故障电流

Fused current method is adopted in the device for fault feeder detection. This method uses vector sum of compensated current and zero-sequence current and selects fault line according to different distribution of the sum.

该装置采用了一种新的接地选线的算法－电流融合算法，该算法将补偿电流与故障零序电流矢量求和，根据故障与非故障线路矢量和分布在不同区间作为选线判据。

It was presented an adaptive fault circuit selection method based on transient current .

在分析小电流接地系统单相电弧接地故障时各线路零序暂态电流特征的基础上，提出一种基于暂态电流的故障选线自适应方法。

A low frequency rolling bearing fault diagnosis method based on local projective noise reduction;2. According to characteristics of both the vibration signals and the stator currents when appering a fault in the rolling bearing of the induction motor,Park vector module signal of the three-phase current is calculated,and the envelope of vibration signals from the rolling bearing of the motor is analyzed.

根据感应电机轴承发生故障时的振动信号特性以及定子电流特性，求出三相电流的Park矢量模信号，并将其与电机滚动轴承振动信号经解调处理后的包络信号进行融合分析，可以从振动信号与电流信号的融合谱图中有效地提取轴承故障特征信息，并将其作为故障识别的依据。

On the basis of analyzing the law of variation of the zero order current, the zero order voltage and the zero order power in the isolated neutral system, a synthetic criteria principle of selecting the grounded fault line according to three criterias at the same time was put forward.

1中性点不接地系统零序电流的分析中性点不接地系统在发生故障时零序电流的变化最明显，因而对故障情形下零序电流的大小、相位及其功率等关系进行分析很有必要。1.1零序电流的大小关系对于NUS，其线路图见图1。图中kl和k：断开。

According to the analysis of reasons of transformer mal-operation in Pingdingshan Electric Power Bureac for years , and according to the present situation of transformer protection studies and applications at home and abroad. This paper points out the shortcomings of discrimination between internal faults and magnetizing inrush, the problems existing in differentiating the slight faults of turn-to-turn in transformer are also advanced. On the base of the electromagnetic characteristics of transformer, the relations between fluxional differential current and voltage of source side analyzed, all the operating states of transformer simulated by EMTP/ATP, the criterion of magnetizing inrush in transformer is got. Through the wavelet analysis of current waveform, using the intense reaction of wavelet transform to the little change of signal, the internal faults of transformer are distinguished by testing local extremum.

本文根据平顶山市电业局历年来变压器保护误动的原因分析，并根据国内外变压器保护使用和研究的现状，指出了现有变压器保护在区分变压器励磁涌流和内部故障方面以及在判断变压器匝间轻微故障方面存在的问题和不足；从变压器电磁特性出发，分析了电源侧电压和电流微分之间的关系，利用电磁暂态仿真程序对变压器各种运行状态进行了仿真，并以此建立了判断变压器是否含有励磁涌流的判据；通过对电流波形的小波分析，利用小波变换对信号微小变化极强的反映能力，通过检测电流的局部极值点来区分变压器运行状态，并作为上述判据的补充。

The Hilbert amplitude envelope of the stator current includes the low frequency of fault characteristic, thus it can reduce the signal length by resample the Hilbert amplitude envelope of the stator current by downsampling, which can avoid spectrum aliasing. Then it can reduce the computation time of the MUSIC Method for the spectrum analysis to the resampled signals for the given bandwidth. Meanwhile combining continuous subdivision Fourier transform and rotor slot harmonics based slip estimation it can in advance estimate the concrete values of the fault characteristic frequency, and then inquiry purposely the fault feature component information in the stator current spectrum in order to accomplish the broken rotor bar fault with high sensitivity and h reliability, which eliminates adverse effect of issuable false peaks to the fault detection and formed a novel scheme to detect broken rotor bar fault.

定子电流Hilbert幅值包络信号包含了低频的故障特征频率调制信号，故通过对定子电流Hilbert幅值包络信号进行降采样率重采样、减少分析信号长度，可避免低频段频谱混叠，再对减少的重采样数据进行具有超分辨率的MUSIC低频段估计，可大大降低MUSIC算法频谱估计时间；运用连续细化傅里叶变换和转子齿槽谐波转差率估计技术，可预知故障特征频率精确值，从而可有目的地查询故障分量，消除MUSIC虚假波峰对故障检测混淆的影响，大大提高了故障检测的灵敏度和可靠性，以此形成异步电动机转子断条故障检测新方法。

Due to capacity increase or structure change of the power system, an extra-high current possibly 100 times of the rated current may appear in some circuits of the power system when a short-circuit fault happens nearby. This current is extra high and exceeds the permitted value of 10% error curve of protection current transformer.

在电力系统中，各回路的最大故障短路电流和额定工作电流的比值应在合理的范围内，以保证保护用电流互感器的工作精度，但由于系统容量增大或因系统结构等原因，某些回路在某些情况下的最大故障短路电流远远超过了正常范围。

The Hilbert modulus is defined as the sum of the square of a signal and its conjugation.Hilbert modulus is used to covert the fundamental component in original phase current to direct current component,the fault characteristics frequency of bar break is transformed into the twice slip frequency.The problem is solved that fault characteristic component in the spectrum analysis of the current is easily to be blanketed by fundamental component and is hard to highlight fault characteristics.

将Hilbert模量定义为原始信号与其共轭信号的平方和，利用Hilbert模量将原相电流中的基波分量转变为直流分量，原频谱分析的转绕组断条的故障特征分量转变为频率为二倍转差频率的电流分量，决了相电流频谱分析方法中断条故障特征成分容易被基波湮没而难以突出故障特征的问题。

This text has analyzed the common malfunction of the asynchronous motor at first. And then it, which is based on symmetrical weight theory, has drawn accurate criterion of the trouble of the motor, confirmed the protective measures of different troubles. Finally, it has realized kinds of protection functions, such as short-circuit protection, rotate-stop protection, over-heat protection, negative current protection, zero current protection, low-voltage protection, over-voltage protection, overlong start-up time protection, frequent start-up protection, lock protection of electric leakage and so on.

本文首先分析了异步电动机的常见故障，以对称分量法为依据，采用检测过流幅值、负序电流、零序电流的方法，得出了电动机故障的准确判据，确定了各种故障的保护措施，对电动机实现了短路、堵转、过热、负序电流、零序电流、低电压、过电压、启动时间过长、频繁启动、漏电闭锁等保护功能。

Furthermore, the dynamic resonance adjustment method is as follows: measuring capacitive current in real-time when the grid operates in normal, tuning arc-suppression coil and making it compensate for the capacitive current completely when single-phase-to-ground fault occurs.

引言消弧线圈的作用是当电网发生单相接地故障后，提供一电感电流IL 补偿接地电容电流IC，使接地电流减小，也使得故障相接地电弧两端的恢复电压速度降低，达到熄灭电弧的目的。

Life. But the intrinsic way of the Internet by wire confines accessing and using of the network information.

然而，Internet固有的有线连接方式大大限制了人们对网络信息的访问和使用。

I have a strong persuasion that this is true .

我坚信这是正确的。