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Im Outdoorlabor des Fachgebietes werden sowohl PV-Module als auch Wechselrichter unter realen Bedingungen untersucht.
Elektrische Energietechnik - Nachhaltige Energiekonzepte
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Im Outdoorlabor des Fachgebietes werden sowohl PV-Module als auch Wechselrichter unter realen Bedingungen untersucht.

Willkommen auf der Webseite der Elektrischen Energietechnik - Nachhaltige Energiekonzepte

Innovative Elektrische Energietechnik für eine nachhaltige Energiewende!

 

 

Teil des Kompetenzzentrums für nachhaltige Energietechnik der Universität Paderborn (KET)

 Veranstalter des Elektrotechnischen Kolloquiums

Arbeitsfelder:

  • Innovative Energieversorgungsstrukturen (zentral und dezentral)
  • Rationeller Energieeinsatz (Energieaufwandsminimierung im Aufbau, Betrieb, und Rückbau)
  • Nutzung regenerativer Energien (Potentialerfassung, effiziente Wandlung, hohe Gebrauchsdauer, Recycling, effektive CO2-Minderung)
  • Verbrauchsmanagement (Anpassung von Lastkurven an aktuelles regeneratives Energieangebot, Speicherminimierung)

Stellenauschreibung

In der Fakultät für Elektrotechnik, Informatik und Mathematik - Institut für Elektrotechnik und Informationstechnik/Fachgebiet Elektrische Energietechnik – Nachhaltige Energiekonzepte – ist zum nächstmöglichen Zeitpunkt eine Stelle als wissenschaftliche*r Mitarbeiter*in (w/m/d) (Entgeltgruppe 13 TV-L) im Umfang von 100 % der regelmäßigen Arbeitszeit zu besetzen. Es handelt sich um eine Qualifizierungsstelle im Sinne des Wissenschaftszeitvertragsgesetzes (WissZeitVG), die zur Förderung eines Promotionsverfahrens im Bereich Elektrische Energietechnik dient. Die Stelle ist befristet für die Dauer des Promotionsverfahrens, abhängig von der bisher erreichten Qualifizierung, jedoch für einen Zeitraum von 4 Jahren, zu besetzen.  Nähere Informationen

2022


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Hybrid Energy System Model in Matlab/Simulink based on Solar Energy, Lithium-Ion Battery and Hydrogen

M.C. Möller, S. Krauter, Energies / Special Issue "Sustainable Energy Concepts for Energy Transition" (2022)

In this paper, a model of a hybrid, hydrogen-based energy system for a household which includes the heating sector is presended. With such an energy system it's possible to enable energy autarky over a whole year based on solar energy. The scope of this study was to present a verified hybrid energy system model created in Simulink which can be used to prospectively size future similar energy systems where hydrogen in combination with a li-ion battery shall be used as energy storage type.


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2021


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Einfluss von Steilaufstellung, Nachführung und Einsatz bifazialer PV-Module auf den Speicherbedarf und die Kosten einer 100% EE-Versorgung Deutschlands

S. Krauter, A. Khatibi, in: Tagungsband des 36. PV-Symposium, 18.-26 Mai 2021, online, ISBN 978-3-948176-14-3, S. 301-304. , Conexio, 2021, pp. 301-304


Comparison and Validation of Irradiance Data: Satellite Meteorological Dataset MERRA-2 vs. Meteonorm and German Weather Service (DWD)

A. Khatibi, S. Krauter, in: Proceedings of the 38th European Photovoltaic Solar Energy Conference and Exhibition (EUPVSEC 2021), 2021, pp. 1141 - 1147

Access to precise meteorological data is crucial to be able to plan and install renewable energy systems such as solar power plants and wind farms. In case of solar energy, knowledge of local irradiance and air temperature values is very important. For this, various methods can be used such as installing local weather stations or using meteorological data from different organizations such as Meteonorm or official Deutscher Wetterdienst (DWD). An alternative is to use satellite reanalysis datasets provided by organizations like the National Aeronautics and Space Administration (NASA) and European Centre for Medium-Range Weather Forecasts (ECMWF). In this paper the “Modern-Era Retrospective analysis for Research and Applications” dataset version 2 (MERRA-2) will be presented, and its performance will be evaluated by comparing it to locally measured datasets provided by Meteonorm and DWD. The analysis shows very high correlation between MERRA-2 and local measurements (correlation coefficients of 0.99) for monthly global irradiance and air temperature values. The results prove the suitability of MERRA-2 data for applications requiring long historical data. Moreover, availability of MERRA-2 for the whole world with an acceptable resolution makes it a very valuable dataset.


Module-Inverters (Microinverters): Influence of Module Size on Conversion Efficiencies and Energy Yields

S. Krauter, J. Bendfeld, in: Proceedings of the 38th European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC 2021), 2021, pp. 659 - 663

Efficiencies and energy yields of microinverters available on the market during 2014‒2021 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 (until 2020) and 360 Wp (starting 2021). Inverters with two inputs have been fed by two of those modules. DC input, AC power output and energy yield of each microinverter have been recorded by individual calibrated electricity meters. CEC and EU efficiency rankings have been computed and compared. To assess the influence of PV module size, two extremes have been investigated: A rather small module with 215 Wp - as it has been used 10 years ago, and a brand-new module (2021) offering 360 Wp. Both types of modules contain 60 solar cells in series connection. Appling the low-power modules, the challenge for the different micro-inverters has been during weak-light conditions, using the high-power modules, some inverters temporarily reach their power limits and yield is reduced. A method using a reference configuration of inverter & module and a linear equation y = ax + b resulting in the actual yield, any module & inverter configuration can be characterized by just the coefficients a and b.


Load Data Acquisition in Rural East Africa for the Layout of Microgrids and Demand–Side–Management Measures

J.N. Kakande, G.H. Philipo, S. Krauter, in: Proceedings of the 38th European Photovoltaic Solar Energy Conference and Exhibition (EUPVSEC 2021), 2021, pp. 1505-1510

With its growing population and industrialization, DREs, and solar technologies in particular, provide a sustainable means of bridging the current energy deficit in Africa, increasing supply reliability and meeting future demand. Data acquisition and data management systems allow real time monitoring and control of energy systems as well as performance analysis. However commercial data acquisition systems often have cost implications that are prohibitive for small PV systems and installations in developing countries. In this paper, a multi-user, multi-purpose microgrid database system is designed and implemented. MAVOWATT 270 power quality analyzers by GOSSEN METRAWATT, raspberry pi modules and sensors are used for measuring, recording and storing electrical and meteorological data in East Africa. Socio-economic data is also stored in the database. The designed system employs open source software and hardware solutions which are best suited to developing regions like East Africa due to the lower cost implications. The expected results promise a comprehensive database covering different electro-technical and socio-economic parameters useful for optimal design of microgrid systems.


Validation and Performance of Satellite Meteorological Dataset MERRA-2 for Solar and Wind Applications

A. Khatibi, S. Krauter, Energies (2021), 14(4), 882

<jats:p>Fast-growing energy demand of the world makes the researchers focus on finding new energy sources or optimizing already-developed approaches. For an efficient use of solar and wind energy in an energy system, correct design and sizing of a power system is of high importance and improving or optimizing the process of data obtaining for this purpose leads to higher performance and lower cost per unit of energy. It is essential to have the most precise possible estimation of solar and wind energy potential and other local weather parameters in order to fully feed the demand and avoid extra costs. There are various methods for obtaining local data, such as local measurements, official organizational data, satellite obtained, and reanalysis data. In this paper, the Modern-Era Retrospective analysis for Research and Applications dataset version 2 (MERRA-2) dataset provided by NASA is introduced and its performance is evaluated by comparison to various locally measured datasets offered by meteorological institutions such as Meteonorm and Deutscher Wetterdienst (DWD, or Germany’s National Meteorological Service) around the world. After comparison, correlation coefficients from 0.95 to 0.99 are observed for monthly global horizontal irradiance values. In the case of air temperature, correlation coefficients of 0.99 and for wind speed from 0.81 to 0.99 are observed. High correlation with ground measurements and relatively low errors are confirmed, especially for irradiance and temperature values, that makes MERRA-2 a valuable dataset, considering its world coverage and availability.</jats:p>


Projekt Art-D Grids: Nachhaltige und stabile Microgrids in Afrika - eine Plattform für Forschung und Lehre für die Entwicklung

S. Krauter, J. Böcker, C. Freitag, B. Hehenkamp, U. Hilleringmann, K. Temmen, T. Klaus, N. Rohrer, S. Lehmann, in: Tagungsband 36. PV-Symposium / BIPV-Forum 18-26. Mai 2021, 2021


Projekt Art-D Grids: Nachhaltige und stabile Microgrids in Afrika - eine Plattform für Forschung und Lehre für die Entwicklung

S. Krauter, J. Böcker, C. Freitag, B. Hehenkamp, U. Hilleringmann, K. Temmen, T. Klaus, N. Rohrer, S. Lehmann, in: Tagungsband des 36. PV-Symposiums, 18.-26 Mai 2021, Conexio, 2021, pp. 305-309


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2020


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Micro-Inverters: An Update of Comparison of Conversion Efficiencies and Energy Yields

S. Krauter, J. Bendfeld, in: Proceedings of the EUPVSEC 2020, 2020, pp. 935 - 938

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.


Einfluss der Betriebstemperatur auf den Wirkungsgrad von Modul-Wechselrichtern für PV-Netzeinspeisungen

S. Krauter, J. Bendfeld, in: Tagungsband des 35. Symposiums für Photovoltaische Solarenergie, Kloster Banz, Bad Staffelstein (Deutschland), 2020


Triggering Demand‒Side‒Management: Correlation of electricity prices, share of renewables, CO2‒contents, and grid‒frequency in the German electricity grid.

S. Krauter, L. Zhang, in: Proceedings of the 37th European Photovoltaic Solar Energy Conference, 07 - 11 September 2020., 2020, pp. 1815 - 1817

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.


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

S. Krauter, D. Rustemovic, A. Khatibi, in: Proceedings of the 37th European Photovoltaic Solar Energy Conference, 07 - 11 September 2020, 2020, pp. 1818 - 1819

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).


Elevated Temperatures Affecting Efficiency, Overall Performance and Energy Yield of PV Microinverters

S. Krauter, J. Bendfeld, in: Proceedings of the EU PVSEC 2020 , 2020, pp. 1179 - 1180

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.


Correlation of grid-frequency, electricity prices, share of Renewables and CO2-contents of German electricity grid to enable inexpensive triggering of Demand-Side-Management

S. Krauter, L. Zhang, in: Proceedings of the 47th IEEE Photovoltaic Specialists Conference (PVSC 47) 2020, 2020, pp. 1672-1674

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.


Comparison of Microinverters: Update on Rankings of Conversion Efficiencies and Energy Yields

S. Krauter, J. Bendfeld, in: Proceedings of the 47th IEEE Photovoltaic Specialists Conference (PVSC 47) JUNE 15 - AUGUST 21, 2020 VIRTUAL MEETING, IEEE, 2020, pp. 1429-1432

To compare efficiency and yield of many micro-inverters available on the world market in 2014-2020, an in- and outdoor test laboratory at the University of Paderborn has been set up. The inverters have been fed by identical and calibrated crystalline silicon PV modules of 215 Wp. To monitor accurately DC input, AC power output and energy yield, each of the micro-inverters has been equipped with a calibrated electricity meter. For micro-inverters requiring control units for grid-feeding that has been acquired also. The comparison covers efficiency-load characteristics as well as electrical energy yields. Purchase costs vary considerably between the models in comparison, sometimes inverter costs are higher than module costs, particularly if an additional grid-connection or interface device is needed for operation. The weighted conversion efficiency according to EU and CEC standards has been measured and calculated. While some inverters have been optimized for high irradiance levels, they ranked better at the CEC efficiency, others performed very well also for low irradiance levels, thus ranking higher at in the EU-efficiency tables. These results are deviating from the actual energy yield measurements, which show a slightly different ranking. At one inverter, an accurate, but very slow MPPT algorithm that barely could follow quickly changing irradiance levels could be the reason for this effect. Another inverter switched off after operation at high power output for a while. Apparently, some inverters are been optimized to show excellent EU and CEC efficiency ratings. Two of the inverters featuring two inputs did not show an exceptional performance at the EU- and CEC-ratings, but they achieved top ranks at the AC energy yield for the first years. For the customer, the AC yield is a major performance indicator of any microinverter and should be included in the datasheet.


Eignung der Netzfrequenz als Instrument der Entscheidungsfindung zur Auslösung von Lastverschiebungen bei niedrigen spezifischen CO2-Emissionen und EEX-Handelspreisen

S. Krauter, L. Zhang, in: Tagungsband des 35. Symposiums für Photovoltaische Solarenergie, Kloster Banz, Bad Staffelstein (Deutschland), 2020


Probability of Correct Decision–Making at Triggering of Load-Shifting Intended for low CO2-intensity and low EEX trading-prices via simple Grid Frequency Monitoring

S. Krauter, L. Zhang, in: Proceedings of the 14th International Renewable Energy Storage Conference, Düsseldorf (Deutschland), 10.–12. März 2020 (verschoben: 16.–18. März 2021), 2020


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2019


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Entwicklung eines thermischen 1D-Simulationsmodells zur Bestimmung der Temperaturverteilung in Solarmodulen

M. Grabo, D. Weber, A. Paul, T. Klaus, W. Bermpohl, S. Krauter, E. Kenig, 2019


Numerische Untersuchung der Temperaturverteilung in PCM-integrierten Solarmodulen

M. Grabo, D. Weber, A. Paul, T. Klaus, W. Bermpohl, E. Kenig. Numerische Untersuchung der Temperaturverteilung in PCM-integrierten Solarmodulen. In: Jahrestreffen der ProcessNet-Fachgruppe Energieverfahrenstechnik und des Arbeitsausschusses Thermische Energiespeicherung, Frankfurt am Main, 2019.


Numerical Investigation of the Temperature Distribution in PCM-integrated Solar Modules

M. Grabo, D. Weber, A. Paul, T. Klaus, W. Bermpohl, S. Krauter, E. Kenig, Chemical Engineering Transactions (2019), pp. 895-900

DOI


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Eigene Tagungen

RIO 15 – Internationale Konferenz zur Nutzung von Erneuerbaren Energien zum Klimaschutz und zur nachhaltigen Entwicklung in Rio de Janeiro am 4.9.2015

Tagungsbeiträge von RIO15: http://www.rio15.net/proceedings.html

Energieeffizienz in der Stadtentwicklung und Architektur (kostenfreie Vorveranstaltung am 3.9.2015 in Rio de Janeiro, auf Portugiesisch). Programm:
http://rio15palestras.blogspot.de/p/programa.html

DPS 2012

Energieautonomie durch dezentrale Energiesysteme

Prof. Dr.- Ing. habil. Stefan Krauter

University of Paderborn
Electrical Energy Technology
Sustainable Energy Conce

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Kontakt

Prof. Dr.-Ing. habil. Stefan Krauter

Elektrische Energietechnik (EET)

Nachhaltige Energiekonzepte für die Energiewende.

Stefan Krauter
Telefon:
+49 5251 60-2301
Fax:
+49 5251 60-3235
Büro:
N1.110
Web:

Sprechzeiten:

Dienstag 10-11 Uhr über ZOOM:
https://uni-paderborn-de.zoom.us/j/7835851211

Dorothea Hermann

Elektrische Energietechnik (EET)

Dorothea Hermann
Telefon:
+49 5251 60-2301
Fax:
+49 5251 60-3235
Büro:
N1.107
Web:

 

Live Broadcast of Prof. Krauters talks on Solar Energy today, 23rd of July 2018, from 10 am to 6 pm (3 pm to 9 pm CET) at São Paulo School of Advanced Science on Renewable Energy (at University of Sao Paulo USP)

Rio 15

RIO 15 – Internationale Konferenz zur Nutzung von Erneuerbaren Energien zum Klimaschutz und zur nachhaltigen Entwicklung in Rio de Janeiro am 4.9.2015

KET

Das Kompetenzzentrum für Nachhaltige Energietechnik (KET) ist im Januar 2012 als Zentrale Wissenschaftliche Einrichtung der Universität Paderborn gegründet worden. Die Aufgaben des KET sind Forschung, Lehre und Technologietransfer auf dem Gebiet der umweltfreundlichen und innovativen…

DPS 2012

Conference Proceedings - Conference on Decentralized Power Systems, 20th Sept. 2012 in Paderborn (Germany)

DPS 2011

Conference Proceedings - Conference on Decentralized Power Systems, 2011 in Paderborn (Germany)

Die Universität der Informationsgesellschaft