广州换流站交流滤波器投切对天广直流换相失败的影响

Influence of AC Filter Switching at Guangzhou Converter Station on Commutation Failure of Tianshengqiao-Guangzhou HVDC Project

采用RTDS仿真工具对500 kV天广直流2012年"10·04"换相失败事件进行仿真分析,并就交流滤波器投切对直流系统暂态特性和换相失败的影响进行详细仿真分析,得出主要结论如下:天广直流"10·04"换相失败事件是由小组交流滤波器在交流电压过零点后延迟90°合闸引起交流电压畸变所致;广州换流站有效短路比小,若交流滤波器投入延迟角度过大,交流电压将发生畸变并引起换相失败,但由于电压畸变持续时间很短,不会引起连续换相失败,也不会引起直流闭锁;直流功率越大,交流滤波器投切不当引起的直流电压跌落越严重,直流电流升高越明显,换流变阀侧电流降低越严重,直流系统越容易发生换相失败现象;减小交流滤波器开关机构动作的离散性,确保交流滤波器在理想相位合闸,能有效防止因交流滤波器大角度合闸引起的换相失败。

＂10 · 04＂ commutation failure of 500 kV Tianshengqiao-Guangzhou HVDC is simulated and analyzed with RTDS tool, andthe influence of AC filter switching operation on the transient process and commutation failure of Tianshengqiao-Guangzhou HVDC aresystemically studied. The main conclusions are as follows： ＂10 · 04＂ commutation failure of Tianshengqiao-Guangzhou HVDC iscaused by the 90° delayed closing of the AC filter after AC current crosses zero point, which leads to AC voltage distortion ; the effec-tive short - circuit - ratio of Guangzhou converter station is small, if AC filter input delay angle is too large, AC voltage will be dis-totted and result in commutation failure, but due to the short voltage distortion duration, this will not cause continuous commutationfailure or DC block; in case of serious AC bus voltage distortion caused by improper AC filter switching operation, with the increase ofDC power, the more DC voltage drops, the more significantly DC current increases, the more converter transformer side current re-duces, the more easily commutation failure occurs in DC system; reducing the dispersing of AC Filter switching operation and ensuringan ideal angle can effectively prevent commutation failure caused by AC filter large angle closing.