用于全直流海上风电系统的单相混合型MMC直流变压器及其控制策略  

Single-phase Hybrid MMC DC Transformer and Its Control Strategy for All-DC Offshore Wind Power System

作　　者：杜舒 赵成勇[1] 冯谟可 汤海雁 DU Shu;ZHAO Chengyong;FENG Moke;TANG Haiyan(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources,North China Electric Power University,Beijing 102206,China;China Huaneng Group Clean Energy Research Institute,Beijing 102209,China)

机构地区：[1]华北电力大学新能源电力系统国家重点实验室,北京102206 [2]中国华能集团清洁能源技术研究院有限公司,北京102209

出　　处：《高电压技术》2023年第1期51-60,共10页High Voltage Engineering

基　　金：华能集团总部科技项目(海上风电与智慧能源系统科技专项(一期))(HNKJ20-H88)。

摘　　要：全直流海上风电场是未来发展大规模远距离海上风电的重要手段之一,然而高变比大容量的直流变压器作为全直流海上风电场中的关键设备,其拓扑结构和控制方式仍有待深入研究。为此,提出了一种单相混合型模块化多电平换流器型直流变压器(single-phase hybrid modular multilevel converter DC transformer,SHMMC-DCT),可以通过最近电平逼近控制实现超高变比的直流升压,并且令子模块电容电压在较低的开关频率下保持均衡。故障处理方面,提出混合子模块与耗能电阻结合的方式清除故障电流,可以代替价格高昂的直流断路器。最后,基于PSCAD/EMTDC搭建了采用SHMMC-DCT的全直流海上风电系统的仿真模型。结果表明,SHMMC-DCT不仅能够可靠高效地送出风电场直流功率,而且可以在高压直流侧短路时快速阻断电流,验证了SHMMC-DCT拓扑及其控制策略的可行性。In the future,all-DC offshore wind farms will be one of the important means to develop large-scale long-distance offshore wind power.However,as DC transformer with high transformation ratio and large capacity is the key device in all-DC offshore wind farms,its topology and control methods still need to be further studied.Therefore,this paper proposes a single-phase hybrid modular multilevel converter DC transformer(SHMMC-DCT),which can realize DC boost with ultra-high transformation ratio and control the capacitor voltage balance of the sub-module at lower switching frequencies by using the nearest level approximation.In terms of fault handling,a combination of hybrid sub-modules and energy-dissipating resistors is proposed to remove the fault current and replace the high-cost DC circuit breaker.At last,the simulation model of the all-DC offshore wind power system using SHMMC-DCT is built based on PSCAD/EMTDC.The results show that the SHMMC-DCT can not only deliver the DC power of the wind farm reliably and efficiently,but also quickly block the circuit current when the high-voltage DC side is short-circuited,which verifies the feasibility of the SHMMC-DCT topology and its control strategy.

关 键 词：海上风电 直流汇集和输送 直流变压器 最近电平逼近控制 故障阻断能力 

分 类 号：TM614[电气工程—电力系统及自动化] TM41