The large scale diffusion of variable Renewable Energy sources (vRES) and the simultaneous dismission of conventional power plants, while being recognized fundamental for the transition to a fully decarbonized energy system, pose new challenges to electricity systems, also in terms of stability of the main grid parameters (frequency and voltage) due to the decrease of the number of rotating masses connected to the grid. This context determines the need to expand the group of resources which can offer voltage and frequency regulation services. In the premise of the Horizon 2020 OSMOSE project Work Package 5, technical characterization of vRES resources providing voltage regulation is investigated by involving two wind power plants (one of which integrates a storage systems) located in Basilicata. In addition to retracing the voltage regulation typical requirements and the implementations realized on the plants in order to allow the service provision, this paper means to offer a first glance at the abovementioned experimentation and first results.