摘要
特高压直流系统送端系统属于弱系统时,一旦被迫进入孤岛运行方式,面临无法稳定运行风险。目前推荐的解决策略是闭锁直流系统、切除交流滤波器和切除配套发电机等。各策略执行过程必然存在先后动作时序,不同时序可能产生不同的结果。文章以±800 kV雁淮直流工程为研究对象,考虑湖关Ⅰ线检修时最大输送功率为4300 MW的运行方式,进行电磁暂态仿真分析。结果表明:雁淮直流工程送端进入孤岛方式后,交、直流电压与功率均发生无序波动,频率跌入机组低频保护动作范围。通过分析不同解决策略下各电气量运行情况,得到如下结论:孤岛后若闭锁直流系统早于切除机组,交流系统将产生约2.0 pu过电压;若只切除机组而不闭锁直流系统,则受端电网有2.00 s以上的功率缺额冲击,频率降低0.2 Hz。针对上述策略存在的不足,提出孤岛后极控系统经短延时闭锁直流系统,确保送端发电机组先被切除情况下,受端协控系统能及时启动功率调制措施。
It may be unstable that isolated island operation mode occurs passively in the delivering side of UHVDC system,which belongs to a weak system.At present,the recommended solutions are blocking DC link,cutting off AC filters and cutting off generators.The coordination problem of the above strategies caused by action sequence remains to be studied.±800 kV Yan-Huai UHVDC is taken as the research object.Its max transmission power is 4300 MW when Hu-Guan line I is uncharged.The isolated island operation process is calculated through the electromagnetic transient simulation.It is found that once the isolated island operation mode occurs,the voltage and power will fluctuate disorderly.The frequency falls into the operation range of low-frequency protection.Different time series of solutions action is analyzed.If the strategy of blocking DC link is earlier than cutting off generators,twice of rated voltage will attack the delivering-side power grid immediately.If blocking DC by low-voltage protection after cutting off generators,power shortage impact on the receiving side will continue for 2.00 s and the frequency reduces 0.2 Hz.It is suggested that when receiving the signal of isolated island,control and protection system blocks DC after a certain delay.So generators will be cut off firstly and overvoltage is eliminated significantly.Cooperative control system can execute the command of power modulation in time.
作者
王亮
盖振宇
蒋维勇
史宇欣
孟庆萌
WANG Liang;GAI Zhengyu;JIANG Weiyong;SHI Yuxin;MENG Qingmeng(State Grid Shanxi Electric Power Research Institute,Taiyuan 030001,China;State Grid Economic and Technological Research Institute Co.,Ltd.,Beijing102209,China)
出处
《电力建设》
北大核心
2020年第8期40-47,共8页
Electric Power Construction
关键词
雁淮直流
孤岛
安控系统
过电压
Yan-Huai UHVDC
isolated island
secure and stable control system
overvoltage
