Abstract: [Objectives]　Large fluctuations in renewable energy output can easily lead to bidirectional and repeated reactive power oscillations at the access points, affecting the voltage stability of the connected grid. To ensure voltage stability, grid scheduling often restricts the output of renewable energy sources (i.e., curtailment), resulting in reduced economic benefits for renewable power plants. For this reason, a method using phase regulation of pumped storage for the voltage stability of power grids with renewable energy integration is proposed. [Methods]　First, the feasibility of pumped storage units operating in phase regulation mode is analyzed, and it is concluded that this condition can be utilized for dynamic reactive power regulation. Second, based on the sending line model of wind farms, the power equations at the sending and receiving ends of transmission lines are obtained, from which the voltage-power relationship at both ends is derived. By analyzing the power curves at the grid connection points and the access points under conditions of constant voltages at both ends, the causes of reverse reactive power flow on the sending line, low voltage at the access points, and grid-side voltage instability are theoretically analyzed when renewable energy output is excessive. Finally, the direction of reactive power compensation in the power grid is analyzed, and combined with the phase regulation condition of pumped storage, a method utilizing phase regulation of pumped storage to compensate for the reactive power on the sending line is proposed. [Results]　This method effectively improves the economic benefits of renewable energy power plants while maintaining the voltage stability of the power grid. [Conclusions]　Case studies validate that the method of using phase regulation of pumped storage to compensate reactive power is equivalent to increasing the reactive power capacity on the grid side. The research findings hold both theoretical and practical implications for enhancing renewable energy output and ensuring safe voltage operation of the power grid.

Key words: renewable energy integration, voltage safety, economic benefits, phase regulation operation, dynamic reactive power regulation, reverse reactive power flow, voltage stability, reactive power compensation