Koen Vanthournout

Control of Microgrids

The motivation to develop microgrids, as a particular form of active networks is explained and presented as an effective solution for the control of grids with high levels of distibuted energy resources. The operation, more in particular the voltage and frequency control, is discussed. Control concepts useful with microgrids are detailed and implemented. Besides technical control aspects, also economical ones are developed. Primary, secondary and tertiary control algorithms are designed operating in a completely distributed way. The theoretical concepts are tested in a extensive laboratory experiment implementing a realistic scenario by using a setup of four inverters able to communicate through an Internet connection.

A taxonomy for resource discovery

Resource discovery systems become more and more important as distributed systems grow and as their pool of resources becomes more variable. As such, an increasing amount of networked systems provide a discovery service. This paper provides a taxonomy for resource discovery systems by defining their design aspects. This allows comparison of the designs of the deployed discovery services and is intended as an aid to system designers when selecting an appropriate mechanism. The surveyed systems are divided into four classes that are separately described. Finally, we identify a hiatus in the design space and point out genuinely distributed resource discovery systems that support dynamic and mobile resources and use attribute-based naming as a main direction for future research in this area.

Development of a measurement system for power quantities in electrical energy distribution systems

The design of an experimental flexible energy measurement system consisting of a DSP, sensor and communication units is treated. This system is intended to be used in modern electricity distribution networks, characterized by multiple suppliers in a deregulated market, bi-directional energy flows due to distributed generation and a diversified demand for the quality of electricity delivery. Various system aspects concerning signal processing, communication and dependability are discussed Examples of the use of such devices are included.

Distributed control of renewable generation units with integrated active filter

Due to the current concern about the environment, there is a growing interest in distributed generation from renewable energy sources. Usually a power electronic converter is required to interface renewable generation units with the utility grid. The power electronic converters can be designed to provide nonactive power in addition to active power supply in order to compensate distorted currents. This paper proposes a distributed control method for converter-interfaced renewable generation units with active filtering capability. Agent-based communication makes coordination between the generation units possible. Experimental results are included to demonstrate the validity of the proposed method.

A Taxonomy for Resource Discovery

Resource discovery systems become more and more important as distributed systems grow and as their pool of resources becomes more variable. As such, an increasing amount of networked systems provide a discovery service. This paper provides a taxonomy for resource discovery systems by defining their design aspects. This allows comparison of the designs of the deployed discovery services and is intended as an aid to system designers when selecting an appropriate mechanism. The surveyed systems are divided into four classes that are separately described. Finally, we identify a hiatus in the design space and point out genuinely distributed resource discovery systems that support dynamic and mobile resources and use attribute-based naming as a main direction for future research in this area.

A Robust Semantic Overlay Network for Microgrid Control Applications

In an electric power converting apparatus comprising a plurality of branches each including a plurality of serially connected semiconductor switching elements, a non-linear resistor is connected in parallel with each semiconductor switching element, and a voltage division element including serially connected capacitor and a resistor is connected in parallel with each semiconductor switching element. A reactor is connected in series with each one of the branches and an arrestor is connected in parallel with a serially connected reactor and an associated branch.

Agents controlling the electric power infrastructure

The electric power grid is evolving from a centrally controlled grid with only a handful of regulated monopolies to an open, liberalised electricity market. In addition, more and more small-scale dispersed generators are deployed in distribution nets. This puts extra stress on the power grid, in an era when electricity is one of the most important commodities for economic, industrial and everyday activities. Therefore, new control strategies are proposed to maintain the desired degree of availability. This paper proposes a general multi-agent approach to cope with these changes, and presents a scheme for distributed control of dispersed generators in a low-voltage distribution net. Based on a thorough investigation of this scheme, we underline the importance of understanding the interdependencies between the power grid and the Information and Communication Technology (ICT) infrastructure controlling it, which may introduce new or amplify existing vulnerabilities. Some mitigation strategies are presented to avoid or deal with these vulnerabilities.

A middleware control layer for distributed generation systems

The deregulation of the electricity market and the increased interest in distributed generators call for new methods of control and data distribution. This work describes a middleware layer that enables power inverters to communicate and cooperate. It is responsible for interconnecting the distributed generators (plug-and-play), coping with changing environments, distribution of status data, failure detection and coordination of the nonactive power production. A test setup with two generators is deployed to verify the described method.

A norm behavior based deterministic methodology for demand response base lines

One of the keystones required to bring demand response from academia and pilots to the industry and the market, is a reliable demand response base line methodology to measure the performance of the DR resources and for DR billing settlement. However, most base line methodologies proposed in the literature use statistical analysis of historic consumption data when no demand response is active. The availability of such data drops as demand response is more continuously used. We propose and define a base line methodology that builds on a norm behavior convention, where this norm behavior can be derived from the status and configuration data of the flexible devices, rather than from historic measurements. This is illustrated for postponable and buffered appliances. Norm behavior base lines can also be used for interfacing between aggregator and user of the flexibility. This has been deployed in the Linear residential demand response pilot to realize intraday balancing. The first results show that the base line methodology operates as expected. They also show the asymmetry of the flexibility offered by postponable non-interruptable white good appliances.

Distributed voltage control mechanism in low-voltage distribution grid field test

In this paper, we present a distributed voltage control mechanism that is being used in the large-scale field-test of the Linear project. The control system developed does not require a communication network between the different households. Only the locally measured household supply voltage is taken into account. The proposed control system is compatible with DSM infrastructure currently being developed, such as home gateways and smart meters. Moreover, the proposed control system can also be used as a fallback mechanism for other communication-based DSM control systems when communication fails or when the system has been compromised due to cyber security issues. Using Monte Carlo simulations on two accurately modeled field test grids and device models, the proposed approach and its various parameter set points are benchmarked against the optimal Dynamic Programming solution. Simulation results point out that on average the amount of over and under voltage occurrences can be lowered by more than 30 %.