多绕组电压互感器误差现场校验技术研究

针对多绕组电压互感器非计量绕组负荷对计量绕组误差的影响问题,本文通过对多绕组高压电压互感器等值电路分析和理论推导,对多绕组电压互感器的计量绕组误差构成进行了研究,提出了一种利用非计量绕组施加不同负荷实现各绕组漏阻抗的测量方法,并计算得到多绕组电压互感器的计量绕组负载误差和非计量绕组对计量绕组的误差影响量。计量绕组各测量点的空载误差测量采用低压侧参考误差方法实现,通过常规方法在一个较低电压下测量电压互感器空载误差及二次回路参考电压点和测试点的参考误差,计算得到互感器各测试点的空载误差数据。本方法无需使用升压器和进行导纳值、直流电阻的测量,并避免了分布电容对误差的影响,试验结果表明测量准确度可以达到检定规程要求。     

基于连续小波变换的电表绕组故障检测方法研究

为有效保障电力电表的稳健运行,基于连续小波变换技术,设计了电表绕组故障检测方法。首先,采用混合模块化多电平特征分析方法分析电表绕组故障特征,并建立电表绕组的等效电路模型;结合混合模块化多电平换滤器(MMC)拓扑分析方法,获得电表绕组的等效电路拓扑结构。然后,提取电表绕组故障的谱特征量,以局部自均压和功率因素为控制自变量,完成电表绕组故障特征的连续小波变换及分解。最后,进行故障特征聚类和属性分布式挖掘,提高电表绕组故障特征检测和信息挖掘能力。仿真结果表明,该方法对电表绕组故障的检测精度较高,对绕组故障特征的辨识度较好,可提高对电表绕组故障的诊断能力。     

MF9905型带定时／调速／自然风／睡眠风功能的电扇程控板

如图所示的是MF9905型电扇专用程控电路板,该电路采用32768Hz晶振作时基,定时根据晶振频率分频所得,精度较高,采用4只(或5只)全电子轻触开关控制,控制功能有: 1.高、中、低风速控制(用图中的VD3、VD2、VD1,板上的三只红色LED指示),接电扇调速绕组对应的抽头(红线接高速绕组,白线接中速绕组,蓝线接低速绕组)。     

电机定子绕组温度烘干系统的设计

根据电机定子绕组温度烘干的工艺要求,采用组态王工控软件进行烘干界面及控制算法的设计,实现对电机定子绕组的温度烘干过程的控制.     

变压器单次短路冲击绕组变形分析

变压器是煤矿电力系统中的重要元件,在使用过程中会面临短路冲击,引起内部电磁力及温度变化,导致绕组变形,造成变压器的破坏及失效。针对此问题,采用有限元仿真的形式分析中压绕组短路冲击作用时的应力及变形。结果表明,绕组中间位置承受较大的冲击应力并产生较大的形变,且具有不可恢复性,影响变压器的安全使用,应对其进行一定的优化处理。     

基于Lyapunov理论的异步电机定子绕组匝间短路故障检测系统设计

为实现对定子绕组匝间短路故障行为的精准识别，确保异步电机的稳定运行状态，设计了基于Lyapunov理论的异步电机定子绕组匝间短路故障检测系统。在DSP外围电量回路中，设置ARM处理器与步进电机驱动模块，采用模数转换单元结构，调节电量互感装置的实时运行状态，实现对异步电机定子绕组匝间短路故障检测系统硬件设计。根据Lyapunov函数定义条件，确定Nussbaum增益参数取值范围，在此基础上，定义Lyapunov算法模型，再通过计算故障预测特征的方法，求解定子绕组的短路故障电压方程与匝间电感参数，对定子绕组匝间短路故障特征进行分析，实现异步电机定子绕组匝间短路故障检测。实验结果表明，所设计系统可以有效控制定子绕组匝间短路故障电流和电压检测结果与标准检测结果之间的差值水平，能够精准识别定子绕组匝间短路故障行为，保障异步电机的稳定运行状态。     

表征绕组特征的参数与绕组变形关系的仿真

为了提升变压器绕组变形判别精度,研究了表征绕组特征的参数与绕组变形关系的仿真方法.利用有限元方法建立表征绕组特征的参数与绕组变形关系的双绕组、同芯式变压器漏磁场模型,通过二维泊松方程混合边值的有限元解分析变压器绕组漏磁场,利用最小二乘算法基于所建立变压器漏磁场模型辨识可表征绕组特征的漏电感参数,通过所获取漏电感值与实际...     

基于ANSYS CFX的变压器绕组温度场监测研究

利用Maxwell电磁仿真软件计算变压器在稳定满载运行过程中绕组损耗情况,将得出的损耗数据转换为发热载荷输入ANSYS CFX中对该35 kV油浸式变压器绕组的温度分布情况进行研究.从60, 120 min两个时间段对绕组的温度分布进行仿真分析,找出最热点分布以及相应的温度值,得出变压器在运行120 min时,为变压器最热点温度时刻,低压绕组最热点位于B相绕组,为75.5℃,高压绕组最热点温度位于C相绕组,为65.4℃;变压器绕组中部温度整体较上部和下部高,且随着变压器工作时间延长,变压器整体温度升高;变压器整体低压绕组温度较高压绕组温度高.     

500 kV高压电网中变压器绕组变形检测方法研究

由于绕组的运行模态受多种因素影响,直接根据运行模态方程式检测绕组变形情况的准确性较低,为此,提出500 kV高压电网中变压器绕组变形检测方法研究。根据绕组电流构成包含非周期分量和部分谐波分量,将绕组的运行模态方程转化为标准的最小二乘形式,通过模态输出结果与变压器高、低压侧端口的电压理论值之间的关系辨识变压器绕组稳态。利用变形影响绕组运行参数,锁定采样值差动保护动作下的绕组漏感参数值,通过计算对应的励磁涌流强度与空载合闸临界状态下励磁涌流强度之间的关系,实现对变压器绕组变形情况的识别。测试结果表明,设计方法可以实现对不同程度变压器绕组线饼幅向变形和线饼间隙变形情况的准确检出。     

一种具有交叉缠绕激励绕组的磁通门电流传感器

本文提出了一种激励绕组为交叉绕组结构的电流传感器,该种缠绕结构能够有效克服变压器效应,降低激励绕组耦合到反馈绕组和原边绕组中的噪声,有利于提高测量精度与灵敏度.对该种缠绕方式的传感器进行了仿真分析,制作了新型电流传感器的样机.测试结果表明交叉绕组结构也能降低磁滞效应的影响并提高灵敏度;所设计的电流传感器在测量范围0～30 A的情况下相对误差小于0.4％.     

基于双模态自适应小波粒子群的永磁同步电机多参数识别与温度监测方法

提出了一种双模态自适应小波粒子群（Binary-modal adaptive wavelet particle swarm optimization,BAWPSO）的永磁同步电机（Permanent magnet synchronous motor,PMSM）多参数识别与温度监测方法.为了提高算法动态寻优性能,群体被划分为正向学习和反向学习两种模态;对处于不同模态的粒子分别采用正向学习策略与反向学习策略协同求解,扩大了解的搜索空间;同时对粒子个体极值采用自适应小波算子增强学习以提高收敛精度.永磁同步电机参数辨识结果表明所 提方法能够有效地辨识电机电阻,dq轴电感与转子磁链等参数,且能有效追踪系统参数变化值.在辨识出电机定子绕阻值后,根据金属阻值与温度之间的线性 原理间接计算定转子温度,从而实现永磁同步电机系统温度在线监测.     

基于SVPWM的永磁同步电动机控制系统的研究

介绍了永磁同步电动机控制系统的组成,空间矢量脉宽调制(SVPWM)的理论及其算法在系统中的实现过程,并对系统进行了Simulink仿真。仿真结果表明:采用SVPWM算法控制永磁同步电动机定子绕组电流谐波成份较少,控制效果较好,具有广阔的应用前景。     

绕组分段永磁直线同步电机切换控制研究

为了实现绕组分段永磁直线同步电机(SW-PMLSM)稳定运行控制,对绕组切换控制方法进行了研究.结合SW-PMLSM的结构及调度策略,分析了绕组切换过程中的推力变化,认为永磁体动子纵向的长度等于单台定子纵向长度的整数倍时,动子在移动过程中所受的合成推力将基本维持不变.提出了基于PMLSM直接推力控制及PLC绕组切换运行控制的总体方案,设计了动子位置检测及绕组切换控制系统.最后利用SW-PMLSM直驱无绳提升机进行了实验研究.实验结果表明,SW-PMLSM定子绕组切换过程运行平稳,能耗制动可将电机的运行速度限制在一个稳定范围,具有较好的后备保护功能.     

Parameter estimation and reliable fault detection of electric motors

Accurate model identification and fault detection are necessary for reliable motor control. Motor-characterizing parameters experience substantial changes due to aging, motor operating conditions, and faults. Consequently, motor parameters must be estimated accurately and reliably during operation. Based on enhanced model structures of electric motors that accommodate both normal and faulty modes, this paper introduces bias-corrected least-squares （LS） estimation algorithms that incorporate functions for correcting estimation bias, forgetting factors for capturing sudden faults, and recursive structures for efficient real-time implementation. Permanent magnet motors are used as a benchmark type for concrete algorithm development and evaluation. Algorithms are presented, their properties are established, and their accuracy and robustness are evaluated by simulation case studies under both normal operations and inter-turn winding faults. Implementation issues from different motor control schemes are also discussed.     

Commutation Torque Ripple Suppression in Three Phase Brushless DC Motor Using Open-end Winding

Three phase brushless DC motor has the characteristics of high power density, simple structure and excellent speed regulation performance, which is widely used in the field of electric drive. Open-end winding brushless DC motor has no neutral point, and each phase winding is electrically isolated, which can realize the independent control of each phase winding. Compared with Y-connected brushless DC motor, the open-end winding brushless DC motor has a wider range of speed regulation under the same voltage, and has certain fault-tolerant performance, which is suitable for the application of low voltage and large current. Compared with the multiphase fault-tolerant motor, open-end winding brushless DC motor has simpler structure and higher winding utilization rate. However, the open-end winding brushless DC motor still has torque ripple, among which the cogging torque is related to the motor body structure, while commutation torque ripple is affected by the mutual inductance of the winding and the current freewheeling loop. The commutation process of the open-winding brushless DC motor is analyzed, and it is concluded that the current change rates of the turn-off phase and turn-on phase are equal under the ideal back electromotive force(back-EMF), which can ensure that the non-commutation phase current and the electromagnetic torque kept constant. The overlapping commutation with phase current closed-loop method is proposed to suppress the commutation torque ripple of open-end winding BLDC motor, and the applied voltage on turn-off phase and delayed time of turn-off phase in overlapping commutation are derived, the sliding mode observer is used to calculate the electromagnetic torque. MATLAB simulation and experimental results verify the effectiveness of this method.

     

永磁电机流固耦合仿真及损耗影响分析

高密度永磁电机功率密度高,散热困难,尤其是其内部的永磁体温度较高时将会出现退磁现象,严重影响电机寿命,电机温升问题成为电机运用的关键问题之一。利用有限体积法对永磁电机进行流固耦合仿真分析计算,研究了永磁电机热分布情况,特别是永磁体温度分布情况,为研究永磁体的局部退磁提供理论依据,并通过样机进行温升实验,验证上述仿真模型的正确性及准确性。同时论文利用上述热仿真模型,深入分析及研究了损耗对永磁电机关键部分的温升影响,为研究永磁电机散热优化提供依据。     

永磁同步电机电机本体数学模型在MATLAB下的仿真

在电机的应用中,永磁同步电机的数学模型可以是在d/q模型或者a b c模型下建立。本文为了更好地实现永磁同步电机的矢量控制,在永磁同步电机的电压、电流、磁链的关系表达式基础上,运用MATLAB建立了其数学模型下的仿真模型,并结合park和clarke变换对所建立的数学仿真模型进行了验证。仿真结果表明所建立的永磁同步电机模型的正确性。由此为永磁同步电机的调速问题提供了更简化的模型和更广泛的应用范围。     

Stator winding fault prediction of induction motors using multiscale entropy and grey fuzzy optimization methods

In the present work, stator winding fault prediction is studied using a multiscale entropy (MSE) algorithm combined with a grey-based fuzzy algorithm. Experiments were performed with a normal motor and a motor with faulty stator winding. Real time, motor current and vibration signals were acquired at different operating speeds and were used for the diagnosis of faults. The obtained signals were denoised by wavelet transform. Grey relational analysis (GRA) coupled with fuzzy logic was used to model the stator winding fault and to predict the optimal setting for running the induction motor within its parameters range. Analysis of variance (ANOVA) was performed to determine the effect of each individual parameter on the response. The results indicate that the proposed novel approach is very effective in predicting the stator winding fault. Furthermore, the best running parameters for the induction motor are also reported.     

永磁同步电机脉振高频电压注入转子位置检测

永磁同步电机的转子位置检测精度直接决定了电机能否平滑起动,为提高转子位置检测精度,提出了基于脉振高频电压注入的表贴式永磁同步电机转子位置检测方法。向永磁同步电机定子绕组中注入脉振高频电压信号,通过电机d、q轴磁路饱和程度的差异,实现永磁同步电机转子初始位置的检测。实验结果表明提出方法的转子位置检测精度高,适用于永磁同步电机的无传感器起动及低转速稳态运行。     

Performance investigation of a permanent magnet generator

Computer simulation using the finite-element method (FEM) is an important tool for the design of highly efficient power devices. In this work combination of FEM-software for magnetic analysis and Simulink-software for non-linear parameter identification for dynamics of a permanent magnet (PM) generator is discussed. An FE model of the generator is developed and its electromagnetic torque analysis is carried out using FEM-software. Simulink has been used for analysis of rotor moment of inertia (MI) due to variation of winding resistance and winding inductance. It is shown that system MI has a significant effect on optimal winding resistance and inductance to achieve steady state operation in shortest period of time.