双馈电机并网前参数优化

分析了双馈并网发电机并网前的数学模型,针对传统电流环的PI调节存在参数整定复杂的问题,引入了含有积分控制的线性二次型最优控制算法LQRI.在双馈电机并网前空载的前提下,建立dq坐标系下的数学模型,给出了双馈电机并网前控制框图,并详细设计了电流内环的LQRI控制算法.针对湘电1.5 MW双馈电机,采用DSP2812进行控制,验证了改进算法的良好性能,消除了LQR控制存在的稳态误差问题,系统的动态、静态性能得到改善.     

基于LQRI控制的三电平PWM整流器的实现

研究了三电平电压型PWM整流器的新颖控制算法,针对传统LQR控制存在稳态误差,提出了含有积分控制的线性二次型最优控制算法(LQRI).建立了基于电网电压定向三电平PWM整流器两相同步旋转坐标系下的数学模型,推导了内环控制的状态方程,实现了电流环控制参数的最优设计,并给出了采用LQRI控制器三电平PWM整流器的整体控制策...     

基于LQR的静止同步补偿器滑模控制研究

在低压配电网中,通常使用静止同步补偿器(STATCOM)补偿无功功率,提出一种综合滑模控制、线性二次型调节器(LQR)方法和空间矢量脉宽调制(SVPWM)的配电网STATCOM(DSTATCOM)新型控制策略,电压外环采用滑模控制来调节和稳定直流电压,同时改变系统动态性能,电流内环采用LQR方法进行设计。搭建了低压DSTATCOM实验平台,实验结果表明采用新型控制策略的DSTATCOM直流电压动态响应快,稳态误差小,系统鲁棒性好,能有效补偿电网无功功率,实现了单位功率因数,电网电流的总谐波畸变率(THD)低于5%。     

基于内模控制的VSC-HVDC风电并网系统控制策略研究

针对轻型直流输电技术(VSC-HVDC系统)在采用双闭环PI控制时的参数多并且整定复杂的问题,采用内模控制原理对PI参数整定算法进行改进,改进算法只需调节一个参数,使参数整定变得简单快捷,同时可以保留双闭环PI控制系统优良性能。仿真结果表明,基于内模控制原理的一个参数整定的VSC-HVDC系统参数保有双闭环PI控制系统的优良性能,系统鲁棒性好,控制精度高,动态响应快。     

基于QPR与TD-FUZZY-PI双闭环单相PWM负载控制策略研究

针对PWM整流电路中晶闸管器件的特点及系统参数随环境的摄动造成直流电压输出不理想的问题,提出了新的双闭环控制策略,即电压外环采用跟踪-微分器+参数自整定模糊PI(TD-FUZZY-PI)控制,电流内环采用准比例谐振(QPR)控制,并对所用控制策略进行了仿真分析。仿真结果表明:文中方法较传统双闭环PI控制不仅过渡过程具有良好的动、静态特性,波形质量明显得到改善;而且电流内环实现了正弦量幅值和相位的无静差调节,提高了功率因数。     

三相电压型PWM整流器滑模控制算法研究

三相电压型PWM整流器通常采用传统的线性双闭环控制器结构,由于PI控制的滞后性,双闭环PI控制难以保证系统在扰动下具有良好的动态性能。考虑三相电压型PWM整流器的非线性特征,利用滑模变结构对外部干扰和系统参数变化的强鲁棒性,设计了一种采用滑模变结构非线性控制算法。在Matlab/Simulink中搭建了PWM整流器控制系统仿真模型。滑模变结构控制算法与双闭环PI控制算法调节性能的对比表明,滑模变结构控制算法具有更好的动稳态性能。     

三相PWM整流器新型复合控制策略的性能研究

由于三相电压型PWM整流器(VSR)采用传统PI控制策略难以在较大扰动和控制对象变化的情况下获得良好的调节效果,论文在传统的双闭环控制策略的基础上,提出了一种新型双闭环复合控制方法,即将PI控制与模糊控制相结合应用于电压外环控制,并将负载电流作为其前馈补偿,电流内环采用准PR(比例谐振)的控制策略。通过MATLAB/Simulink仿真,结果表明了系统不仅有优良的动稳态性能,而且对外界扰动具有很强的鲁棒性,从而验证了该种控制方案的可行性。     

级联式双向DC-DC变换器的优化控制方法

级联式双向DC-DC变换器的传统双闭环比例-积分(PI)控制方法存在调节器参数多、整定工作量大等不足,而且受限于PI控制的内在局限性,系统的动态性能不够理想。针对级联式双向DC-DC变换器的实际控制需求,综合考虑传统双闭环PI控制和模型预测控制的各自优势,将二者有机结合,构建了一套折中优化的控制方法,即在第一级双向DC-DC变换器中采用传统双闭环PI控制,而在第二级双向DC-DC变换器中设计并实现改进的模型预测控制策略。将提出的优化控制方法与传统双闭环控制和经典模型预测控制分别进行了仿真和实验比较。结果表明,相对于传统的双闭环控制,采用提出的优化控制方法可以显著改善级联式双向DC-DC变换器的动态性能,而相对于经典的模型预测控制,该优化控制方法运算量减少了45.22%。     

基于模糊控制的双闭环直流电机调速系统

为优化双闭环直流电机控制系统、减小双闭环控制系统中传统PI控制器速度超调、解决模糊直流电机控制系统中电流环PI参数调节不能很好地发挥电流反馈作用的问题,提出一种双模糊闭环控制系统,在此双模糊闭环系统中,速度环和电流环均采用模糊控制,通过衰减比例法对双闭环调节器相关参数进行整定。实验仿真结果证明了双模糊闭环控制系统在直流调速控制系统中实现了对转速和电流的有效控制,更优于传统的控制方法。     

双馈风力发电系统双PWM变换器比例谐振控制

在双馈风力发电系统功率变换器及发电机数学模型的基础上,结合比例谐振(proportional resonant,PR)控制器的特性,提出了双脉宽调制(pulse-width modulation,PWM)变换器PR控制策略。该方法充分利用了PR控制器能够在静止坐标系下对交流输入信号无静差控制的优势,将矢量控制策略下的有功电流和无功电流分量转换到静止坐标系下进行调节,实现网侧变换器维持直流电压稳定和调节功率因数的控制任务和双馈电机有功、无功功率的解耦控制,与传统的双闭环PI控制相比,该策略无需繁琐的坐标旋转变换,不存在受温度及电路参数影响的耦合项和前馈补偿项,且易于实现对系统低次谐波电流的补偿,减小了控制算法实现难度,提高了控制系统的鲁棒性和电网电能质量。     

无刷直流电机双闭环模糊自适应控制方法研究

在分析无刷直流电机数学模型的基础上,提出了一种双闭环模糊自适应控制方法。该控制系统是以电流环作为内环,采用传统的PI控制;转速环作为外环,采用PI控制与模糊控制相结合的方法,即模糊自适应控制方法。以速度误差及速度误差变化率作为模糊控制器的输入,大偏差时采用模糊控制,以增强系统的响应速度和鲁棒性;小偏差时采用传统的PI控制,使系统稳态无误差。仿真实验结果表明,相比于传统的PI控制系统,模糊双闭环自适应控制系统具有良好的动、静态特性,以及较强的鲁棒性。     

Adaptive and robust speed control of interior permanent magnet synchronous motor drives

This paper presents a robust speed controller for field oriented controlled interior permanent magnet synchronous motor (IPMSM) drives. The proposed controller is designed using integral variable structure control (IVSC) combined with linear quadratic regulator (LQR). The LQR scheme is used to decide the optimal feedback gain to shape the system dynamics by tuning the IVSC switching plane to guarantee the robustness of the control algorithm. The complete drive is implemented in real-time using digital signal processor (DSP) control board DS1102. The tracking properties and robustness of the proposed scheme are examined through both simulations and experimental work. It guarantees accurate control performance in the presence of parameter variations, step speed change and load disturbances. The performance of IPMSM drive system with a conventional proportional-integral (PI) controller is presented in comparison with the proposed controller. The results show a significant improvement in both the transient and steady state responses over the conventional PI controller.     

基于LQRI方法的蓄电池充电调节器控制策略

为提高卫星电源蓄电池充电调节器(BCR)的工作性能,基于带积分环节的线性二次型调节器(LQRI)设计方法提出了一种新型的BCR控制策略。根据BCR的工作机理,获得了系统的小信号数学模型;通过引入状态积分环节,实现了状态方程的扩维;通过定义二次型性能指标函数和加权矩阵,获得了一种新型BCR状态反馈控制策略,有效消除了系统的稳态输出误差。仿真结果验证了所提控制策略的有效性。     

基于多级线性最优方法的多频段直流附加阻尼控制器设计

通过总体最小二乘-旋转不变技术辨识出系统振荡模式和降阶模型,对应系统的不同振荡模式,利用巴特沃斯带通滤波器将控制器分解为多个频段,基于多级线性最优方法控制和阿克曼公式,设计出带状态观测器的多频段高压直流附加阻尼控制器,为不同频段的振荡模式提供阻尼,实现同时抑制低频振荡和次同步振荡的功能。同时,在PSCAD实际系统中进行了仿真实验,并对比线性二次型最优控制和比例积分控制,证明了本文所设计控制器的有效性和鲁棒性,对于工程实践具有一定意义。     

基于改进粒子群算法的精密隔振系统LQR控制

为解决线性二次型控制器(LQR)权值参数难以通过经验选取最优组合的问题,采用一种贪婪Lévy PSO算法对LQR权值矩阵Q进行寻优。传统粒子群算法易局部收敛,在此基础上加入Lévy飞行原理和贪婪选择方法从而扩大参数寻优范围且提高收敛速度,得出最优权值矩阵Q。对在LQR控制下的双层精密隔振系统模型在扫频激励和随机激励两种情况时隔振对象的加速度响应和位移响应进行分析。最终结果为收敛速度提升75%,针对两种激励情况的加速和位移削弱程度均在90%以上。仿真结果表明贪婪Lévy PSO算法可有效增加种群分布的均匀性提高收敛速度寻得最优解,且在更短的时间内寻得更好的结果,两种激励情况时均能有效实现隔振。     

Excitation control for multimachine power systems

The control of power systems on the basis of energy analysis offers many advantages. An essential condition to achieve this control is the measurement of the angles of the major generator groups, which are available using satellite Global Positioning Systems.This paper develop two strategies based on energy function higher order derivatives to design nonlinear excitation controllers for multimachine power systems taking into consideration field flux decay effects.The design is based on maximum reduction of energy and can be successfully implemented with as many controllers as major modes, when few controllers are available control on the basis of energy function higher order derivatives produce good results.The first strategy is based on energy function higher order derivatives design where one controller is required to control one mode of oscillation.The second strategy capable of suppressing the oscillation modes with only one controller is based on a linear optimal control design where a linear quadratic regulator (LQR) control component added to energy function higher order derivatives design.     

On the issue of control system adjustment of a direct current drive on the modular optimum. Part 1

A mathematical model of a two-loop control system of a dc drive with a control unit realized on the basis of the widely used P and PI controllers was obtained. The optimized parameters of the system are the gain coefficients of the current and speed closed loops and coefficients of the integral components of the corresponding controllers. Two variants of optimization of the system structure and parameters are considered: (1) standard consecutive adjustment of the current and speed loops to the modulus optimum, which leads to a static control system with a P speed controller and a PI current controller; and (2) system adjustment to the modulus optimum as a united whole, which leads to an astatic system with a PI speed controller and a P current controller or without a current controller with proportional current feedback to the power converter input. The formulas for optimal values of adjustable parameters for both variants are obtained. It was shown for instance by simulation in Matlab–Simulink that the system adjusted in accordance with the second variant has better performance indices, such as offset, transient time, and overshooting at a changing set point and disturbance variable.     

Power Quality Enhancement Using Linear Quadratic Regulator Based Current-controlled Voltage Source Inverter for the Grid Integrated Renewable Energy System

This paper presents an optimal control strategy using linear quadratic regulator (LQR) applied in current-controlled voltage source inverter (CCVSI) to control the real and reactive power flow between the renewable energy system (RES) and the grid. It also compensates harmonic current components drawn by the load from the grid terminal. A simplified equivalent circuit is used to develop the reduced order state space model of the three-phase grid connected renewable energy system. This makes the analysis and design of control law simpler by reducing the number of weighing variables used in LQR. The extension real–reactive power (p–q) method implemented in a–b–c frame is used to generate the reference current for controlling the real and reactive power to the grid to minimize the total harmonic distortion (THD) and to achieve unity power factor (UPF) operation at the grid side. The stated technique makes the grid current sinusoidal even under unbalanced grid voltages and the harmonic distortion factors are well within the IEEE limits. The system is simulated under changes in the real power fed from RES to the grid for both balanced and unbalanced grid conditions. The simulation results are validated by the experimental results.     

Optimal tuning of linear controllers for power electronics/power systems applications

This paper presents a new method for tuning various linear controllers such as Proportional-Integral (PI), Proportional-Integral-Derivative (PID) and Proportional-Resonant (PR) structures which are frequently used in power electronics and power system applications. The linear controllers maintain a general structure defined by the Internal Model Principle (IMP) of control theory. The proposed method in this paper is twofold. The first perspective uses the well-known concept of the Linear Quadratic Regulator (LQR) to address the problem as a regulation problem. The Q matrix of the LQR design is then finely adjusted in order to assure the desired transient response for the system. The second perspective redefines the LQR in order to add capability to address the optimal tracking problem and is then generalized to systems with more than two states. These methods are then applied to two specific examples, one in an uninterruptible power supply (UPS) inverter system and the other one in a distributed generation (DG) system. In these examples, the tuning of PR and PI controllers is studied in great detail. These proposed design methods provide an easy and algorithmic procedure without jeopardizing stability or robustness. These tuning methods can also be utilized for linear state-space realization of any power converters. Both examples are supported via simulation and the results, which confirm analytical derivations, are presented and discussed.