A decentralized coordinated optimization method for secondary voltage control in large urban power grids

In large hub city power grids, load centers often lack flexible and continuously adjustable reactive power sources across multiple voltage levels, leading to a “hollowing-out” of power supply. This paper proposes a coordinated two-level voltage control optimization method tailored for such “hollowed-out” power grids. In this method, the high-voltage busbar of all controllable power plants within a region are generalized as voltage-dominant nodes, and regional voltage regulation is achieved by minimizing the sum of squared deviations between the busbar voltages and their reference values. Meanwhile, the coordination relationships among upper-level and lower-level regions are explicitly distinguished, and threshold-based control objectives between hierarchical regions are introduced to improve the reactive power support capability of lower-level areas. The effectiveness of the proposed method for regional reactive voltage control in hollowed-out power networks is verified through simulations using a standard test system combined with actual grid data from China.