摘要
随着直流输电技术的迅速发展,未来我国新建的直流输电线路将越来越多以分层接入方式馈入受端交流电网。由于多馈入短路比仅考虑交流受端系统中不同直流落点间的相互作用,无法考虑由于直流侧阀串联后,与受端交流系统间的相互作用。因此亟待提出适用于直流分层接入的交直流系统的短路比定义。通过理论分析推导分层直流短路比。通过提出的分层接入的交直流系统的解耦模型推导分层直流临界短路比的函数表达式,证明分层直流临界短路比与电压灵敏因子的等价关系,提出判断直流分层接入的交直流系统强弱的指标。最后采用电力系统分析软件PSD-BPA对即将投运的分层直流系统进行仿真验证,证明分层短路比能够表征分层直流系统的电压稳定性,当分层直流短路比在临界短路比附近,电压失稳风险较高。该指标对完善短路比理论和应用体系,指导我国电力系统规划、运行具有重大意义。
DC transmission technology has developed rapidly in China. According to the plan, the new DC will mostly be hierarchical access to the receiving-end AC system in the future. Multi-infeed short circuit ratio is used to evaluate the interaction between AC and DC systems. However, it can only take the interaction between different DC drop points into account. The influence of AC/DC interaction due to the series connection of the DC side valve series can’t be considered. Therefore, it is urgent to propose the definition and index of short circuit ratio of AC/DC system under DC hierarchical connection mode. Through theory analysis, hierarchical connection short circuit ratio（HSCR） was proposed. Based on it, a decoupled model of HCDC was proposed and hierarchical connection critical SCR（HCSCR） was derived, and then the criteria of weak HCDC system were presented. The relationship between HCSCR and nodal voltage sensibility factor（NVSF） was discussed. Finally, the actual hierarchical DC system was verified by PSD-BPA, which proves that the hierarchical connection short circuit ratio and the index can characterize the voltage stability of the hierarchical AC/DC system. When HSCR equals to HCSCR, the voltage instability may be occur. This index is of great significance to perfect the theory and application system of short circuit ratio and guide the planning and operation of China’s electric power system.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2017年第22期6627-6635,共9页
Proceedings of the CSEE
关键词
分层直流
短路比
电压稳定
交流系统强弱
hierarchical connection direct current
short circuit ratio
voltage stability
the strength of AC system
