具有直流故障阻断能力的柔性直流输电换流站拓扑研究

Because of the lack of mature topology which can cleaning DC fault, led to the current existing VSC-HVDC projects must use the cable transmission lines which is low failure rate but expensive. In order to solve this problem,this topic mainly studies novel topologies which have DC fault current blocking capability, and research its operating characteristic, modeling and analysis methods and control strategy. Project intends to begin from the classification of the fault current blocking way,combining with the handling requirements of the fault residual energy conversion.Divided into three categories to study the structure of the topology and its modeling and analysis methods and its control strategy.On this basis of the theories above all,through expansion and transformation of the experimental platform to develop experimental verification. The application team’s preliminary studies show that three kinds of topologies structure are feasible. The research offers such deep insight into the current block and the residual energy conversion of the novel topology as well as the influence of the dissipation mechanism,mainly focuses on the key scientific problems such as the internal energy fluctuation mechanism of the converter station when transient DC fault ride-through.Expected to carried out novel topologies which are suitable for overhead lines,and proposed the transient and steady-state control strategy is suitable for the new topologies. The results can not only enrich and perfect intelligent transmission and distribution power system,but also through the study of the novel topology mentioned above, the theoretical guidance will be offered for the engineering practical application of the VSC-HVDC suitable for overhead lines.

由于缺乏成熟的直流侧故障处理方案，导致目前已有柔性直流输电工程均采用故障率低但成本昂贵的电缆型输电线。针对这一问题，本课题主要研究具有直流故障电流阻断能力的柔性直流输电换流站新型拓扑结构及其运行特性、建模仿真方法和调控方法。本课题拟以直流故障电流阻断方式的分类为基础，结合对于故障时电路残余能量的处理要求，分别研究三类拓扑结构族，并通过已有实验平台的扩充和改造来进行实验验证。申请人已有初步研究结果表明三类拓扑结构族均具有可行性。课题重点解决新型拓扑结构对于电流阻断和残余能量吸收耗散的影响机理、直流侧故障穿越时换流站内部能量波动机理两个关键科学问题，预期提出适用于架空线路的新型拓扑结构族及其暂稳态调控策略，丰富和完善智能输配电理论体系，为适用于架空线路场合的柔性直流输电技术的工程实用化提供理论参考。

柔性直流输电是以电压源型换流站为基础的新型直流输电技术，是输配电技术领域的一项重大突破，但目前已投运的柔性直流输电工程由于换流站通常采用基于半桥子模块的模块化多电平拓扑，不具备直流侧故障阻断能力，因此无法应用于短路故障多发的架空线输电场景中。.针对这一问题，本项目从换流站拓扑、换流站运行特性分析、换流站控制策略三个方面展开研究，旨在提出具备直流故障阻断能力且具备最优经济性的换流站拓扑与控制方案。.在具备直流故障电流阻断能力的换流站新型拓扑结构研究方面，提出了三种换流站设计方法。针对子模块阻断设计方法，提出了一种新型的子模块电路拓扑，针对桥臂阻断设计方法，提出了一种新型桥臂阻断拓扑；针对出口电压阻断设计方法，提出了多种基于加装直流断路器或嵌入子模块的拓扑方案。.在基于新型换流站拓扑结构的柔性直流输电系统建模分析及运行特性研究方面，建立了桥臂阻断型换流站的数学模型、建立了出口直流断路器阻断型方案的数学模型；对比了多种子模块阻断型、桥臂阻断型、出口模块阻断型方案的运行特性，构建了基于多评价因子的换流站统一评估模型。.在新型换流站拓扑调控策略研究方面，提出适用于全桥子模块级联结构的能量均衡控制策略，提出桥臂阻断型拓扑方案的模型预测控制策略；提出适用于出口阻断型方法的双向直流断路器的控制方案，并针对直流电网应用，提出一种直流潮流控制方法。.项目总计发表论文9篇，其中SCI检索论文3篇，EI检索论文6篇；获得省部级科技进步奖两项；受理发明专利3项。在人才培养方面，培养博士2名，硕士2人。总体来看，项目圆满完成所有研究目标，并达到预期研究成果。