不对称电网馈线零序电流分布特征分析

小电流接地系统在正常运行时,由于线路参数不平衡的普遍存在,系统中性点将产生不平衡电压。不平衡电压在系统馈线中将产生不平衡电流,对该电流的分布特征进行研究,有助于系统故障分析。该文从理论上分析不平衡电流在系统馈线中的分布特征,从馈线的视角出发,通过戴维南定理对系统电路进行等效,得到各馈线不平衡电流表达式。以此为基础求得单相接地故障时馈线稳态零序全电流表达式,揭示其对单相接地故障下馈线零序电流幅值与相位的影响。提出通过对故障前后馈线零序电流作差消除不平衡电流的影响。最后,在matlab软件平台搭建仿真模型,验证该文的分析结果。

Analysis on distribution characteristics of zero sequence current of feeders in asymmetric grid

During the operation of small current grounding system,unbalanced voltages would be induced in neutral points as the unbalanced parameters of transmission lines.And this unbalanced voltage produces an unbalanced current in feeder system.Therefore,studying the distribution characteristics of the unbalanced current is helpful for analyzing system faults.This article theoretically analyzed the unbalanced current in feeder systems.Starting from the feeder,the equivalent circuit of the system is obtained based on Thevenin's theorem while the expressions for unbalanced currents in feeders are also obtained.Then,under the condition of the single-phase disconnection fault,the influence of unbalanced currents on the amplitude and phase of zero sequence current on feeder lines is revealed.Finally,the simulation model is built in MATLAB to verify the analytical results.