摘要
为解决MMC-HVDC直流电压控制站侧交流系统故障时直流电压失控的问题,通过加入低压限流单元对MMC的有功功率控制器进行了改进。改进后的控制器可根据直流电压的变化和预先设计的电流限幅曲线,自动调节有功功率控制站的内环有功电流指令值,以保证直流电压控制站侧交流系统故障时直流电压的稳定。仿真结果显示,在使用低压限流单元后,直流电压控制站侧交流系统故障时,直流电压上升或下降的幅度均在5%以内,直流系统可以保持连续运行,不会因直流电压异常而闭锁。证明所设计的低压限流单元可以在直流电压控制站交流侧故障情况下,保持MMC-HVDC系统直流电压的稳定,保证换流器不闭锁,并在故障清除后迅速恢复原有的有功功率,有效增强系统的故障穿越能力。
In MMC（modular multilevel converter）-HVDC systems, DC voltage may become unstable when there is fault at the AC side of DC voltage control（DCVC） converters. To enhance the low-voltage ride-through（LVRT） capability of MMC-HVDC systems, we propose to improve active power control stations by installing DC voltage dependent current order limiter（VDCOL）. VDCOL changes the active current reference according to the DC link voltage and keeps the active power to be balanced in DC system. Communications between converter stations are not necessary under the fault conditions. Simulation results based on PSCAD/EMTDC demonstrate that the DC voltage is limited to fluctuate within 5% higher or lower than its nominal value when an AC fault is applied on DCVC converter side. It is concluded that, in a DCVC converter station, by using the proposed VDCOL, DC voltage can be stabilized when AC voltage drops due to AC faults.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2014年第5期1574-1581,共8页
High Voltage Engineering
基金
国家高技术研究发展计划(863计划)(2012AA050205)~~
关键词
模块化多电平换流器
交流系统故障
直流电压控制
低压限流单元
直流过电压
故障穿越
modular multilevel converter
AC fault
DC voltage control
voltage dependent current order limiter（VDCOL）
dc overvoltage
fault ride through
