Evaluation of Inertia Levels in Provincial Power Grids with High Proportions of Renewable Energy

Renewable energy sources, including wind farms and solar power plants, are gradually replacing traditional synchronous generators (SGs) as part of the effort to achieve net-zero carbon emissions. However, this transition also leads to a reduction in the power system's inertia, especially as a significant proportion of renewable energy is integrated into the grid. Over time, operators of provincial-level grids have faced a challenge in assessing and monitoring the inertia levels within the system, which is crucial for guiding the planning of new energy installations and the scheduling of unit operations. In this article, a methodology for grid inertia calculation is proposed based on the known grid events, under the premise of clarifying the meaning of inertia level and its relationship with the system frequency security and stability. In this article, we focus on two provincial power grids where hydropower and thermal power are the main power generation structures respectively for analysis and the predict the grids’ future inertia levels by considering the grids’ future capacity expansion plans, the current grid status, and changes in the proportion of renewable energy output. Based on this analysis, various methods to enhance inertia, such as virtual inertia and synchronous phase adjustment, are explored, and recommendations for improving the grid's inertia levels are provided.