增补P′Q节点直接计算电压崩溃点的潮流方法

A Direct Calculation Method of Voltage Collapse Points by Supplement of a New Type of P’Q Bus

为实现静态电压稳定边界的快速准确计算,提出一种直接求取电压崩溃点的算法。该算法在负荷节点上以小阻抗增补一个P’Q节点,增补节点的功率极限相当于负荷节点的电压稳定裕度。P’Q节点定义为已知节点有功功率对电压幅值的全导数P’及无功功率Q的节点。由此,可利用崩溃点处有功功率对电压幅值全导数为零的特点形成方程对该点进行直接求解。方法避免了连续潮流（continuous power flow,CPF）的多次潮流计算,在崩溃点附近具有二阶收敛特性。其系数矩阵的求取可复用已得到的雅可比矩阵因子表,能够有效地降低计算量。通过对简单系统进行对比分析证明了算法的有效性,最后给出了算法在IEEE118节点系统中的应用示例。

In order to calculate the steady-state voltage margin rapidly and precisely, a new algorithm is presented to directly obtain the voltage collapse point. In the method, a P＇Q bus is connected to one load bus with small impedance. The power limit of the new bus is equivalent to the voltage stability margin of the load bus. P＇Q bus takes the total derivative of its active power with respect to the amplitude of voltage and its reactive power as given quantity. Therefore, the voltage collapse point can be calculated directly by using the characteristic of the point where the total derivative equals zero. Comparing with the continuous power flow（CPF）,the proposed method avoids multiple power flow calculations and has second-order convergence approaching the collapse point. The formation of the coefficient matrix reuses the calculated factorial table of Jacobian matrix. Thus, the computational cost is reduced. The effectiveness of the method was verified by a simple system and an instance in IEEE 118 bus system was given.