一次消谐装置对小电流接地系统单相接地故障检测影响分析

Influence of Primary Harmonic Elimination Device on Single-Phase Grounding Fault Line Detection in Neutral Un-Grounded System

一次消谐技术广泛应用于配电网中以预防系统铁磁谐振问题,其对小电流接地系统单相接地故障检测的影响需进一步明确。首先通过理论和仿真研究一次消谐装置接入对电压互感器二次侧开口三角电压的影响,其次,对比分析一次消谐接入前后系统发生单相接地故障时电压互感器二次侧开口三角电压特征。得出:一次消谐装置的接入会引起系统正常运行时电压互感器二次侧开口三角产生一定幅值的基波电压和以3次谐波为主的谐波电压,该异常电压的产生会对单相接地故障检测的可靠性和高阻接地的灵敏性产生影响,并且系统电容电流越大,对高阻接地检测能力影响越大。

The primary harmonic elimination technology is widely used in the distribution network to prevent the ferromagnetic resonance problem of the system,and its influence on the single-phase grounding fault detection of the small current grounding system needs to be further clarified.The author firstly studies the influence of the connection of the primary harmonic elimination device on the delta voltage of the secondary side opening of the voltage transformer through theory and simulation,and then compares and analyzes the opening of the secondary side of the voltage transformer when a single-phase ground fault occurs in the system before and after the primary harmonic elimination is connected.It is concluded that the connection of the primary harmonic elimination device will cause the open delta of the secondary side of the voltage transformer to generate a certain amplitude of the fundamental voltage and the harmonic voltage dominated by the third harmonic.It affects the reliability of single-phase grounding fault detection and the sensitivity of high-resistance grounding.Besides,the system capacitor current is larger,the primary harmonic elimination device has a greater impact on the detection ability of high resistance grounding.