多端柔性直流输电系统启动控制及其仿真

Control and simulation of VSC-MTDC start-up procedure

启动控制是多端柔性直流输电(VSC-MTDC)系统中重要的附加控制。合适的启动控制策略可以减小VSC-MTDC启动时产生的过电压和过电流,缓解其对交流电网和各个元器件的冲击,防止设备损坏。为此,首先分析了VSC-MTDC系统过电压过电流的形成原因,针对不同的启动阶段设计了适合于VSC-MTDC系统的启动控制策略,最后在PSCAD/EMTDC环境下建立了VSC-MTDC系统的模型,验证了设计的启动控制策略。仿真结果表明,该控制策略可以有效地抑制启动过程中的过电压和过电流,保证系统平稳地过渡到额定运行状态。

Start-up control is an important additional control in the system of multi-terminal HVDC based on voltage source converter （VSC-MTDC）. Appropriate startup control can reduce the impact of over-voltages and over-currents on the AC grid, and avoid the damage to equipment. To this end, the analysis of the over-voltage and over-current causes has been done; and then a start-up control strategy which is suitable for the VSC-MTDC system has been designed; at last a VSC-MTDC system model has been built in the software PSCAD / EMTDC to verify the effectiveness of the procedure. Simulation results show that the control strategy can effectively restrict the over-voltage and over-current in the start-up process, which ensures the system＇s smooth transition to its rated state.