高比例新能源送端系统暂态电压运行风险分析

针对交、直流故障下的高比例新能源送端系统暂态电压演化传播机理及运行风险尚不明晰的问题，首先，基于交直流系统间的无功电压交互作用机理分析，明确了交、直流系统故障下的暂态电压特性及主导影响因素，阐明了高比例新能源送端系统电力电子设备主导的暂态电压演化传播路径。其次，从“交直流故障强耦合作用持续加强，暂态无功功率成分复杂”、“新能源比例不断提升，暂态电压问题凸显”及“故障承载与调节能力下降，连锁脱网风险增大”三方面系统地阐述了暂态电压运行风险。然后，基于DIgSILENT/PowerFactory建立了实际高比例新能源多直流外送系统仿真模型，不同新能源占比、不同故障工况下的仿真结果验证了暂态电压运行风险分析的正确性。最后，从增强耦合运行特性机理认识、提升新能源涉网性能、增加多尺度协同控制策略、加强交流网架结构等方面提出了应对暂态电压运行风险的技术展望。

Transient voltage operational risk of a high-proportion new energy sending system

The transient voltage evolution and propagation and operational risk of a high-proportion new energy sending system in AC/DC faults are unclear. Thus, first, based on an analysis of the reactive voltage interaction mechanism between AC and DC systems, the characteristics and dominant influencing factors of transient voltage in AC and DC faults are identified, and the transient voltage evolution propagation path dominated by power electronic equipment in such a system is clarified. Second, the transient voltage operational risk is systematically considered from three aspects: the strong coupling effect of AC and DC faults continuing to strengthen, and the transient reactive power component is complex; the proportion of new energy continuing to increase, and the transient voltage problem becomes prominent; the tolerance for fault and adjustment ability decreases, and the risk of new energy tripping increases. Then, based on the DIgSILENT/PowerFactory, a simulation model of an actual high-proportion new energy multi-HVDC transmission system is established. The results with different new energy ratios and fault conditions verify the correctness of the transient voltage operational risk analysis. Finally, the technical prospect of coping with the operational risk of transient voltage is examined from the aspects of enhancing the mechanism understanding of coupling operational characteristics, improving the performance of a new energy-related grid, increasing the ability of multi-scale cooperative control strategy, and strengthening the AC grid structure.