In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line select...In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.展开更多
When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is...When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.展开更多
为了精确识别直流配电网故障线路,缩小失电范围,并降低支节点附近故障选线盲区,提出了基于变相位系数–电磁时间反转(variable phase coefficient-electromagnetic time reversal,VPC-EMTR)的多端故障选线方法。该方法根据配电网拓扑和...为了精确识别直流配电网故障线路,缩小失电范围,并降低支节点附近故障选线盲区,提出了基于变相位系数–电磁时间反转(variable phase coefficient-electromagnetic time reversal,VPC-EMTR)的多端故障选线方法。该方法根据配电网拓扑和线路参数建立了无损镜像线路网络,利用测量点处的时间反转后的1模电流在无损镜像网络中建立电流源,并计算该线路网络中每一点处的假想故障的故障电流有效值,最大有效值所处线路即为故障线路。该方法设置各镜像支路的相位系数与其长度呈高斯分布函数关系,使得支节点附近的故障测距结果偏移至线路中间处。同时,该方法利用最少测量点二次计算故障选线结果,减少了多余测量点对选线结果的影响,保证了故障选线结果的可靠性。在理论上对该方法进行了证明,并在PSCAD中建立了“手拉手”型多端直流配电网络来验证该方法的有效性,仿真结果表明:基于VPC-EMTR的多端故障选线法的选线结果准确,能够减少支节点附近选线的盲区。展开更多
文摘In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.
文摘When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.
文摘为了精确识别直流配电网故障线路,缩小失电范围,并降低支节点附近故障选线盲区,提出了基于变相位系数–电磁时间反转(variable phase coefficient-electromagnetic time reversal,VPC-EMTR)的多端故障选线方法。该方法根据配电网拓扑和线路参数建立了无损镜像线路网络,利用测量点处的时间反转后的1模电流在无损镜像网络中建立电流源,并计算该线路网络中每一点处的假想故障的故障电流有效值,最大有效值所处线路即为故障线路。该方法设置各镜像支路的相位系数与其长度呈高斯分布函数关系,使得支节点附近的故障测距结果偏移至线路中间处。同时,该方法利用最少测量点二次计算故障选线结果,减少了多余测量点对选线结果的影响,保证了故障选线结果的可靠性。在理论上对该方法进行了证明,并在PSCAD中建立了“手拉手”型多端直流配电网络来验证该方法的有效性,仿真结果表明:基于VPC-EMTR的多端故障选线法的选线结果准确,能够减少支节点附近选线的盲区。
