Adaptive Nonlinear Control of Wind Energy Conversion System Involving Induction Generator

This paper presents a theoretical framework for adaptive control of a wind energy conversion system (WECS), involving a squirrel cage induction generator (SIG) connected with an AC/DC/AC IGBT‐based PWM converter. A multi‐loop nonlinear controller is designed to meet two main control objectives, i.e., (i) speed reference optimization in order to extract a maximum wind energy whatever the wind speed, and (ii) power factor correction (PFC) to avoid net harmonic pollution. These objectives must be achieved despite the mechanical parameters uncertainty. First, a nonlinear model of the whole controlled system is developed within the Park coordinates. Then, a multi‐loop nonlinear controller is synthesized using the adaptive backstepping design. A formal analysis based on Lyapunov stability is carried out to describe the control system performances. In addition to closed‐loop global asymptotic stability, it is proven that all control objectives (induction generator speed tracking, rotor flux regulation, DC link voltage regulation and unitary power factor) are asymptotically achieved.     

Robust control of synchronous motor through AC/DC/AC converters

The problem of controlling synchronous motors, driven through AC/DC rectifiers and DC/AC inverters is addressed. The control objectives are threefold: (i) forcing the motor speed to track a varying reference signal in presence of motor parameter uncertainties; (ii) regulating the DC Link voltage; (iii) assuring a satisfactory power factor correction (PFC) with respect to the power supply net. First, a nonlinear model of the whole controlled system is developed in the Park-coordinates. Then, a robust nonlinear controller is synthesized using the damping function version of the backstepping design technique. A formal analysis based on Lyapunov stability and average theory is developed to describe the control system performances. Despite parameter uncertainties, all control objectives are proved to be asymptotically achieved up to unavoidable but small harmonic errors (ripples).     

交流矿井提升机控制系统实训平台的设计

设计了基于PLC的交流矿井提升机控制系统实训平台,介绍了控制系统的总体设计及软硬件设计方案。该控制系统采用S7-1200PLC作为控制核心,三相异步电动机作为动力源,直流电动机作为负载,并分别采用变频器和直流调速器对三相异步电动机和直流电动机进行调速,实现了对交流矿井提升机在特定负载下运行工况的模拟。通过实训平台,受训人员能够基本了解现代交流矿井提升系统的运行原理与操作方法,从而达到培训目的。     

交直流并联输电系统的非线性鲁棒控制

针对含有常参数不确定性的交直流输电系统,使用自适应逆推方法设计了直流系统的非线性鲁棒控制器.基于该方法的设计,无需对原系统进行反馈线性化,并能保证闭环误差系统渐近稳定.设计过程表明逆推方法设计的控制器拥有更优越的性能.     

ARM平台的矢量和PID交流电机控制系统

交流电机具有结构简单、制造容易、成本低、容易控制等等特点,在许多场合中逐步取代直流电机,成为电机使用者的首选,但是交流电机的调速系统复杂,在使用上很难达到和直流电机相媲美.文章设计一套基于ARM平台的矢量控制和PID算法的交流电机控制系统,实现对交流电机的精确的控制.系统分为硬件、软件、和上位机界面三部分,硬件电路包括电流采集电流和IGBT电路,软件部分采用C语言开发,使用KEI MDK软件开发工具编程,上位机采用LabVIEW软件编写测试界面,运行PID程序,最终开发出一套用于交流电机调速系统的电机控制.     

基于六脉波交交变频的闭环调压调速方法研究

针对六脉波交交变频调速技术在高频段存在各频级间转速差较大的问题,提出了一种基于六脉波交交变频的闭环调压调速方法。该方法在2个高频段之间设置多个电压等级,通过改变交交变频输出电压的大小,进行交交变频闭环有级调压调速。仿真和实验结果表明,该方法能够有效利用存储器空间,扩大交交变频调速范围,调速效果较好。     

Self-tuning adaptive feedback linearizing output voltage control for AC/DC converter

This paper presents a cascade output voltage control law adopting the self-tuning adaptive inner and outer-loop controllers for a AC/DC converter modelled as a nonlinear system. The first contribution is to design the inner and outer-loop controllers updating their control gains to enhance the closed-loop performance, estimating unknown parameters. The second one is to show that the proposed inner-loop controller stabilizes not only current error dynamics but also output voltage dynamics viewed as internal dynamics. The effectiveness of proposed method is shown by performing experiments using a 3-kW AC/DC converter.     

Control of Grid Connected Photovoltaic Systems with Microinverters: New Theoretical Design and Numerical Evaluation

This paper addresses the problem of controlling grid connected photovoltaic (PV) systems that are driven with microinverters. The systems to be controlled consist of a solar panel, a boost dc–dc converter, a DC link capacitor, a single‐phase full‐bridge inverter, a filter inductor, and an isolation transformer. We seek controllers that are able to simultaneously achieve four control objectives, namely: (i) asymptotic stability of the closed loop control system; (ii) maximum power point tracking (MPPT) of the PV module; (iii) tight regulation of the DC bus voltage; and (iv) unity power factor (PF) in the grid. To achieve these objectives, a new multiloop nonlinear controller is designed using the backstepping design technique. A key feature of the control design is that it relies on an averaged nonlinear system model accounting, on the one hand, for the nonlinear dynamics of the underlying boost converter and inverter and, on the other, for the nonlinear characteristic of the PV panel. To achieve the MPPT objective, a power optimizer is designed that computes online the optimal PV panel voltage used as a reference signal by the PV voltage regulator. It is formally shown that the proposed controller meets all the objectives. This theoretical result is confirmed by numerical simulation tests.     

于非仿射非线性模型的AC/DC系统H∞鲁棒控制器设计

讨论了交直流联合输电系统的 H∞ 鲁棒控制问题. 首先对交直流输电系统提出一种五阶非仿射非线性不确定控制模型, 该模型能综合反映交直流系统的动态特性. 基于该模型采用分层控制思想设计了系统的 H∞ 鲁棒控制器, 通过对直流系统换流器触发角的控制实现系统内部稳定和鲁棒性能的提高. 仿真结果验证了控制策略的有效性.     

基于锁相环与双A/D的交流采样技术及其应用

为了保证对电力系统的实时监控、调度,需要对电力参数进行交流采样;介绍了电力系统参数交流采样的设计思想,对频率跟踪电路进行了分析,提出了由锁相环CD4046和双MAX125构成的硬件解决方法,并给出了由CD4046构成的频率跟踪电路图以及双MAX125与80C196KC单片机的接口设计电路,解决了电力系统中多路电压、多路电流的交流采样问题,保证电网频率变化时采样数据的精度和稳定性;该采样算法可以应用于多种场合,具有一定的实用和推广价值.     

基于智能变电站交直流一体化电源系统研究

交直流电源智能化运行是通过整合交、直流电源实现的,为供电用电的一体化提供了解决方案,能有效地提高运行的稳定安全性,从而提高了变电站电源管理能力。而交直流一体化电源系统具有集成度高、管理简便等优势,可集中监控和管理多套电源系统,提高了多套站用电源系统蓄电池组的共享性,随着交直流一体化电源系统方案的广泛应用,其所存在的问题急需从根本上进行解决(包括标准化程度不高、各品牌间的兼容性差等)。为确保变电站的可靠运行,提出全模块化电源系统方案,以期提高维护效率并降低维护成本,为提高交直流一体化电源系统的标准化程度提供参考。     

A nonlinear robust HVDC control for a parallel AC/DC power system

In this paper, a parallel AC/DC power system is investigated, and a nonlinear robust controller is proposed to improve transient stability of the power system and to damp out any prolonged oscillation after a fault is cleared. Lyapunov's direct method is used to synthesize the control, and asymptotic stability of the closed loop system and improved dynamic performance are shown by both theoretical proof and simulation results.     

Efficient Single-Stage Bridgeless AC to DC Converter Using Grey Wolf Optimization

Bridgeless single-stage converters are used for efficient (alternative current) AC-(direct current) DC conversion. These converters control generators, like electromagnetic meso- and micro-scale generators with low voltage. Power factor correction helps increase the factor of the power supply. The main advantage of the power factor is it shapes the input current for increasing the real power of the AC supply. In this paper, a two-switch bridgeless rectifier topology is designed with a power factor correction capability. For the proposed converter topology to have good power quality parameters, the closed loop scheme, which uses the grey wolf optimization (GWO) algorithm, is implemented. The successes of GWO encourage this research to implement GWO in the topology. The performance of the proposed topology is analyzed under different load conditions. Simulation is carried out using the MATLAB/Simulink environment, and the results are compared with those of conventional (proportional integral derivative) PID and (particle swarm optimization) PSO controllers. To validate the simulation results, a 350-W hardware prototype is implemented, and the voltage ripple, efficiency, and power factor under different load conditions are analyzed and tabulated. The comparative study clearly indicates that the proposed converter topology with a closed loop control scheme using the GWO algorithm improves the power factor to 0.9732 and reduces the voltage ripple to 0.12% with a conversion efficiency of 98.25%.     

基于六脉波交交变频的分频启动方法研究

在分析六脉波交交变频的基础上及根据软启动中的电压双斜坡启动原理,提出了一种基于六脉波交交变频的分频启动方法。该方法根据交交变频原理和晶闸管触发规律,在电动机启动时,直接在电动机定子侧加电动机启动所需最小转矩所对应的电压值,然后逐级增加变频输出电压值,直至最终所需电压。仿真结果表明,通过合理选择变频输出电压的大小,调节每个等级电压作用的时间,能够有效控制电动机分频启动过程中定子电流的大小,获得良好的转矩变化曲线,改善电动机启动性能。     

基于ML4841的具有APFC功能的AC/DC变换器设计

AC／DC变换器具有体积小、重量轻、变换效率高等优点，而被广泛地应用到从工业到民用的各个领域。但随之而来的对供电系统的污染的缺点也越来越引起人们的广泛关注，最主要的是由于谐波电流的增加从而使电网的功率因数降低，无功功率增加。本文简要分析了造成这种问题的原因及解决方法，以及采用ML4841构成具有有源功率因数校正功能的AC／DC变换器的设计方法，并给出了典型电路。采用这种电路可使功率因数提高到接近于1。     

矩阵变换器励磁控制的无刷双馈风力发电系统

应用在双馈风力发电系统中的功率变换器必须具有功率双向流动的能力, 交直交循环变流器和交交矩阵变换器都可满足功率的双向流动要求. 而矩阵变换器能同时提供正弦的输入电流和输出电压, 输入电流可调节为超前、滞后或同相于输入电压, 输出电压可实现幅值、频率和网侧功率因数的独立控制. 利用矩阵变换器, 通过控制无刷双馈电机控制绕组的电压幅值、频率, 为风力发电系统提供励磁. 压频比控制器采用模型参考模糊自适应控制策略, 对电机的转速和功率因数进行控制. 采用DSP,CPLD构建了基于四步换流方案的矩阵变换器实验励磁系统, 仿真和实验结果验证了系统设计的正确性、可行性和稳定性, 为矩阵式变换器的实际应用提供了实验基础.     

模糊PI在船用交流电机直接转矩中的运用

基于船用三相交流电机直接转矩增加模糊PI控制,改善电机的调速性能。根据三相交流电机数学模型,和按定子磁链控制的直接转矩控制理论,再增加模糊PI进行偏差调节,最后用Matlab/Simulink软件搭建电机仿真模型。实验结果表明基于模糊PI的三相交流直接转矩电机系统比传统PI控制的电机响应速度更快、动稳态性能更好,可满足实际电机调速要求。     

基于MATLAB的三闭环交流伺服运动控制系统仿真与设计

针对交流伺服运动控制系统,在PMSM伺服系统电流环和速度环的基础上,进行位置环设计,保证伺服电机位置跟踪的精确性。同时,利用S曲线加减速算法进行速度规划,减小电机在加减速过程中的机械振动,以保证控制系统的稳定性和快速性。在MATLAB/Simulink中建立伺服系统仿真模型,仿真结果表明,上述方法能使系统具有很好的精确性、快速性和抗扰动性。     

Output‐Feedback Nonlinear Adaptive Control of Single‐Phase Half‐Bridge Ups Systems

We consider the problem of controlling single‐phase half‐bridge power converters in UPS systems operating in the presence of changing load. The control objective is twofold: (i) ensuring a satisfactory power factor correction (PFC) at the grid–UPS connection; (ii) guaranteeing a tight regulation of the DC bus voltage and the half‐bridge inverter output voltage despite changes in load. The considered control problem entails several difficulties including: (i) the high dimension and strong nonlinearity of the system; (ii) the numerous state variables that are inaccessible to measurements; (iii) the uncertainty that prevails on some system parameters. The problem is dealt with using a multi‐loop nonlinear adaptive control system that makes use of the backstepping design technique. The inner loop ensures the PFC objective and involves an adaptive observer estimating the grid voltage and impedance parameters. The intermediary loop regulates the inverter output voltage to its reference, which is a sinusoidal wave, and it also contains an observer estimating the current in the inverter coil. The outer loop regulates the DC bus voltage up to small size ripples. The controller performances are formally analyzed using system averaging theory.     

Output feedback control of a three‐phase four‐wire unified power quality conditioner

The increasing penetration of power electronics in electrical equipment entails a significant impact on the deterioration of power supply quality. In this paper, the problem of power quality is addressed for distorted three‐phase four‐wire power grids supplying non‐linear unbalanced loads. A unified power quality conditioner (UPQC) is considered to ensure satisfactory electrical energy quality. To this end, a UPQC controller is designed to meet four control objectives: i) compensation of the harmonics and the reactive load currents; ii) compensation for the harmonic voltages at the point of common coupling (PCC); iii) cancelation of the neutral current; iv) and regulation of the inverter DC voltage. The control design relies on the UPQC nonlinear model that accounts for the electrical grid line impedance. Unlike previous works, the proposed controller features an output‐feedback nature as it combines a nonlinear regulator, designed with a sliding‐mode technique, and a state observer designed using a Lyapunov stability based technique. The latter provides the former with online estimates of the series filter AC voltages, which are not assumed to be accessible to measurements. The closed loop error system is analyzed using the average stability approach. It turns out that all (tracking and estimation) errors are asymptotically vanishing, except for the DC bus voltage tracking error, which is periodic in steady‐state with an amplitude depending on the (DC bus) capacitor, the larger the capacitor the smaller the steady‐state DC voltage tracking error level. This theoretical result is confirmed by simulations involving wide range variations of the load current.