环境激励与小幅持续周期扰动表现特征及统计学分析

系统中时刻存在新能源有功输出随机波动、负荷投切等环境激励,使得系统响应表现为类似噪声的小幅波动,当周期扰动幅值较小时,很容易淹没于环境激励下的随机响应信号中。本文详细推导环境激励和小幅周期扰动共同作用下系统响应的数学解析表达式,从数学角度对环境激励与小幅周期扰动共同作用的功率表征进行了阐释。在深入分析环境激励及环境激励与小幅周期扰动共同作用下系统响应统计学特征的基础上,提出基于滑动峰态系数法(SKM)的小幅周期扰动检测法。首先统计环境激励下系统联络线有功响应的四阶中心矩与方差二次方,计算得到对应的峰态系数,进而通过对所得峰态系数的量化比较,检测出淹没在环境噪声中的小幅周期扰动。IEEE 4机2区域系统、IEEE 16机68节点系统及实际系统量测数据计算分析结果证明了本文方法的可行性及有效性。

The Statistical Characteristics of Response Undergoing Slight Sustained Periodic Disturbance and Ambient Excitation

The system response is similar to the small fluctuations in noise because of ambient excitations, such as random fluctuations of renewable energy outputs and the switching of loads. If the magnitude of periodic perturbation is small, it might be submerged in the random responses undergoing ambient excitations. This paper derives the mathematical expressions of the dynamic responses undergoing slight sustained periodic disturbance and ambient excitation. And then the related mechanism of active power characterization was explained from a mathematical point-of-view. Based on sliding Kurtosis method (SKM), a method for slight sustained periodic disturbance detection was proposed according to the statistical characteristics of dynamic response undergoing slight sustained periodic disturbance and ambient excitation. Firstly, the fourth moment and the variance of the active power of tie line were analyzed, and then the corresponding Kurtosis was calculated. Finally, the slight sustained periodic disturbance can be detected by quantitative comparisons of the kurtosis results. Simulations in 4-machine 2-area system and 16-machine 68-bus system have verified the proposed method.