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Auf dem Weg zu einer CO2-neutralen Produktion kommt der Energieeffizienzsteigerung eine besondere Bedeutung zu. Dafür müssen auch Technologien, die bereits seit mehr als 100 Jahren eingeführt und bewährt sind, in Frage gestellt werden. Der Einsatz eines Gleichstromnetzes (DC) und damit die Abkehr vom Wechselstrom (AC) in der Fabrik ist ein Umbruch, der Energieeffizienzsteigerung und eine einfache Optimierung der Energienutzung ermöglicht. Das hier vorgestellte Vorgehensmodell beginnt bei der Analyse und Bewertung der DC-Technologie im Kontext des individuellen Anwendungsfalls und endet mit der Realisierung eines DC-Netzes in der Produktion.

We study the scope for international cooperation in macroprudential policies. Multinational banks contribute to and are affected by fire sales in countries they operate in. National governments setting quantity regulations noncooperatively fail to achieve the globally efficient outcome, underregulating domestic banks and overregulating foreign banks. Surprisingly, noncooperative national governments using revenue-generating Pigouvian taxation can achieve the global optimum. Intuitively, this occurs because governments internalize the business value of foreign banks through the tax revenue collected. Our theory provides a unified framework to think about international bank regulations and yields concrete insights with the potential to improve on the current policy stance.

Die Gesellschaft strebt nach nachhaltiger Energieversorgung und einem effizienten Netz. Um die Energieeffizienz in Gleichstrommikronetzen zu steigern, müssen Antriebsumrichter direkt, also ohne Wandlung, an das Gleichstromnetz angeschlossen werden können. Diese Anpassung muss über die Komponenten- und Maschinenhersteller erfolgen, die aufgrund der aktuellen Nachfrage noch keine Notwendigkeit für die Entwicklung neuer Produkte sehen. Für die Übergangsphase wird in diesem Beitrag eine Methodik zur Umrüstung von Produktionsmaschinen auf den Betrieb in einem Gleichstrommikronetz entwickelt. Society is striving for sustainable energy supply and an efficient grid. To increase energy efficiency in DC microgrids, connecting drive converters directly to the DC grid must be possible without conversion. This adaptation is the responsibility of the component and machine manufacturers. However, due to current demand the latter do not yet see the need to develop new products . To master the transition phase, this paper develops a methodology for converting production machines for operation in a DC microgrid.

Solving dynamic economic models that capture salient real-world heterogeneity and nonlinearity requires the approximation of high-dimensional functions. As their dimensionality increases, compute time and storage requirements grow exponentially. Sparse grids alleviate this curse of dimensionality by substantially reducing the number of interpolation nodes, that is, grid points needed to achieve a desired level of accuracy. The construction principle of sparse grids is to extend univariate interpolation formulae to the multivariate case by choosing linear combinations of tensor products in a way that reduces the number of grid points by orders of magnitude relative to a full tensor-product grid and doing so without substantially increasing interpolation errors. The most popular versions of sparse grids used in economics are (dimension-adaptive) Smolyak sparse grids that use global polynomial basis functions, and (spatially adaptive) sparse grids with local basis functions. The former can economize on the number of interpolation nodes for sufficiently smooth functions, while the latter can also handle non-smooth functions with locally distinct behavior such as kinks. In economics, sparse grids are particularly useful for interpolating the policy and value functions of dynamic models with state spaces between two and several dozen dimensions, depending on the application. In discrete-time models, sparse grid interpolation can be embedded in standard time iteration or value function iteration algorithms. In continuous-time models, sparse grids can be embedded in finite-difference methods for solving partial differential equations like Hamilton-Jacobi-Bellman equations. In both cases, local adaptivity, as well as spatial adaptivity, can add a second layer of sparsity to the fundamental sparse-grid construction. Beyond these salient use-cases in economics, sparse grids can also accelerate other computational tasks that arise in high-dimensional settings, including regression, classification, density estimation, quadrature, and uncertainty quantification.

Kurzfassung Die zukunftige Stromversorgung einer Fabrik soll Energie effizient, sicher und robust bereitstellen. Das industrielle DC-Smart-Grid verfugt uber das technologische Potenzial, dieses Zie...

This paper analyzes an energy storage system (ESS) in a direct current (DC) link to mitigate the high power ratio. Furthermore, it examines how the ESS control architecture can be modelled to coordinate the interaction among the prosumers in the DC link so that the peak shaving target is achieved. First, the paper presents a simulation model of the ESS connected to the DC link. Then, the DC link supply of passive rectifier and active infeed converter are discussed separately with measured data. The inverter control system is simplified and integrated in the software framework. Peak shaving can be achieved by droop control or power control. After that, the paper presents a system configuration with communication via OPC UA for a potential forecast control strategy and energy management. The simulation shows the potential for optimized load management with a mid-sized ESS.

The future electric grid faces challenges by a rising share of renewable generation. This development increases the number of smaller decentralized power plants and therefore the volatility of energy generation. A technical approach to overcome these challenges is to cluster distributed energy generation and local power demand in microgrids. These can be used to balance power generation and demand locally and in short time frames. The industry relies on an high quality and reliable power supply, which can be ensured in a microgrid architecture, even if the main AC power grid does not meet the requirements. In specific industrial applications prototypes of direct current (DC) microgrids are built. Such a multi terminal architecture is in need for a grid control that adjusts the respective power flow of each device. This study aims on determining the implications for the DC microgrid design process with respect to stability of the control system.

In order to meet the challenges of upcoming decentralized energy systems, local direct current (DC) microgrids (MG) and energy storage systems (ESS) for industrial production sites have been studied. During charging and discharging processes the state of charge (SoC) of an ESS changes. Microgrid control, often based on droop curves, enables intelligent power distribution as well as voltage restoration in multi-infeed topologies and is necessary for taking care of the occurring SoC deviations. This paper compares different SoC control strategies based on droop control. An adaptive state of charge control has been developed using a proportional controller parameter (PCP) for shifting the droop curve on the current axis. In a case study the adaptive SoC control is validated for a droop-controlled industrial DC-microgrid with an ESS used for peak shaving. The performance of the adaptive SoC control is evaluated using quality criteria, e.g. peak load reduction, cut-off frequency and settling time. It is shown that the state of charge can be successfully kept within the desired range over time.

We develop a new framework to study regulatory policy in the presence of unregulated financial institutions ("shadow banks'') when there are pecuniary externalities. Using sufficient statistics, we show that optimal regulation in the presence of shadow banks is scaled by a "regulatory arbitrage multiplier.'' This multiplier only depends on aggregate shadow banking activity. Our framework provides guidance on how to regulate currently unregulated financial institutions and sectors. To first order, the marginal welfare gain of regulating a shadow bank is large when a notion of its intermediary activity substitution effects across its activities is large. We further characterize optimal activity-based regulation whereby the planner regulates a particular activity across all shadow banks, e.g. a tax on debt. To first order, gains from activity regulation are large when average substitution effects across intermediaries are large for the regulated activity. We show how our results extend to broader classes of non-pecuniary externalities.

Converter technologies powering drive systems established direct current technology in industrial applications. Recent developments expand the regular Direct Current (DC) link from a multi-axis-drive-systems to an interlinked multiple machine supply system. The extended DC-link allows for the exchange of recuperated energy between different processes and increases the overall system efficiency. The comparison of the extended DC link and the DC microgrids shows that the integration of multiple supply systems, like distributed generation and storage systems, allows for further optimization with respect to reliability, efficiency and robustness. One possible optimization strategy is to reduce dynamic load peaks with a storage system and downsize the grid infeed converter. Several applications for power smoothing can be found in literature, however there is no approach for sizing storage capacity and power for these applications. This paper introduces a systematic approach, which aims for storage sizing based on a load profile of industrial machines.

We provide a framework to study bail-in regimes for banks. In the presence of a monitoring problem, the optimal bank capital structure combines standard debt, which liquidates the bank and provides strong monitoring incentives, and bail-in debt, which recapitalizes the bank but provides weaker incentives. A bail-in regime, which increases use of bail-in debt, is the optimal regulatory policy when liquidation is socially costly due to fire sales or bailouts. Bail-ins fully replace bailouts. Bail-ins can generate self-fulfilling crises in long-term debt markets, leading to bank runs. Debt guarantees and an expanded notion of lender of last resort prevent these crises, and should complement bail-ins in the crisis resolution toolkit.

This paper investigates the implications of heterogeneous price rigidities across sectors for the distributional and aggregate effects of monetary policy. First, we identify and characterize analytically a new set of earnings and expenditure channels of monetary policy that emerge in the presence of sectoral heterogeneity. Second, we establish empirically that (i) prices are more rigid in sectors selling to college-educated households, (ii) prices are more rigid in sectors employing college-educated households, and (iii) sectors that employ college-educated households also sell more to these households. These new facts suggest that monetary policy stabilizes sectors that matter relatively more for college-educated households, due to an expenditure channel (from (i)), an earnings channel (from (ii)), and their amplification by feedback loops (from (iii)). Finally, we develop a multi-sector incomplete-markets Heterogeneous Agent New Keynesian model, in which households of different education levels work and consume in different sectors. We quantify the aggregate and distributional effects from heterogeneous price rigidities using this model. In the baseline calibration, we find that the consumption of college-educated households is 22% more sensitive to monetary policy shocks as that of non-college households, while the aggregate real effect of monetary policy is 5% stronger than with homogeneous price rigidities.

The industrial energy supply of the production with direct current offers the chances of higher energy efficiency, better integration of generative energy and at the same time robust power supply. In addition to the technological challenges for electrical devices, an intelligent grid management, which regulates the load flow between the participants, is crucial. The distributed grid management supports a scalable, modular network with a hierarchical structure. The paper defines a direct current (DC) grid management by the different roles of every participant. Each role provides special services, needed for a stable grid operation. These services are described and a simulative analysis is carried out. The simulation shows that network stability is ensured and at the same time, the possibility of optimizing the operation management is maintained. The presented results are part of the DC-INDUSTRIE research project, funded by the German government.

This paper describes the analytic model of a permanent magnetic synchronous machine (PMSM) of a flywheel in outer rotor design. The model is used for loss prediction within a parametric optimization algorithm. It accounts for iron and copper losses as function of electric power and rotational velocity. Magnetic state and currents are approximated by empirical assessments and an analytical model for the magnetic vector potential. A comparison of the proposed model with finite element (FE) simulations and measurements show that the fit with the FE model is already sufficient but that there are significant deviations between both models and the measurements due to the switching of the used frequency inverter.

Mechanical tunnel drive methods are gaining ever more significance on account of their mechanisation and efficiency. Mechanical boring can achieve particularly high advance rates in combination with segment lining systems. In order to investigate the load bearing capacity and robustness of segments, high-strength and ultra high-strength concrete segments were made by HOCHTIEF as part of the European Integrated Project TUNCONSTRUCT (www.tunconstruct.org), investigated through numerical simulation and in the laboratory, and then load tested at STUVA in Cologne. The results included an increase of load-bearing capacity in bending of up to 20 %. The development of segments made of high-strength concrete does indeed enable higher load bearing capacities, but there are applications under very high overburden and related pressure where this alone is not sufficient. For such cases, a compressible mortar has been developed for the annular gap filling. This has a compression potential of up 50 % and is capable of absorbing deformation of the rock mass and thus reducing the loading of the segment lining. This type of mortar has been successfully used in a large-scale trial in 2009 at the Jenbach Tunnel in the Inn valley, including the manufacture of the mortar on the construction site, the transport chain to the TBM and the injection into the annular gap. Maschinelle Vortriebsverfahren gewinnen durch ihre hohe Mechanisierung und Effizienz weiter an Bedeutung. Besonders in Kombination mit Tubbingauskleidungssystemen konnen sie hohe Vortriebsleistungen ermoglichen. Um die Steigerung der Tragfahigkeit und Robustheit von Tubbings zu untersuchen, wurden von HOCHTIEF im Rahmen des Europaischen Verbundforschungsprojekts TUNCONSTRUCT (www.tunconstruct.org) Tubbings aus hochfesten und ultrahochfesten Betonen hergestellt, rechnerisch und labortechnisch untersucht und bei der STUVA, Koln, Belastungstests unterzogen. Dabei konnte unter anderem eine Steigerung der Biegetragfahigkeit von bis zu 20 % festgestellt werden. Die Entwicklung von Tubbings aus hoherfesten Betonen ermoglicht zwar hohere Tragfahigkeiten, dennoch gibt es bei sehr hohen Uberlagerungsdrucken Anwendungsfalle, bei denen dies alleine nicht ausreicht. Fur solche Anwendungen wurden komprimierbare Ringspaltmortel entwickelt, die mit einem Stauchpotenzial von bis zu 50 % in der Lage sind, Gebirgsverformungen aufzunehmen und so die Belastung auf den Tubbingausbau zu vermindern. Ein solcher Mortel wurde im Jahr 2009 beim Tunnelvortrieb Jenbach im Inntal in einem Grosversuch erfolgreich einem Praxistest unterzogen, bei dem der Herstellungsprozess des Mortels auf der Baustelle, die Transportkette zur TVM und das Einbringen in den Ringspalt erprobt wurden.

In this paper we study the evolution of central banks’ balance sheets in 12 advanced economies since 1900. We present a new dataset assembled from a wide array of historical sources. We find that balance sheet size in most developed countries has fluctuated within rather clearly defined bands relative to output. Historically, clusters of big expansions and contractions of balance sheets have been associated with periods of geopolitical or financial crisis. This explains the co-movement between the size of central bank balance sheets and public debt levels in the past century. Relative to the size of the financial sector, moreover, central bank balance sheets had shrunk dramatically in the three decades preceding the global financial crisis. By that yardstick, their recent expansion partly marks a return to earlier levels. Some of the recent increase could therefore prove to be permanent if the financial sector maintains permanently higher liquidity ratios.