Weak Fault Detection of Rotor Winding Inter-Turn Short Circuit in Excitation System Based on Residual Interval Observer

Aiming at the fact that the rotor winding inter-turn weak faults can hardly be detected due to the strong electromagnetic coupling effect in the excitation system,an interval observer based on current residual is designed.Firstly,the mechanism of the inter-turn short circuit of the rotor winding in the excitation system is modeled under the premise of stable working conditions,and electromagnetic decoupling and system simplification are carried out through Park Transform.An interval observer is designed based on the current residual in the two-phase coordinate system,and the sensitive and stable conditions of the observer is preset.The fault diagnosis process based on the interval observer is formulated,and the observer gain matrix is convexly optimized by linear matrix inequality.The numerical simulation and experimental results show that the inter-turn short circuit weak fault is hardly detected directly through the current signal,but the fault is quickly and accurately diagnosed through the residual internal observer.Compared with the traditional fault diagnosis method based on excitation current,the diagnosis speed and accuracy are greatly improved,and the probability of misdiagnosis also decreases.This method provides a theoretical basis for weak fault identification of excitation systems,and is of great significance for the operation and maintenance of excitation systems.

Calculation of torque and speed of induction machines under rotor winding faults

Based on the multi-loop method, the rotating torque and speed of theinduction machine are analyzed. The fluctuating components of the torque and speed caused by rotorwinding faults are studied. The models for calculating the fluctuating components are put forward.Simulation and computation results show that the rotor winding faults will cause electromagnetictorque and rotating speed to fluctuate; and fluctuating frequencies are the same and their magnitudewill increase with the rise of the severity of the faults. The load inertia affects the torque andspeed fluctuation, with the increase of inertia, the fluctuation of the torque will rise, while thecorresponding speed fluctuation will obviously decline.

Coordinated Rotor-Side Control Strategy for Doubly-FedWind Turbine under Symmetrical and Asymmetrical Grid Faults

In order to solve the problems of rotor overvoltage,overcurrent and DC side voltage rise caused by grid voltage drops,a coordinated control strategy based on symmetrical and asymmetrical low voltage ride through of rotor side converter of the doubly-fed generator is proposed.When the power grid voltage drops symmetrically,the generator approximate equation under steady-state conditions is no longer applicable.Considering the dynamic process of stator current excitation,according to the change of stator flux and the depth of voltage drop,the system can dynamically provide reactive power support for parallel nodes and suppress the rise of DC side voltage and rotor over-current.When the grid voltage drops asymmetrically,the positive and negative sequence components are separated in the rotating coordinate system.The doubly fed generator model is established to suppress the rotor positive sequence current and negative sequence current respectively.At the same time,the output voltage limit of the converter is discussed,and the reference value is adjusted within the allowable output voltage range.In order to adapt to the occurrence of different types of power grid faults and complex operating conditions,a fast switching module of fault type detection and rotor control mode is designed to detect the type of power grid faults and voltage drop depth in real time and switch the rotor side control mode dynamically.Finally,the simulation model of the doubly fed wind turbine is constructed in Matlab/Simulink.The simulation results verify that the proposed control strategy can improve the low-voltage ride through performance of the system when dealing with the symmetrical and asymmetric voltage drop of the power grid and identify the power grid fault type and provide the correct control strategy.

A fault warning for inter-turn short circuit of excitation winding of synchronous generator based on GRU-CNN

Synchronous generators are important components of power systems and are necessary to maintain its normal and stable operation.To perform the fault diagnosis of mild inter-turn short circuit in the excitation winding of a synchronous generator,a gate recurrent unit-convolutional neural network(GRU-CNN)model whose structural parameters were determined by improved particle swarm optimization(IPSO)is proposed.The outputs of the model are the excitation current and reactive power.The total offset distance,which is the fusion of the offset distance of the excitation current and offset distance of the reactive power,was selected as the fault judgment criterion.The fusion weights of the excitation current and reactive power were determined using the anti-entropy weighting method.The fault-warning threshold and fault-warning ratio were set according to the normal total offset distance,and the fault warning time was set according to the actual situation.The fault-warning time and fault-warning ratio were used to avoid misdiagnosis.The proposed method was verified experimentally.

GENERATOR VIBRATION FAULT DIAGNOSIS METHOD BASED ON ROTOR VIBRATION AND STATOR WINDING PARALLEL BRANCHES CIRCULATING CURRENT CHARACTERISTICS

Rotor vibration characteristics are first analyzed, which are that the rotor vibration of fundamental frequency will increase due to rotor winding inter-turn short circuit fault, air-gap dynamic eccentricity fault, or imbalance fault, and the vibration of the second frequency will increase when the air-gap static eccentricity fault occurs. Next, the characteristics of the stator winding parallel branches circulating current are analyzed, which are that the second harmonics circulating current will increase when the rotor winding inter-turn short circuit fault occurs, and the fundamental circulating current will increase when the air-gap eccentricity fault occurs, neither being strongly affected by the imbalance fault. Considering the differences of the rotor vibration and circulating current characteristics caused by different rotor faults, a method of generator vibration fault diagnosis, based on rotor vibration and circulating current characteristics, is developed. Finally, the rotor vibration and circulating current of a type SDF-9 generator is measured in the laboratory to verify the theoretical analysis presented above.

基于二维CNN与多源机电信息融合的同步电机转子匝间短路故障诊断方法

为提高同步电机转子绕组匝间短路故障的诊断准确率,以一台型号为SDF-9的一对极同步发电机为研究对象,提出了一种基于二维卷积神经网络(Convolutional Neural Networks, CNN)与多源机电信息融合的匝间短路故障诊断方法。首先选取故障前后的定子环流、转子振动、定子振动信号为故障特征,采用信号-图像转换方法将一维时序信号转化为二维灰度图像。其次将处理后的图像分别作为二维CNN模型的前置输入进行训练。最后采用D-S证据理论将3种证据体的输出概率进行决策融合。结果表明:该方法消除了单一信号易受传感器故障及环境变化的影响,故障诊断准确率显著提高,并与其他传统故障诊断算法的诊断结果进行对比分析,验证了此方法的有效性。

新型同步调相机转子匝间短路故障定位方法

转子绕组匝间短路故障是新型同步调相机的一种典型故障,对调相机长期运行和电网稳定都有严重影响。为保障新型同步调相机高可靠稳定运行,文中提出一种转子绕组匝间短路故障在线诊断与定位的方法。从故障导致的气隙磁场磁动势畸变出发,推导出定子同相两支路将出现偶次谐波环流现象,并通过对支路环流进行傅里叶分解,提取谐波中的明显特征量。对该特征量进行分析,得出其大小仅与故障所在转子上的空间位置有关,而与故障匝数无关的结论,最后通过查表的方式来实现故障诊断与定位。文中基于已规模投入使用的TTS-300-2型同步调相机开发有限元软件的仿真模型,并搭建基于新型调相机的模拟机实验平台进行实验。仿真与实验结果验证了利用支路环流谐波进行转子匝间短路故障定位的有效性。

双馈异步风力发电机转子匝间短路故障振动特性分析

针对双馈异步风力发电机转子匝间短路的故障振动机理尚不明确且无法为故障诊断提供理论依据的问题,开展了双馈异步风力发电机转子匝间短路故障振动特性分析.首先,结合有限元仿真及解析推导,分析转子匝间短路下双馈异步风力发电机的气隙磁密规律,得到转子所受的不平衡磁拉力;然后,考虑转子不平衡磁拉力的情况下构建双馈异步风力发电机转子-轴承系统非线性动力学模型,利用非线性动力学仿真获取转子匝间短路故障下系统的振动仿真信号;最后,在双馈异步风力发电机故障模拟实验台上进行转子匝间短路故障实验,利用实验分析验证非线性动力学仿真结果的有效性.非线性动力学仿真及实验分析结果均表明,转子匝间短路故障下双馈异步风力发电机转子-轴承系统振动信号的频谱存在转频的谐波成分,通过检测转频的谐波分量可诊断双馈异步风力发电机转子匝间短路故障,有效揭示了双馈异步风力发电机转子匝间短路的故障振动机理.

可变速抽蓄机组转子绕组新型主保护方案性能分析

丰宁可变速抽蓄机组的投运使得其转子绕组保护方案的配置备受关注。运用多回路分析法,对湘潭电机厂制造的12 kW交流励磁样机所有实际可能发生的转子绕组内部故障进行了仿真,在此基础上对基于定子分支谐波环流的转子绕组新型主保护方案的性能进行了分析,并进一步明确了新型转子绕组主保护方案不能动作故障类型及相应的改进措施,为后续国产化示范项目中可变速抽蓄机组的稳定运行奠定基础。

一起隐极同步发电机转子阻尼绕组烧损故障的检测与处理

针对灵活性运行方式下发电机转子故障日趋增多的问题,以某台148.5 MVA汽轮发电机为例,介绍了启机过程中出现的轴振爬升情况,轴振与有功功率的相关性明显强于无功功率和励磁电流,重复脉冲法试验结果显示转子匝间绝缘性能存在下降趋势。转子返厂解体后,发现护环内阻尼绕组存在明显的烧损现象。该案例是典型的转子阻尼绕组烧损故障案例,采用的检测判断方法和故障处理经验对相关人员具有一定的借鉴作用。

同步发电机转子绝缘监察方法

随着电力工业的发展,电力系统越来越庞大且复杂。目前仅依靠人工检测发电机转子绕组绝缘电阻的方式耗时耗力,越来越无法满足电力系统的需求。为此提出了同步发电机的转子绝缘监察方法,该方法可自动计算出发电机转子绕组的接地电阻,能够用于非在线监测同步发电机转子绕组接地电阻。阐述了同步发电机的基本原理,分析了转子接地的发生及其危害性,并给出相应的措施,进一步提出了转子在运行中的监视方法。该方法能够节省大量人工测量和计算的劳动强度,对确保发电机安全可靠运行具有重要意义。

基于径向基函数神经网络算法的汽轮发电机转子绕组匝间短路故障诊断

转子绕组匝间短路是汽轮发电机的主要故障之一,对该故障的既有诊断方法仍有不足。在分析径向基函数神经网络基础上,提出一种基于该神经网络的汽轮发电机转子绕组匝间短路故障诊断方法。详细介绍了该方法的故障诊断流程,并对其进行了仿真验证。研究表明,该方法精度高且收敛速度快,可有效诊断汽轮发电机转子绕组匝间短路故障。

基于端口频域特性的水轮发电机转子绕组匝间短路故障诊断

包含抽蓄发电机在内的大型水轮发电机转子为具有多匝长绕组的显极式转子,传统的基于交流阻抗测量的绕组匝间短路故障诊断方法存在灵敏性和便捷性等方面的不足。基于多导体传输线理论建立了显极式转子绕组的端口频域特性模型,通过仿真分析提出了故障判别和定位方法。最后通过真机转子的故障模拟和测试对诊断方法的有效性进行了验证。仿真和试验结果表明,所提方法能够在无需断开磁极间电气连接的测量条件下实现绕组匝间短路故障的诊断和定位。

基于FFT-LSTM的变速抽蓄机组转子绕组短路故障和偏心故障诊断方法

变速抽水蓄能机组是适应系统功率波动的重要调节手段。转子绕组短路故障和转子偏心故障是其常见的故障类型,两种故障均会在定子侧感应生成特征频带相近的谐波环流,导致两种故障难以被区分。提出了一种基于快速傅里叶变换-长短期记忆(fast Fourier transform-long short-term memory,FFT-LSTM)网络的故障诊断方法,以细化分辨故障特征相近的转子绕组短路故障和转子偏心故障。所提方法以定子分支环流的谐波分量为特征量进行故障诊断,分别推导了两种故障发生时定子侧环流谐波特征,并总结二者间的相似性和差异性。鉴于该差异较为微弱,引入长短期记忆(long short-term memory,LSTM)神经网络算法对其进行辨识。利用内部故障仿真模型对可能发生的转子绕组短路故障和偏心故障进行批量仿真,以得到用于LSTM网络训练和测试的数据集。仿真结果表明FFT-LSTM能够准确诊断不同转速下变速抽蓄机组的转子绕组短路故障和转子偏心故障。

异步电机综合故障实验教学平台设计与开发

由于异步电机实验教学平台多是针对正常工况设计开发的,缺乏对故障状态的模拟和分析,因此造成了教学和实际需求的脱节。该文设计开发的异步电机综合故障实验教学平台可以开展定子绕组匝间故障、转子断条故障、轴承故障实验和在线诊断,该平台综合了异步电机拆解与组装、故障特征分析以及数字信号处理技术的实际应用,有助于学生深入理解相关知识,提升实际动手能力。

变速抽蓄机组转子绕组接地故障保护及定位方法

变速抽蓄机组转子绕组采用三相交流励磁的特殊结构,导致现有的转子接地保护方法不再适用。为此,提出一种变速抽蓄机组转子绕组接地故障的保护及定位方法。通过在转子滑环外经限流电阻接注入式装置构成转子接地保护的方案。基于注入式原理,提出对地电容参数和故障电阻的在线计算方法,根据接地故障电阻大小判断是否发生接地故障并确定保护出口方式。根据转子转向和转速大小考虑转子绕组电势的相位分布,将故障相绕组各槽导体连接处视为虚拟故障点并计算其对应的参考电势比值。比较实际电势比值与各虚拟故障点的参考电势比值,将差异最小的虚拟故障点视为故障位置,实现接地故障定位。PSCAD/EMTDC仿真结果验证了所提方法的有效性。

基于重复脉冲法的变速抽蓄机组转子绕组短路故障诊断方法

变速抽蓄机组的转子侧采用特殊的三相交流绕组结构,导致其转子绕组短路故障诊断困难。为此,提出了一种基于重复脉冲法(repetitive surge oscillograph,RSO)的离线故障诊断方法。首先设计了重复脉冲法在变速抽蓄机组中的应用方案,通过在转子三相同时注入低压脉冲并检测响应曲线来判断机组故障情况。基于不同短路故障的响应特性分析,提出了转子绕组短路故障类型和故障相别的识别方法。然后,结合变分模态分解与Teager能量算子(variational mode decomposition-teager energy operator,VMD-TEO)估计注入脉冲和特征曲线的起始突变位置,并通过时间差值和实测波速确定故障位置。最后,利用指数还原故障因子衡量匝间短路故障的严重程度,以解决克服行波衰减引起的特征波形幅值重叠问题。仿真结果表明,所提方案能准确诊断变速抽蓄机组的各种转子绕组短路故障。

一起RSO检测无效的大型隐极同步电机转子动态匝间短路故障检测与处理

发电机的安全可靠运行对电网具有重要意义。本文以某台330MW汽轮发电机为例,介绍了其启机过程中出现的轴振明显上升情况,在重复脉冲法、直流电阻、交流阻抗和功率损耗试验结果均正常的情况下,根据轴振与励磁电流相关性、励磁电流特征、轴电压及气隙探测线圈波形综合判断出转子存在动态匝间短路故障。经将转子返厂解体,发现4~8号线圈存在明显的顶匝变形现象,经修复后机组重新投入运行。本案例是典型的重复脉冲法检测无效案例,本文采用的综合检测判断方法和故障处理经验对类似机组处理具有一定的借鉴作用。

基于DCS的汽轮发电机转子绕组匝间绝缘早期故障预警研究

文章针对大型汽轮发电机转子绕组匝间绝缘早期缺陷预警问题开展研究,提出了一种汽轮发电机转子绕组绝缘状态评估与缺陷预警模型。首先基于机组DCS系统实时监控数据采用多层感知机(Multi-layer Perceptron,MLP)构建发电机励磁电流预测模型,为提高模型泛化能力和预测精度,通过双MLP抽取DCS实时监控数据的时间和电磁空间特征,并结合残差连接、层标准化等技术实现时空信息的融合。考虑到DCS数据噪声较多易导致预测残差波动较大,采用Savitzky-Golay滤波分析法对预测结果进行平滑处理,提高模型的稳定性。最后,基于残差越限法对转子绕组的匝间绝缘早期故障进行预警。实例分析结果表明,所提出的模型具有较高的灵敏度和准确性。

基于定子线圈探测的转子匝间短路故障识别方法

该文通过对汽轮发电机转子线圈匝间短路时的电磁特性进行分析和计算,提出转子绕组匝间短路时,转子绕组主磁场变化比漏磁场明显,用定子线圈作为探测故障线圈,确立了转子绕组匝间短路故障程度和有效磁场损失之间的对应关系;提出转子匝间短路导致发电机定子绕组并联支路之间出现了电势差和环流,其大小和分布与短路严重程度有一定对应关系;利用动模试验机组进行了有关的验证,试验结果和理论推导相吻合。