A detailed harmonic resonance analysis of power systems is more and more important due to the increasing number of power electronic devices. The topic is especially wellgrounded in wind power plants that besides having several possible sources of harmonics have many inductive and capacitive elements. This combination forms a severe concern over harmonic resonance that composes a threat to the power quality and the function of wind power plants. This paper presents and applies the harmonic resonance mode analysis (HRMA) in a model of an off shore wind power plant with and without a passive filtering. The results of the harmonic resonance mode analysis are verified and compared with the results calculated with the frequency scan.