The increasing rise of distributed generation integration in the energy mix is a challenging issue. Indeed distributed generation based on renewable energy sources like solar and wind creates fluctuation of the grid’s parameter and can lead to minor issues like harmonics, over or under voltages, flicker and so on, or to major failure like blackouts. The concept of microgrid associated with energy storage systems is seen as a potential solution to increase renewable energy integration to the grid, while increasing efficiency and reliability at the same time.A review of energy Storage technologies is carried out and it results that currently none of these technologies can offer energy and power capabilities while fast response and efficiency at the same time. The use of Hybrid Energy Storage System allows to reach such performance. For this thesis, a Li-Ion and a Vanadium Redox Flow Battery have been selected for their good power and energy abilities respectively, and their high round trip efficiency.The main contribution of this work lies in the structural limits analysis of the topology and the control algorithm for the four leg three level NPC used as a multipurpose interface between a Renewable Energy Source, a Hybrid Energy Storage System and a Microgrid. The effectiveness of the proposed algorithms and limits model are tested both in simulation and experiments. Ancillary services like frequency and voltage support are then developed and tested in simulation under various conditions.