计及换流站控制特性的多端混合直流线路故障分析与继电保护研究

多端混合高压直流输电技术由于有效地解决了传统高压直流输电系统的换相失败问题，且具有较好的技术经济性，已引起了广泛的关注并得到了具体的工程应用。然而，由于不同原理的多换流站间存在复杂的故障相互作用，而直流线路拓扑结构和边界等值特性也复杂多样，这些都大大增加了多端混合直流线路故障过程及故障特征的复杂性，对其继电保护更是带来了极大的挑战。本项目拟充分考虑多端混合高压直流输电系统各换流站不同的故障控制响应特性及相互间的耦合特性，研究适用于多端混合直流线路的故障分析模型与方法；在此基础上，实现基于多测点的时频关联故障特征分析与提取，进而研究基于时频关联故障特征的多端混合直流线路保护新原理；最后，研究多端混合直流线路的故障性质识别方法以及故障隔离与恢复优化策略。上述研究将突破现有高压直流输电线路故障分析及其继电保护的局限性，为多端混合高压直流线路继电保护技术的发展奠定重要的理论基础。

The multi-terminal hybrid HVDC transmission technology effectively solves the commutation failure problem of traditional HVDC transmission system and has good technological economy, which has attracted extensive attention and has been applied in project applications. However, there are complex fault interactions between multiple converter stations which are based on different commutation principles, and the topology and boundary equivalent characteristics of DC lines are also complex and diverse. These factors greatly increase the complexity of fault process and fault characteristics of transmission lines in multi-terminal hybrid HVDC, and bring great challenges to the protections. This project intends to researches the fault analysis model and method suitable for multi-terminal hybrid HVDC transmission lines, fully considering the fault control response characteristics and mutual coupling characteristics of all the converter stations in multi-terminal hybrid HVDC. On this basis, the time-frequency correlations of fault characteristics are analyzed and extracted based on multiple measurement points, and then the novel protections based on time-frequency characterisitics for multi-terminal hybrid HVDC lines are studied. Finally, the method of fault property discrimination and optimization strategy of fault isolation and recovery for multi terminal Hybrid DC line are studied. The above research will break through the limitations of existing fault analysis method and protections of HVDC transmission line, and lays an important theoretical foundation for the development of protections for multi-terminal hybrid HVDC lines.