基于线路电压稳定指标的连续潮流计算方法

Calculation Method for Continuation Power Flow Based on Line Voltage Stability Index

为获得准确的系统稳定裕度,提出一种以线路无功损耗为参数化方程的连续潮流改进算法。该方法利用线路电压稳定性指标来确定待参数化的线路,利用拓展潮流方程预测方向向量的角度变化,对连续潮流的计算阶段进行判断,并针对不同的计算阶段,自适应地选取步长控制策略。算例表明,本文所提方法物理概念清晰,计算速度快,实现参数化线路与系统稳定状态的对应更新,能体现电压失稳的局部特性,反映系统的弱节点和弱区域,能较完整地计算得到PV曲线,在对大规模电网进行电压稳定裕度分析时具有一定优势。

To obtain the accurate value of system stability margin,an improved continuation power flow(CPF)method is proposed by adopting line reactive power loss as a parameterized equation.With this method,line voltage stability index is used to determine the lines to be parameterized,and the calculation stages of CPF are judged by the angle changes of direction vectors predicted by the extended power flow equation;moreover,an adaptive step length control strategy is selected according to different calculation stages.The result of a numerical example indicates that the proposed method has a clear physical concept and a fast computing speed,and it realizes a one-to-one update of parameterized lines with respect to the system’s stable states;in addition,it considers the local characteristics of voltage instability,which can reflect the weak nodes and weak areas in the power system.As a result,the relatively complete photovoltaic(PV)curves can be obtained through calculations,showing certain advantages when analyzing the voltage stability margin for a large-scale power grid.