混合直流输电系统送端交流暂态电压特性研究

Research on sending end AC transient voltage characteristics of hybrid HVDC transmission system

对于大规模新能源特高压直流外送系统,受端电网故障可能导致送端电网电压剧烈变化,严重威胁送端电网的安全稳定运行,因此送端电网暂态电压是直流输电系统适应性的重要考虑因素。混合直流输电结合了常规直流和柔性直流的优势。针对大规模新能源混合直流外送应用场景,首先介绍了两端混合直流输电系统典型拓扑,建立了相应数学模型,阐述了基本控制结构。然后分析了当受端交流电网发生短路故障,采用不同直流输电拓扑方案时送端电网的交流暂态电压特性。最后在 PSCAD/EMTDC 搭建了不同混合直流输电系统仿真模型,验证了上述分析的有效性。

For large-scale renewable energy UHVDC transmission system, fault happens on the receiving end may cause drastically change on the sending end power grid, which seriously threatens the stability of the sending end power grid. Therefore, voltage characteristic of the sending end is an important consideration for the adaptability of the HVDC transmission system. Hybrid HVDC combines the advantage of LCC-HVDC and VSC-HVDC. In view of the application scenario of large-scale renewable energy transmission through hybrid HVDC, this paper first introduces the typical topologies of two-terminal HVDC transmission system. The corresponding mathematical model is established and the basic control structure is also expounded. Then the AC voltage characteristics of the sending end power grid when short-circuit fault occurs in the receiving end under different hybrid HVDC topologies are analyzed. Finally, the simulation model of different hybrid HVDC topologies is established in the PSCAD/EMTDC simulation platform, and the effectiveness of the above analysis is verified.