负荷模型不确定性对多机系统小扰动稳定的影响分析

Analysis of Effects of Load Model Uncertainty on Small Signal Stability of Multi-machine System

由于负荷模型是大量实际负荷元件的聚合,具有不确定性,因此研究负荷模型的不确定性对系统小扰动稳定的影响具有重要意义。基于综合负荷模型的状态空间描述,建立了系统状态方程和代数方程对状态变量和代数变量的偏导数矩阵的负荷子块的解析式,据此分析综合负荷模型对系统状态矩阵的影响。用所提出的灵敏度因子的定义分析其对系统特征根分布的影响,获得了一种分析负荷模型的不确定性对多机系统特征值分布影响的方法。该方法很好地解决了负荷模型参数在其不确定性范围内变化时如何影响多机系统的振荡模式这一问题。通过两区域四机系统的计算分析说明了所提出方法的有效性。

Because load model is the aggregation of various load components with considerable uncertainties,it is very important to investigate the effects of load model on power system small signal stability.A method using sensitivity factors is proposed to study the load model impact on system eigenvalues for small signal stability assessment.The method is based on state space description of composite load model.It is based on analytical form of the partial derivative matrix of system differential and algebraic equations with respect to the state and algebraic variables of the load model sub-matrix.Finally,a method to analyze the effects of the uncertainty in load model on the distribution of system eigenvalues is given.This method can be used to effectively describe how oscillation modes in multi-machine systems are affected as the parameter of load model is varying within the uncertainty scope.The effectiveness of the proposed method is illustrated by case studies using the classic two-area fourmachine system.