Online Inertia Estimation: A Pumped Storage Hydropower Turn-Off Traces Based-Method in Large Interconnection Systems

Real-time inertia monitoring is essential for maintaining stable power system operations, particularly in grids with high levels of renewable energy penetration. Existing inertia estimation methods often overlook the contributions of loads or inverter-based resources synthetic inertia. They also do not verify individual inertia values through response measurements. To address this challenge, a real-time, low-cost, and accurate inertia monitoring and estimation technology is developed to quantify the effective inertia for the actual grid response. First, the mechanism of the synchrophasor response during pumped storage hydro (PSH) is analyzed. Then, a comprehensive synchrophasor traces-based trigger is designed to detect the operation from PSH plants, utilizing its instantaneous step change in active power at the plant’s connection point during the pump turn-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> operation. Next, an improved adaptive-window prior-event rate of change of frequency tolerant inertia calculation method is proposed, with the advantage of real-time, noise immunity, and high accuracy. Furthermore, an inertia monitoring system based on PSH operation traces is established, integrating measurements from frequency disturbance recorders. By partnering with NERC, Dominion Energy, and Tennessee Valley Authority, this initiative addresses one of the primary challenges of operating a high-penetration renewable, thereby paving the way for a carbon-free power sector with significantly improved operational performance in the U.S.