互联系统交流联络线随机功率波动分析(一)频域特征与原因初探

Analysis on Stochastic Power Fluctuations of AC Tie-lines Between Interconnected Power Systems Part One Frequency Domain Features and Their Cause

控制区域间交流联络线功率存在自然波动以及因各种扰动引起的波动,波动幅值过大时,可能引起系统稳定及电压问题,影响互联电网的安全稳定运行。文中基于某大区互联系统交流联络线功率波动的实际数据,利用频域分析和自相关分析方法对联络线功率波动进行全面分析,发现功率波动中周期在110s左右的分量比较突出这一特点。产生该现象的原因是电网区域控制偏差(ACE)的实时调整,即ACE实时调整环节虽能显著抑制ACE中的低频慢速分量,但对周期在110s左右的分量有放大作用,但综合来看ACE实时调整对抑制联络线功率波动是有利的。最后,通过在某大区实际开展的试验进行了验证,退出ACE实时调整后周期在110s左右的分量显著减小,而低频分量增大。该研究为深入分析大区互联系统交流联络线随机功率波动机理和控制措施改进提供了依据。

There do exist natural power fluctuations and the fluctuations caused by various disturbances on the alternating current （AC） tie-lines among control areas. But large-magnitude power fluctuations on the tie-lines may threaten the security of the system. Based on the practical data of power fluctuations on a tie line between two large power systems, the frequency domain analysis method and the autocorrelation analysis method are used to analyze stochastic power fluctuations of tie-lines. It is found that the component with the period about 110 s is prominent in the fluctuations. This is caused by the real time area control error （ACE） regulation of the power system, i.e. the real-time ACE regulation can reduce the magnitude of the low frequency slow component in the area control error, but it may amplify the area control error with the period around 110 s. The reason is verified with an experiment in practical systems. When the real-time ACE regulation stops, the component with the period about 110 s is significantly reduced while the low-frequency component increases. The study provides basis for analysis of tie-line power fluctuation mechanism and the improvement of tie-line control.