以"电机学"课程为例,将传统成绩评价体系和多元化成绩评价体系进行对比分析,构建了一种适用于线上/线下混合式教学的多元化学习成绩评价体系.结果表明,采用多元化成绩评价体系,评价项目增多、过程学习权重提高,加强了过程学习监控,能够更合理地评价学生的学习过程,对学生的自主学习能力提升和学习成绩的提高有明显促进作用.

高校为适应社会经济与科技发展对解决复杂工程问题能力的人才需求,对实践教学提出了新的要求.运动控制系统是电气工程专业综合性、实践性强的核心课程,有利于培养学生解决复杂工程问题的能力.以新工科倡导的创新型、综合型工程教育理念为核心,以产学合作协同育人项目为依托,改革实践教学内容、方法,以适应当前行业技术发展要求.在配置虚拟仿真与硬件实验系统相结合的快速控制原型运动平台基础上,提出采用分学科实验解析方法进行实践教学,并匹配渐进式、分层式的实践教学模式,以达到综合设计与运用的目的,形成体系化的解决复杂工程问题能力的实践教学方案.

弧形直线感应电机可用作实现竖直转子无轴承电机,但次级转子偏心所导致的气隙不均匀对气隙磁场有显著影响.针对此问题,在推导气隙宽度数学表达式基础上,首先提出一种针对弧形直线电机不均匀气隙时的气隙磁场解析计算方法.接下来将此方法与有限元计算结果进行比较.结果表明,这种解析计算方法相比采用均匀气隙的计算方法能够大大提升气隙磁场的计算准确度.针对大气隙时计算精确度下降的问题,提出一种修正方法,进一步提升了计算结果的精确性.最后,将解析方法与瞬态场有限元结果进行了对比.对比结果表明,考虑了气隙不均匀的磁密解析计算公式能够将不同情况下的磁密计算误差减小50％ ～90％.这种解析方法为通过弧形直线感应电机的解耦控制实现无轴承电机的结构奠定了基础.

电导增量法步长的设置会使最大功率追踪速度和系统运行稳定性之间存在矛盾.为此,设计了一种改进型的电导增量法,采用自抗扰控制算法对定步长电导增量法进行改进,利用电导变化率与最大功率点电导之间的关系,通过自抗扰算法调节步长.在Matlab/Simulink环境下,基于Boost升压电路搭建了最大功率点追踪系统的仿真模型.仿真实验结果表明,在光伏发电系统中,采用基于自抗扰算法的改进电导增量法进行最大功率点追踪时,不但响应速度快和超调量小,而且抗干扰能力出色,可减小系统稳定运行时的振荡问题.

Both the high frequency pulsation signal injection method and sliding mode observer (SMO) can be utilized to identify the position of permanent magnet synchronous motor (PMSM) sensorless system. When the speed of motor runs high, the high-frequency signal injection method is no longer utilized. When the speed of motor runs low, the rotor position signal cannot be accurately detected because of the weak back-EMF signal, so SMO is not used. For the sake of effectively identify the rotor position in full speed range, a composite identification method combining the high frequency injection and SMO is adopted. Therefore, two identification methods need to be switched in the full speed range. The weighted switching function is used to identify the rotor position, so that that rotor position error estimate by the sensorless PMSM in the full speed range is smaller. The results of simulation verify the availability of this method.

在永磁同步直驱风力发电Z源逆变器并网系统中,对Z源逆变器采用电容电压外环和电流内环的双闭环控制.针对Z源逆变器中电容的启动冲击电压过高问题,在电容电压外环中引入自抗扰控制算法,设计了自抗扰控制器,以稳定启动时的电容电压;将基于自抗扰控制的Z源逆变器与LCL滤波器结合,由滤波电容电流和网侧并网电流构成的电流内环采用PI算法,以降低并网电流谐波畸变率,改善并网电流质量;通过控制直通零矢量对永磁同步发电机的转速进行调节,以实现风力发电最大功率跟踪.仿真实验验证了方法的可行性和有效性.

For the classical maximum power point tracking algorithm, the setting of small step increases the speed of maximum power tracking of photovoltaic power generation system and the stability of operation in stable state. To solve this problem, this paper designs a maximum power point tracking system based on booster circuit, and adopts fuzzy auto-disturbance rejection control to improve the conductance increment method with variable step length. Based on the relationship between the rate of conductance change and the maximum power point conductance, the step size of the adrc is adjusted by using the fuzzy logic control. The MPPT system of photovoltaic power generation is designed by combining the incremental conductance method and the improved fuzzy control method with the correction factor. The control method does not depend on the mathematical model of the system, the design is flexible, the control effect is robust, stable and accurate. It can be used for reference for other types of solar photovoltaic power generation control system.

Dynamic Time Warping(DTW) algorithm has strong resistance to synchronous error. Aiming at the similarity and asynchrony of meteorological factor, a method of applying DTW to photovoltaic power prediction is proposed. The meteorological factors which have great influence on photovoltaic power generation are selected by Pearson correlation coefficient method. Based on the DTW algorithm, the similarity of meteorological factors between the predicting days and the historical days can be measured. Through weighted calculation of similarity:, the similar days are used to obtain training data of Partial Least Squares(PLS) prediction model. The simulation study on a photovoltaic power station verifies the correctness and effective of the proposed prediction method. The results show that the prediction model has great forecasting accuracy and certain feasibility and practicability.

为了提高光伏发电功率预测的精度,选择相似日作为预测模型的训练样本,提出了一种基于加权灰色关联度和格拉布斯准则的马尔科夫链预测方法.通过计算预测日与历史日气象因素的加权灰色关联度,初步选择相似日,再采用格拉布斯准则对相似日的功率数据进行异常判断,完成二次筛选,得到最终的相似日样本并建立马尔科夫链预测模型;利用MATLAB对实际光伏电站的功率进行预测分析.结果 表明,双重筛选能够有效提取相似日样本,提高预测的精度.

Soft optical fiber curvature sensor for finger joint angle proprioception was proposed, which was composed of a protective silicone layer, an optical fiber curvature sensor and two wearable fingertips. The key element of the sensor is an in-line Mach-Zehnder interference structure with a seven-core fiber and two single-mode fiber ball. The optical path difference between core mode and surrounding core modes of the sensor could be varied with the changes of curvature, which will cause the shift of interference spectrum. Experimental results show that when the curvature change in the range of 0 similar to 1 m(-1), the curvature sensitivity of the sensor was 2.744 nm/m(-1), and the linearity was 0.9967. Through the verification test of sensing equipment, the based Mach-Zehnder interference soft optical fiber curvature sensing approach is effective for the measurement of the bending shape of the joint angle model. The Mach-Zehnder interference sensor proposed in this paper has a more compact structure, simple manufacturing process and high reliability, which would find potential applications in the sports medicine rehabilitation or robotic monitoring fields.

We propose an asymmetrical Fabry-Perot interferometer (AFPI) based on fiber Bragg gating (FBG) with low reflectivity and a segment of single-mode fiber (SMF). The AFPI occurs in the narrow bandwidth of FBG. The theoretical analysis of measurement for refractive index (RI) and temperature is explained in detail, and experimental results are consistent with the theory. As the temperature and RI of environment change, the peak wavelength and the extinction ratio of the interferometer show different trends, and the measurement of RI and temperature simultaneously can be achieved. The fiber sensor has the RI sensitivity of 33.55 dB/RIU in the range from 1.333 to 1.413 and temperature sensitivity is 9 pm/degrees C in the range from 10 degrees C to 70 degrees C.

In order to improve the accuracy of wind power prediction and solve the parameter selection problem of support vector machine(SVM)model for the wind power prediction, the artificial fish swarm algorithm(AFSA) is proposed to look for the support vector machine’s optimal parameter of kernel function and the parameter of error penalty. The model of AFSA-SVW is established to predict the wind power with the numerical weather forecast(NWP) data after clustering analysis. Form the result of simulation experiment, it shows that the model of AFSA-SVW has a higher accuracy than the model of BP and the model of BP and the model of BP and the model of PSO-SVM in the short-term wind power prediction.

针对虚拟同步发电机控制策略的优良特性,研究了其在电流下垂控制中的应用.采用电流下垂控制算法取代虚拟同步发电机的有功/频率调节和无功/电压调节控制策略,保留其机械转动所具有的惯性和阻尼特性,舍弃其定子电气模块,使逆变器不仅具有电流下垂控制的优越性能,而且具备虚拟同步发电机的阻尼和惯性特征,增强电网频率和电压幅值的稳定性.通过在电压/电流双闭环控制器中引入虚拟阻抗,提升并网逆变器的鲁棒性.仿真实验结果验证了所提出控制策略的可行性和有效性.

基于三电平逆变器的感应电机直接转矩控制无速度传感器系统存在着逆变器结构复杂、元器件使用较多、基于转子磁链定向的无速度传感器算法使磁链计算复杂、磁链观测环节不精确等问题.为解决上述问题,对三电平逆变器的拓扑结构进行简化,针对直接转矩控制的特点,采用基于定子磁链的无速度传感器算法,并与改进的磁链观测器相结合,进行速度观测,构建了改进拓扑结构、改进磁链观测算法的感应电机直接转矩控制无速度传感器系统.通过仿真实验验证了上述改进方法在减少开关器件损耗的同时,可提高磁链观测精度,使转速估算更精确.

针对虚拟同步发电机控制算法在新能源并网中具有稳定系统运行的积极作用,提出了采用传统功率下垂控制算法取代虚拟同步发电机算法中的有功/频率调节和无功/电压调节部分,保留虚拟同步发电机的机械方程所具有的惯性和阻尼特性,使逆变器具备同步发电机的阻尼和惯性特征.利用Matlab/Simulink仿真验证了所提出控制算法的可行性和有效性,提高了电网频率和电压的稳定性.

传统三电平正交坐标系下空间矢量脉宽调制法(SVPWM)在矢量合成过程中,涉及大量函数运算,计算复杂,占用了计算机大量存储空间、导致运算效率下降.为更好的实现编程控制,进行60°坐标系下的SVPWM算法研究,改进和简化传统的SVPWM算法,避免了计算过程中大量的逻辑运算.最后通过对系统进行仿真分析与实验平台验证,结果表明,该算法减少了运算时间,提高了计算精度,更能满足实际工况需求.

结合本校电气工程学科研究生培养目标和教育特点,优化"分布式发电与微型电网"的教学内容,使研究生能够接触电力领域的新知识与新技术,同时引入"研讨式教学法"、"项目教学法"和多样化考核方式,激发研究生的学习兴趣,培养研究生对新问题的分析和解决能力,提高研究生实践动手能力,实现"知识、素质、能力"的综合培养.

The grid-connected inverter has excellent characteristics based on the control strategy of virtual synchronization generator (VSG). In this paper, the rotor rotation model is applied to the current droop and power drooping control algorithm, replacing the active/frequency adjustment and reactive/voltage regulation control strategies of virtual synchronous generators. Not only can the inverter have the damping and inertial characteristics of the virtual synchronous generator, while simplifying the control model. Finally, the algorithm is validated by Matlab/Simulink. The experimental results show that the proposed algorithm is feasible and effective, and the stability of the grid frequency and voltage is enhanced.

为了提高逆变器并联运行的鲁棒性、抑制环流的产生以及实现功率均分,采用电流下垂控制策略,通过调节并网逆变器的输出的电压频率和幅值来控制其输出的有功电流和无功电流,减轻并网逆变器并联时因输出电流不同而导致的环流,实现功率均分.设计了电流下垂控制器和基于二阶广义积分器(second-order generalized-integrator,SOGI)的虚拟阻抗构成的电压电流双闭环控制器,在其控制系统中引入一定的虚拟电感,使得逆变器的输出阻抗呈电感性且大小可控,提升并网逆变器并联运行的鲁棒性.仿真实验表明所提出控制策略提高了系统并联运行的稳定可靠性.

Mathematical model of the 3D rigid pendulum constructed by MATLAB,based on experimental platform,fuzzy controller or it combined with the P controller controlled (permanent magnet synchronous motor,PMSM) and posture of 3D rigid pendulum,fuzzy controller programming was edited through LABVIEW,and we could observe control curve of 3D rigid pendulum in PC.The results showed that the fuzzy control strategy was effective for 3D rigid pendulum in actual engineering.