三相不接地系统桥式固态限流器的故障诊断方法

提出一套基于离散傅里叶变换的桥式固态限流器桥路故障诊断方案。针对不同桥臂的元件故障,选择直流侧电感电流和续流二极管电流作为检测点,对检测点波形进行综合比较分析,实现了对桥路故障类型的诊断和故障桥臂定位。通过将检测点的波形从时域变换到频域进行波形特征分析,突出故障特征,简化判据,有利于计算机自动识别与诊断。仿真结果表明,该方案检测量小且包含了完整的故障信息,各次谐波分量的幅值可以确定故障类型,基波相角可以定位故障桥臂,故障诊断和定位快速准确。

A Fault Diagnosis Method for Solid-state Fault Current Limiters Used in Three Phase Ungrounded System

A fault diagnosis scheme based on the discrete Fourier transform is proposed for solid-state fault current limiters (SSFCLs) used in three phase ungrounded system. For the faults occurred on different bridge arms,the inductance current on the DC side and free-wheeling diodes current are selected as detecting parameters in the fault type diagnosis and fault locating. By transforming the time domain waveforms of detecting parameters into the frequency domain,the fault characteristics are distinguished,and the criterion is simplified,which facilitates the automatic diagnosis by computers. Simulation results indicate that the proposed scheme need minimum measurements but include complete fault information. The magnitude of each harmonic component can be used to determine the fault types,and the phase angles of the fundamental waveform to locate the faulty arms. The fault diagnosis and locating are accurate and fast.