Techno-economic comparison of a schedule-based and a forecast-based control strategy for residential photovoltaic storage systems in Germany

Postprint (published version

Hochstabiler optischer Resonator im Fallturmbetrieb für Präzisionsmessungen in Schwerelosigkeit

The development of optical clocks has made a great progress in the past years. Optical atomic clocks have demonstrated higher accuracies and stabilities than state of the art microwave oscillators and show their potential to target fractional frequency inaccuracies below 10a 17. This has led to a proposal to redefine the SI second using an optical transition of an atom clock. Possible candidates are evaluated and within the next year one should be elected. Not only for such fundamental definitions of the metric system, but also for tests of the fundamental theories have these clocks provided an astonishing tool. Reaching into the atto-scale of fractional frequency inaccuracy the gravitational redshift is readily measurable within the laboratory. Prospects for tests of the Einstein equivalence principle both earth and space bound will open new boundaries for alternative theories of gravitation. Even the recently observed gravitational waves can be a research target of satellite missions with optical atomic clocks on board. In this work, a highly stable optical local oscillator for the use in the drop tower Bremen was developed. The drop tower Bremen allows the experimentalist for the use of 4,7 s free fall in microgravity. It is a first step in the evolution of experiments outside the laboratory and in terms of technology readiness this presents a first demonstration of an operation of an optical cavity in a relevant environment. Stringent requirements for weight, space and power consumption make it difficult to achieve the worlda s best performance. In this work the measured frequency stability was found to be I y(3,5 s) 7,2 A 10a 15 in the Allan deviation. The optical cavity used in the apparatus is a spherical ULE spacer with fused-silica mirrors. It shows a finesse of F a 480.000 for the reference cavity and F a 330.000 for the dropped cavity. We can report successful drops in the drop tower Bremen with no degeneracy in the performance. A detailed description of both apparatus is given and the special steps taken for the capsule integration are explained. Another part of this work is the detailed discussion of the mathematical framework for the electric signals of a photo detector, if two laser fields are detected simultaneously. The heterodyne measurement is explained and applied to the case, where the linewidth is to be measure by a self-referencing scheme. This includes both the long known delayed self-heterodyne interferometers as well as the discussion of the possibility for short-delayed self-heterodyne interferometers. A published work is disproved and discussed

Impact of operation strategies of large scale battery systems on distribution grid planning in Germany

Due to the increasing penetration of fluctuating distributed generation electrical grids require reinforcement, in order to secure a grid operation in accordance with given technical specifications. This grid reinforcement often leads to over-dimensioning of the distribution grids. Therefore, traditional and recent advances in distribution grid planning are analysed and possible alternative applications with large scale battery storage systems are reviewed. The review starts with an examination of possible revenue streams along the value chain of the German electricity market. The resulting operation strategies of the two most promising business cases are discussed in detail, and a project overview in which these strategies are applied is presented. Finally, the impact of the operation strategies are assessed with regard to distribution grid planning.Postprint (author's final draft

Shared-Service-Organisationen als Möglichkeit wertorientierter Steuerung des IT-Bereichs

Zusammenfassungen: Um den IT-Bereich im Konzern wertorientiert zu steuern, scheinen Shared-Service-Organisationen (SSO) grundsätzlich gut geeignet. Eine SSO als konzerninterner Dienstleister übernimmt dabei die IT-seitige Unterstützung der Kernprozesse. Neben der Herausarbeitung des Begriffsverständnisses in der Literatur können mittels eines entwickelten Klassifizierungsrasters SSO anhand relevanter Kriterien eingeordnet werden. Dabei wird, je nach konkreter Merkmalsausprägung, auf die unterschiedlichen Anforderungen an ein Steuerungssystem für SSO eingegangen. Die Darstellung der Ausgestaltung der Geschäftsmodellmerkmale sowie der jeweiligen Auswirkungen auf das Steuerungssystem am Beispiel der Bayer Business Services (BBS) rundet den Beitrag ab. Dieses Forschungsprojekt beruht auf Erkenntnissen, gewonnen aus Literaturrecherche sowie einer Vielzahl von Experteninterview

Techno-economic assessment of flexibility options versus grid expansion in distribution grids

In this paper five different flexibility options are analysed from a techno-economic perspective as alternatives to traditional grid expansion for a specific distribution grid in Germany. The options are: two reactive power control strategies with photovoltaic inverters (as a function of the power feed-in, or of the voltage at the connection point), one residential and two large scale battery storage applications (primary control reserve with autonomous reactive power control or self consumption maximisation strategy with autonomous reactive power control). For the pilot grid located in Southern Germany a photovoltaic expansion pathway is determined. The main goal of this work is to quantify the grid expansion actions that can be avoided by applying these five flexibility options for the assumed expansion pathway, focusing on large scale battery storages. It is shown that the five flexibility options increase the hosting capacity for PV systems, compared to a scenario without, by up to 45%. Furthermore, the results of the economic assessment indicate that the analysed flexibility options might be a viable alternative to traditional grid expansion as all of them show a cost reduction potential for the pilot region. These results could encourage DSOs to consider the integration of additional PV and battery storage systems not as a problem which triggers grid expansion, but as part of the solution reducing future grid expansion costs.Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantPostprint (author's final draft

Technical and economic comparison of grid supportive vanadium redox flow batteries for primary control reserve and community electricity storage in Germany

Aquesta és una còpia de la versió author’s final draft d'un article publicat a la revista [International journal of energy research]. URL d'aquest document a UPCommons E-prints: http://hdl.handle.net/2117/127058Primary control reserve and maximising self-consumption are currently two of the main applications for large-scale battery storage systems. Although being currently the most profitable application for large-scale batteries in Germany, storage systems applying primary control reserve have not been implemented in a grid supportive manner in distribution grids yet. Despite a current unfavourable regulatory framework and reimbursement scheme for community electricity storages in Germany, they are potentially more profitable than residential storages, which is mainly due to their economy of scale, and thus they may become the major large scale battery application in the future. The two applications: primary control reserve and maximising self-consumption, are combined with a grid supportive behaviour by providing reactive power control and/or peak shaving and are fitted to a vanadium redox flow battery prototype, which is installed in a distribution grid in southern Germany. Based on measured data from the prototype, two battery models for two different time resolutions (1s, 1min) are presented in detail along with their respective operation models. The operation strategy model for primary control reserve comprises the so-called degrees of freedom used to reduce the energy needed to recharge the battery. The operation strategy to maximise self-consumption is based on a persistence forecast. The model for the operation strategy for a grid supportive primary control reserve was validated in a field test revealing a relative error of 2.5 % between the simulated and measured state of charge of the battery for a multi-week time period. The technical assessment of both applications shows that the use of the degrees of freedom can reduce the energy to recharge the battery by 20 %; and in the case of self-consumption, the curtailment losses can be kept under 1 %. The economic assessment, however, indicates that even for the most promising primary control reserve case, the investment costs of vanadium redox flow batteries must be reduced by at least 30 % in order to break even. Finally, the encouraging key finding is that the negative impact of a grid supportive behaviour, additionally to its primary purpose, is less than 1 % of the revenues. This may encourage distribution grid and battery operators to consider the integration of large scale batteries in distribution grids as part of the solution of a rising share of a decentralised renewable energy generation.Postprint (author's final draft

MusikveranstalterInnen mit türkischem Migrationshintergrund in der Wiener Kreativwirtschaft

Series: Schriftenreihe / Forschungsbereich Wirtschaft und Kultu

Financial Instruments for Enterprises - Final Report : Ex post evaluation of Cohesion Policy programmes 2007 - 2013, focusing on the European Regional Development Fund (ERDF) and the Cohesion Fund (CF)

For many Member States financial instruments (FI) were a new approach to delivering Cohesion policy. Their increased use in 2007-13 created significant challenges especially for Managing Authorities with limited experience. The regulatory framework provided flexibility to accommodate domestic arrangements, but demanded considerable administrative capacity. FIs can be more sustainable than grants, generate better quality projects, and may be considered more cost-effective in some circumstances. However, their main rationale in the OPs has been to facilitate access to finance for SMEs, which became more important in the crisis. The scale of FI varies between countries, as does the share reaching final recipients. In most countries, FI are over 80% invested, but some very large FIs have been overcapitalised and the EU average is 61%. Governance arrangements tend to be context specific, but build heavily on existing public financial institutions. Implementing FI proved complex with demands for greater clarity and certainty met through successive changes to the Regulations and guidance, many of which have been consolidated into the 2014-20 regulatory framework. Monitoring systems for FI are weak, with little hard data on outcomes such as private funding, job creation and innovation, but some evidence that FI increase access to finance and can help develop private markets