适用于海上风电场直流互联的双极性输出非隔离型自耦直流变换器  

Directly-coupled Non-isolated Bipolar Output DC Converter Suitable for Offshore DC Wind Farm

作　　者：郭灵瑜 姚钢[1] 殷志柱[2] 周荔丹[1] GUO Lingyu;YAO Gang;YIN Zhizhu;ZHOU Lidan(Key Laboratory of Control of Power Transmission and Conversion(Shanghai Jiao Tong University),Minhang District,Shanghai 200240,China;Central Research Academy of Shanghai Electric Group,Jing’an District,Shanghai 200070,China)

机构地区：[1]电力传输与功率变换控制教育部重点实验室(上海交通大学),上海市闵行区200240 [2]上海电气集团中央研究院,上海市静安区200070

出　　处：《电网技术》2020年第1期174-182,共9页Power System Technology

基　　金：国家自然科学基金项目(61374155);上海市自然科学基金项目(18ZR1418400)~~

摘　　要：多端直流输电与直流电网是解决新能源并网的一项重基金项目:国家自然科学基金项目(61374155);上海市自然科学基金项目(18ZR1418400)。Project Supported by National Natural Science Foundation of China(61374155);The Nature Science Foundation of Shanghai(18ZR1418400).要技术手段,不同直流电压等级间互联离不开各种类型的直流变换器。针对近海、远海全直流海上风电场,新能源直流源内部复杂性致使难以直接实现对称双极性直流输出;此外,海上换流站建设成本高,传统的非隔离型直流变换器含有较大的工频变压器,占地面积大。为了满足单极直流传输线与双极直流传输线间的互联,同时考虑到变换器的体积与成本,提出了一种不含隔离变压器双极性输出的直流变换器拓扑,并提出了与之相配合的调制与控制方法。该直流变换器拓扑与其他双极性输出直流变换器相比,不需要使用工频变压器,体积、成本降低;没有交直流变换过程,效率较高;开关频率低,损耗小;子模块可增减,有较好的冗余度与容错性。基于Matlab/Simulink对提出的拓扑进行仿真验证,通过搭建实验平台,验证了拓扑及控制方式的可行性。Multi-terminal HVDC and DC grids are important in resolving the problem of renewable energy integration,and DC converter is the key equipment for connecting transmission lines of different voltages in DC grids.Especially,for offshore DC wind farm,complexity of renewable energy DC source makes it difficult to realize bipolar DC output directly.Moreover,traditional non-isolated DC converter contains large power transformer not suitable for offshore station.In order to interconnect unipolar DC system with bipolar DC transmission line,this paper proposed a new directly-coupled DC converter with bipolar output based on cascaded submodules.Its modulation and control strategies are also presented.Compared with other bipolar output DC converters,the new directly-coupled DC converter offers several merits:1)its volume and cost are reduced because it eliminates isolation transformer;2)it doesn’t have AC-DC conversion process,so it can achieve high efficiency;3)its switching frequency is reduced,so the power loss is reduced;4)the number of submodules can be changed to realize redundancy and fault tolerance.Finally,simulation of the proposed DC converter on Matlab/Simulink platform and experiment are performed to verify feasibility of the topology and theoretical analysis.

关 键 词：双极性输出 非隔离型 直流变换器 模块化多电平变换器 全直流海上风电 

分 类 号：TM721[电气工程—电力系统及自动化]