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Predictive Data Analytics for Energy Demand Flexibility

Verteidigung im Promotionsverfahren von M. Sc. Bijay Neupane (Institut für Systemarchitektur, Professur Datenbanken)

27.9.2017, 15:00 Uhr, APB 1004 (Ratssaal)

The depleting fossil fuel and environmental concerns have created a revolutionary movement towards the installation and utilization of Renewable Energy Sources (RES) such as wind and solar energy. The RES entails challenges, both in regards to the physical integration into a grid system and regarding management of the expected demand. The flexibility in energy demand can facilitate the alignment of the supply and demand to achieve a dynamic Demand Response (DR). The flexibility is often not explicitly available or provided by a user and has to be analyzed and extracted automatically from historical consumption data. The predictive analytics of consumption data can reveal interesting patterns and periodicities that facilitate the effective extraction and representation of flexibility. The device-level analysis captures the atomic flexibilities in energy demand and provides the largest possible solution space to generate demand/supply schedules. The presence of stochasticity and noise in the device-level consumption data and the unavailability of contextual information makes the analytics task challenging. Hence, it is essential to design predictive analytical techniques that work at an atomic data granularity and perform various analyses on the effectiveness of the proposed techniques. The Ph.D. study is sponsored by the TotalFlex Project (http://www.totalflex.dk/) and is part of the IT4BI-DC program with Aalborg University and TU Dresden as Home and Host University, respectively. The main objective of the TotalFlex project is to develop a cost-effective, market-based system that utilizes total flexibility in energy demand, and provide financial and environmental benefits to all involved parties. The flexibilities from various devices are modeled using a unified format called a flex-offer, which facilitates, e.g., aggregation and trading in the energy market. In this regards, this Ph.D. study focuses on the predictive analytics of the historical device operation behavior of consumers for an efficient and effective extraction of flexibilities in their energy demands. First, the thesis performs a comprehensive survey of state-of-the-art work in the literature. It presents a critical review and analysis of various previously proposed approaches, algorithms, and methods in the field of user behavior analysis, forecasting, and flexibility analysis. Then, the thesis details the flexibility and flex-offer concepts and formally discusses the terminologies used throughout the thesis. Second, the thesis contributes to a comprehensive analysis of energy consumption behavior at the device-level. The key motive of the analysis is to extract device operation patterns of users, the correlation between devices operations, and influence of external factors in device-level demands. A novel cost/benefit trade-off analysis of device flexibility is performed to categorize devices into various segments according to their flexibility potential. Moreover, device-specific data preprocessing steps are proposed to clean device-level raw data into a format suitable for flexibility analysis. Third, the thesis presents various prediction models that are specifically tuned for device-level energy demand prediction. Further, it contributes to the feature engineering aspect of generating additional features from a demand consumption timeseries that effectively capture device operation preferences and patterns. The demand predictions utilize the carefully crafted features and other contextual information to improve the performance of the prediction models. Further, various demand prediction models are evaluated to determine the model, forecast horizon, and data granularity best suited for the device-level flexibility analysis. Furthermore, the effect of the forecast accuracy on flexibility-based DR is evaluated to identify an error level a market can absorb maintaining profitability. Fourth, the thesis proposes a generalized process for automated generation and evaluation of flex-offers from the three types of household devices, namely Wet-devices, Electric Vehicles (EV), and Heat Pumps. The proposed process automatically predicts and estimates times and values of device-specific events representing flexibility in its operations. The predicted events are combined to generate flex-offers for the device future operations. Moreover, the actual flexibility potential of household devices is quantified for various contextual conditions and degree days. Fifth, the thesis presents user-comfort oriented prescriptive techniques to prescribe flex-offers schedules. The proposed scheduler considers the trade-off between both social and financial aspects during scheduling of flex-offers, i.e., maximizing the financial benefits in a market and at the same time minimizing the loss of user comfort. Moreover, it also provides a distance-aware error measure that quantifies the actual performance of forecast models designed for flex-offers generation and scheduling. Sixth, the thesis contributes to the comprehensive analysis of the financial viability of device-level flexibility for dynamic balancing of demand and supply. The thesis quantifies the financial benefits of flexibility and investigates the device type specific market that maximizes the potential of flexibility, both regarding DR and financial incentives. Henceforth, a financial analysis of each proposed technique, namely forecast model, flex-offer generation model, and flex-offer scheduling is performed. The key motive is to evaluate the usability of the proposed models in the device-level flexibility based DR scheme and their potential in generating a positive financial incentive to markets and customers. Seven, the thesis presents a benchmark platform for device-level demand prediction. The platform provides the research community with a centralized repository of device-level datasets, forecast models, and functionalities that facilitate comparisons, evaluations, and validation of device-level forecast models. The results of the thesis can contribute to the energy market in materializing the vision of utilizing consumption and production flexibility to obtain dynamic energy balance. The developed demand forecast and flex-offer generation models also contribute to the energy data analytics and data mining fields. The quantification of flexibility further contributes by demonstrating the feasibility and financial benefits of flexibility-based DR. The developed experimental platform provide researchers and practitioners with the resources required for device-level demand analytics and prediction.

Probabilistic Model Checking for Fault-Tolerance Techniques (Statusvortrag)

Vortrag im Promotionsverfahren von Dipl.-Inf. Linda Leuschner

10.10.2017, 10:10 Uhr, APB 1004 (Ratssaal)

Today's computer systems suffer from increasing bit-flips rates, triggered by transistors becoming
smaller and smaller and more prone to transient errors. Thus, fault-tolerance is of increasing interest.
Well-known and newly developed fault-tolerance techniques cover a large range of computer
architectures, fault models, and overhead tradeoffs. Evaluation of these techniques is typically done by
running fault-injections or simulations. Due to the complexity of today's hardware and software, this
cannot guarantee to provide reliable results. Furthermore, many fault-tolerance mechanisms comprise
configuration parameters, e.g., the number of data copies to be maintained or the percentage of
redundancy to be added. Thus, finding a well-suited technique is also a configuration problem. Due to
the large span of possible configurations it is often impossible to find an optimal configuration using
simulation techniques.

Betreuerin: Prof. Dr. Christel Baier
Fachreferent: Prof. Dr. Christof Fetzer

In this talk we illustrate the applicability of probabilistic model checking (PMC) as a quantitative
evaluation method for fault-tolerant systems, that also supports finding good parameter settings. We
present two concrete systems that are evaluated and configured using PMC. The first case study is a
set of processes communicating via an inter-process communication protocol as developed for the
Fiasco.OC microkernel. The communication channels of these processes are affected by and shall be
protected against bit-flips. Second, we look at applications that are protected against bit-flips by
transaction- and redo-based resilience techniques. We report on pitfalls that arose during evaluation,
concerning the well-known state-space explosion problem as well as accuracy when handling small
error probabilities. We show how these pitfalls can be overcome in the context of fault-tolerance
evaluation and report on first evaluation and configuration results.

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