摘要
现有混合直流系统中,存在送端交流系统故障时电压严重跌落导致直流系统功率中断的情况。为解决这一问题,提出了一种新型的混合直流输电系统,其整流站采用电网换相换流器(LCC),逆变站采用半桥和全桥子模块混合的混杂式模块化多电平换流器(FHMMC)。重点推导了FHMMC在满足直流故障清除、功率续传要求下其子模块个数的配置要求,给出了混合直流系统的控制特性。并从换流站级和阀级两个层次上,对FHMMC的控制策略进行了研究设计。采用PSCAD/EMTDC,从起动、送端交流故障和直流故障3方面对相应模型进行了仿真研究。结果表明,与现有混合直流系统相比,所提出的系统能够更好地维持交流故障下的功率续传,并具有直流故障自清除能力。
In existing hybrid high-voltage direct-current （HVDC） systems, when a fault on an AC system at sending end causes remarkable drop of AC voltage, the power transfer will be interrupted. In order to solve this problem, we put forward a novel hybrid HVDC system, which adopts line commutated converters （LCCs） in rectifier station, and hybrid modular multilevel converters （FHMMCs） based on half bridge sub-module （HBSM） and full bridge sub-module （FBSM） in inverter station. On the premise of being capable of clearing DC faults and transferring power under AC faults, the configuration of the number of sub-modules is deduced, and the corresponding control characteristic of the hybrid HVDC system is presented. Moreover, we designed the control strategy of FHMMC on both the converter station layer and the valve layer. Using PSCAD/EMTDC models, we studied three cases such as start-up, AC system fault at the sending end, and DC fault. The simulation results indicate that, compared with the existing hybrid HVDC systems, the proposed one is more favorable for clearing DC faults while being able to transfer more power under AC system faults.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2014年第8期2520-2530,共11页
High Voltage Engineering
基金
国家高技术研究发展计划(863计划)(2012AA050205)~~
关键词
混合直流
电网换相换流器
混杂式模块化多电平换流器
子模块数配置
功率续传
直流故障清除
hybrid high voltage direct current
line commutated converter
hybrid modular multilevel converter
configuration of sub-module number
power continuity
dc fault clearing
