Power and Energy Student Summit (PESS) 2015

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http://hdl.handle.net/2003/33915

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Generalized Implementation of Switching-Loss-Minimized Space-Vector Modulation for Three-Level Converters
(2015-01-14) Pai, Ajay Poonjal; Siddique, Hafiz Abu Bakar; De Doncker, Rik W.; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
With increasing integration of the intermittent and volatile renewable energy resources into the existing ac grid infrastructure, the grid stability is decreasing. Large battery storage systems are proposed to act as short-time buffer to cope with transient instabilities. A promising converter to interface such low-voltage high-power battery banks is the T-type Neutral- Point-Clamped Converter (TNPC). A generalized implementation of a variant of the well-known space vector modulation featuring lower losses is proposed in this work. The derived relations to select a particular switching sequence are based on the binary logic and symmetry of the possible states in such a three-level converter. The algorithm proposed in this work dynamically adjusts the switching sequences to accommodate capacitive as well as inductive behavior.
Modular Polymer Electrolyte Membrane Fuel Cell and Electrolyser Stack Design with Hydraulic Compression
(2015-01-14) Rost, Ulrich; Roth, Jeffrey; Brodmann, Michael; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
An energy economy with high share of renewable but volatile energy sources is dependent on storage strategies in order to ensure sufficient energy delivery in periods of e.g. low wind and/or low solar radiation. Hydrogen as environmental friendly energy carrier is thought to be an appropriate solution for large scale energy storage. In 2011 the NOW (national organisation for hydrogen in Germany) calculated the demand for hydrogen energy systems as positive (0.8 GW to 5.25 GW) and negative supply for varying power demand (0.68 to 4.3 GW) for the German energy economy in 2025. Due to its dynamic behaviour on load changes polymer electrolyte membrane fuel cells (PEMFC) as well as water electrolyser systems (PEMEL) can play a significant role for large scale hydrogen based storage systems. In this work a novel design concept for modular fuel cell and electrolyser stacks is presented with single cells in pockets surrounded by a hydraulic medium. This hydraulic medium introduces necessary compression forces on the membrane electrode assembly (MEA) of each cell within a stack. Furthermore, ideal stack cooling is achieved by this medium. Due to its modularity and scalability the modular stack design with hydraulic compression meets the requirements for large PEMFC as well as PEMEL units. Small scale prototypes presented in this work illustrate the potential of this design concept.
Implementation of a Solid-State Power Controller for High-Voltage DC Grids in Aircraft
(2015-01-14) Terörde, Michael; Grumm, Florian; Schulz, Detlef; Wattar, Housam; Lemke, Jens; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Conventional electrical distribution systems onboard aircraft use a three-phase system with a typical voltage of 115 VAC or 230 VAC to supply electrical loads. Future aircraft demand more electric power due to the replacement of hydraulic and pneumatic systems by electrical ones and the increased use of multimedia entertainment systems. However, the aircraft weight can be decreased if a high-voltage direct current (HVDC) grid with a voltage level of ±270 VDC or 540 VDC is implemented to supply the electrical loads. These higher voltages reduce cable weight, but are a new challenge for solid-state power controllers (SSPC), which are used as protection devices for cables and loads. Currently available SSPCs are limited to lower voltages and currents mainly because of the available power semiconductors. A SSPC for aircraft applications with a nominal voltage of 540 VDC and a nominal load current of 10 A has been developed at the Helmut Schmidt University in Hamburg in cooperation with Airbus Group Innovation using SiC-MOSFETs and has been tested. In this paper the design and experimental results are presented. The SSPC is able to supply itself from the high voltage autarkic and can accomplish various functions.
Optimierung von Mittelspannungsnetzen durch Reduktion der Netzverluste
(2015-01-14) Wißmann, Timo; Haubrock, Jens; Ottensmann, Ansgar; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Durch die Umstrukturierung von Mittelspannungsnetzen in Deutschland sowie durch die Veröffentlichungs- und Ausschreibepflicht von Netzverlusten bekommt die Optimierung von Energieversorgungsnetzen mehr und mehr an Bedeutung. Dieser Beitrag befasst sich mit der Optimierung von einem Mittelspannungsnetz, welches durch verschiedene Spannungsebenen (110 kV und 30 kV) gespeist wird. Durch ein erhöhtes Anlagenalter der 30-kV-Betriebsmittel, soll überprüft werden ob die Möglichkeit besteht ein Umspannwerk 30/10 kV durch eine 10-kV-Stützpunktstation zu ersetzten. Hierzu werden zwei Varianten entwickelt und mit der Netzberechnungs- und Simulationssoftware PSS®Sincal hinsichtlich der Netzverluste untersucht. Als Vergleichsnetz wird ebenfalls auch das Ursprungsmittelspannungsnetz herangezogen, und untersucht welche Betriebsmittels zu ersetzen sind. Als weiterer Ansatzpunkt wer-den die ungefähren Kosten für die beiden Varianten und den Weiterbetrieb des Netzes aufgestellt.
Steady State Analyse of existing Compressed Air Energy Storage Plants
(2015-01-14) Kaiser, Friederike; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
As compressed air energy storage (CAES) is a promising energy storage technology that has already proven its reliability in commercial operation some basic thermodynamic information on this process are elaborated in this paper. It shows a comparison of the thermodynamic process cycles of the CAES plants in Huntorf and McIntosh that has been modeled in EES (Engineering Equation Solver). Detailed T-s-Diagrams are given to show the differences of reversible and irreversible thermodynamic modeling of CAES. It is demonstrated that irreversibility assumption leads to an over estimation of the plant efficiency and therefore newer CAES concepts (like adiabatic CAES) should not be approximated with reversibility assumptions to avoid misleading statements.
A Study of Uncertain Wind Power in Active-Reactive Optimal Power Flow
(2015-01-14) Mohagheghi, E.; Gabash, A.; Li, P.; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Wind power fluctuates with time and it is reasonable to regard it as a random variable. Recently, an active-reactive optimal power flow (A-R-OPF) method in active distribution networks with wind stations has been developed to handle the problem of wind power curtailment (WPC). Since the mentioned method is deterministic, it may fail to handle uncertain wind power (UWP). Therefore, our study in this paper will firstly discuss the issue of UWP and secondly develop a new strategy which can improve the A-R-OPF by considering UWP. The new strategy can be distinguished from the original so that: 1) it considers shorter time intervals, i.e., 15 minutes instead of one hour and 2) it can handle both UWP and WPC simultaneously. The effectiveness of the new strategy is shown by using a real case medium-voltage distribution network.
Tagungsband zum power and energy student summit 2015
(2015-01-14) Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Blitzeinschlagsanalyse für rückwärtige Überschläge einer Hybridleitung
(2015-01-14) Nilges, Matthias; Mackow, Andrzej; Kizilcay, Mustafa; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
A new method to transfer energy over short and long distances is to use hybrid lines. In this paper a lightning surge analysis for backflashovers on overhead transmission lines with one DC and three AC systems on the same tower is considered. Lightning strikes are the most common source of failures on transmission systems and are not considered for hybrid lines. The main aim is to get essential information about the behavior of the HVDC system due to a backflashover. We simulate a lightning stroke into a hybrid line using EMTP-ATP. The results clearly show that the 110-kV AC systems provide protective effects for the HVDC system. Therefore, it is concluded that the backflashover performance of HVDC systems is better on AC/DC hybrid lines, compared to identically constructed towers with just one HVDC system installed.
Herausforderungen und Lösungsansätze bei der Erbringung von Primärregelleistung durch Energiespeicher
(2015-01-14) Wandelt, Fabian; Gamrad, Dennis; Deis, Wolfgang; Myrzik, Johanna; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Aufgrund der Energiewende, mit dem Wandel von einer fossil befeuerten zu einer regenerativen Energieversorgung, wird die Erforschung von alternativen Konzepten für Netzdienstleistungen immer wichtiger. Ein solches Konzept ist die Erbringung von Regelleistung mit Energiespeichern. In diesem Beitrag wird u. a. der Verlauf der Netzfrequenz analysiert und ein Simulationsmodell zur Untersuchung eines Speichers in der Anwendung Primärregelleistung entwickelt. In diesem Zusammenhang wird ein Konzept, gestützt durch entsprechende Simulationsergebnisse, vorgestellt, das insbesondere für Betreiber großer industrieller Verbrauchsanlagen zeigt, wie diese in Kombination mit Batteriespeichern zur Regelleistungserbringung genutzt werden können. Eine Wirtschaftlichkeitsanalyse vergleicht die verschiedenen Konzepte der Primärregelleistungserbringung mit Batteriespeichern.
Dynamic Data Driven Dimensioning of Balancing Power with k-Nearest Neighbors
(2015-01-14) Ohsenbruegge, Anja; Klingenberg, Thole; Lehnhoff, Sebastian; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
This paper proposes a novel dynamic design for control reserve dimensioning. In contrast to the current statistical analytic design we present a data driven approach with methods of computational intelligence. The chosen k-nearest neighbor algorithm is one of the most sucessfully used methods in machine learning. The model is able to predict complex nonlinear behavior by assuming that similar observations have similar outcomes. A condition for the success of this method is to determine the salient features. Therefore the core of this paper is to show the dependencies of the influencing parameters. Numerical experiments on the basis of freely available data for the years 2011 until 2013 show that there are time and space patterns as well as inter dependencies with the active power market.
Information Parameters of Electrical Quantities of the Transient for Determining the Single-Phase Earth Fault Location in Сable Medium-Voltage Systems
(2015-01-14) Shuin, Vladimir; Filatova, Galina; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Rapid fault determination of single-phase earth fault (SPEF) and SPEF location on the line are extremely important for the speedy elimination of damage and restoring normal operation of the power supply. Effective methods of SPEF determination on the cable lines under voltage do not still exist in medium voltage networks. The electrical values of the transition process that occurs during the breakdown of the insulation can be used for solving the problem of determining the place of single-phase including self-eliminating faults. The best method to study the electromagnetic transients at SPEF in medium-voltage networks and to identify the information parameters, which can be used for distant SPEF determination, is a combination of analytical methods on the basis of simplified models of the electrical networks and the method of computer simulation.
Einfluss dezentraler Wärmepumpen auf die Netzausbaukosten des Niederspannungsnetzes
(2015-01-14) Rupp, Linda; Brunner, Marc; Tenbohlen, Stefan; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
In diesem Paper werden anhand von Monte-Carlo-Simulationen die Auswirkungen von Wärmepumpen auf die Netzausbaukosten eines Niederspannungsnetzes untersucht. Es kann gezeigt wer-den, dass mit einer zentralen Regelung der Wärmepumpen die auftretenden Spannungsbandverletzungen aufgrund von Photovoltaikanlagen (PVA) reduziert, jedoch nicht vollständig behoben werden können. In Verbindung mit einer Wirkleis-tungsregelung der PVA lässt sich jedoch effektiv eine Reduktion der Spannungsbandverletzungen erreichen. Wärmepumpen führen hierbei zu einer weiteren Senkung der Kosten des Einspeisemanagements, indem sie die ansonsten abgeregelte Energiemenge aufnehmen und in Wärme umwandeln. Metho-disch wird auf eine probabilistische Netzplanung zurückgegrif-fen, welche wirtschaftliche Vorteile gegenüber einer worst-case gestützten Betrachtung aufweist. Es zeigt sich, dass ein Einspeise- bzw. Verbrauchsmanagement unter bestimmten Umständen wirtschaftlicher sein kann als ein klassischer Netzausbau. Die Ergebnisse lassen jedoch zudem vermuten, dass derartige Fest-stellungen stark von der jeweiligen Netztopologie abhängen und nicht pauschal beantwortet werden können.
Calculation of the Electric Field below Hybrid Overhead Lines
(2015-01-14) Schindler, Jakob; Romeis, Christian; Jaeger, Johann; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
The demand for increased transmission capacities in Germany will be covered in part by high voltage direct current (HVDC) lines. In order to reduce the need for new corridors, hybrid systems with AC and DC circuits together on the same tower are planned. Therefore, the characteristics of such arrangements need to be studied. In the first part of this paper, electromagnetic coupling mechanisms between overhead lines are summarized. Next, the method of image charges as a way to calculate the electric field around overhead lines is presented. The method is then used to analyze the electric field on ground level below three different hybrid line configurations.
Parametrierung einer kontinuierlichen DC-Spannungsregelcharakteristik für vermaschte HGÜ-Netze
(2015-01-14) Linke, Franz; Marten, Anne-Katrin; Westermann, Dirk; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
The energy turnaround caused a lot of challenges for the power system as well in the distribution level as in the transmission level. For the transmission level significant distances between areas of high renewable generation, storage capacities and centers of load require a bulk power transmission. As the existing transmission system is not designed for such tasks, a suitable solution is a meshed HVDC grid spanning the existing AC grid. Most state of the art methodologies for controlling DC node voltages can provoke DC oscillations due to their points of discontinuity. This paper proposed a new continuous local control characteristic and presents a methodology for its parameterization according to available AC balancing control capabilities.
Real-Time Implementation and Evaluation of a Support Vector Machine Based Fault Detector and Classifier for Distribution Grids
(2015-01-14) Ehsan, Mohammad Umair; Keune, Björn; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Bridging the gap between theoretical modeling and practical implementation is essential in fault detection, classification, and location methods for modern distribution grids. Currently distribution grids are characterized by dispersed infeed and distributed power generation that render conventional protection settings more challenging, and, hence, new methods must be investigated to resolve these issues. In this paper, a novel framework capable of detecting and classifying faults in power distribution grids is presented. The proposed algorithm formulates a unique fault classification technique based on measurement samples of three-phase voltage and currents after the occurrence of a fault event in power distribution grid. Thereby, negative sequence components of three-phase voltage and current quantities are used for online fault detection that triggers a fault classification method based on a support vector machine. In order to simulate fault scenarios, a model of a reference distribution grid incorporating distributed generation is developed, simulated, and analyzed under fault conditions. For the final evaluation, the designed protection scheme is implemented on a Programmable Logic Controller connected to the model running on a real-time simulator hardware that provides voltage and current measurements. Thus experimental results are provided to demonstrate and prove the contribution of the algorithm in its ability to correctly identify and classify faults in modern distribution grids.
Potentialermittlung von Energiespeichern zur Stützung des elektrischen Verteilnetzbetriebes
(2015-01-14) Klabunde, Christian; Röhrig, Christian; Moskalenko, Natalia; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
In der vorliegenden Untersuchung werden Einsatzpotentiale von Energiespeichern der Klasse 30 MW im Verteilnetz näher betrachtet. Das Ziel dieser Untersuchung ist das Aufzeigen von Grenzen sowohl für den Speicher als auch für das elektrische Netz, wobei marktorientierte und netzorientierte Speicherkonzepte berücksichtigt und miteinander verglichen werden. Für die Untersuchung wurde ein 110 kV-Verteilnetzbereich modelliert. Nach der Modellierung unterschiedlicher Speichereinsatzmöglichkeiten und der Implementierung dieser in das modellierte Netz konnten die verschiedenen Speichermodelle hinsichtlich ihrer Einsatzzeiten und Auswirkungen auf das elektrische Netz miteinander verglichen werden.
Electricity supply reliability of the industrial enterprises with local power plants and the outage cost evaluation
(2015-01-14) Iuldasheva, Alina; Malafeev, Aleksei; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
In this article, the algorithm of reliability evaluation of electricity supply systems operation is presented. It includes evaluation of the reliability of consumer’s electricity supply and the reliability of power generation by the local power plants. Proposed algorithm is based on the method of sequential network reduction and allows calculating the reliability indices of the selected consumer or of the certain point of power distribution. This algorithm is implemented in the program complex (PC) KATRAN. The calculation of reliability indices allows assessing the consumer’s outage cost and the interruption costs of the enterprise’s power plants.
Lastabwurfkonzept auf Basis von Jahresmittelwerten
(2015-01-14) Richter, André; Hauer, Ines; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
Vor dem Hintergrund des steigenden Anteils von erneuerbaren Erzeugungsanlagen im Netz werden immer mehr konzeptionelle Anpassungen zur Sicherstellung der Systemstabilität notwendig, um z.B. einen vermehrten Leistungsfluss vom Verteilungsnetz zum Übertragungsnetz zu berücksichtigen. Die vorgestellten Untersuchungen befassen sich speziell mit dem frequenzabhängigen automatischen Lastabwurf gemäß eines modifizierten 5-Stufenplans zur Behebung der Unterfrequenz. Da die Schutzsysteme bzw. die Frequenzrelais unabhängig von der Lastflussrichtung automatisch auslösen, kann es im Problemfall dazu kommen, dass anstatt Lasten Erzeugungsanlagen vom Netz getrennt werden. Für die Lösung dieser Problematik wurde in den Untersuchungen ein neues, alternatives Lastabwurfkonzept auf Basis von Jahresmittelwerten analysiert und unter Anwendung verschiedener Szenarien an einem Netzmodell getestet. Dafür wurden auf Grundlage einer gegebenen Datenbasis der 50Hertz Transmission GmbH Referenzwerte je Transformator und anschließend die Wahrscheinlichkeit, dass an einem Transformator die geforderte Last abgeschaltet werden kann, ermittelt. Weiterhin werden Lastabwurf und Erzeugerzeitreihen berechnet sowie eine Lastabschätzung für jedes Szenario vorgenommen und in das Modell implementiert. Das Paper bietet abschließend einen qualitativen Vergleich des aktuellen Lastabwurfkonzepts auf Basis der Jahreshöchstlast mit dem neuen Konzept auf Basis des Jahresmittelwerts.
A Comparative Study of Optimization- and Rule-Based Control for Microgrid Operation
(2015-01-14) Kanwar, Aastha; Rodríguez, Diego I. Hidalgo; von Appen, Jan; Braun, Martin; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
As local renewable energy based generation units are being deployed worldwide, distribution grids are facing integration challenges. Here, microgrids provide a solution, by allowing intentional islanding and connection to the public distribution grid depending upon its current state. Microgrids may consist of loads, generation units and storages which can be operated as a single controllable entity. This paper investigates two control approaches for cost-efficient operation of grid-connected microgrids: optimization- and rule-based control. For optimizationbased control, a model predictive control algorithm with mixed integer linear programming formulation is used. A case study for a microgrid in an office building consisting of distributed generation units and different storage units is presented to assess the performance of the two control approaches. The simulation results show the effectiveness of the optimization-based approach and a potential for lower microgrid operating costs compared to the rule-based approach.
Energy System Modelling: Power Plant Dispatch and Electricity Generation Costs
(2015-01-14) Weiss, Thomas; Sperling, Christoph; Schulz, Detlef; Kubis, Andreas; Rehtanz, Christian; Shapovalov, Anton; Hilbrich, Dominik; Plota, Ewa
The growing share of intermittent renewable energy on the electricity production has also an influence on the remaining thermal power plants. The full load hours, especially of fossil fired power plants, are decreasing over time. In the meantime, the energy surplus produced by renewable sources is increasing and without building new controllable power plants, the back-up capacity is decreasing because old fossil fired power plants will shut down. A lot of modelling has been done in this field yielding to very different results. This paper shows a generic approach to the calculation of the power plant dispatch and the electricity generation cost. The main focus is on the influence different scenario assumptions can have on the outcome of the investigation. The aim is to show how important an extensive sensitivity analyses is. As the ambitious climate targets of the government, the strong development of intermittent renewable energies as well as the nuclear phase out provide very good scenarios, the model will be explained on the example of Germany.

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