Annual Report 2009 - webfiles its vmware

The electric grid in two different areas in Gothenburg, one residential and onecommercial have been examined during the year. The maximum power level wasfound as well as the maximum number of PEVs that could be supported underdifferent charging strategies. Statistical data was then analyzed to find out howand when the vehicles are used. The result will be used to obtain more reliablecharging scenarios. Existing measurement data for different heating alternativeswill be analyzed in order to examine the effect in the electric grid.Stability Issues Related to Implementation of Large Wind FarmsParticipantes: Marcia Martins, Massimo Bongiorno, Ola CarlsonSponsors: Vindforsk, ChalmersThis thesis focuses on the impact of voltage stability when introducing large windfarms on the power system. To this end fixed speed wind turbines equipped withconventional induction generators were studied. The investigations have beencarried out with respect to short and long term voltage stability. A comparison withfield measurements was performed in order to validate the simulation models usedfor the investigations.For short-term voltage stability studies, a comparison was made betweeninduction machines operating as a generator or as a motor. Further investigationshave been performed to study the behaviour of the system during and after a shortcircuit fault at the terminals of the wind park. The investigations have examinedfactors affecting the short-term voltage stability limit such as: generated power,fault types, fault duration, fault clearing time and retained voltage. The voltagetolerance curve was introduced to describe the stability limit of a systemconnected to a wind farm.For long-term voltage stability a comparison was made between wind powerplants, thermal power plants and a combination of both the production sources.For both wind power and thermal power the requirement of the Swedish grid codewas taken into account. Different control strategies of the reactive powerproduction were analysed for the wind park. An important conclusion is that underthe normal operation of a wind park, a voltage control mode will be beneficial forthe network of which it is part.Voltage Stability Analysis and Improvement for the South West Network ofLibyaParticipants: Mohamed Ramadan Wadi, Ola CarlsonSponsor: The Libyan GovernmentThe project aims to investigate, analyze and suggest improvements for the voltagestability of the south-west electrical network of Libya, which is supplied by differentgenerating regimes and automatic tap-changers operating at maximum networkcapacity. The research will include the carrying out of a generic analysis of the32 |