By use of mathematical meaning of Lagrange multiplies for equality and inequality constraints in linear programming based optimal load shedding model, the sensitivity of EDNS to component capacity is deduced. 利用基于线性规划的最优负荷削减模型中等式和不等式约束的拉格朗日乘子的数学含义,导出了电力不足期望对元件容量的灵敏度。