We have performed a numerical parameter study in order to find MHD stable operating regimes for advanced tokamak experiments. In this study we have concentrated on internal modes. Ballooning stability and stability with respect to infernal modes are considered. Our calculations confirm that pressure gradients are the main driving force for infernal modes. It is possible to stabilise infernal modes by elimination of pressure gradients in the region of small shear. We show that an increase of the difference between q on axis and the minimal value of q leads to destabilisation of infernal modes. Higher shear around the minimum q surface stabilises these modes. Resistivity does not lead to a significant more unstable situation. In the region of positive shear pressure gradients are limited by the destabilisation of ballooning modes. The results of the study have been used to construct an equilibrium that is stable up to βp = 2.39, βN = 3.58.