To solve the problem of negative sequence current generated when an asymmetric fault occurs on the AC side of a converter station in a flexible DC grid,which causes large fluctuations in instantaneous power and DC side voltage and current,thereby affecting the stable operation of the system,a converter station level control strategy for flexible DC grids based on linear active disturbance rejection control(LADRC)was proposed.This strategy uses a proportional-integral(PI)controller and a second-order LADRC controller to control the outer loop and inner loop current,respectively.Taking the modular multilevel converter(MMC)as the controlled object,frequency domain analysis was conducted on the second-order LADRC controller to determine the reasonable values of the controller parameters.Finally,a four-terminal flexible DC grid model was built based on the PSCAD/EMTDC platform for example analysis.The results indicate that compared with traditional PI control,the proposed control strategy effectively suppresses negative sequence current,significantly reduces the second harmonic fluctuations of active and reactive power and DC side voltage,and improves the system's fault ride-through capability and dynamic response speed.

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.

PLC控制技术与应用是电气工程及其自动化专业中实践性强的专业基础课程.为适应社会发展对创新创业人才的需求,实现学校PLC控制技术应用人才培养与企业需求间的无缝对接,提升高校本科教育质量,制订PLC课程实践教学培养目标,以建立PLC架构为实践教学根本,依据应用类型构建实践教学基本体系,提出主动+互动式教学模式贯穿始终,利用组态软件的视图效果增强学生学习兴趣,进一步提高教学目标达成度.

为使学生更好地理解异步电机调速系统的结构与特点,设计了基于MatLab/GUI的异步电机调速系统仿真实验平台.仿真实验平台借助MatLab/GUI良好的人机交互性,设计了调压调速、SPWM调速、矢量控制、直接转矩控制等多个仿真实验.每个实验可进行参数设置、仿真实验、实验示例、结果演示等操作,界面友好,使用简单,可操作性强,能够加深学生对理论知识的理解,激发学生的学习兴趣,并为以后使用MatLab软件从事相关研究工作打下坚实的基础.

The randomness of wind power is the reason of wind power abandonment. Considering the grid flow constraints and load frequency regulation ability of hydroelectric power generator, to smooth wind power output, the output of wind power and hydro power could be controlled according to the plan; therefore, the wind farm could be considered as dispatchable node. In order to improve the stability of the total output power of coordinated hydro and wind power generation, a new method based on bird swarm algorithm was proposed. Through the example analysis, before the control system was optimized, the system flow calculation was carried out to ensure the power flow security. It can effectively control the output power of the hydraulic generator on time, and quickly track the desired output power. The influence of high wind abandonment punishment and high power fluctuation punishment on the coordinated operation of wind power and hydropower.

基于可编程控制器,在Visual Basic环境下设计了电梯模拟实验平台.在上位计算机中采用Visual Basic软件实现电梯模拟界面与动画设计,在欧姆龙可编程控制器中设计梯形图程序实现三层电梯控制,二者通过RS232串口实现实时通讯.该实验平台不受场地限制,使用便利,具有一定的应用价值.

将成果导向教育理念应用到《电气控制与PLC技术》课程教学实践中,在思想上实现从学科导向向目标导向、从教师中心向学生中心、从质量监控向持续改进的三个转变,在实践上在教学大纲编写、教学策略设计以及考核方式设置三方面进行了教学实践探索,教学效果良好.

可编程逻辑控制器(Programmable Logic Controller,PLC)是机电类专业实践性较强的专业基础课程.在实践教学中为达到解决复杂工程问题能力培养的目标,在实验室配套建设与规划的基础上,提出建设PLC实践教学体系,探索互动式实践教学模式,采用组态软件强化学生学习兴趣.体系化、层次化、互动式的实践教学环节可有效提高学生学习的积极性、主动性、创造性,形成教与学的相互促进、相生相长的良性循环.

可再生能源并网发电的可靠性、稳定性是微电网协调控制分布式发电系统实现能源综合梯级利用及大电网稳定运行的重要保障.针对交流微电网中太阳能光伏并网,采用单级式LCL型光伏并网逆变器拓扑结构并设计滤波器参数;采用有源阻尼消除LCL谐振尖峰,抑制逆变器输出电流的振荡;利用电压前馈控制削减并网公共节点电网电压对并网电流的影响;应用准比例谐振调节器实现电流跟踪控制.仿真结果表明,在光伏能源功率波动情况下,逆变器能实现能量以单位功率因数并网,以及系统快速稳定运行,证明控制方法可行、有效.

我校“电机节能技术”实验课程中,设置了电动机静态和动态无功补偿研究的内容.为了满足该实验内容的要求,本文对电动机静态和动态无功补偿实验方法进行了研究,设计了电动机无功补偿实验内容和实验装置.本装置能够实现电动机无功功率的静态阶梯补偿和动态跟踪补偿,为学生理解和掌握电动机无功补偿节能方法创造了良好的条件.

A kind of PLC temperature monitoring system based on Matlab is designed,combining the advantages of simple structure,rich hardware interfaces,strong anti-disturbance and reliability of PLC,with the advantages of strong scientific computing function,convenient software interfaces,and friendly graphical user interface of Matlab.A temperature monitoring interface based on PLC is designed in this system,which has perfect visibility and powerful operability.The communication between the upper computer and PLC is set,and an example of temperature control with Dalin algorithm is provided.Simulation tests for temperature control system of heating furnace are accomplished,and the result shows that the control performance is satisfying when temperature set value is varied.What 's more,the advanced complex control algorithms are easy to be realized as this system is based on Matlab.

For the convenience of scientific research, a simulation experimental platform for temperature control is designed based on PLC. In this platform, the monitoring interface and the furnace simulation model are developed base on Visual Basic programming language, which are more practical and versatile. Aiming at the temperature control system with characteristics of nonlinearity, pure time delay, large inertia and difficulty to precise control, a control exemplification based on Dahlin algorithm is given. The control results indicate that this algorithm has fast response speed, small steady state error, and good control effect.

Under certain assumptions,based on power flow tracing technique,the relationship between the output of the generator and it's distribution on the transmission lines is proved to be approximately linear.According to the basic principles of responsibility allocation,the method of determining the congestion responsibility is put forward based on the power flow change of each generator with and without transmission constraints.There is no need to trace the power flow of each generator on the congestion lines.The calculation results based on the output of the generator and that on it's distribution are the same.But the new method is simpler and with less computation.

掌握专业英语是了解国外学术及业内最新动态、掌握专业领域最新知识的基础,是各专业人才必备的重要素质。论文结合本校电气工程及其自动化专业实际情况和专业英语教学现状,从教学内容和教学模式两方面对电气工程及其自动化专业英语教学进行了探讨。

To cover the shortage of the classic PI control,the fuzzy PI control based on gray prediction of speed error is introduced to the variable voltage speed control system of asynchronous motors.A control scheme accessible to calculation is proposed.In this scheme,GM(1,1) model is applied to predict the speed error,and the fuzzy controller is applied to self-adjust PI parameters in real time,so the control performance of this system is improved.Simulation experiment results show that this scheme has better control effect than classic PI control method when the given speed or the load torque is varied.

The electric control and PLC technology is a course with strong practicality,and the experimental links are important in this course.A new type of experimental facility is designed for application-orientated undergraduate education.The facility is more close to the actual circumstance in industry.It is practical,open,comprehensive,and the students' practical and innovative ability would be greatly improved.

The basic principal of current flyback switching power supply is introduced.A two-channel output of +12 V and +5 V flyback switching mode power supply based on TOP223Y is designed,and the structure of circuit system is analyzed briefly.The improving and optimizing project is put forward then.By testing the signal waveform,it is demonstrated that the design of this method can reduce the switching power supply ripple,improve the power supply efficiency and ensure stable voltage output.

Wavelength selecting can be used to select a research space with all combinations of strong correlativity wavelength and large magnitude of the concentration information as final wavelength regions to build a PLS calibration model of NIR.Uninformative variables elimination(UVE) algorithm based on the PLS regression coefficients b is presented,which can be used to select wavelength regions of NIR(near infrared spectroscopy) for building a PLS(partial least squares) calibration model.the influence of density matrix and noise on wavelength selection is considered.The apparent amylose content test results showed that the numbers of wavelengths for building the models can be reduced from 1102 to 726.Correlation coefficient can be increased from 0.9212 to 0.965 4,standard deviation of cross validation in calibration can be reduced from 2.4142 to 1.3725,and the root means squared error in prediction was reduced from 2.4572 to 2.2001.The prediction precision was greatly improved by Uninformative variables elimination algorithm.This method is compared with other traditional wavelength selecting method and the calibration model is best built by Uninformative variables elimination algorithm.

以创新能力培养为目标,以创新人才培养为教育理念,结合重点课程建设,以学生为主体,在课程体系、教学内容、教学方法及手段、考核方式及实验教学等方面对"电机与拖动"课程进行教学改革,并取得了一定的成果。

本文结合应用型本科的实际情况,从实践教学体系的合理规划、实践教学内容的多层次化、实践教学方式的多元化、实践教学手段的多样化四方面对电气控制类课程的实践教学进行了探讨。