考虑负荷变化特性的电压稳定判据分析

Analysis of Voltage Stability Criterion Considering Load Characteristics

在采用戴维南等值参数跟踪方法分析需要考虑非线性和动态元件影响的暂态电压稳定性时,通常以负荷节点的等效阻抗与该节点的网络戴维南等值阻抗相等作为暂态电压稳定的临界条件。通过电力潮流方程推演该电压稳定判据,并从理论上分析该判据在负荷以恒功率因素变化以及其他变化特性下判断系统暂态电压稳定性的适用性。明确当负荷不满足恒定功率因数变化特性时,将该电压稳定判据作为暂态电压稳定的临界条件是无效的。提出通过拉格朗日因子法,构造修正目标函数求取不同负荷特性下暂态电压稳定临界点的计算方法。最后通过2个仿真算例证明该文结论。

When using the method of Thevenin equivalent tracing to analyze transient voltage stability, which need to consider, the effects of nonlinear and dynamic components, the criterion that load equivalent impedance equaling to Thevenin equivalent impedance is usually used to be transient voltage stability critical condition. Based on power flow equations, the paper deduced the criterion, and analyzed the applicability under the constant power factor and other different load characteristics. The results show the criterion is ineffective when the load changes under other characteristics except for constant power factor. The calculation method of voltage stability critical point by constructing correction objective function based on Lagrangian factor was proposed. Finally, two simulation examples proved the conclusions.