Field Tests of Wind Turbines Submitted to Real Voltage Dips under the New Spanish Grid Code Requirements E. Gómez*, Renewable Energy Research Institute, Department of Electrical, Electronic, and Control Engineering, EPSA, Universidad de Castilla-La Mancha, 02071 Albacete, Spain J. A. Fuentes, A. Molina-García and F. Ruz, Department of Electrical Engineering, Universidad Politécnica de Cartagena, 30202 Cartagena, Spain F. Jiménez, Engineering Department, Gamesa Eólica S.A., Polígono Agustinos, calle A, E-31013 Pamplona, Spain This paper adds the new Spanish grid code to the previously published works about the comparison of international regulations for connection of wind turbines to the network. All the electrical magnitudes—currents and active and reactive power—regulated in the Spanish grid code are studied when the wind turbines are submitted to real voltage dips. Because grid codes and, specifically, the Spanish grid code do not fix the reactive power def- inition to be applied, four definitions commonly used have also been studied.Taking advan- tage of the voltage dips field tests carried out to the Gamesa G80 wind turbines, the results obtained for two representative voltage dip tests are presented: a three-phase and a phase- to-phase voltage dip. Copyright © 2007 John Wiley & Sons, Ltd. Received 13 November 2006; Revised 16 March 2007; Accepted 10 May 2007 WIND ENERGY Wind Energ. 2007; 10:483–495 Published online 27 June 2007 in Wiley Interscience (www.interscience.wiley.com) DOI: 10.1002/we.234 Copyright © 2007 John Wiley & Sons, Ltd. Research Article * Correspondence to: E. Gómez, Renewable Energy Research Institute, Department of Electrical, Electronic, and Control Engi- neering, EPSA, Universidad de Castilla-La Mancha, 02071 Albacete, Spain. E-mail: emilio.gomez@uclm.es Introduction Grid-tied wind-powered electricity generation has grown at a phenomenal pace in recent years. It is clear that wind power has become a competitive technology for clean energy production. Therefore, electric utilities are beginning to develop large-scale wind power projects as an attractive alternative to conventional capacity expansion in the face of high electrical demands, growing uncertainties in conventional generation, together with current policies and incentives offered in some countries. Due to these policies, renewable sources of energy, which can be considered national resources, have and will have an important role to play in reducing the energy imports. Integration of distributed generation in the utility grid offers technical, environmental and economical benefits, from both the utility and the end-user point of view. 1–3 With increasing wind farm penetration in power systems, many national grid codes are demanding to wind power installations additional requirements to integrate them with the other conventional types of generation. Specifically, national grid codes are requiring uninterrupted generation throughout power system disturbances supporting the network voltage and frequency, and therefore, extending characteristics such as low voltage ride through, or reactive and active power capabilities. Low voltage ride through is particularly important to main- Key words: voltage dips; wind turbines; reactive power; grid codes