MMC-UPFC Power Distribution Method for Power Loss Reduction

With the continuous construction of energy internet, in order to realize the accurate regulation of grid voltage and power flow among different district power grids, modular multilevel converter (MMC) based unified power flow controllers (UPFCs) are adopted in the urban power grid, such as Nanjing 220 kV Tiebei station UPFC project and Suzhou Sunan 500 kV UPFC project. However, the reactive power operation range and how the reactive power distribution between the parallel side MMC and series side MMC of UPFC influences the operation power loss is not clear. Therefore, the power operation range of MMC-UPFC is analyzed in detail in this paper. And then, a simplified power loss mathematical model of MMC-UPFC is proposed. Based on the mathematical model, a power distribution method is proposed. With the proposed method, the MMC-UPFC can achieve minimum power loss operation. Finally, the proposed method is studied on PSCAD/EMTDC software and Nanjing 220 kV Tiebei station UPFC project. Both the simulation and experiment results verify the correctness and effectiveness of the proposed method.