@article{30033, author = {{Stender, Marius and Wallscheid, Oliver and Böcker, Joachim}}, issn = {{0278-0046}}, journal = {{IEEE Transactions on Industrial Electronics}}, keywords = {{Electrical and Electronic Engineering, Control and Systems Engineering}}, number = {{9}}, pages = {{8646--8656}}, publisher = {{Institute of Electrical and Electronics Engineers (IEEE)}}, title = {{{Comparison of Gray-Box and Black-Box Two-Level Three-Phase Inverter Models for Electrical Drives}}}, doi = {{10.1109/tie.2020.3018060}}, volume = {{68}}, year = {{2020}}, } @inproceedings{30036, author = {{Stender, Marius and Wallscheid, Oliver and Böcker, Joachim}}, booktitle = {{2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)}}, publisher = {{IEEE}}, title = {{{Accurate Torque Estimation for Induction Motors by Utilizing Globally Optimized Flux Observers}}}, doi = {{10.1109/speedam48782.2020.9161955}}, year = {{2020}}, } @article{29649, author = {{Heid, Stefan and Weber, Daniel and Bode, Henrik and Hüllermeier, Eyke and Wallscheid, Oliver}}, journal = {{Journal of Open Source Software}}, number = {{54}}, pages = {{2435}}, title = {{{OMG: A scalable and flexible simulation and testing environment toolbox for intelligent microgrid control}}}, volume = {{5}}, year = {{2020}}, } @article{29644, author = {{Bode, Henrik and Heid, Stefan and Weber, Daniel and Hüllermeier, Eyke and Wallscheid, Oliver}}, journal = {{arXiv preprint arXiv:2005.04869}}, title = {{{Towards a scalable and flexible simulation and testing environment toolbox for intelligent microgrid control}}}, year = {{2020}}, } @inproceedings{29641, author = {{Gedlu, Emebet Gebeyehu and Wallscheid, Oliver and Böcker, Joachim}}, booktitle = {{The 10th International Conference on Power Electronics, Machines and Drives (PEMD 2020)}}, pages = {{937–942}}, title = {{{Permanent magnet synchronous machine temperature estimation using low-order lumped-parameter thermal network with extended iron loss model}}}, volume = {{2020}}, year = {{2020}}, } @inproceedings{30339, author = {{Ahmmad, Mohsin Ejaz and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{Proc. IEEE International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM digital days)}}, location = {{Nuremberg, Germany}}, publisher = {{IEEE}}, title = {{{Practical Implementation and Verification of Simple-to-Implement Digital Current Observer for Half-Bridge Topologies}}}, year = {{2020}}, } @misc{30362, author = {{Schafmeister, Frank}}, pages = {{39}}, title = {{{Apparatus and method for charging an electric battery vehicle}}}, year = {{2020}}, } @article{29643, author = {{Wallscheid, Oliver and Ngoumtsa, Etienne Florian Bouna}}, journal = {{IEEE Transactions on Power Electronics}}, number = {{12}}, pages = {{13563–13572}}, publisher = {{IEEE}}, title = {{{Investigation of disturbance observers for model predictive current control in electric drives}}}, volume = {{35}}, year = {{2020}}, } @article{29642, author = {{Hanke, Sören and Wallscheid, Oliver and Böcker, Joachim}}, journal = {{arXiv preprint arXiv:2003.06268}}, title = {{{Data Set Description: Identifying the Physics Behind an Electric Motor–Data-Driven Learning of the Electrical Behavior (Part II)}}}, year = {{2020}}, } @article{29640, author = {{Kirchgässner, Wilhelm and Wallscheid, Oliver and Böcker, Joachim}}, journal = {{arXiv preprint arXiv:2001.06246}}, title = {{{Data-Driven Permanent Magnet Temperature Estimation in Synchronous Motors with Supervised Machine Learning}}}, year = {{2020}}, } @misc{15419, author = {{Sadeghi-Kohan, Somayeh and Hellebrand, Sybille}}, keywords = {{WORKSHOP}}, pages = {{4}}, publisher = {{32. Workshop "Testmethoden und Zuverlässigkeit von Schaltungen und Systemen" (TuZ'20), 16. - 18. Februar 2020}}, title = {{{Dynamic Multi-Frequency Test Method for Hidden Interconnect Defects}}}, year = {{2020}}, } @phdthesis{30853, author = {{Vogt, T.}}, title = {{{Multikriterielle Betriebsstrategien industrieller Microgrids}}}, doi = {{10.17619/UNIPB/1-867}}, year = {{2020}}, } @article{17598, author = {{Nakatani, Tomohiro and Boeddeker, Christoph and Kinoshita, Keisuke and Ikeshita, Rintaro and Delcroix, Marc and Haeb-Umbach, Reinhold}}, journal = {{IEEE/ACM Transactions on Audio, Speech, and Language Processing}}, pages = {{1--1}}, title = {{{Jointly optimal denoising, dereverberation, and source separation}}}, doi = {{10.1109/TASLP.2020.3013118}}, year = {{2020}}, } @techreport{30034, author = {{Stender, Marius and Wallscheid, Oliver and Böcker, Joachim}}, title = {{{Data Set Description: Three-Phase IGBT Two-Level Inverter for Electrical Drives}}}, doi = {{10.13140/RG.2.2.23335.37280}}, year = {{2020}}, } @inproceedings{18390, abstract = {{ Efficiencies and energy yields of microinverters available on the market during 2014‒2020 have been measured, compared, and ranked. Conversion efficiencies as a function of load have been measured indoors with high accuracy and ranked according to Euro- and CEC weightings. Energy yields have been measured outdoors via identical and calibrated crystalline silicon PV modules of 215 Wp each. Inverters with two inputs have been fed by two of those modules. DC input, AC power output and energy yield of each micro-inverter have been recorded by individual calibrated electricity meters. Apparently, some inverters have been optimized for high irradiance levels and ranked better at the CEC efficiency ranking, others performed very well also at low irradiance levels, thus ranking higher at in the EU efficiency ranking. Efficiency ranks are slightly deviating from rankings by energy yield measurements. At one inverter, a slow MPPT algorithm that barely could follow quickly changing irradiance levels is most probably responsible for this effect. Another inverter switched off for a while after operation at high power, another one failed permanently. Apparently, some inverters are been optimized to show excellent datasheet ratings for EU- or CEC- efficiency. On the other hand, two inverters (each featuring two inputs) did not show an outstanding performance at the EU- and CEC-ratings but achieved leading ranks for AC energy yields. For the customer, AC yield is a major performance indicator of a microinverter and should be included in the datasheet.}}, author = {{Krauter, Stefan and Bendfeld, Jörg}}, booktitle = {{Proceedings of the EUPVSEC 2020}}, isbn = {{ 3-936338-73-6}}, location = {{online}}, pages = {{935 -- 938}}, title = {{{Micro-Inverters: An Update of Comparison of Conversion Efficiencies and Energy Yields}}}, doi = {{10.4229/EUPVSEC20202020-4DO.7.2}}, year = {{2020}}, } @inproceedings{16857, author = {{Krauter, Stefan and Bendfeld, Jörg}}, booktitle = {{Tagungsband des 35. Symposiums für Photovoltaische Solarenergie, Kloster Banz, Bad Staffelstein (Deutschland)}}, location = {{Bad Staffelstein}}, title = {{{Einfluss der Betriebstemperatur auf den Wirkungsgrad von Modul-Wechselrichtern für PV-Netzeinspeisungen}}}, year = {{2020}}, } @inproceedings{19393, abstract = {{To provide a simple instrument to operate residential Load-Shifting or Demand-Side-Management systems, the measurement of the actual grid frequency seems to be an appropriate method. Due to the present inflexibility and the lack of sufficient throttling capabilities of lignite and nuclear power plants, a surplus of electricity generation occurs during periods of high wind and solar power generation. While the specific CO2- emission is decreasing then ‒ due to the increased share of Renewables, the grid frequency is increasing (to a certain limit). Using the grid frequency as an indicator to switch-on and off certain loads (loads that do not require power permanently (e.g. dishwashers, washing machines, dryers, fridges and freezers, heaters) could provide a simple, inexpensive demand-side management indicator to lower specific CO2‒emssions and costs (if a dynamic consumption tariff is available). To check the truthfulness of that hypothesis, the grid and frequency data of the German grid of the year 2018 have been collected and a the correlation between grid frequency, power surplus, share of renewables vs. CO2-contents and price at the European energy exchange (EEX) have been calculated. The results show: Correlation between frequency and share of renewables is quite low (r = 0.155) due to the fact that primary grid control quickly compensates deviations from the 50 Hz nominal frequency. There is a good anti-correlation (r = - 0.687) between the EEX‒prices and the share of renewables in the grid. Over the years, correlation between electricity trading prices (EEX) and CO2 emissions is quite good (r =0.665), within the one year (2018) that correlation almost doesn’t exist, possibly due to the inflexibility of the bulky lignite power plants that even operate at negative prices. }}, author = {{Krauter, Stefan and Zhang, L.}}, booktitle = {{Proceedings of the 37th European Photovoltaic Solar Energy Conference, 07 - 11 September 2020.}}, issn = {{ 3-936338-73-6}}, keywords = {{Keywords: Load-Shifting, Demand-Side-Management, DSM, grid frequency, EEX, electricity trading prices, renewable share, flexibility, emissions, CO2}}, location = {{online}}, pages = {{1815 -- 1817}}, title = {{{Triggering Demand‒Side‒Management: Correlation of electricity prices, share of renewables, CO2‒contents, and grid‒frequency in the German electricity grid.}}}, doi = {{10.4229/EUPVSEC20202020-6BV.5.9}}, year = {{2020}}, } @inproceedings{19390, abstract = {{Due to the strong reduction of PV prices, storage plays a dominating role in overall system costs. A steeper elevation angle would result in a more balanced seasonal PV yield, at the cost of PV yield reductions during summer, but allowing reduced storage capacities. Additionally, the effect of a single-axis tracking system has been investigated, generating more electricity during the morning and evening hours, thus reducing daily storage requirements. The necessary PV size and storage capacities required for the German energy supply (1,500 TWh after electrification of all sectors) via 100% renewable energies and a 50% solar share have been calculated via the HOMER Pro software, considering the bridging of periods of "dark lulls“ in winter, using costs of 2030 (Table 1). Results: The increase of module elevation angles above the typical 30° leads to a reduction of investment and supply costs. The optimum is reached at a cost reduction of -1.5% for an elevation angle at the latitude of the installation site. An explanation is that high elevation angles are favorable for clear winter days, but not at all for the critical days with diffuse irradiance only, so the battery capacity must be increased. For the same reason, tracking systems do not offer any cost advantage (at least for the ones without an option for horizontal positioning during diffuse days).}}, author = {{Krauter, Stefan and Rustemovic, D. and Khatibi, Arash}}, booktitle = {{Proceedings of the 37th European Photovoltaic Solar Energy Conference, 07 - 11 September 2020}}, isbn = {{3-936338-73-6}}, keywords = {{Energy Storage, PV system integration, Large Grid-connected PV systems, Simulation, Energy Supply Options}}, location = {{online}}, pages = {{1818 -- 1819}}, title = {{{Reduction of required storage capacities for a 100% renewable energy supply in Germany, if new PV systems are installed with east-west tracking systems at increased elevation angles}}}, doi = {{10.4229/EUPVSEC20202020-6BV.5.10}}, year = {{2020}}, } @inproceedings{18387, abstract = {{ During comparative measurements of different PV microinverters, two yield issues came up that could not be explored via conventional efficiency measurements, but do have a significant impact on electrical energy yield: First category of issues are either sluggish or nervously acting maximum–power–point–tracking devices, which lead to reduced energy yields. The other category of issues is thermal: As a first explanation for observed reduced energy yields, it has been assumed that the conversion efficiency degrades at higher operating temperatures. This matter has been investigated in this article: A change in conversion efficiency could not be observed for elevated operation temperatures up to 50°C, despite high-precision and repeated measurements. But it was found that some inverters temporarily interrupted (or entirely stopped) operation after long periods of running at high temperatures. Also, a reduction in potential maximum power output has been detected for those inverters. Summarizing: With a high degree of certainty it can be stated that those reported yield losses have been caused by the temporary shutdowns and power limitations of the inverters.}}, author = {{Krauter, Stefan and Bendfeld, Jörg}}, booktitle = {{Proceedings of the EU PVSEC 2020 }}, issn = {{3-936338-73-6}}, keywords = {{AC-modules, Microinverter, Power Conditioning, Thermal Performance, Ventilation, Stability, Efficiency, Yield}}, location = {{online}}, pages = {{1179 -- 1180}}, title = {{{Elevated Temperatures Affecting Efficiency, Overall Performance and Energy Yield of PV Microinverters}}}, doi = {{10.4229/EUPVSEC20202020-4AV.3.6}}, year = {{2020}}, } @inproceedings{19383, abstract = {{Due to the present inflexibility and the lack of sufficient throttling capabilities of lignite and nuclear power plants, a surplus of electricity generation occurs during periods of high wind and solar power generation in the German electricity grid. While the specific CO2-emission is decreasing then - due to the increased share of Renewables, the grid frequency should be increasing (to a certain limit). Using the grid frequency as an indicator to switch-on and -off certain loads (loads that do not require power permanently (e.g. dishwashers, washing machines, dryers, fridges and freezers, heaters) could provide a simple, inexpensive demand-side-management indicator to lower specific CO2-emissions and costs (if a dynamic consumption tariff is applied). To check the truthfulness of that hypothesis, the grid and frequency data of the German grid of the year 2018 have been collected and the correlations between grid frequency, share of renewables, CO2-contents, and actual price at the European energy exchange (EEX) have been calculated. The results show: Correlation between grid frequency and the share of renewables is quite low (r=0.155) due to the fact that primary grid control quickly compensates deviations from the 50 Hz nominal frequency. As expected, there is a good anti-correlation (r=-0.687) between the EEX-prices and the share of renewables in the grid. Over the years, correlation between electricity trading prices (EEX) and CO2 emissions is quite good (r=0.665), within the one year (2018) that correlation almost doesn't exist, possibly due to the inflexibility of the bulky lignite baseload power plants that even operate at negative prices.}}, author = {{Krauter, Stefan and Zhang, L.}}, booktitle = {{Proceedings of the 47th IEEE Photovoltaic Specialists Conference (PVSC 47) 2020}}, keywords = {{CO2, EEX, Grid frequency, DSM, electricity price, Renewable share}}, location = {{online}}, pages = {{1672--1674}}, title = {{{Correlation of grid-frequency, electricity prices, share of Renewables and CO2-contents of German electricity grid to enable inexpensive triggering of Demand-Side-Management}}}, doi = {{10.1109/PVSC45281.2020.9300487}}, year = {{2020}}, }