电力系统电压稳定鞍结分岔点的快速求取方法

Fast Calculation Method for Saddle Node Bifurcation Point of Voltage Stability of Power System

为快速求取电力系统电压稳定鞍结分岔点,提出一种自动变步长的连续潮流法和局部曲线拟合法相结合的方法。运用广义戴维南动态等值原理,证明非线性电力网络传输功率达到极值必要条件,定义阻抗模裕度指标,判定系统静态电压稳定性最薄弱节点。由当前运行点阻抗模预测下一运行点潮流状态,得到增长步长,实现自动变步长,快速逼近而不越过鞍结分岔点。当阻抗模裕度值达到满足局部曲线拟合要求的设定值时,满足阻抗模裕度判据,对鞍结分岔点精确拟合,得到较准确的鞍结分岔点值。多个IEEE测试系统的仿真表明,该算法简单、精度高、速度快、计算次数少,且适用于规模较大的电力网络。

In order to fast calculate the saddle node bifurcation point of voltage stability of power system,a combinationmethod with automatic variable step is proposed based on continuation power flow method and local curve fitting meth-od. By using generalized Thevenin dynamic equivalence theory,the essential conditions for reaching the extreme valuesof transmission power in a nonlinear power network are proved. Moreover,impedance modulus margin index is definedto determine the weakest node of static voltage stability of the system. An increasing step length is obtained according tothe power flow state at the next operation point predicted by the impedance modulus at the current operation point,thusan automatic variable step is realized,and the saddle node bifurcation point is approached fast but not crossed over.When the impedance modulus margin satisfies the value required by local curve fitting,i.e.,impedance modulus mar-gin criterion,the saddle node bifurcation point will be accurately fitted and a more accurate value will be obtained.Simulations of several IEEE test systems show that the proposed method is simple,accurate,fast and with less computa-tional load,thus it can be applied to large-scale power networks.