Annual Report 2009 - webfiles its vmware

Both steady-state high-frequency components such as harmonics, as well astransients of irregular nature will be covered. Important components in the windpark treated in the study are: cables, breakers, surge arresters and transformers.An important goal is to compare the theoretically obtained results withmeasurements.The results of this project are increased knowledge and understanding about highfrequencydisturbances in a wind park. In addition, the results will give concreteindications regarding how future sea-based wind parks should be designed inorder to avoid similar problems that have occurred in some wind parks.The licentiate report was presented in April 2009. Most of the effort during 2009was put into the modelling and additional case studies in order to identifypotentially dangerous transients in medium voltage cable systems equipped withdry-type and/or oil-insulated transformers.DFIG Wind Turbine Cluster Transients during DisconnectionsParticipants: Julia Paixao, Ola Carlson, Massimo Bongiorno, Torbjörn Thiringer,Sponsor: ElektraThe aim of this project is to study the transients occurring in a DFIG-system(doubly-fed induction generator system) with ride-through ability, when the radialcircuit breaker is opened. In order to fulfil the emerging grid codes, largeinstallations of DFIG-turbines are equipped with voltage-dip ride-through systems.Harmful over-voltage transients in a DFIG-system with ride-through ability havebeen reported during events of disconnection/reconnection of the cluster circuitbreakercompromising the reliability of this wind turbine system. The main idea isto investigate and improve the operation of the DFIG wind turbines during asudden disconnection of the cluster circuit-breaker and the following loss offeeding voltage through simulation models and measurements. The handling of asudden reconnection of the DFIG wind turbine cluster before the turbines havereached the complete shut-off state is also investigated.DC wind park module - design, function and controlParticipants: Lena Max, Ola Carlson and Torbjörn ThiringerSponsor: VindforskIn this project, the design and control of a wind farm with an internal dc grid isinvestigated. The purpose of using an internal dc grid in the wind farm is todecrease the cost since dc cables are cheaper, and the transformers in dc/dcconverters are much smaller than ordinary ones. The aim of the project is tofurther investigate the control of the internal voltage levels in the dc grid and alsothe control of the wind turbine generators, as well as the choice of voltage levelsand grounding system. Normal operating conditions are treated along with29 |