区域互联多回直流换相失败对送端系统的影响

Affects of Commutation Failure in Multi-Circuit HVDC Transmission System Interconnecting Regional Power Grids on AC Power System at Sending End

为增强直流互联大系统运行特性认识水平,针对区域电网间多回互联直流同时换相失败展开研究。分析其成因;摸索其发生后送端系统频率、电压的变化特性;剖析其对送端系统的影响范围和程度。研究结论是:虽然区域互联多回直流换相失败往往不可避免,但是直流功率由于换相失败和控制系统的作用突变时,送端近区机组出力在各种因素的作用下紧跟着变化,送端近区显现出功率相对平衡的暂态特性。多回直流同时换相失败对送端系统的影响仅局限在近区较小范围内,不会影响大系统稳定运行。

To deepen the comprehension on operating characteristics of large-scale interconnected HVDC transmission system, the commutation failure simultaneously occurred in multi-circuit HVDC transmission system interconnecting regional power grids is researched. The cause of the failure is analyzed; the Variation characteristics of frequency and voltage in sending system after the occurrence of the failure is explored and the affecting range and extent of the fault on sending end system are dissected. The conclusions of this research are as following： it is hard to avoid the commutation failure occurred in multi-circuit HVDC transmission system interconnecting regional power grids, however when the sudden change of DC power due to commutation failure or fault in control system occurs, the output of units closed to the AC sending end varies under the action of various factors and it makes the area closed to the AC sending end presenting the transient characteristic with relative power balance. Thus the affection of commutation failure in multi-circuit HVDC transmission system on AC sending system is only limited within a smaller area and the steady operation of the whole interconnected grid will not be affected.