Research on the Sequence of Converting Conventional Generating Units to Flexible Excitation Systems to Enhance Grid Voltage Stability

Large-scale AC and DC feed-in leads to a reduction in the number of local generators started up in the receiving end grid. The decrease in dynamic reactive power sources, primarily synchronous generators, will result in reduced voltage support capability and power angle stability. The control advantage of flexible excitation technology lies in achieving decoupling control between the excitation system's ceiling voltage and AC input voltage, significantly enhancing the system's transient voltage and power angle stability support capability without increasing the number of generators started up. However, applying flexible excitation systems to all units in the receiving end grid poses dual issues of scheduling flexibility and operational economy. Therefore, it is crucial to determine the priority order of key generators. This paper studies the retrofitting sequence of conventional units by integrating factors such as the timing of generator instability and electrical distance from the fault point, and conducts simulation verification based on actual power grids.