The integration of inverter-based resources like wind turbines and photovoltaic power plants in electrical power systems is increasing very fast. This increase comes with several challenges for grid operation. This presentation focuses on power system stability challenges and first solution approaches, more specifically on N-1 security and protection. We first introduce Dynamic Performance Optimization as a tool to continuously improve system stability and N-1 security while operating in different generation mixes. The optimization builds on tuning controller parameters of inverter-based and other resources. We demonstrate the performance of this approach in a Controller Hardware-in-the-Loop testbed for Hawai’i Island. Second, we present recent advances on protection of inverter dominated systems through protection-inverter co-design. The challenge is the joined analysis and design of fault-ride through functions of grid-forming inverters as well as the response of protection functions to the resulting fault currents. We show first results from simulations of a simplified model representing Hawai’i Island