Achieving carbon neutron targets lead the energy generation structure towards high renewable energy share. As the PV and wind capacity is increasing rapidly across the world, the impacts on the grid system due to the characteristics of variability and uncertainty become more visible and more severe. Those impacts include voltage and frequency fluctuation, unbalance thus threatening the stability and reliability of power systems. Therefore, some solutions aiming to increase the stability and reliability of power systems are sought under this background. However, before developing the solutions, the metric that could evaluate the impacts of variable renewable energy (VRE) need to be confirmed.