Large-scale unit commitment under uncertainty: an updated literature survey

The Unit Commitment problem in energy management aims at finding the optimal production schedule of a set of generation units, while meeting various system-wide constraints. It has always been a large-scale, non-convex, difficult problem, especially in view of the fact that, due to operational requirements, it has to be solved in an unreasonably small time for its size. Recently, growing renewable energy shares have strongly increased the level of uncertainty in the system, making the (ideal) Unit Commitment model a large-scale, non-convex and uncertain (stochastic, robust, chance-constrained) program. We provide a survey of the literature on methods for the Uncertain Unit Commitment problem, in all its variants. We start with a review of the main contributions on solution methods for the deterministic versions of the problem, focussing on those based on mathematical programming techniques that are more relevant for the uncertain versions of the problem. We then present and categorize the approaches to the latter, while providing entry points to the relevant literature on optimization under uncertainty. This is an updated version of the paper "Large-scale Unit Commitment under uncertainty: a literature survey" that appeared in 4OR 13(2), 115--171 (2015); this version has over 170 more citations, most of which appeared in the last three years, proving how fast the literature on uncertain Unit Commitment evolves, and therefore the interest in this subject

Integration dezentraler Batteriespeichersysteme in das deutsche elektrische Energieversorgungssystem

Die zunehmende installierte Leistung von Wind und Sonne stellt das elektrische Energieversorgungssystem aufgrund der fluktuierenden Einspeisung und der Verdrängung konventioneller Kraftwerke vor neue Herausforderungen. Um die ebenfalls zunehmende Kapazität von PV-Speichersystemen zu nutzen, könnten diese auch für weitere Anwendungen (z.B. Systemdienstleistungen) eingesetzt werden, indem sie zu einem Virtuellen Batterie-Energiespeicher (VBES) gepoolt werden. Dies motivierte die in dieser Arbeit vorgestellten Forschungsaktivitäten, den Zusammenschluss von PV-Speichersystemen zu einem VBES zu untersuchen und sie somit sowohl zur Erhöhung des Eigenverbrauchs der von der PV-Anlage bereitgestellten Energie als auch zur Erbringung von Primärregelleistung (PRL) zu nutzen. Dazu wurde ein hybrides Simulationsmodell eines VBES implementiert. Es enthält dessen zentrale Steuerung zur Verteilung der gesamten kontrahierten PRL auf die einzelnen PV-Speicher und ein Modell eines jeden Wohnhauses inklusive einer lokalen Steuerung zur physikalischen Bereitstellung von PRL und zur Erhöhung des Eigenverbrauchs der von der PV-Anlage bereitgestellten Energie. Neben den Erkenntnissen aus der Beantwortung der aufgestellten Forschungsfragen resultiert somit ein umfassendes und validiertes Simulationsmodell eines VBES. Ein Schwerpunkt dieser Arbeit ist die Untersuchung der Verteilung der gesamten kontrahierten PRL auf die einzelnen PV-Speicher, um PRL effizient und zuverlässig mit einem VBES bereitzustellen. Die Anwendung einer intelligenten zentralen VBES-Steuerungsstrategie ermöglicht einen effizienten und zuverlässigen Betrieb des VBES. Die Verluste können im Vergleich zu anderen untersuchten Strategien um mehr als zehn Prozentpunkte verringert werden. Dies motivierte eine kurze Fallstudie, welche die Integration eines VBES anstelle von Pumpspeicherkraftwerken in die Kraftwerkseinsatzplanung untersucht. Aufgrund des höheren Wirkungsgrads verbessert sich dadurch die Effizienz der gesamten Energieproduktion. Zusammenfassend zeigen die Untersuchungen, dass es möglich ist, einen VBES aus vielen dezentralen PV-Speichern mit hoher Effizienz und Zuverlässigkeit zu betreiben und den Haushalten zusätzliche Vorteile im Vergleich zu konventionellen PV-Speichern zu bieten.The increasing generation capacity of wind and solar poses new challenges to the electrical power system due to their fluctuating injection and the displacement of fossil fired generation units. In order to use the simultaneously increasing capacity of PV-storages in Germany, they could be used for additional applications such as the provision of ancillary services. This can be realized by pooling them to a Virtual Battery Energy Storage (VBES) and motivated the research activities presented within this thesis. It investigates the efficient pooling of decentralized batteries (PV-storages) to a VBES providing Frequency Containment Reserve (FCR) power. Therefore, a hybrid simulation model of a VBES was implemented. It contains a central controller of the VBES for coordinating the provision of FCR power and a model of each residential household including a local controller for modeling the physical provision of FCR power and the self-consumption of PV-converted power. In addition to the findings from answering the posed research questions, an extensive, approved, and validated simulation model of a VBES results from this work. One focus of this thesis is the investigation different allocation methods for dispatching the total contracted FCR power to the single PV-storages to ensure an efficient and reliable provision of FCR power. Applying a smart central VBES control strategy allows to operate the VBES more efficiently and reliably compared to other investigated strategies. The overall losses can be decreased by more than ten percentage points. Concerning a single household, a PV-storage integrated in the considered VBES increases the self-consumption of PV-converted power significantly and can be a profitable investment. As the findings presented within this thesis approves that it is possible to run the considered VBES efficiently, a small case study was carried out to analyze its integration into the daily unit commitment in Germany. Replacing the existing pumped hydroelectric energy storage units by VBESs increases the efficiency of the electrical power supply. In conclusion, it is possible to run a VBES composed of many decentralized PV-storages at a constant high efficiency by means of a smart central control strategy guaranteeing benefits for the households in parallel

Coherent Enantiomer-Selective Population Enrichment Using Tailored Microwave Fields

We report the experimental demonstration of coherent enantiomer-selective enrichment of chiral molecules by employing a novel microwave five-pulse scheme. Our results show that enantiomers can be selectively transferred to a rotational level of choice by applying sequences of resonant microwave pulses in a phase- and polarization-controlled manner. This is achieved by simultaneously exciting all three kinds of electric dipole-allowed rotational transitions and monitoring the effect on a fourth rotational transition of choice. Using molecular beams, we apply our method to two chiral terpenes and obtain a 6 % enantiomeric enrichment, which is one order of magnitude larger than that recently reported in a buffer-gas cell experiment. This approach establishes a robust scheme for controlled manipulation of enantiomers using tailored microwave fields and opens up new avenues for chiral purification and enrichment that can be used in a broad scope of analytical or spectroscopic applications

Coherent Enantiomer‐Selective Population Enrichment Using Tailored Microwave Fields

We report the experimental demonstration of coherent enantiomer-selective enrichment of chiral molecules by employing a novel microwave five-pulse scheme. Our results show that enantiomers can be selectively transferred to a rotational level of choice by applying sequences of resonant microwave pulses in a phase- and polarization-controlled manner. This is achieved by simultaneously exciting all three kinds of electric dipole-allowed rotational transitions and monitoring the effect on a fourth rotational transition of choice. Using molecular beams, we apply our method to two chiral terpenes and obtain a 6 % enantiomeric enrichment, which is one order of magnitude larger than that recently reported in a buffer-gas cell experiment. This approach establishes a robust scheme for controlled manipulation of enantiomers using tailored microwave fields and opens up new avenues for chiral purification and enrichment that can be used in a broad scope of analytical or spectroscopic applications

TECHNIQUES FOR HIGH-BANDWIDTH (≥\geq30 GHz) CHIRPED-PULSE MILLIMETER/SUBMILLIMETER-WAVE SPECTROSCOPY

Author Institution: Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904; National Institute of Standards and Technology, Optical Technology Division, Gaithersburg, MD 20899; National Institute of Standards and Technology, Electromagnetics Division, Boulder, CO 80305Due to the increased availability of active multiplier chains for converting microwave pulses into the millimeter/submillimeter with reasonably high power ($\geq$1 mW), chirped pulses with high phase stability and complete arbitrary waveform generator (AWG) frequency agility can be created and employed for high-sensitivity molecular spectroscopy, as demonstrated at the Symposium in the past few years.$^{,}$ The bandwidths of multiplier chains, however, can exceed the current limitations on digitizer bandwidth. Therefore, in order to obtain $\geq$30 GHz spectra in ~1 ms or less, techniques are being developed in which a two-channel AWG creates both the chirped pulses for molecular irradiation and a local oscillator pulse for heterodyne detection. These approaches reduce the digitizer bandwidths to 500 MHz or less to collect a high-bandwidth spectrum. A single instrument design can be used to measure both absorption and emission spectra, only requiring that the AWG pulses are changed. Due to the phase stability of the pulse generation and detection, coherent time-domain signal averaging can be performed to enhance sensitivity as desired. Preliminary results from prototype instruments designed at UVa and NIST will be presented, with sensitivity, frequency accuracy, and measurement speed comparisons to current millimeter/submillimeter-wave spectrometers

Ned Drinker

the Electronic Tax Administration Advisory Committee (ETAAC). ETAAC has a primary duty of providing input to the Internal Revenue Service (IRS) on its strategic plan for electronic tax administration. Accordingly, ETAAC’s responsibilities involve researching, analyzing and making recommendations on a wide range of electronic tax administration issues. Pursuant to RRA 98, ETAAC also annually reports to Congress concerning: • IRS ’ progress in meeting the goal to receive electronically 80 % of tax and information returns; • The status of IRS ’ strategic plan for electronic tax administration; • Legislative changes that would assist IRS in meeting the 80 % goal; and, • The effects on small businesses and the self-employed of electronically filing tax and information returns. IRS ensures that ETAAC membership reflects broad experience and stakeholder perspectives, including representation from state departments of revenue, large tax preparation companies, solo tax practitioners, software companies and business filers from both the non-profit and for-profit sectors. ETAAC member biographies are found in Appendix A. In conducting its assessments and formulating its recommendations, ETAAC relies on a variety o