Research on Mixed Logic Dynamic Modeling and Finite Control Set Model Predictive Control of Multi-Inverter Parallel System

Parallel connection of multiple inverters is an important means to solve the expansion,reserve and protection of distributed power generation,such as photovoltaics.In view of the shortcomings of traditional droop control methods such as weak anti-interference ability,low tracking accuracy of inverter output voltage and serious circulation phenomenon,a finite control set model predictive control(FCS-MPC)strategy of microgrid multiinverter parallel system based on Mixed Logical Dynamical(MLD)modeling is proposed.Firstly,the MLD modeling method is introduced logical variables,combining discrete events and continuous events to form an overall differential equation,which makes the modeling more accurate.Then a predictive controller is designed based on the model,and constraints are added to the objective function,which can not only solve the real-time changes of the control system by online optimization,but also effectively obtain a higher tracking accuracy of the inverter output voltage and lower total harmonic distortion rate(Total Harmonics Distortion,THD);and suppress the circulating current between the inverters,to obtain a good dynamic response.Finally,the simulation is carried out onMATLAB/Simulink to verify the correctness of the model and the rationality of the proposed strategy.This paper aims to provide guidance for the design and optimal control of multi-inverter parallel systems.

Research on AC Electronic Load with Energy Recovery Based on Finite Control Set Model Predictive Control

Nowadays,AC electronic loads with energy recovery are widely used in the testing of uninterruptible power supplies and power supply equipment.To tackle the problems of control difficulty,strategy complexity,and poor dynamic performance of AC electronic load with energy recovery of the conventional control strategy,a control strategy of AC electronic load with energy recovery based on Finite Control Set Model Predictive Control(FCSMPC)is developed.To further reduce the computation burden of the FCS-MPC,a simplified FCS-MPC with transforming the predicted variables and using sector to select expected state is proposed.Through simplified model and equivalent approximation analysis,the transfer function of the system is obtained,and the stability and robustness of the system are analyzed.The performance of the simplified FCS-MPC is compared with space vector control(SVPWM)and conventional FCS-MPC.The results show that the FCS-MPC method performs better dynamic response and this advantage is more obvious when simulating high power loads.The simplified FCS-MPC shows similar control performance to conventional FCS-MPC at less computation burden.The control performance of the system also shows better simulation results.

Finite-Control-Set Model Predictive Control of Permanent Magnet Synchronous Motor Drive Systems——An Overview

Permanent magnet synchronous motors(PMSMs)have been widely employed in the industry. Finite-control-set model predictive control(FCS-MPC), as an advanced control scheme, has been developed and applied to improve the performance and efficiency of the holistic PMSM drive systems. Based on the three elements of model predictive control, this paper provides an overview of the superiority of the FCS-MPC control scheme and its shortcomings in current applications. The problems of parameter mismatch, computational burden, and unfixed switching frequency are summarized. Moreover, other performance improvement schemes, such as the multi-vector application strategy, delay compensation scheme, and weight factor adjustment, are reviewed. Finally, future trends in this field is discussed, and several promising research topics are highlighted.

Finite Control Set Model Predictive Current Control of a Five-Phase PMSM with Virtual Voltage Vectors and Adaptive Control Set

This paper presents an improved finite control set model predictive current control(FCS-MPCC)of a five-phase permanent magnet synchronous motor(PMSM).First,to avoid including all the 32 voltage vectors provided by a two-level five-phase inverter into the control set,virtual voltage vectors are adopted.As the third current harmonics can be much reduced by virtual voltage vectors automatically,the harmonic items in the cost function of conventional FCS-MPCC are not considered.Furthermore,an adaptive control set is proposed based on voltage prediction.Best control set with proper voltage vector amplitude corresponding to different rotor speed can be achieved by this method.Consequently,current ripples can be largely reduced and the system performs much better.At last,simulations are established to verify the steady and transient performance of the proposed FCS-MPCC,and experiments based on a 2 kW five-phase motor are carried out.The results have validated the performance improvement of the proposed control strategy.

Finite control set model predictive control of three-port converter for interfacing a PV-battery energy storage system to a three-phase stand-alone AC system

This paper proposes a multiport bidirectional non-isolated converter topology that provides advantages in terms of simultaneous multiple operations,single-stage conversion,high power density and reduced power losses due to the lower number of switches.The proposed multiport converter uses a centralized non-linear controller known as a finite control set model predictive controller to manage the flow of power between different ports.It deals with the parallel operation of photovoltaic and battery energy storage systems for stand-alone alternating current(AC)systems.The converter connects the lower voltage battery to the photovoltaic port using a bidirectional buck/boost converter and the photovoltaic port is linked to the stand-alone AC load through a three-phase full-bridge inverter.Each leg of the three-phase converter will act as a bidirectional direct current(DC)/DC converter as well as an inverter simultaneously.Only six switches manage the power transfer between all the connected ports of photovoltaic-battery energy storage system linked to the stand-alone AC load.The proposed multiport converter is mathematically modelled and controlled by a finite control set model predictive controller.The system is validated in simulation(1-kW rating)and experimental environment(200-W rating).The hardware prototype is developed in the laboratory and the controller is implemented on the field-programmable gate array board.Two independent case studies are carried out to validate the efficacy of the system.The first scenario is for a change in solar irradiance,while the second scenario is for a change in the output load.

Model Predictive Control-Based Direct Torque Control for Matrix Converter-Fed Induction Motor with Reduced Torque Ripple

To reduce the torque ripple in motors resulting from the use of conventional direct torque control(DTC),a model predictive control(MPC)-based DTC strategy for a direct matrix converter-fed induction motor is proposed in this paper.Two new look-up tables are proposed,these are derived on the basis of the control of the electromagnetic torque and stator flux using all the feasible voltage vectors and their associated switching states.Finite control set model predictive control(FCS-MPC)has then been adopted to select the optimal switching state that minimizes the cost function related to the electromagnetic torque.Finally,the experimental results are shown to verify the reduced torque ripple performance of the proposed MPC-based DTC method.

电容电压平衡的四电平有源中性点钳位逆变器的改进模型预测电流控制

多电平有源中点钳位(ANPC)逆变器具有功率器件电压应力小、电流谐波低和器件损耗可调控等优点,被广泛应用于工业驱动中。针对四电平ANPC(4L-ANPC)逆变器的控制与调制研究相对较少,现有的调制方案实现复杂,中点电压(NPV)控制难度较大。因此,该文针对三相4L-ANPC逆变器,提出一种改进的有限集模型预测电流控制(FS-MPCC)算法,避免了复杂的调制过程。首先,使用仅包含电流误差的代价函数对位于六边形顶点的6个大电压矢量进行寻优;其次,对参与第一步寻优的大矢量划分扇区,使用包含电流误差和电容电压误差的代价函数对最优大矢量所在扇区的所有电压矢量滚动寻优,得到目标电压矢量并作用于逆变器;最后,仿真和实验结果表明,与传统的FS-MPCC相比,所提方法在降低系统计算负担的同时,还具有较好的控制性能和电容电压平衡能力。

基于FCS-MPC的分布式HESS功率协调控制

针对孤岛直流微电网中分布式混合储能系统(HESS)协调运行问题,提出一种基于有限控制集模型预测控制(FCSMPC)的功率协调控制策略。该策略采用小波包变换来分解分布式HESS的功率需求,由于分解后信号的特点和分布式HESS中蓄电池初始状态的不同,于是对分解后最低频信号基于蓄电池荷电状态(SOC)设计自适应因数来进一步再分解。由于DC/DC变换器开关状态组合数量较少,使得多步FCS-MPC的滚动优化计算量较少,于是采用FCS-MPC取代双闭环PI控制,提高系统动态响应。搭建含有分布式HESS的孤岛直流微电网模型,并做了3种方案的仿真对比,验证该策略有效平缓了直流母线波动并实现蓄电池SOC一致。该策略有利于提高电网运行的稳定性,并延长蓄电池使用寿命。

基于模糊PID型代价函数的永磁同步电机模型预测电流控制

针对永磁同步电机控制中有限集模型预测电流控制在参数失配时稳定性能和动态性能有所下降的问题,提出一种基于模糊PID型代价函数的模型预测电流控制方法。该控制方法设计了一种包含比例、积分和微分项的代价函数,将传统的电流误差作为比例项实现转速的跟踪,电流误差的积分作为积分项用来消除预测误差,预测电流的差值作为微分项减小转速纹波。同时使用加入了滤波器的模糊控制对PID参数进行动态调整。该控制方法可以在参数失配的情况下降低转速振荡,提高动态响应能力,降低参数失配对控制器性能的影响,同时保留在参数匹配时的各项性能。仿真与实验结果表明,该方法较传统有限集模型预测电流控制在参数失配时有更快的响应速度、更小的转速振荡和更好的负载突变响应。

基于多参数辨识的永磁同步电机磁链预测控制

在永磁同步电机(PMSM)有限集模型预测磁链控制策略(FCS-MPFC)中,磁链给定值计算、实际值获取以及未来值预测都要用到电机参数。受工况和温度的影响,电机参数具有变化性,参数偏差将影响实际预测控制性能。为提高控制系统鲁棒性,需要对电机d、q轴电感和永磁磁链进行在线辨识。鉴于此,该文提出了永磁同步电机多参数辨识方案,并基于此设计了FCS-MPFC策略。首先,依据电机稳态方程,设计了广义比例积分观测器(GPIO)对PMSM的q轴电感和永磁磁链进行辨识。其次,利用FCS-MPFC中电机定子电流变化较大的特征,提出了基于电流变化量的d轴电感辨识方法,克服了多参数辨识的欠秩问题。再次,依据FCS-MPFC策略下逆变器电压输出特性,优化设计了电流采样,有效避免了逆变器死区对辨识效果的影响。最后,针对磁链预测过程,设计了基于GPIO的磁链预测模型,进一步提高磁链预测的参数鲁棒性。该文的分析、设计以及性能提升均得到实验验证。

基于三端柔性直流的光热储能站与新能源场站功率协同控制策略

新能源基地大多经传统交流方式接入高压交流或直流外送通道,为解决大规模新能源经交流接入方式下并网容量小、损耗大,以及功率波动对电网稳定性影响等问题,构建了一个基于柔性直流输电并网的风电和光伏、光热储能及电网三端柔性直流系统。基于直流电压-有功功率特性,提出一种适用于该系统的站间协调控制策略,根据柔性直流输电系统的直流电压波动情况,调整光热储能机组的出力,以平抑风、光功率波动,降低其对电网的影响。针对光热储能侧换流站,采用直流电压裕度下垂混合控制策略,通过控制器参数配置,抑制控制模式切换过程中的暂态过电压,提高系统响应速度。最后,在PSCAD/EMTDC中搭建三端柔性直流系统仿真模型,验证所提控制策略的有效性。

基于拓展控制集的PMSM有限控制集无模型预测电流控制策略

永磁同步电机(permanent magnet synchronous motor,PMSM)具有高效率、高功率密度与高可靠性等优势,已在工业界得到广泛应用。文中针对PMSM驱动系统,提出基于拓展控制集的有限控制集无模型预测电流控制(finite-control-set model-free predictive current control,FCS-MFPCC)。首先,分析PMSM系统的数学模型并详述有限控制集模型预测电流控制(finite-control-set model predictive current control,FCS-MPCC)的原理。其次,介绍基于线性扩张状态观测器(linear extended state observer,LESO)的传统FCS-MFPCC。针对传统FCS-MFPCC稳态性能不足的问题,采用基于离散空间矢量调制(discrete space vector modulation,DSVM)的控制集拓展方案,将控制集的电压矢量数目拓展至25。然后,为解决拓展控制集带来的高计算量问题,提出一种快速寻优策略,阐述该策略的实施原理与流程。最后,基于一台500 W PMSM实验平台,对比传统FCS-MFPCC与所提FCS-MFPCC的控制性能,验证所提算法的有效性与优越性。实验结果表明,所提算法能够有效提升系统稳态性能,且定子绕组电流总谐波畸变率由10.07%降低至6.48%。

基于双层级联模型预测电流控制的零序环流抑制策略

逆变器并联系统在运行过程中,由于功率分配不均、控制参数失配等因素导致两逆变器开关状态不同步,使得环路中产生零序环流。为此,提出一种基于双层级联模型预测电流控制的零序环流抑制策略,通过将零序环流加入综合目标函数,选取最优开关状态组合实现零序环流的抑制。同时,通过改变目标函数结构、利用双层级联的方式进行开关状态组合选取,在消除权重系数对控制系统影响的同时减轻计算负担。最后,通过仿真和试验验证了所提控制策略的有效性。

基于改进有限状态多步模型预测控制的MMC-APF技术研究

基于模块化多电平变换器的有源电力滤波器MMC-APF(modular multilevel converter-based active power filter)是用来处理非线性负载对电网带来的污染问题最有效的拓扑之一。提出了一种基于改进有限状态多步模型预测控制的MMC-APF,仅通过基波同步旋转坐标系实现对所有谐波的控制。首先,使用PI加重复控制的电流环复合控制得到上、下桥臂预导通子模块数,在此基础上进行多步交流侧电流模型预测,最终得到桥臂投入子模块数的最优解,缩小了寻找目标函数最优电平的搜索范围,无需设计权重因子,每相桥臂子模块的总投入数为[N-1,N+1],交流侧输出电平数最大可达2N+1,提高了MMC-APF交流侧电流补偿精度,并改善了系统动态性能。最后,搭建了MMC-APF平台,仿真和实验结果与理论分析一致,进一步验证了所提研究方案的可行性和有效性。

基于简化空间矢量调制的三电平整流器级联式无差拍控制策略

为解决有限控制集模型预测控制(FCS-MPC)运行过程中计算强度过大与计算时间过长的问题,提出了一种基于简化空间矢量调制的三电平整流器级联式无差拍控制策略,通过构建特定扇区选出最佳电压矢量。为建立精确的系统模型,深入分析三电平整流器,构建二维离散系统数学模型,基于无差拍控制理念设计了一套功率内环与电压外环的双环控制方案,并建立Luenberger观测器对电力扰动及负载变化进行精确估测与补偿,使无功功率与有功功率快速解耦和响应。结合上述系统架构,分别建立常规、单预测、简化预测FCS-MPC模型,并证明其等效性。分析不同约束变量对电压矢量决策的影响,并构建特定选择扇区设计简化的空间矢量调制策略。实验结果表明,所提控制控制策略能够在多重约束条件下改进性能,并且在保持控制效果不变的前提下,大幅度减少计算量。

基于改进SMO的PMSM有限集模型预测电流控制

针对永磁同步电动机三矢量有限集模型预测控制系统对于电机转子信息依赖性较高的问题,利用滑模观测器观测电机转子信息,并对其进行改进,采用新型趋近率函数代替符号函数,削弱系统抖振现象,采用同步旋转坐标系下的滤波器达到补偿相位滞后、增强滤波效果的目的,实现对于转子位置和角速度的准确观测。仿真及实验结果表明采用的该控制方法具有较好的稳定性,改善了系统控制性能。

永磁同步电机预测控制参数畸变影响分析

当永磁同步电机(PMSM)预测控制系统在高温等复杂环境中工作时,受电机齿槽效应、边端效应、饱和效应以及外部干扰的影响,电机参数如定子电阻、d轴电感、q轴电感、永磁体磁链常会发生畸变。针对上述问题,建立了PMSM的有限控制集模型预测电流控制(FCS-MPCC)模型,对不同参数畸变的影响进行分析,计算给出由畸变导致的d、q轴预测电流偏差。对参数畸变范围进行分区设置并依次施加在模型中。在不同畸变程度下,实验分析不同参数畸变对PMSM动、静态性能的影响,包括d、q轴电流、预测电流偏差、电磁转矩以及转速。

神朔铁路万吨重载列车涌动有限集预测控制研究

神朔铁路是我国重要的重载货运线路,重载列车运行环境恶劣,操纵困难,列车涌动严重影响运行平稳性和行车安全。针对神朔铁路行车过程中的涌动问题,文章分析了重载列车涌动发生时的信号特征,搭建了基于弹性阻尼车钩的列车多质点动力学模型,通过仿真分析了重载列车无涌动和有涌动时的运行状态,针对重载列车的涌动问题提出了一种有限集预测控制方法,仿真验证了该预测控制能够减小列车涌动时的速度波动和最大车钩力。

基于FCS-MPC的PMSM自抗扰弱磁控制系统设计与分析

永磁同步电机(Permanent Magnet Synchronous Motor,PMSM)弱磁控制系统常用于电动汽车领域。电动汽车运行于低速时,PMSM需要输出大转矩,以响应快速起步、加速及爬坡需求;电动汽车运行于高速,且超过额定速度时,PMSM处于弱磁状态,需具备一定的带载能力,以满足高速行驶和超车工况。针对PMSM弱磁控制中的转速突变,文章设计了自抗扰控制器(Active Disturbances Rejection Controller,ADRC)替代速度外环PI控制器,对扰动项快速观测和补偿,减小速度突变对系统造成干扰,实现转速精准跟踪。针对转矩项干扰,结合转矩和磁链输出值设计有限集模型预测控制(Finite Control Set Model Predictive Control,FCS-MPC)以替代传统直接转矩控制(Direct Torque Control,DTC),构建令转矩和磁链脉动最小的价值函数,再通过价值函数的计算寻优,选取出最优空间矢量控制信号输送给逆变器。基于ADRC和FCS-MPC的优化作用,弱磁控制系统的抗扰能力、电流和转矩输出精度增强,试验验证了所设计系统的可行性和性能优势。

新能源侧储能系统自治运行的协调控制策略研究

随着“双碳”目标下的新能源占比逐年增加,电网稳定性要求与新能源波动性的冲突愈发凸显,新能源侧标配储能成为解决冲突的重要手段,各地也相继出台了新能源配备储能的相关政策,新能源发电侧配备储能系统的场站逐步增多,为提升新能源发电侧储能系统的深度利用率,提出了储能系统自治运行的协调控制策略。所提策略依据储能系统的现有应用方式,结合一次调频场景、自动发电控制场景、功率预测场景、储能充放电场景,设计了总体技术框架,并进一步探究了各场景下的协调控制策略。通过搭建仿真系统对协调控制策略进行论证,仿真结果表明结合应用场景设计的协调控制策略可以实现储能系统的自治运行,显著提升运行效果。