Probabilistic multi-stability operational boundaries in power systems with high penetration of power electronics

•A probabilistic multi-stability operational boundary assessment based on frequency, large-disturbance rotor angle, small-disturbance rotor angle, and voltage stability for varying renewable energy source penetration levels and loading conditions was investigated and established.•Establishing system’s operational boundary from a singular stability type is dangerous as the established operational boundary from each stability type is very different.•The established multi-stability operational boundary is heavily influenced by frequency and large-signal disturbance rotor angle stability.•A significant improvement in the system’s operational stability boundaries occur when the VSC-HVDC’s ability to independently control active and reactive power via VDC-Q control is fully utilized.