A Comparative Study of Optimization- and Rule-Based Control for Microgrid Operation

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

Assessment of the Economic Potential of Microgrids for Reactive Power Supply

As power generation from variable distributed energy resources (DER) grows, energy flows in the network are changing, increasing the requirements for ancillary services, including voltage support. With the appropriate power converter, DER can provide ancillary services such as frequency control and voltage support. This paper outlines the economic potential of DERs coordinated in a microgrid to provide reactive power and voltage support at its point of common coupling. The DER Customer Adoption Model assesses the costs of providing reactive power, given local utility rules. Depending on the installed DER, the cost minimizing solution for supplying reactive power locally is chosen. Costs include the variable cost of the additional losses and the investment cost of appropriately over-sizing converters or purchasing capacitors. A case study of a large health care building in San Francisco is used to evaluate different revenue possibilities of creating an incentive for microgrids to provide reactive power

Observing the oceanic heat flux toward retreating outlet glaciers in NE-Greenland

Warming of subsurface water of Atlantic origin has been suggested to be a major driver of the ongoing retreat of marine terminating glaciers around the coast of Greenland. In recent years, also the outlet glaciers of the Northeast Greenland Ice Stream have undergone major changes leading to an increased mass flux from the ice sheet into the ocean. Both, the thinning of the 80-km long floating tongue of the 79 North Glacier and the collapse of the floating tongue of the adjacent Zachariæ Isstrøm have been attributed to increasing ocean temperatures. However, it has been unclear whether the bathymetry was sufficiently deep to allow warm Atlantic water to reach Zachariæ Isstrøm. Here we report on the first station-based bathymetric and oceanographic measurements carried out in summers 2016 and 2017 close to the calving front of Zachariæ Isstrøm. They reveal 1°C-warm waters of Atlantic origin in a layer between 300 to 600-m depth to be in direct contact with the calving front of the glacier. Also, 12-month long mooring based observations demonstrate Atlantic origin waters to flush the cavity beneath the 79 North Glacier causing high basal melt rates along the 80-km-long glacier base. Based on moored measurements further offshore on the Northeast Greenland continental shelf we discuss the processes that govern the oceanic heat transport toward both glaciers. A better understanding of these processes is relevant to distinguish short-term variability from long-term changes in the oceanic heat flux toward the glaciers

Application of the Software as a Service Model to the Control of Complex Building Systems

In an effort to create broad access to its optimization software, Lawrence Berkeley National Laboratory (LBNL), in collaboration with the University of California at Davis (UC Davis) and OSISoft, has recently developed a Software as a Service (SaaS) Model for reducing energy costs, cutting peak power demand, and reducing carbon emissions for multipurpose buildings. UC Davis currently collects and stores energy usage data from buildings on its campus. Researchers at LBNL sought to demonstrate that a SaaS application architecture could be built on top of this data system to optimize the scheduling of electricity and heat delivery in the building. The SaaS interface, known as WebOpt, consists of two major parts: a) the investment& planning and b) the operations module, which builds on the investment& planning module. The operational scheduling and load shifting optimization models within the operations module use data from load prediction and electrical grid emissions models to create an optimal operating schedule for the next week, reducing peak electricity consumption while maintaining quality of energy services. LBNL's application also provides facility managers with suggested energy infrastructure investments for achieving their energy cost and emission goals based on historical data collected with OSISoft's system. This paper describes these models as well as the SaaS architecture employed by LBNL researchers to provide asset scheduling services to UC Davis. The peak demand, emissions, and cost implications of the asset operation schedule and investments suggested by this optimization model are analysed

Sizing and operation of residential photovoltaic systems in combination with battery storage systems and heat pumps

Zugleich: Universität Kassel, Dissertation, 201

Assessment of the Economic Potential of Microgrids for Reactive Power Supply

As power generation from variable distributed energy resources (DER) grows, energy flows in the network are changing, increasing the requirements for ancillary services, including voltage support. With the appropriate power converter, DER can provide ancillary services such as frequency control and voltage support. This paper outlines the economic potential of DERs coordinated in a microgrid to provide reactive power and voltage support at its point of common coupling. The DER Customer Adoption Model assesses the costs of providing reactive power, given local utility rules. Depending on the installed DER, the cost minimizing solution for supplying reactive power locally is chosen. Costs include the variable cost of the additional losses and the investment cost of appropriately over-sizing converters or purchasing capacitors. A case study of a large health care building in San Francisco is used to evaluate different revenue possibilities of creating an incentive for microgrids to provide reactive power

Konzeption und Evaluation von Verfahren für die Ausreißer-Erkennung : Outlier-Detection zur Identifikation von auffälligen Belegen in Buchungsjournalen aus Finanzbuchhaltungssystemen

Durch die stetige Automatisierung und Digitalisierung der Geschäftsprozesse im 21. Jahrhundert entstehen immer mehr Finanztransaktionen, die auf unbeabsichtigte Fehler oder Betrugsversuche analysiert werden müssen. Das bisherige Vorgehen ist die manuelle Überprüfung eines Ausschnittes aller Transaktionen oder die Analyse aller Transaktionen mit Hilfe vordefinierter statischer Regeln. In dieser Arbeit wird evaluiert, ob die unüberwachten Verfahren DBSCAN, OPTICS, LOF, ROCK und Autoencoder sinnvoll in der Wirtschaftsprüfung angewendet werden können. Hierzu wurden die Verfahren auf drei Konten erprobt, die vorher von Wirtschaftsprüfern analysiert wurden. In dem zweiten Teil der Arbeit wird ein Versuch unternommen, mit Hilfe einer verbesserten Datenvorverarbeitung, die erreichten Ergebnisse zu verbessern.The steady automation and digitalisation of business processes in the 21st century is creating more and more financial transactions that need to be analysed for unintentional errors or fraud attempts. The current approach is to manually review a subset of all transactions or to analyse all transactions using predefined static rules. This thesis evaluates if the unsupervised methods DBSCAN, OPTICS, LOF, ROCK and autoencoder can be applied in the auditing process. For this purpose, the procedures were tested on three accounts that were previously analysed by auditors. In the second part of the thesis an attempt is made to improve the achieved results by improving the data preprocessing

A short linear motif in scaffold Nup145C connects Y-complex with pre-assembled outer ring Nup82 complex

The Nup82–Nup159–Nsp1 complex, which plays a key role in mRNA export, is recruited late during the process of nuclear pore complex (NPC) assembly. Here the authors combine crosslinking mass spectrometry, biochemical reconstitution and molecular modeling to gain insights into the mechanism of Nup82 recruitment to the NPC