Optimization of LCC-HVDC Control Strategy for Improving Transient Voltage Stability Characteristics of Partial Power Grids

With the implementation of the flexible interconnection project of Guangdong Power Grid Load Center, the AC connection between power grid partitions has become weaker, and the dynamic reactive power support capacity of local power grids fed by large capacity line-commutated converter HVDC (LCC-HVDC) has decreased. Transient voltage instability may be caused by severe AC fault impact in the near area of the inverter station. Based on the transient voltage stability problem in the near area of the Sui-dong converter station, this paper proposes an optimized control strategy for optimizing the voltage dependent current order limiter (VDCOL) parameters and attaching restrictions to the HVDC power rise rate, and an adaptive switching logic based on the AC bus voltage characteristics of the inverter station is designed. The method is adopted to effectively reduce reactive power consumption during the HVDC recovery process, achieving the goal of achieving optimal control effect with the minimum control cost. Finally, based on the simulation of the actual operation mode of the power grid and the HVDC control and protection system, it is verified that the designed scheme can be adopted to significantly improve the transient voltage stability in the near area of the converter station and to reduce the HVDC commutation failure after AC faults. The relevant technical solutions have been put into practical application in multiple HVDC projects. © 2024 Science Press. All rights reserved.