Study on Suppression of Transient Overvoltage at DC Sending End by MGP

With the increasing penetration of renewable energy power sending through HVDC, the transient overvoltage problem is threatening the sending end. Motor-Generator Pair is capable of leading phase operation, which can effectively restrain overvoltage. In this paper, based on the grid-connected structure of the MGP, the transient and sub-transient characteristics of MGP are analyzed, it is pointed out that the power angle and excitation regulation of the generator are the key factors to improving its dynamic reactive power compensation capability. Then, based on the fast response of the converter, a fast active power reduction and additional excitation control strategy are proposed, which takes the blocking signal and AC voltage of the converter station at the sending end as input signals, aiming at increasing the depth of MGP leading phase. Finally, based on PSCAD/EMTDC software, the simulation model of multiple new energy stations connected to grid through DC transmission is built, and the effectiveness of the coordinated control strategy is verified. The results show that the proposed strategy can enhance the transient overvoltage suppression capability of MGP at sending end.