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    Item type:Publication, Access status: without files ,
    Echtzeit-Zustandsschätzung und Leitungslängen-Identifikation in Niederspannungsnetzen
    (2020)
    Ipach, Hanko
    ;
    Ritt, Bendic
    ;
    Becker, Christian
    Aufgrund der zunehmenden Anzahl an dezentralen Erzeugungseinheiten und neuartigen Verbrauchern, die an die elektrischen Niederspannungs-Verteilnetze angeschlossen sind, steigt deren Auslastung und damit das Risiko unzulässiger Betriebszustände. Um diese in Echtzeit zu verhindern bzw. zu korrigieren, ist die Erfassung des Netzzustands eine Voraussetzung. Dafür eignet sich das Verfahren der leitungsstrombasierten Netzzustandsschätzung, das numerisch besonders effizient lösbar ist, wenn keine Spannungsbetragsmessungen zum Messwertsatz gehören. Um die numerische Effizienz auszunutzen und die zukünftig z.B. von Smart Metern gelieferten Spannungsbetragsmesswerte dennoch sinnvoll einzusetzen, werden letztere zur Identifikation der Leitungslängen verwendet, die üblicherweise bei der Zustandsschätzung als bekannt vorausgesetzt werden. Dabei wird ein Least-Squares Ansatz auf Basis der Netzzustandsschätzungen über mehrere Zeitpunkte angewandt. Die Simulationsergebnisse für zwei Testnetze zeigen, dass sich mit dem Verfahren in Netzen mit nicht genau bekannten Leitungslängen über einen hinreichend großen Zeitraum die Schätzungen der Leitungslängen deutlich verbessern lassen.
    Publicationtype: Conference Paper
      120
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    A distribution system state estimation for an efficient integration of electric vehicle charging infrastructure into low-voltage grids
    (2019)
    Ritt, Bendic
    ;
    Scheffer, Volker
    ;
    Ipach, Hanko
    ;
    Becker, Christian
    Due to political reasons, a growth in the usage of electric vehicles (EV) is expected for the coming years. The consequenceis an increasing amount of EV charging operations, where the charging devices are mainly connected to the low-voltagelevel of the distribution grid. A high simultaneity factor of the charging processes together with inherent high and constantload demands can lead to a higher stress on grid assets and in extreme situations to violations of grid operation constraints.For a resolution of this problem, direct load management represents a favorable instrument in the view of distributionsystem operators. An efficient load management scheme, which acts on the loads only in critical grid situations, demandsa grid state estimation of high accuracy. A deteriorating factor for the estimation quality in low-voltage grids is the verylow-availability of real-time measurements.This work presents a methodology for implementing an accurate state estimation scheme for low-voltage grids, withoutthe need for real-time measurements and solely based on historical smart meter data. For the realization of the objective,the methodology consists of the synthesis of two concepts. The first concept implements a state estimation algorithmfor low-voltage grids using three-phase line models. In order to handle the low-availability of real-time measurementdata, a concept for the generation of pseudo-measurements flanks the first concept. Hereby, neural networks trained withhistorical smart meter data are used to estimate the real-time load behavior of household loads.A series of exemplary simulations in a typical low-voltage grid from the city of Hamburg proves the applicability of thedeveloped concept.
    Publicationtype: Conference Paper
      253
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    Item type:Publication, Access status: without files ,
    Provision of control reserve by wind power plants – a system study
    (Springer, 2016-09)
    Scheffer, Volker
    ;
    Ritt, Bendic
    ;
    Becker, Christian
    The share of wind power plants of the overall installed capacity of electrical power generation is continuously rising since the last years. Nowadays, provision of ancillary services as frequency control is mainly supported by conventional power plants. However, in connection with a decreasing number of conventional power plants, wind power plants need to contribute to frequency control to a greater extend in the future. This paper presents an analysis of the impacts of an increasing supply of control reserve by controllable wind power plants on grid performance. The grid performance is thereby measured by grid frequency response metrics after a major generation loss. The European interconnected power system is simulated with focus on the four German control areas. Providing control reserve by wind power plants can be performed by a variation of the rotor pitch angle and the tip speed ratio. A control strategy for variable speed wind turbines to supply control reserve in order to stabilize the grid frequency is presented. Comparing the frequency response metrics of the future and the present scenario, it is shown that the grid performance is equal. The maximum frequency deviation is even lower in the future scenario. A sensitivity analysis shows, that even a further decrease of rotating masses in the grid is tolerable. Apart from all these technical challenges, it needs tobe reflected that the current legal framework in Germany must be changed in order to give wind power plants the possibility to participate in the primary and secondary balancing market.
    Publicationtype: Conference Paper
      28