基于EMTDC电压暂降随机预估的仿真研究

Simulations of Stochastic Assessment of Voltage Sags Based on EMTDC

现代电网和负荷构成的变化使电压暂降成为热点。研究电压暂降特征的方法有电压质量监测和随机预估。与电压质量监测相比,随机预估方法能够在短期内得到负荷处的电压暂降特征。总结了两种较成熟预估方法的不足,提出了运用蒙特卡洛法(Monte-Carlo)进行此项研究的思想。建立了电力系统故障状态变量的数学模型,基于EMTDC/PSCAD对典型的IEEE RBTS 6母线测试系统的故障情况做了大量的仿真。通过比较各故障状态变量数学模型的概率分布值与其仿真中取值的概率分布,可以证明仿真结果是可信的。最后获得了6个负荷点处的电压暂降分布图,并分析了网络结构对电压暂降分布的影响。本文所做的仿真对实际系统的暂降特征的研究有一定参考价值。

Voltage sags have become a new focus of the study on power quality owing to significant changes of modern power systems and load profiles. Two common methods are used in study of characteristics of voltage sags, which are the measurement on voltage quality and the stochastic assessment. Compared with the former, the stochastic assessment can capture information about characteristic of voltage sags at load side in a shorter period of time. This paper summarizes the shortcomings of these methods and proposes a new approach to stochastic assessment of voltage sags using Monte-Carlo method. Mathematical models of state variables associated with failure states were developed. Simulations of typical IEEE RBTS-6 bus testing system were carried out based on EMTDC/PSCAD. Compared probability distri- butions of state variables in mathematical models with that of variable values in lots of simulations, it was proved simulation results were believable. This paper also presents characteristic distributions charts about sags of six buses and discusses how the structure of network influences distribution of sags. The simulation examples could serve as references to study on voltage sags of complicated systems.