental basis for an Unmanned Aerial System (UAS)-driven, remote, and non-invasive current sensing application. Using the COMSOL software, the methodology presented here consists of the Computer Aided Design (CAD) for stranded Transmission Line (TL) geometries composed of 7 to 91 sub-filaments and discretized via tetrahedral-element-based meshes. The radiated Magnetic Field (MF) around each TL is then solved by means of Finite Element Analysis (FEA) after selecting the proper materials for TLs under the coil geometry analysis study. For each TL, all resultant MFs’ norms are presented as tabulated data, with respect to the inducing currents. Eventually, the complex mathematical model needed to evaluate these MFs, radiated around stranded TLs, is surpassed by the scalable models designed through this study. The min/max MFs radiated around each TL resulting from the min/max injected current values are hence obtained. This would serve in the accurate choosing/positioning of magnetic-based sensors in UAS applications, reliably. Additionally, related future works are concretely presented.

Die Übertragungskapazitäten von Freileitungen und Energiekabeln werden durch thermische Modelle bestimmt, die konservative und statische Grenzwerte mit substantiellen Sicherheitsfaktoren festlegen. Ungenutzte Potenziale verstärken die Kapazitätsengpässe der Netzinfrastruktur. Um die Überlastung von Betriebsmitteln zu verhindern, werden die teuren und nicht-ökologischen Maßnahmen des Netzengpassmanagements eingesetzt (Redispatch, Einspeisemanagement und Netzreservekraftwerke). Dieser Beitrag untersucht, inwiefern sich Erhöhungen der Übertragungskapazitäten auf den Einsatz des Netzengpassmanagements auswirken. In der 50Hertz-Zone wurde festgestellt, dass eine statische Erhöhung der Übertragungskapazität um durchschnittlich 7,86 % bzw. 3,83 % für 220 kV- bzw. 380 kV-Systeme ausreicht, um mindestens 50 % der Einspeisungsreduktion zu verhindern. Um 90 % der Reduktion zu verhindern, sind durchschnittlich 23,70 % bzw. 11,90 % für 220 kV- bzw. 380 kV-Systeme notwendig. Bereits geringe Erhöhungen der Energieübertragungskapazität führen folglich zu signifikanten Reduktionen des Netzengpassmanagements.

Dieser Applikationshinweis beschreibt die Gefahr, die bei unzureichender Überstrom-Absicherung von DC-SPDs in DC-Schnell-Ladesystemen besteht. DC-Schnell-Ladesysteme verbinden sich direkt mit der Traktionsbatterie eines elektrischen Kraftfahrzeuges. Tritt ein niederohmiger Kurzschluss des DC-SPD‘s auf, speist die Traktionsbatterie den entstehenden Kurzschlussstrom. Aufgrund der hohen Kurzschlussströme von Traktionsbatterien im Kiloampere-Bereich entsteht bei unzureichender Überstrom-Absicherung des DC-SPD‘s eine Brandgefahr innerhalb des DC-Schnell-Ladesystems. In diesem Beitrag werden zwei Maßnahmen zur Überstrom-Absicherung der DC-SPDs vorgestellt, um die Brandgefahr zu vermeiden.

Electricity price forecasting is important for managing supply and demand, planning investments in energy projects, ensuring energy security and efficient use of resources. This paper presents a hybrid neural network of two types of neural networks: the convolutional neural network (CNN) and the recurrent neural network (RNN) for energy market data analysis to forecast electricity prices. CNN is used to extract features from the raw data by applying a convolution operation on the temporal axis with different filters. At the same time, bidirectional gated recurrent units (BiGRU) of RNN are used for subsequent analysis of the temporal dependence of the extracted features, allowing the historical data to be considered. BiGRU is particularly useful for applications where the current input depends on past and future contexts. Thus, the ID-CNN-BiGRU method allows effective time series analysis and prediction of future values and can be widely used in the tasks of forecasting electricity prices, stocks, traffic, and other time series. The results indicate that the presented model is promising for use in a highly dynamic energy market.