In this paper, transients that can occur in collection grids of large offshore wind parks (WPs) are investigated. Issues concerning modeling of components, such as cables and circuit breakers, for transient studies are discussed. A WP including 80 wind turbines for a total rated power of 160MW is simulated with PSCAD/EMTDC (Manitoba HVDC Research Centre, Winnipeg, Manitoba, Canada). Examples of transient events occurring in the WP are presented. Both switching operations in normal conditions, such as energizing feeders, and faults are considered. Copyright © 2007 John Wiley & Sons, Ltd.