受端系统过电压对两种不同直流输电方式传输能力的影响研究

Impacts of Receiver System Overvoltage on Transmission Capability of HVDC and MMC-HVDC

在PSCAD/EMTDC环境下,基于直流输电CIGRE标准模型和21电平模块化多电平换流器高压直流输电(MMC-HVDC)模型,研究了当逆变侧交流系统换流母线遭遇由计划性合闸空载线路和自动重合闸而引起的操作过电压时对直流系统传输能力的影响。重点分析了不同程度的过电压持续时间和过电压倍数对传输功率下降幅度及恢复速度的影响。推导了传统直流方式中因交流系统侧过电压造成换相失败过程中关断角在不同阶段变化的计算公式。

In the PSCAD/EMTDC environment,based on the CIGRE DC transmission standard model and 21-level modular multilevel converter HVDC（MMC-HVDC） model,this paper analyzes the impacts on DC system transmission capability made by inverter side AC system overvoltage,which emerges when the converter bus encounters the planned closing no-load circuit lines and automatic reclosing in operation.The analysis particularly focuses on the influence of various overvoltage duration time and overvoltage multiples on the decrease extent and recovery rate of transmission power.Finally,the calculation formula of the turn-off angle is derived in the course of HVDC commutation failure caused by AC system side overvoltage.