有源配电网故障场景下的电压暂降仿真与评估方法研究

Voltage Sag Simulation and Evaluation in Active Distribution Network With Fault Cases

针对含有分布式电源的配电网进行电压暂降仿真与评估问题,提出基于点估计法的电压暂降仿真与评估方法。首先建立故障信息模型,包括对故障线路率、故障点、故障类型、故障持续时间、故障阻抗等,以及分布式电源输出功率的随机模型,然后基于点估计法将随机概率密度问题转换为多个确定性问题。通过计算随机变量的期望、标准差、三阶中心矩,利用Cornish-Fisher级数来表示每个节点电压暂降的概率密度函数,以及计算电压暂降指标SARFI,发现网络的薄弱环节。通过对含两个不同类型分布式电源的IEEE13-bus和IEEE 33-bus系统的测试,并与Monte Carlo法进行对比,证明了算法的有效性。通过对不同类型风机模型的应用,证实了该文提出算法的可行性和高效性。

A novel voltage sag simulation and evaluation method was proposed based on point estimation method （PEM） in smart distribution network with distributed generations （DG）. With stochastic models of line fault, fault point, fault type, fault duration, fault impedance and DG stochastic output, the probability density functions （PDFs） were built up. By using PEM, the random probability problem in voltage sag simulation is transformed into multiple deterministic problems： Through computing the mean, standard deviation and the third central moment of each node in distribution network, PDF of each node can be got based on Cornish-Fisher expansion series, and then the voltage sag index SARFI can be computed. Weak branches in distribution network were analyzed. Experiments have been made on the IEEE 13-bus test case and the IEEE 33-bus test case with the consideration of two stochastic DG units. Thirteen scenarios simulations about voltage sag and comparison with Monte Carlo simulation were made. The feasibility and-effectiveness of the proposed algorithm for voltage sag evaluation are proved.