计及发电功率随机性的暂态稳定裕度概率分布计算

Calculation of Transient Stability Margin Distribution Under Random Power Injection Conditions

基于扩展等面积准则(EEAC),将电力系统中发电机驱动功率的概率数字特征,变换成失稳模式对应的两群驱动功率的概率数字特征;并将系统稳定裕度按Taylor级数表示成以两群驱动功率为变量、以稳定裕度灵敏度为系数的线性化表达式,通过半不变量求取稳定裕度的概率数字特征;最后利用Gram-Charlier级数计算出系统暂态稳定裕度的概率分布。其中,对于理想两群失稳模式,仅需解析方法即可完成快速计算;对于非理想两群失稳模式,则采用时域仿真计算灵敏度系数,并用分段函数的方法解决由失稳模式变化导致稳定裕度或灵敏度系数突变的描述问题。最后,用两个算例对所提出的算法进行了仿真验证。

Based on extend equal area criterion （EEAC）, the numerical probabilistic characteristics of the driving power of generators in a power system are first transformed into those of two coherent generator groups corresponding to the instability mode, and then the numerical probabilistic characteristics of the system stability margin are calculated via semi-invariant by using the linearized expression of stability margin, i.e. , a Taylor series with two generator groups＇ driving power as variables and sensitivity parameters of the stability margin as coefficients. Therefore, the probability distribution of the transient stability margin can be calculated using the Gram-Charlier series. For the ideal two-coherent-group instability mode, fast calculation can be achieved just by an analytical method. For the nonideal two-coherent-group instability mode, sensitivity coefficients of the stability margin are calculated by time-domain simulation and a piecewise function based method is used to describe the stability margin distribution in case of sudden changes of the stability margin or sensitivity coefficients due to changes of the instability mode. The effectiveness of the proposed algorithm is verified by two numerical examples.