The increasing penetration of inverter-based generation in distribution grids, coupled with the replacement of synchronous gen-

erators in transmission grids, has a profound impact on the stability of the electricity grid. To address this, grid-forming (GFM)

controls for inverters that emulate the behaviour of traditional synchronous generators are essential. However, experience is

lacking regarding their impact on the system stability including the prevention of mutual interferences of the control algorithms.

Thus, the control interaction between two inverters operated in parallel to each other are investigated in a Power Hardware-in-the-

Loop microgrid. By systematically varying the active power control parameters of one inverter, the the dynamic power sharing

and its effect on the voltage and frequency between the two GFM inverters in the event of a repetitive load step was investigated.

The experimental test results demonstrate that unequal settings of the GFM control parameters decreased the stability of the

overall system.