The connection of offshore wind turbines to the European grid has been growing in the recent years. Many European countries are adopting this renewable energy and are increasing the number of wind power plant additions into their electrical transmission networks. In this paper, the impacts of harmonic frequencies introduced by the wind parks in a low-inertia grid are studied. Despite of classical methods which are mainly based on single-input single-output (SISO) systems, a novel approach, based on Singular Value Decomposition (SVD) techniques, considering a multiple-input multiple-output (MIMO) system is presented and discussed. The proposed SVD is a powerful mathematical tool to discover the harmonic frequencies. It can be used to analyse the system at a certain harmonic frequency and show which input(s) of the system will have more influence in the system dynamics and which output(s) will be the most affected by that input(s). According to the presented study, an SVD based methodology is provided to model any electrical network via its passive electrical elements, and to perform a harmonic analysis.