针对电流互感器(CT)运行中出现的一例零序保护动作事故及开关柜内二次端子局部烧熔现象,采用直流电阻试验和励磁特性试验对事故原因进行分析,发现CT二次绕组线圈匝间短路是引起零序电流保护动作的直接原因,而运行中CT间歇性开路可能是造成CT二次绕组匝间短路和端子烧熔的原因所在。

Aiming at that a case of zero sequence protective action fault turned up in operational current transformer(CT) and the switchgear in-ternal secondary terminal partial burnt out, this paper adopted DC resistance test and excitation magnetic characteristic test to carry out fault cause analysis, finding that short circuit of CT between secondary winding turns was the direct cause to lead to zero sequence current protective action, moreover the interval open circuit of CT in operation may be the cause to result in short circuit of CT between secondary winding turns and termi-nals burning-out.

针对一起水轮发电机横差保护动作故障进行分析,找出故障原因,提出改进措施。分析结果表明:由于7号、8号磁极间连片烧断,导致绕组发生匝间短路,引起横差保护动作;更换7号、8号磁极后,机组运行正常,再未发生横差保护动作现象。

Aiming at the failure of transverse differential protection device action of a hydraulic gen-erator, checks and analyzes the reasons, brings forward the improvement measures. The analysis result shows that owing to the connector between No.7 and No.8 magnetic pole burns out, brings on interturn short circuit of the winding, aroses transverse differential protection device action. After chenging No.7 and No.8 magnetic pole, the unit operates normally, and transverse differential protection device action never happened again.

基于实际工程介绍了一种超高压磁控式并联电抗器的励磁系统构成,分析了控制绕组匝间短路的故障特征。结合MATLAB数字仿真和动模实验结果,提出了以过电压保护作为控制绕组匝间保护方案存在延时动作且可能拒动的潜在问题,分析其原因在于故障时直流母线极间电压中的故障特征只含有间断的电压尖峰而非连续的交流过电压,且在某些情况下完全不显示故障特征。建立了故障后励磁系统的电流分布模型,得出故障后直流母线极间电压中故障特征的出现依赖于总控制电流过零的结论。提出以总控制电流中的基波分量作为判据的控制绕组匝间保护新方案,该方案在小匝间故障时仍具有很高的灵敏度,结合仿真结果论证了新方案的有效性。

Based on the engineering application,the excitation system of an extra-high voltage (EHV) magnetic controllable shunt reactor (MCSR) is described and the characteristics of control winding turn-to-turn fault of a MCSR is analyzed. According to numerical simulations and experimental tests,a problem in the application of overvoltage protection against control winding turn-to-turn fault is discovered,that is,such a protection operation is delayed or even a malfunction.This is because the fault features DC buses during a turn-to-turn fault intermittent voltage spikes rather than standard sinusoidal overvoltage and the fault feature may even not exist in some fault cases.The current distribution model for the excitation system during a turn-to-turn fault is built and it is concluded that the appearance of fault features on DC buses depends on the zero-crossing of the total control current.A new protective scheme that uses the fundamental component in the total control current as criterion i

为准确分析双馈风力发电机多种故障发生时的电磁特性,为故障预测、结构优化和保护提供方法和数据,针对双馈发电机,给出一种用于多工况运行时多种短路故障发生的分析方法。先利用有限元方法建立发电机全区域模型,计算电磁场,然后用得到的数据编程进行傅里叶级数分解得出磁密分布频谱。利用该方法对1.5 MW发电机建模,对超同步、亚同步及同步正常运行状态及典型的定子部分绕组匝间及单相短路故障的电磁场计算,并进行了分析对比。仿真结果表明,该方法能够根据磁密云图的波形以及频谱图中高次谐波分量等特征量对多种短路故障进行判别,与正常运行状态进行区分。

In order to analyze Doubly-fed Induction Generator (DFIG) electromagnetic property accurately when multiple faults happen and provide method and data to failure prediction, structure optimization and protection, this paper proposes an analytical method used for multiple short-circuit fault at multiple working conditions. The generator entire area model is set up by finite element method (FEM), electromagnetic field is calculated, and flux density distribution frequency spectrum is obtained by dealing with programmed data and FFT decomposition. 1.5 MW generator is modeled by this method, and the electromagnetic fields of sub-synchronous, super-synchronous and normal synchronization state and typical stator turn-to-turn and single-phase short-circuit fault are calculated and contrasted. Results of simulation manifest that this method can distinguish multiple short-circuit faults from the normal operation state according to waveforms of flux density nephogram and the characteristic quanti

指出民用建筑中柴油发电机作为应急或备用电源,由于其短路容量有限,短路电流的周期分量及非周期分量都会衰减,同时大量的电动机负荷,也会向短路点反馈电流。针对工程实际,对发电机与电动机的短路电流分别计算,衰减时间常数分别考虑,短路电流为二者算术和,并算出常用规格发电机出口处三相短路电流值。根据计算的短路电流,校核保护电器的短路分断能力和短路接通能力,以及线路保护选择性配合的问题。

As an emergency or stand -by power supply for civil buildings, diesel generator has a limited short - circuit capacity, so both the periodic component and non- periodic component of short-circuit current will be attenuated, and a large number of motor loads will also provide current to the short- circuit point. According to the actuality of the engineering, short -circuit currents of generator and motor are calculated respectively, which the attenuation time constant is eonsided respectively. The short- circuit is arithmetic sum of them. The 3- phase short- circuit values at the outlet of common specification generators are also calcuted. According to the computed results of the short- circuit current, short- circuit breaking capacity and short- circuit making capacity of the protective devices, and the selective coordination for the line protection are checked.