Study on Reactive Power Response Characteristics of Grid-Forming Renewable Energy Systems with Virtual Internal Potential

The wind energy resources and load distribution in China are inversely correlated. To meet the demand for long-distance power transmission from large-scale clean energy bases in desert areas, ultra-high voltage (UHV) transmission lines have become a strategic choice for the development of China's power grid. However, the lack of conventional synchronous power support in the AC sending-end system poses challenges when Commutation Failures or DC Blocking occur at the DC receiving-end, leading to transient overvoltage issues. These problems can result in large-scale disconnection of wind turbines, thereby limiting the ability of the sending-end grid to integrate renewable energy. Suppressing transient overvoltage in the sending-end grid imposes higher requirements on the reactive power support response speed of renewable energy sources. Therefore, this paper investigates the reactive power response characteristics of grid-forming renewable energy systems. It analyzes the influence of various factors such as different control coefficients, voltage measurement delays, and current loop control parameters on the reactive power response characteristics of grid-forming converters. This research provides theoretical support for the design of control strategies, parameter tuning, and capacity configuration of grid-forming renewable energy systems.