The European research project MIGRATE, and especially its Work Package 3 (WP3) demonstrated that grid-forming controls for some converters is a necessary condition to operate a system without synchronous machines with a sufficient level of reliability . Despite the limited overcurrent capability of the converters, several control concepts showed their effectiveness to ensure the stable voltage source behaviour of parallel converters, even during transients on the grid, such as phase-jumps or three-phase faults. The main theoretical results have already been validated on real hardware in lab environment. However, until now, DC side dynamics, as well as unbalanced and disturbed AC grid conditions have often been overlooked. A step further toward standardisation of grid-forming converter should prove its technical feasibility taking into account those aspects. In the WP3 of the European research project OSMOSE, RTE builds upon the MIGRATE results to increase the maturity level of grid-forming converters. In concrete terms, RTE will install a demonstrator on its own network in August 2020: a one-Megawatt grid-forming inverter backed up with batteries (500kW for one hour) and ultra-capacitances (1MW for 10 seconds). Our previous work focused on the development of suitable DC side power sharing and energy management strategies and a negative sequence control using Matlab while considering an ideal network. In this work, we validate the latest version of the demonstrator control as will be implemented onsite with a more realistic grid model available in EMTP. Expected performance are observed: the ultra-capacitances smooth the battery power output and the overcurrent is limited. However, as the fault behaviour in grid codes was specified for grid following converter, additional work is required to make regulation and grid forming controls response compatible.