电压暂降频次两点估计随机评估方法

摘要

暂降域求解方程是关于故障距离的高阶非线性方程,求解时统一考虑敏感设备耐受电压、系统母线正常运行电压等随机因素是难点.针对此问题,提出了基于两点估计法的电压暂降频次评估方法.该方法综合考虑了以上两个随机因素,以各随机变量的高阶矩构造估计点,通过较少的确定计算获得频次的期望值.对IEEE30节点系统仿真分析,并与蒙特卡罗法比较证明,频次的两点估计法在具有较高精度的同时,计算时间成倍减少,体现了精度高、计算量少的优点;相比原有理想确定性模型,评估结果量化了不同随机扰动特征的影响,具有适应性好、符合客观实际的特点,有一定的工程实用价值.%The solution equation for the area of vulnerability of voltage sag is a high-order nonlinear equation about the fault distance.It is difficult to consider the random factors together, such as the withstand voltage of the sensitive equipment, normal operation voltage of the system bus and so on.To solve the problem, the evaluation method for the frequency of voltage sag is proposed based on the two-point estimate method.It considers the above two random factors, establishes the estimate point based on the higher moment of each random variable, and obtains the expectation value of frequency through less deterministic calculation.Simulation results of IEEE 30-bus system and the comparison with the Monte Carlo method show that the two-point estimate method has the advantages of high precision and less calculation amount; comparing with the original ideal deterministic model, the evaluation results of the proposed method quantify the effect of different random disturbances, has a good adaptability, and is in line with the reality practice, as well as has a certain practical value in engineering.