基于Park矢量的变频电源供电的笼型异步电机转子断条故障诊断方法

基于工频电源驱动时扩展Park矢量方法诊断笼型异步电机转子断条故障的有效性，研究了在变频电源供电情况下该方法的诊断有效性。对断条故障电机变频电流进行了实测、分析和对比，结果表明：当采用变频电源供电时，传统的单相电流频谱分析方法无法正确诊断转子断条故障，而扩展Park矢量方法仍然具有良好的诊断准确性和适用性。     

基于Clarke变换的鼠笼异步电机故障诊断方法研究

在交流电机坐标变换分析的基础上,指出了国际上通用的Park矢量方法及其扩展方法的不足之处,提出了Clarke矢量轨迹识别方法和扩展Clarke方法,利用矢量轨迹识别的方法判断电机的常见电气故障;基于负序电流的思想,进行定子绕组匝间短路判别,经仿真和实验验证,表明方法有效可行。     

基于Clarke变换的鼠笼异步电动机故障诊断方法

在交流电机坐标变换分析的基础上,指出了国际上通用的Park矢量方法及其扩展方法的不足之处。提出利用Clarke矢量轨迹识别方法判断电机的常见电气故障;基于负序电流的思想,进行定子绕组匝间短路判别,经仿真和实验验证表明方法有效可行。     

采用Park变换感应电机转子复合故障检测

针对感应电机转子断条与偏心故障特征受定子电流基波信号的影响而难以提取的难点,提出了一种基于旋转Park变换滤波的感应电机转子复合故障检测方法.该方法利用电压与电流基波频率相等,通过旋转Park变换,将电流Park矢量的基波正序分量完全滤除而不影响其它的谐波分量,从而使转子断条和偏心故障特征更清晰地显示出来,然后对旋转Park变换滤波后的电流Park矢量的频谱进行分析,可以准确检测到电机转子复合故障时的故障特征.解决了电流频谱分析方法转子故障特征频率分量容易被基波湮没而难以突出故障特征的问题.实验结果表明,应用该方法可有效的对电机转子复合故障进行实时检测.     

基于Hilbert模量频谱分析的异步电动机转子故障在线监测与诊断方法

Hilbert变换是数字信号处理中的一种理想的移相方法。对某一信号进行这种变换，可得到其共轭信号。该文将Hilbert．模量定义为原始信号与其共轭信号的平方和，并在此基础上提出了一种基于定子电流Hilbert模量频谱分析的异步电动机转子故障在线监测与诊断方法。理论分析和实验结果表明该方法可以有效地诊断鼠笼式异步电动机的转子故障。与需要同时采样三相电流的扩展的Park’矢量方法相比，该方法大大节省了硬件和软件开销。     

双馈风力发电机定子绕组匝间短路诊断与实验研究

当双馈风力发电机定子绕组发生轻微匝间短路时,三相定子电流的时域波形变化比较微小,而三相电流Park’矢量轨迹随着故障变化明显。对双馈电机采用多回路理论进行仿真,并进行动模实验测试,得出了正常及匝间故障情况下的Park’矢量轨迹,通过对Park’矢量轨迹的形状和椭圆环的宽度比较来确定是否短路并估计匝间短路的严重程度。     

基于Park矢量模频率特征的变压器励磁涌流识别方法

提出一种基于Park矢量模频率特征的新型变压器励磁涌流识别方法。首先分析了变压器内部故障和励磁涌流状态下三相差电流的相对相位关系特征,并讨论了对应的Park矢量模中不同频率分量的特点。在此基础上分别定义Park矢量模中二次谐波相对基波和直流的含量系数,并根据这两个系数大小来识别励磁涌流状态。利用动模实验和数字仿真结果对该方法进行验证分析,并与常规二次谐波闭锁方法进行比较。比较分析结果表明所提方法能有效区分励磁涌流和故障电流,在可靠性上优于常规二次谐波闭锁方法,同时空载合闸于轻微故障变压器时受非故障相涌流的影响小,能够更快地开放保护。     

EMD分解在感应电机转子复合故障诊断中的应用

针对感应电机转子断条与偏心复合故障特征受定子电流基波信号的影响而难以提取的难点,提出了一种基于定子电流Park矢量模EMD分解的诊断方法。首先从理论上分析了Park矢量模在凸显复合故障特征方面优于单相瞬时功率,然后通过仿真验证了这一结论的正确性。仿真结果还表明,基于定子电流Park矢量模EMD分解方法诊断灵敏度高、故障特征直观清晰,同时提取的故障特征IMF分量还可以从定量上对故障严重程度作出分析,是一种优越的可行方法。     

基于矢量旋转的永磁同步电机容错控制系统

永磁同步电机(PMSM)矢量控制系统中电流传感器故障将导致整个系统无法正常工作。为实现电流传感器故障诊断及其容错控制,引入了基于矢量旋转的故障诊断方法,利用在不同轴定向的坐标系下定子电流分量,判断相电流传感器故障信息,然后通过基于α,β坐标系的逻辑判断机制选取恰当的反馈电流以重构系统。为避免该方案中反馈电流恒等于指令值,引入了一种电流估计算法,当故障发生时,保证电机能更加平稳地运行。基于Matlab/Simulink和dSPACE1007进行仿真和实验研究,证明了该容错控制方法的正确性和可靠性。     

基于随机森林的异步电动机转子断条故障诊断

为了快速准确识别异步电动机转子断条故障,提出一种随机森林算法(Random Forests,RF)的异步电动机转子断条故障诊断方法。该方法以Park矢量模平方函数为故障特征提取手段,然后采用随机森林进行故障模式自动识别。Park矢量模平方函数方法可以较好地削弱定子电流中基频信号的影响,便于故障特征量的准确提取。而随机森林泛化能力好、训练时间短,提高了故障识别的成功率。实例验证表明,基于随机森林的异步电动机转子断条故障诊断方法性能良好。     

用矢量控制原理的异步电动机在线监测与故障诊断方法——原理分析

利用传动领域的矢量控制概念，将异步电动机的三相定子电流通过坐标变换，转换到同步旋转的（M，T）坐标系中，M轴的方向与转子磁链矢量的方向重合，在新坐标系中电流分量iM为励磁分量，主要与定子外加电压的频率，大小及故障程度有关；ir分量为转矩分量，主要与负载大小有关，对iM分量进行频谱分析既可达到文献[1]所证明的特征频率提取效果，还可避免波动性负载造成的误诊断，从总结的两种求取坐标转换角度的方案看出，该方法物理意义明确，适用于不进行速率调节的异步电动机。     

基于扩展反电势估算的内插式永磁同步电动机无传感器控制

提出一种基于扩展反电势估算的内插式永磁同步电动机(IPMSM)无传感器控制策略，拟用于永磁无轴承电机地无位置/速度传感器运行。定义了包含传统反电势及定子电感位置信息的扩展反电势(Extended EMF, EEMF)，以此建立静止坐标系中的IPMSM新型数学模型。通过滑模观测器对两相静止坐标系中分量EEMF的估算检测出转子的空间位置；基于Lyapunov函数分析观测参数的收敛性；采用模型参考自适应算法得到了转子的估算速度。实验运行验证了该无传感器控制策略的有效性。     

Management of reactive power sharing & power quality improvement with SRF-PAC based UPQC under unbalanced source voltage condition

This paper is proposed to establish a new control algorithm for UPQC (unified power quality conditioner) to improve power quality and manage effectively equal reactive power sharing between shunt and series inverter of UPQC under unbalanced source voltage condition. The extraction of instantaneous power angle for reactive power sharing faces difficulty with unbalanced source voltage condition. This paper presents a new SRF (synchronous reference frame) based PAC (power angle control) method using decoupled load current parameters for efficient utilization and coordination of UPQC inverters. The proposed controller contributes in improvement of source current and load voltage harmonic profile, provides efficient way of load reactive power compensation and load voltage compensation for sag, swell and unbalanced condition. Effect of source voltage variations in the form of sag, swell or unbalancing on variable power angle estimation and reactive power calculations are also validated through a mathematical analysis. SRF based PAC control approach and PAC based UVT (unit vector template) control approach is adapted for estimating the reference signals of shunt and series inverter respectively and thus reducing the need of extra computation. The simulation and experimental analysis is carried out using Matlab/Simulink software package for computer simulation and a dSPACE based experimental setup for real time verifications.     

Loop frame of reference based three-phase power flow for unbalanced radial distribution systems

This paper introduces a novel three-phase power flow approach for unbalanced radial distribution systems. The proposed approach is developed based on the loop frame of reference, rather than the traditional bus frame of reference. On the basis of the loop frame of reference, a simple direct iterative method in impedance form is applied. Basic graph theory and injection current technique are also applied in the proposed approach. The clear theoretical foundation and the simple topology of the radial distribution network make the proposed method efficient and reliable. To demonstrate the better convergence performance and the efficiency of the proposed approach, four three-phase IEEE test feeders are used for comparisons. The test results show that the proposed method has robust convergence characteristics and high performance, especially for large-scale radial distribution systems.     

Flux position estimation in cage induction machines using synchronous HF injection and Kalman filtering

This paper proposes a new approach to the tracking of the flux position saliency of an induction machine by means of high-frequency (HF) signal injection in the synchronous rotating frame. The paper shows that existing synchronous pulsating injection methods perform poorly in the presence of secondary saliencies. A modified scheme is proposed in which a rotating HF field is established in the dq rotating reference frame. The scheme enhances the performance of harmonic elimination methods to reduce the effects of secondary saliencies. A new harmonic elimination method based on the Kalman filter is proposed in the paper. Experimental results are given showing the effectiveness of the harmonic elimination and the resulting tracking of the saturation saliency.     

A novel and fast single-phase three-wire power flow solution for a modern home premises wiring systems

Single-phase 2-wire (1φ2w) and single-phase 3-wire (1φ3w) circuit layouts are commonly adopted in premises wiring systems. Compared with 1φ2w circuits, the arrangements of 1φ3w circuits have some advantages such as reduced voltage drop, reduced line loss, and fewer conductors. Currently, more detailed power flow solutions of premises wiring systems are required because they can be used in more applications, such as power loss analysis, conservation voltage regulation (CVR), load balancing, and network reconfiguration especially in the design and operation of modern home energy management systems (HEMSs). This paper presents a novel approach to solve the power flow problem of a 1φ3w premises wiring system. The proposed approach is based on the loop frame of reference rather than the conventional approach, which is normally based on the bus frame of reference. Because the proposed approach is mainly based on graph theory, feeders and branch circuits of a premises wiring system are represented in a more detailed fashion than in previous corresponding mathematical models. In addition, the proposed approach provides an efficient and simple way to help engineers build a performance equation and full-scale system model of a premises wiring system. The simulation results of the proposed approach are verified through the OpenDSS software package and field testing. The proposed approach and implementation technique are of value to engineers and technicians in the design and operation of premises wiring system for dwelling units or smart buildings and may be implemented in HEMSs.     

基于故障电流解析表达的FCL协助DFIG低电压穿越研究

双馈感应电机(DFIG)与公共耦合点(PCC)间投入故障电流限制器(FCL)实现低电压穿越(LVRT)时,定子电压受FCL阻抗与网侧变流器(GSC)电流影响,无法设定定子电压,需要对DFIG与FCL整体建模以分析故障电流。基于恒定电流控制策略推导转子侧变流器(RSC)与GSC电流,提出DFIG故障电流的解析表达式。考虑到电压定向下定子相角振荡会导致dq轴恒定电流在xy轴下变化,不利于定子电流稳定,采用dq轴与xy轴相重合的定向方案。对比不同的RSC与GSC电流参考值、FCL阻抗值与切出时间下DFIG LVRT过程中的电磁转矩振荡,选择LVRT性能较好的一组控制参数。仿真结果表明,FCL阻抗取值受RSC与GSC电流参考值影响,且FCL阻抗越大,所取切出时间越短。     

基于基波相位补偿策略的无延迟谐波检测

提出了在基于同步参考坐标系的检测算法中引入基波相位补偿实现无延迟谐波检测的策略。采用改进的基于数字信号处理器(DSP)基波提取的混合型检测方案,既有效减小了时延和误差,又使得时延的影响仅局限于基频分量;分析了时延对谐波补偿失效性的影响;介绍了延迟时间的评估和基于同步控制相位补偿的数字实现。实验结果表明,该策略和实现方法硬件简单、成本低,可实现无延迟、高精度的谐波检测。     

Single-Phase Permanent-Magnet Motor Analysis

A unified theoretical approach is presented for the calculation of the performance of the single-phase capacitor-start permanent-magnet (PM) ac line-start motor. The earlier work of Chang and of Finch and Lawrenson on capacitor reluctance motors is extended. As far as possible, a common set of reference frame transformations for steady-state, transient, and asynchronous performance is also provided, permitting the use of all the theory developed for the analysis of the balanced polyphase PM motor. A new approximate technique is given for estimating the average asynchronous torque/speed curve from computed acceleration curves.     

Improved voltage regulation for current-source inverters

Voltage regulation schemes for current-source inverters (CSIs) commonly use a simple proportional-integral (PI) stationary frame controller, but this approach is known to suffer from significant steady-state error. In contrast, the more advanced schemes that are routinely used for current regulation of voltage-source inverters (VSIs) avoid these problems. This paper presents an approach to directly utilize VSI current regulation strategies to control the voltage for a CSI, without requiring significant modification or development. The approach uses a space-vector mapping technique to convert VSI modulation signals to CSI gate drive signals, which allows VSI closed-loop current control strategies to be directly applied to CSI voltage regulation. Three new voltage regulation CSI controllers based on hysteresis, synchronous frame PI, and stationary frame P+Resonant control principles are presented based on this concept