基于两点估计法的交直流混合系统电压稳定概率评估

Probabilistic assessment on voltage stability of AC/DC hybrid systems based on two-point estimate method

传统的交直流系统电压稳定分析大多是建立在确定性方法上的,没有考虑系统中各种随机因素的影响,不利于交直流系统运行的经济性和合理性。为了弥补确定性方法的不足,提出了一种基于两点估计法的交直流混合系统电压稳定分析方法。该方法考虑负荷水平和负荷增长系数的随机性,建立了交直流混合系统的负荷裕度模型。通过少量确定性计算求出负荷裕度和临界点处节点电压的前3阶矩,从而得到待求变量的近似概率分布,确定某一负荷水平下交直流系统电压失稳的概率。与蒙特卡罗法进行比较,计算精度满足要求,并且大大地缩短了计算时间。

Traditional voltage stability analyses of AC/DC hybrid systems are mostly based on deterministic methods, without taking into account the influence of various uncertain factors, this will do harm to the economy and rationality of system operation. In order to make up the deficiency of deterministic analysis method, this paper proposes a voltage stability analysis of AC/DC hybrid systems based on two-point estimate method. The method takes into account the uncertainties of load levels and power growth factors and establishes the loading margin model of AC/DC hybrid systems. The first three statistic moments of loading margin and bus voltage on the point of voltage collapse are computed by a few deterministic computations, thus the probabilistic distributions of the desired variables are obtained and the probability of voltage instability under some load level is determined. Compared with Monte Carlo simulation, the computational accuracy is satisfied and the execution time is significantly shortened.