基于瞬时值的电力系统不对称故障分析方法研究

电力系统所发生的各类故障中,以不对称故障最为常见.不对称故障的分析主要采用相量对称分量法,而该方法在诸多方面存在局限性.文章首先介绍传统对称分量法,并引入动态分析的基本方法,阐述dq0坐标系和120坐标系的特点,建立动态分析模型,列写120坐标系下的网络方程,解出单相短路和两相短路两种典型不对称故障的电流基频分量初始值.最后通过具体算例的演示,比较两种解法的结果,结论是采用瞬时值法同步电机模型的精确性较高.

Analysis Method for Power System Unbalanced Faults Based on Instantaneous Value

Of all kinds of faults in electric power system,unbalanced faults are most common.A main method of unbalanced faults analysis is based on symmetrical components of phasors,but it has limitations in many aspects.The characteristics of the symmetrical component method and the instantaneous value based method are discussed.The paper first reviews the basic principles of the conventional symmetrical component method widely used,and then gradually shows the primary steps of the dynamic analysis,presenting the characteristics of 120 coordinates and dq0 coordinates.After that,it depicts the approach of the mathematical modeling of dynamic power system,writing out the network equations in 120 coordinates,then calculating the initial value of the fundamental frequency compo.nent of the short circuit current under two typical faults which are the single line-to-ground fault and the line-to-line fault.Finally,an example is demonstrated to com.pare the results of two methods and prove a conclusion of higher accuracy by using syn.chronous machine model under instantaneous value.