621.3 Elektrotechnik, Elektronik
Refine
Year of publication
Document Type
- Article (24)
- Course Material (6)
- Conference Proceeding (4)
- Report (4)
- Doctoral Thesis (3)
- Book (1)
- Part of a Book (1)
- Other (1)
Has Fulltext
- yes (44)
Is part of the Bibliography
- no (44)
Keywords
- Signaltechnik (6)
- Poynting-Vektor (4)
- Energiemanagement (3)
- Harmonische Analyse (3)
- Harmonische Synthese (3)
- PROFInet (3)
- Regelungstechnik (3)
- Vermittlungstechnik (3)
- Bedienungstheorie (2)
- Computersicherheit (2)
Electrical power system operators (SOs) are free to realize grid operations according to their own strategies. However, because resulting power flows also depend on the actions of neighboring SOs, appropriate coordination is needed to improve the resulting system states from an overall perspective and from an individual SO perspective. In this paper, a new method is presented that preserves the data integrity of the SOs and their independent operation of their grids. This method is compared with a non-coordinated local control and another sequential method that has been identified as the most promising distributed optimization method in previous research. The time series simulations use transformer tap positioning as well as generation unit voltage setpoints and reactive power injections as flexibilities. The methods are tested on a multi-voltage, multi-SO, realistic benchmark grid with different objective combinations of the SOs. In conclusion, the results of the new method are much closer to the theoretical optimum represented by central optimization than those of the other two methods. Furthermore, the introduced method integrates a sophisticated procedure to provide fairness between SOs that is missing in other methods.
Electrospun polymer fiber mats feature versatile applications in tissue engineering, drug delivery, water treatment and chemical processes. The orientation of fibers within these mats is a crucial factor that significantly influences their properties and performance. However, the analysis of fiber samples using scanning electron microscopy (SEM) has limitations such as time consumption, fixed assembly, and restricted field of vision. Therefore, a fast and reliable method for qualitative measurements of fiber orientation is required. Mueller matrix polarimetry, a well-established method for measuring orientation of chemical and biological species, was employed in this case. We investigated the effect of four important parameters of the electrospinning process, namely collector speed, applied voltage, needle-to-collector distance, and solution concentration, on fiber orientation using Mueller matrix polarimetry thus extending the range of parameters analyzed. Measurements were performed using two extreme values and a central optimized value for each fabrication parameter. Changes in matrix values were observed for each fabrication parameter, and their correlation with fiber orientation was analyzed based on the Lu-Chipman decomposition. The results were compared with SEM images, which served as the ground truth, and showed overall good agreement. In the future, the analysis of electrospun polymer fibers can be done by using Mueller matrix polarimetry as alternative to current technology and fabrication parameters, including solution concentration for the first time in this context and the production can quickly be adjusted based on the outcome of the measurements
In light-processing systems, light energy is converted into a photocurrent due to the photoelectric effect. This project focuses on the development of a high-precision energy-to-voltage conversion technique to optimize signal processing in light-processing systems, specifically for applications in space analytics or solid state physikcs, such as Mössbauer spectroscopy. Analog circuit development plays a vital role as downstream voltage conversion is necessary for signal processing. The objective is to enhance the signal quality and improve the signal-to-noise ratio through the design, optimization, and comparison of various circuits for voltage conversion. The development process involves the design and optimization of amplifier circuits, supplemented with the incorporation of filters and/or regulators for further improvement. A transimpedance amplifier is approximated as a second-order low-pass filter, while a state controller is designed and analyzed to efficient transient oscillation of the system towards optimal amplitude values for subsequent signal processing. The project's results contribute to the advancement of light-processing systems, enabling more precise analysis of light energy in Mössbauer spectroscopy. The findings are presented in a series of scientific publications, showcasing the effectiveness of the developed circuits and their impact on signal quality. Future work could focus on further optimization and validation of the circuits in real-world applications to confirm their performance and reliability. Overall, this project emphasizes the significance of meticulous circuit development and optimization for enhancing signal processing in light-processing systems, thus supporting their application in space analytics.
Using special ac current sensors, it was shown that short-circuit protection of the latest CoolSiC™ MOSFET technology is possible. This simplifies the use of CoolSiC™ MOSFETs in applications such as industrial drives, where a certain robustness against short circuits is required. The use of CoolSiC™ MOSFETs leads to a more efficient drive inverter, which can help to reduce the energy costs over lifetime. In addition, the CoolSiC™ MOSFET enables inverter integration into the motor, which is challenging with state-of-the-art IGBTs. Furthermore, fast short-circuit protection can also help to increase the efficiency of an IGBT-based inverter by increasing the gate voltage.
The collaborative effort between SAXOGY® and Hannover University of Applied Sciences has resulted in the development of an advanced modular dv/dt pulse generator. This innovative testbench represents a significant leap forward in accelerated insulation endurance testing. It offers a valuable tool for validating existing and developing new insulation systems, thereby contributing to the enhancement of future power electronic systems.
The PROFINET protocol has been extended in the current version to include security functions. This allows flexible network architectures with the consideration of OT security requirements to be designed for PROFINET, which were not possible due to the network segmentation previously required. In addition to the manufacturers of the protocol stacks, component manufacturers are also required to provide a secure implementation in their devices. The necessary measures go beyond the use of a secure protocol stack. Using the example of an Ethernet-APL transmitter with PROFINET communication, this article shows which technical and organizational conditions will have to be considered by PROFINET device manufacturers in the future.
Im Herbst 2013 wurde in Essen ein supraleitendes dreiphasiges Koaxial-Kabel-System installiert. Dieses Ereignis regte dazu an, die Art und Weise der Leistungsübertragung auf diesem Kabel genauer zu analysieren, um die physikalischen Vorgänge besser zu verstehen. Mit Hilfe elementarer Gesetze und Gleichungen wird gezeigt, dass bei reiner symmetrischer Blindlast auf dem Kabel dennoch eine zirkulierende Wirkleistung auftritt, die in Lehrbüchern bisher nicht beschrieben ist. Bei reiner symmetrischer Wirklast treten dagegen keine Besonderheiten auf.
Das PROFINET Protokoll wurde in der aktuellen Version um Security-Funktionen erweitert. Damit können für PROFINET flexible Netzwerkarchitekturen unter Berücksichtigung von OT-Security Anforderungen entworfen werden, die durch die bisher erforderliche Netzwerksegmentierung nicht möglich waren. Neben den Herstellern der Protokollstacks sind nachfolgend auch die Komponentenhersteller gefordert, eine sichere Implementierung in ihren Geräten umzusetzen. Die erforderlichen Maßnahmen gehen dabei über die Nutzung eines sicheren Protokollstacks hinaus. Der Beitrag zeigt am Beispiel eines Ethernet-APL Messumformers mit PROFINET-Kommunikation die künftig von PROFINET-Geräteherstellern zu berücksichtigenden technischen und organisatorischen Rahmenbedingungen.
In this paper a new rotor position observer for permanent magnet synchronous machines (PMSM) based on an Extended-Kalman-Filter (EKF) is presented. With this method, just one single EKF is sufficent to evaluate the position information from electromotive force (EMF) and anisotropy. Thus, the PMSM can be controlled for the entire speed range without a position sensor and without the need to switch or synchronize between different observers. The approach covers online estimation of permanent magnetic field and mechanical load. The resulting EKF-based rotor position estimator is embedded in the existing cascaded control concept of the PMSM without need of additional angle trackers or signal filters. The experimental validation for the position sensorless control shows optimized dynamic behaviour.
