Die ständige Verfügbarkeit der „Edelenergie“ Strom wird von Wirtschaft und Haushalt als selbstverständlich vorausgesetzt. Mit dem Einbinden von immer mehr dezentralen Stromerzeugern, die Strom vor allem aus regenerativen Energieträgern erzeugen, muss die Fahrweise des auf große zentrale Kraftwerke orientierten Elektroenergiesystems überdacht werden. Eine dabei mögliche Strategie können „virtuelle Kraftwerke“ (VKW) sein, die als ein intelligenter Verbund kleinerer Einheiten in zentrale Systeme eingefügt werden können. Dabei treten technische und organisatorische Probleme auf, die im vorliegenden Beitrag aus der Sicht der Forschungsergebnisse eines DFG-Graduiertenkollegs behandelt werden. / The uninterrupted availability of electric power is taken for granted by industrial and household users. The strategy for operation of a centralised power system based on high-capacity power stations, however, needs to be revised, as more and more decentralised units, above all installations using renewable resources, are integrated into the system. “Virtual power plants” (VPP), where several smaller power generators of different types are managed as a whole, are able to contribute to a new strategy. This paper reports on some of the technical and organisational problems which have been solved through the research work of a graduate college of the German Research Foundation (DFG).

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xii, 191 p. : ill. Includes abstract. Includes bibliographical references (p. 182-191).

Thesis (M.S.)--Marshall University, 2009. / Title from document title page. Includes abstract. Document formatted into pages: contains vi, 43 p. Includes bibliographical references p. 41-43.

Thesis (M.S. in electrical engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 28, 2010). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 99-101).

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xv, 165 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 133-142).

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph.D.) -- University of Texas at Arlington, 2008.

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Hybrid renewable energy systems (HRESs) have become increasingly popular, especially for isolated regions. This thesis describes the design of a HRES for the isolated Ha'apai Island group in Tonga following a devastating cyclone which happened in 2014. Several renewable power generation and storage possibilities were investigated; solar, wind and battery were found to be feasible for Ha'apai. The conceptual design of a new energy storage system, the Subterranean Ocean Energy Storage System (SOESS), is also discussed as a possible alternative to batteries and a more viable substitute for an ocean renewable energy storage (ORES) system. For the proposed Ha'apai system, the optimum system configuration (solar 450 kW, wind 550 kW, battery 1,216 kAh/4,864 kW) with 90% renewable penetration was obtained using the HOMER software. Based on the optimum system configuration, load flow simulations of both the previous system and the proposed HRES were performed in DIgSILENT PowerFactory. The results of the load flow analysis show that all the transformers and transmission lines in both systems operate safely in both peak and nominal load conditions, and that the voltage levels of all LV buses are within the acceptable range of ±5%. The detailed system topology of the proposed HRES is discussed from the system implementation point of view. A unique set point control algorithm for the start-up/shut-down of the diesel generators was developed. The system dynamic performance was simulated according to the control logic during the three main switching events in DIgSILENT PowerFactory. The dynamic simulation results indicate that the proposed system would operate safely with acceptable voltage and frequency oscillations. This thesis could be used as a template for the design of other isolated HRESs with high renewable penetrations.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy