  Security and stability challenges in future power systems with high
penetration Inverter-Based Resources (IBR) have been anticipated as the main
barrier to decolonization. Grid-following IBRs may become unstable under small
disturbances in weak grids, while, during transient processes, system stability
and protection may be jeopardized due to the lack of sufficient Short-Circuit
Current (SCC). To solve these challenges and achieve decarbonization, the
future system has to be carefully planned. However, it remains unclear how both
small-signal and transient processes can be considered during the system
planning stage. In this context, this paper proposes a coordinated planning
model of different resources to enhance system-level stability. The system
strength and SCC constraints are analytically derived by considering the
different characteristics of synchronous units and IBRs, which are further
effectively linearized through a novel data-driven approach, where an active
sampling method is proposed to generate a representative data set. The
significant economic value of the proposed coordinated planning framework in
both system asset investment and system operation is demonstrated through
detailed case studies.
