Marcus Venzke

Application specific vs. standard Web service interfaces for the vertical integration of fieldbus systems

The paper compares two approaches for developing Web service interfaces for the vertical integration of TTP/A fieldbus systems. High-level abstractions are provided by application specific interfaces, generated from metadata describing fieldbus systems. In contrast standardised interfaces such as OPC XML DA only allow lower levels of abstractions. But these enable accessing the fieldbus system from a broad range of standard clients, while high-level abstractions reflecting the application programmers view on the system facilitate the development of more specific clients and workflows.

Simulative evaluation of demand response approaches for waterbeds

This paper quantitatively compares five demand response (DR) approaches for waterbeds using simulation. The approaches enable privacy by design with a local control and contribute to the planning phase of the electricity networks balancing process. Approaches are assessed by their energy consumption, their ability to shift power consumption to times of high availability, and the effort of realization and configuration. Load steps were identified as a risk for power network stability. A classification of DR methods, based on the position of their contribution within the electricity networks balancing process, is used to distinguish our approach from the DR approaches found in the literature.

Understanding price functions to control domestic electric water heaters for demand response

A well-known mechanism for demand response is sending price signals to customers a day ahead. Customers then postpone or advance their usage of electricity to minimize cost. Setting up price functions that adapt the customers’ load to availability is a big challenge. This paper investigates the feasibility of finding day-ahead price functions to induce a desired load profile of domestic electric water heaters (DEWHs) minimizing their electricity cost for demand response. Bilevel optimization is applied for a single DEWH using a simplified linear model and full knowledge. This leads to a solvable bilevel problem and allows understanding optimality of price functions and resulting heating profiles. It is shown that with the resulting price functions the DEWH may select many significantly different heating profiles leading to the same cost. Thus the price does not uniquely induce the desired heating profile. The acquired knowledge forms the basis for a procedure to create price functions for controlling the load profile of many DEWHs.

Impacts of domestic electric water heater parameters on demand response

This paper analyzes the impact of the high dimensional parameter space of domestic electric water heaters (DEWH) for demand response (DR). To quantify the consumer comfort a novel metric is introduced considering a stochastic distribution of different water draw events. Incorporating three control algorithms from literature, it is shown that all considered parameters of a DEWH except the heat conductivity have a significant impact on consumer satisfaction. The effect on DR is mainly influenced by the temperature range and the planning horizon, but also by the heat conductivity and the volume. In contrast, the rated power of the heating element and the nominal temperature have no significant impact on the effect on DR. The impacts are analyzed by varying these parameters in a simulation of 1000 DEWHs considering three different controllers: a common thermostat, an exchange price dependent nominal temperature changing mechanism and an energy scheduling algorithm proposed by Du and Lu.

A demand response approach locally implementable for waterbeds

This paper presents a demand response scheme for waterbeds that can be implemented with currently available infrastructure. It balances the requirements of saving energy and shifting power to times with higher power availability by scheduling heating phases such that costs according to an electricity exchanges virtual electricity tariff are minimized. The approach was successfully validated with a real waterbed under real conditions.

Field Trials with Wireless Sensor Networks: Issues and Remedies

Extensive field trials are essential to evaluate protocols and algorithms for wireless sensor networks. The high costs of such trials demand for a systematic approach. This paper discusses the issues of setting up a field trial such as packaging, logging, and deployment. Details about a concrete field trial to evaluate a topology discovery algorithm are presented.

Spezifikation von interoperablen Webservices mit XQuery

The thesis solves interoperability issues regarding Web Services. The W3C standard for the specification of their interfaces (WSDL) is made more precise. This is done by developing a specification technique (SXQT), which allows specifying interfaces using expressions of first order logic (in XQuery). Compliance with such specifications is checked with the automatic validation.

A Generic Java Interface for Vertical Integration of Wireless Sensor Networks

The paper presents a generic, high-level Java interface for the vertical integration of wireless sensor networks. The intuitive interfaces are implemented in a framework that is easy to use. The classes of the framework can be extended to meet the requirements of a wide range of applications. In particular, the framework supports sending packets to and receiving packets from nodes of the sensor network. Packet types are represented as Java classes generated from meta-data based on XML schema. This approach fosters short development cycles and provides the productivity needed in vertical integration applications. The ScatterWeb platform is used as a sample platform for sensor networks