Review on the Design of Flexible DC System to Improve the Operation Performance of 220kV Subdivision Power Grid

The role of 220kV power grid as the main grid in most cities in China is gradually changing. In addition to taking on some of the transmission functions, it is also gradually taking on the power distribution and power supply functions. As the load continues to grow, its operational complexity increases. The power supply capacity and power supply stability of 220kV subdivision power grid have important influence on urban development. The existing 220kV partitioned power grid has the risks of unbalanced power supply capacity, insufficient mutual supply capacity and low reliability. This paper studies the interconnection problem of applying flexible DC to 220kV partitioned power grid. According to the actual situation of the power grid, the paper studies the improvement of the operation performance of the subdivision power grid with different input positions of flexible DC converter stations. Firstly, the mathematical model of the power supply capacity is established. Next, according to the model, the feeder and receiver are determined, and the capacity of the flexible DC system is determined. In addition, the selection method of flexible DC landing point is put forward considering different factors. Finally, it is verified on PSD-BP A. Through calculation, it is found that many indicators are greatly improved with good effects.