电力系统暂态稳定概率评估是确定性评估的有益补充。以安全域概率稳定模型为基础,基于动力系统理论确定电力系统暂态稳定主导不稳定平衡点附近的动态安全域线性边界,并采用以半不变量为基础的埃奇沃斯(Edgeworth)级数展开获得随机变量加权的联合概率分布,从而构建电力系统暂态稳定概率模型。该模型能有效计及发电机的出力和内电势、负荷的有功和无功功率、故障类型、故障位置和故障切除时间等多个不确定性因素,不需要繁琐的公式推导,物理意义清晰,实现简单,计算效率高。经IEEE 10机39节点系统测试和蒙特卡罗(Monte-Carlo)模拟法的验证,表明所提模型和方法是有效可行的,具有广阔的工程应用前景。
Probabilistic assessment of power system transient stability is a useful complement to determinate evaluation.The linear boundary of dynamic security region of the controlling unstable equilibrium point was determined on the basis of dynamical system theory.Then,Edgeworth series expansion based on semi-invariant was employed to calculate the weighted joint probability distribution.Consequently,power system transient stability probabilistic model was established.The model can effectively consider many uncertain factors,such as generator output and internal potential,load active power and reactive power,fault location,fault type,fault-clearing time,et al.The model and its solution do not require complicated formula derivation,and take advantage of clear physical meaning and high calculation efficiency.Finally,the numerical results of IEEE 10-machine 39-bus system demonstrate that the proposed model and its solution are effective and feasible and have broad prospects for engineering application.