摘要
交直流电力系统中直流系统对交流系统的扰动较为敏感,整流站或逆变站的扰动都可能造成直流功率的传输中断。经研究发现,换流站近端交流线路重合闸投入时序对直流系统的电压、功率、关断角等运行参量有较大影响。在交直流电力系统中探讨其机理,首先采用开关函数法对直流系统进行等值,求解交流线路上任一点发生单相接地故障时一侧重合后的换流母线电压。通过比较合于永久故障时两种重合时序下换流母线电压的大小,得到了影响重合时序的故障距离临界点。进而剖析换流变分别为Y0/Y、Y0/D接线时网侧、阀侧换相电压间的变换关系,分析直流系统在不同控制模式下直流电压、直流功率、关断角等运行变量与换流母线电压间的变化趋势。在此基础上得出结论:换流站近端交流线路故障时,使换流母线电压较高的一侧首先重合,可提高直流电压和输送功率,减少换相失败的发生机率,从而减小重合于永久故障时对直流系统的再次冲击。PSCAD数字实验验证了结论的正确性。
DC systems are sensitive to AC systems＇ disturbances in the AC/DC power systems. The transmission of DC power may be interrupted by the disturbances of rectifier stations or inverter stations. Through researches it was discovered that the reclosure sequence of transmission lines near converter stations has effects on the operation parameters such as voltage, power, and turn-off angle of DC systems. Its mechanism was discussed in an AC/DC power system. Firstly, the DC system was equated using the switch function method, and then the converter bus voltage of AC side was solved after one side of the line reclosed when a single-phase fault occurred on any point of the line. The critical fault distance affecting reelosure sequence was obtained by comparing the converter bus voltages of AC side under two different reclosure sequences. Furthermore, when the communication transformers respectively adopted Y0/Y and Y0/D connections, the relationship between the commutation voltages of network side and valve side was analyzed, and also the relationship between DC voltage, power, turn-off angle and the converter bus voltage of AC side were researched. On this basis, the conclusion was obtained： when a fault occurs on the lines near converter stations, higher DC voltage and power can be maintained and the probability to cause communication failure can be reduced by reclosing to the side of the line having higher converter bus voltage, and thus the impacts brought by reclosing to a permanent fault can be decreased. Theconclusion was verified to be correct by large digital test in the PSCAD.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2012年第7期114-123,199,共10页
Proceedings of the CSEE
基金
国家自然科学基金项目(50977039
50847043
90610024)
云南省自然科学基金项目(2005F0005Z)
云南省教育厅基金重点项目(2010Z105)
Project Supported by National Natural Science Foundation of China(50977039
50847043
90610024)
Yunnan Natural Science Foundation of China(2005F0005Z)
Yunnan Education Bureau Keynote Foundation(2010Z105)
关键词
交直流系统
换流站近端
重合时序
换相失败
AC/DC system
nearby the converter stations
reclosure sequence
commutation failure
