Volume 59, Issue 3 -

This paper presents the design of an H ∞ -based local decentralized power system stabilizer (PSS) controllers, using selected suitable remote signals from the whole system as supplementary inputs, for a separate better damping of specific inter-area modes, considering uncertainty in time delay. The wide area or global signals are taken from suitable remote network locations where the oscillations are well observable. The PSS controller uses only those local and remote input signals in which the assigned single inter-area mode is most observable and is located at a generator which is most effective. Zusammenfassung Im Beitrag wird ein dezentraler H ∞ -Regler für die Dämpfung von ausgewählten Inter-Area-Oszillationen in elektrischen Übertragungsnetzen vorgestellt. Als Eingangsgrößen nutzen die lokalen Regler Signale von entfernten Standorten des Netzes wo die Schwingungen am besten zu beobachten sind und greifen auf Generatoren mit der besten Steuerbarkeit bezüglich der betrachteten Frequenz. Die Unsicherheit bei der Laufzeitverzögerung der Signale wird beim Reglerentwurf berücksichtigt.

Energy market activities together with an increasing integration of high capacity unpredictable renewable resources (e. g. wind power) pose an increased utilization of electrical transmission networks. In order to eliminate consequential congestions it is necessary to upgrade the grid. Constructing new lines is difficult due to environmental specifications. An alternative is the integration of power flow controllers in order to dynamically redirect power flows. In this paper we present a multi-agent based algorithm that allows for an autonomous distributed coordination of power flow controllers.

Nowadays, local utilities face new challenges by operating their grids. This is mainly due to the increasing amount of distributed generation. Furthermore, measurement is sparsely spread in distribution grids. Thus, the grid state is not entirely observable and violations may not be detected. So, local utilities trying to achieve a highly automated energy supply do not aim at a global governor but the grid has to be controlled locally using small adaptive systems due to missing infrastructure. The final aim is a plug´n´play distribution system.

The potential of adjusting the demand of certain appliances with time-flexible duty cycles is currently used for load balancing purposes only (e. g. Demand Side Management). However, a coordinated operation scheme for consumers and producers of electrical energy may also be used for grid stabilization or in general for a more efficient utilization of existing distribution grids, directly influencing line currents and voltage profiles along the network.

In this paper the optimal operation control of a virtual power plant is studied. Therefor the control problem of the micro-cogeneration units is reduced to a mathematical bilevel problem. The target functions and constraints for that Stackelberg Game are identified. Finally the coupling of both levels is realized by the solution set of the lower level. A simple example of the real application (use) is shown.

The introduction of battery electric vehicles, allows to minimze the participation of fossile energy by controlling the charging process with respect to renewables, like wind, solar or hydro power. First investigations have shown a concentration of charging power during already existing peak power periods. As a matter of fact there will be an overload on distribution grid devices. The following paper deals with the modeling and optimization of the expected electric load caused by electric vehicles.

Algorithms of conventional distance protection relays estimate the time constant resistance and reactance of the faulty line from time-discrete sampled values of the voltage and current. Based on such an algorithm a total new type of method is developed to estimate the time-variant impedance of the switching arc of current limiting low voltage circuit breakers. This method is basis for new selective protection schemes in low voltage networks.