基于Lyapunov控制策略的光伏储能型qZSI控制系统

光伏发电采用储能型准Z源逆变器(quasi-Z-source inverter, qZSI)能够降低功率波动,但非线性储能型qZSI常采用线性PI控制策略,难以达到理想的控制性能,为此提出基于非线性Lyapunov控制的储能型qZSI控制系统。首先,为满足负载功率要求,设计出储能单元能量管理系统;然后,根据Lyapunov理论为储能型qZSI系统设计出能量存储函数和控制律,并选取合适的Lyapunov控制增益;最后,在Matlab/Simulink仿真平台上,在4种不同工况下对所提Lyapunov控制与传统PI控制两种控制系统做了控制性能实验仿真比较,结果表明所提Lyapunov控制系统的响应速度更快、控制精度更高、鲁棒性更强。     

Nonlinear Decentralized Feedback Linearizing Controller Design for Islanded DC Microgrids

This paper aims to design decentralized controllers for different components in islanded DC microgrids. The major components in the DC microgrid as considered in this paper include a fuel cell, solar photovoltaic (PV) unit, and battery energy storage system (BESS) along with critical and non-critical loads. The main control objective is to maintain the power balance within the DC microgrid through the regulation of the common DC-bus voltage. The controllers are designed based on the dynamical models of the fuel cell, solar PV unit, and BESS. The feedback linearization technique is employed to obtain the control laws, which simplifies the original dynamical models and decouples different components in the form of several subsystems. In this way, the feedback linearization technique allows different components in DC microgrids to achieve the desired control objectives by using only the local information (i.e., in a decentralized manner). The performance of the proposed decentralized controllers for different components is evaluated on a test DC microgrid under different operating conditions. Simulation results demonstrate that the proposed control scheme performs in a much better way as compared to an existing proportional integral controller.     

MPC-Based Distributed Control for Intelligent Energy Management of AC Microgrids

Abstract

Power scheduling of distributed storage devices and renewable energy resources in microgrids is crucial for their reliable and optimal operation. Conventionally, the power scheduling problem is solved with a centralized energy management control, which has access to all the information from the overall system. This type of control has limitations related to computational burden, communication latencies, and missing information. Therefore, the primary objective of this paper is to propose a distributed energy management strategy, to reduce the operational cost of microgrids, and to enhance the computation time. The strategy is formulated based on the model predictive control method since it allows the control action in the current time-step to be optimized while taking into account the future time-steps. Outputs of the energy management system are the optimal power references generated for all energy resources based on the system’s demand, constraints, and objective functions. To illustrate the effectiveness of the distributed model predictive control, the proposed algorithm is validated through simulation, on a microgrid candidate via MATLAB/Simulink, and controller hardware-in-the-loop experiment on a LabVIEW platform using National Instruments control devices (myRIO). The results will show the computation time in the distributed IEM method is improved compared to centralized IEM. Additionally, the results will show the robustness of the distributed IEM in the plug and play scenario.     

A Flexible Voltage Control Strategy Based on Stage-Division for Microgrids

The occurrence of power flow reversal and off-limit of the voltage on common bus becomes more frequent because of the increasing penetration of renewable energy sources (RES) in microgrids. To guarantee the safe and stable operation, adjusting the power output of RES-based inverters to avoid the off-limit voltage is necessary. Considering the apparent power characteristics of inverters, as well as the minimum participation of active power, a voltage control strategy based on stage division to be within the voltage limit is investigated in this paper. In the case of unknown demand and distribution of loads, the proposed control strategy is able to make full use of the apparent power to regulate voltage using simple calculations, while the performance in economical operation is satisfactory. Simulation results prove the effectiveness of the proposed method on the common bus off-limit voltage adjustment.     

Microgrids: Architectures,Controls, Protection,and Demonstration

Abstract—In the recent years, there has been a growing interest in the concept of microgrids to integrate distributed generation systems and to provide higher reliability for critical loads. Several microgrid demonstration projects have been implemented to investigate further and advance this emerging concept. This article provides a detailed review of microgrid systems. It describes different architectures, including AC, DC, and hybrid systems. Various microgrid components, including sources, converters, and loads, are illustrated. Microgrid management and controls are discussed, and a modified natural droop control is described in detail. Both physical layers and standard protocols are explained for communication in the microgrid structure. The unique protection complexities have been raised and discussed in the presence of distributed generations and bidirectional power flow. A demonstration of a military microgrid system at Fort Sill is illustrated, and the experiment of a typical microgrid operation scenario is provided.     

直流微网混合储能控制及系统分层协调控制策略

为了充分利用超级电容动态响应快、锂电池能量密度高的特点来提高微网储能系统的动态特性和运行寿命,利用这2种储能器件构成了光伏型直流微网的混合储能系统(HESS).基于对超级电容和锂电池储能下垂特性的分析和工作区间的划分,提出改进型混合储能控制策略;再根据直流微网系统的功率方程、母线电容储能变化与电压变化方程,导出直流母线电压变化与系统功率流向之间的关系,提出对光伏型直流微网的电压分层协调控制策略.实验结果表明,该策略根据电压变化将直流微网的运行划分为5个层区,通过检测直流母线电压的变化量来决定系统的运行层区及光伏、超级电容和锂电池功率变换器的工作方式,保证各层区都有相应变换器来调整直流母线电压、平衡系统功率,实现直流微网电压稳定的控制目标.因此,基于混合储能系统的电压分层协调控制策略能够有效调节直流母线电压,保证直流微网的功率平衡.     

混合储能系统平抑风力发电输出功率波动控制方法设计

风力发电系统输出功率的随机性对大规模风电并网会产生诸多不利影响,近年来采用储能装置平抑风电输出功率的研究取得了一定进展.文中分析了单独采用蓄电池组或超级电容器对风力发电输出功率进行补偿时的不足之处,在此基础上构架了采用蓄电池组和超级电容器的混合储能系统,并进一步提出了利用其平抑风力发电输出功率的控制方法.所提出的控制方法将补偿功率分为高频和低频2个部分进行补偿,一定程度上克服了储能设备单独使用时的不足,并且在补偿过程中考虑了电网调度的需求.经仿真验证该方法能够较好地平抑风力发电系统输出功率.     

轨道交通超级电容能量回收控制系统设计

根据能量回收系统检测、控制策略与通信功能要求,设计了控制系统软硬件,较好实现了对能量回收系统的控制。系统通信部分采用光纤CAN总线进行内部通信,有效解决了高压强电磁环境抗干扰问题。文章还设计了一种简易光纤集线器,用于实现光纤构成CAN总线形式。     

基于无源性理论的光伏储能型准Z源并网逆变器控制方法研究

储能型准Z源逆变器（qZSI）在光伏发电中具有突出优势,有助于减少光伏发电系统中的功率波动。为解决比例微分（PI）控制响应速度慢、超调量大、控制参数多且不易确定等问题,提出储能型qZSI的非线性无源控制方法。首先,对储能型qZSI无源控制系统进行无源性和稳定性证明;然后,依据储能型准Z源的E-L模型,设计无源控制器;最后,通过Matlab/Simulink验证了在光伏光照变化及网侧功率变化时,采用无源控制方法的优越性。与PI控制器对比,设计的无源控制器响应速度更快、控制参数更少,实现了对系统的鲁棒性控制,获得了更好的动态性能。     

变风速下永磁同步发电机无源线性反馈控制设计

为了实现永磁同步发电机(permanent magnetic synchronous generator,PMSG)的最大功率跟踪(maximum pow er point tracking,M PPT),文章设计了一款无源线性反馈控制(passivity-based linear feedback control,PBLFC)。首先,基于无源控制理论构建能量函数,通过详细分析系统各项的物理意义,保留有益系统的非线性项以改善其暂态响应特性。其次,引入线性反馈控制作为额外输入,通过能量重塑使得能量函数中的能量得以快速耗散,进而使PMSG能在快速时变风速下有效实现MPPT。此外,对闭环系统稳定性进行了深入分析,验证了闭环系统的稳定性。最后,进行了4个算例研究,即阶跃风速、随机风速、电网电压跌落和参数不确定。仿真结果表明,与矢量控制(vector control,VC)、反馈线性化控制(feedback linearization control,FLC)相比,PBLFC在各种工况下均能快速稳定地捕获最大风能,且其故障穿越(fault ride-through,FRT)和鲁棒性得到明显改善。     

Optimal Resource Management of Microgrids in a Competitive Market Environment Using Dual Layer Control Approach

Abstract

Renewable integrated microgrids effectively contribute in reducing GHG emissions substantially, at a global level. A multi-agent control system to facilitate information exchange for a microgrid participating in the deregulated framework of the electricity market is proposed. A novel energy management system, aimed at the effective utilization of RES and stored energy in PHESS in order to ensure maximum priority based social benefit to the microgrid controller is presented. The intermittent nature of RES which might cause uncertainties in availability during real-time dispatch, is effectively dealt in the proposed dual layer control approach, through optimal usage of PHESS and employment of load prioritization technique in the proposed renewable microgrid. Thus, the research carried out in this work not only ensures the committed power exchange is maintained constant in both DASL and RTDL, but also contributes significantly in PBSB maximization of the microgrid, while managing real-time uncertainties in RES availability. The importance of pre-prioritizing the loads is put forth, in order to ensure that, if load curtailing needs to be done during peak demand intervals, the critical loads must not suffer. The developed algorithm has been successfully implemented on a 16 bus microgrid interconnected with a 30 bus main grid.     

基于DSP的单相光伏并网控制系统的设计

提出一种基于改进型重复控制和传统PI控制的光伏并网复合控制策略,重复控制器用来减小并网电流的稳态误差,传统PI控制用米提高系统的动态性能.为验证提出的算法,搭建了基于TMS320F2812的单相光伏并网逆变系统实验模型.实验结果表明.提出的算法能够减少并网电流谐波,同时系统兼顾了良好的动静态性能.     

三相四线制PV-AF系统的模型预测电流控制策略

提出了一种基于模型预测电流控制(model predictive current control,MPCC)的具有有源滤波功能的光伏并网(photovoltaic power generation and active filter,PV-AF)系统控制策略。电流环采用模型预测控制(model predictive control,MPC)方法,在???坐标系下实现对光伏逆变电流指令和谐波补偿电流指令的无静差跟踪,使PV-AF系统将光伏阵列的能量注入交流电网的同时,有效补偿本地并联负载谐波电流。建立了MPC中的预测模型、优化函数等,分析了模型参数对系统稳定性和控制精度的影响。实验结果验证了所提策略的有效性。     

直流微网中混合储能系统的无互联通信网络功率分配策略

直流微网中通常采用混合储能系统作为缓冲环节,对分布式能源和负载引起的不同时间尺度功率波动进行补偿。为实现功率在能量密度型储能元件和功率密度型储能元件之间合理分配,提出无互联通信网络的分层控制策略。其中,底层控制以电压变化率作为虚构的信息载体,通过设置不同储能接口变换器输出电压关于功率的"灵敏度",确保超级电容在负载突变瞬间能够提供大部分功率;二次控制对底层控制产生的稳态误差进行补偿,以实现输出电压稳定,并保证超级电容稳态电流为零。在此控制框架下,各储能单元仅需本地信号即可实现自主协调运行,避免了互联通信网络所带来的经济性和可靠性问题。最后,实验结果验证所提方法的可行性和有效性。     

超级电容储能系统鲁棒分数阶PID控制设计

针对超级电容储能系统(supercapacitor energy storage system,SCES)设计了一款鲁棒分数阶PID(robust fractional-order PID control,RFOPID)控制.首先,利用高增益扰动观测器(high-gain perturbation observer,H...     

风储交流微电网自动功率平衡控制策略

风储交流微电网主要包含风力发电设备、储能系统和交流负荷。在风储微电网中,需要建立发电、储能和负荷间的协同功率调控机制,以确保风能得以高效利用;同时尽可能避免储能系统发生过度充电与放电。为此,提出了一种适用于风储交流微电网在离网运行模式下的自动功率平衡控制策略。在负荷轻载下,通过储能系统主动改变微电网频率,由风机主动降功率,放弃部分风能,使得电池不易过度充电;在负荷重载下,微电网频率主动上升,主动切除部分负荷,使得电池不易过度放电。暂态数值仿真说明了该控制策略可实现交流微电网的功率自动平衡,同时有效避免了储能系统的过度充电与放电。     

一种新的三相Boost-PWM整流器控制技术

针对传统的三相Boost-PWM整流器控制技术在电网电压不平衡和变换器输入阻抗不相等时控制性能不理想,本文提出一种新的控制方法。首先分析和建立了三相Boost-PWM整流器的数学模型,该模型放宽了原控制方法中要求电网电压平衡和输入阻抗相等的条件,在保持输出功率不变的基础上,求出三相电流的期望值。在电流环控制上,采取正负序分量分解和静止的三相到两相坐标变换,在两相坐标系中,实现对正序分量幅值和负序分量幅值的分别控制。仿真和实验结果表明,该方法在电压平衡或不平衡下均能得到低次谐波的输入电流和单位功率因数,在输入阻抗不平衡度达到三倍时,仍能得到较高的功率因数。     

电池储能管理系统控制策略的设计与实现

从储能系统的应用角度出发,通过理论的研究,并结合实际的工程项目,论述了满充放及电池容量标定控制策略、恒功率/恒电流按时间控制策略、固定运行模式控制策略、光储协调控制策略以及负荷预测与削峰填谷等几种常用的储能系统控制策略设计和工程实现。     

基于寿命量化的混合储能系统协调控制参数优化

混合储能系统控制策略中参数对控制效果具有一定影响,应量化分析其影响并进行参数优化。文中采用考虑自放电率和充放电效率等因素影响的储能系统数学模型;在基于锂电池充放电状态的混合储能系统控制策略基础上,提出超级电容储能荷电状态协调响应裕量指标;结合适用于实际不规则充放电应用的锂电池寿命量化模型,建立基于锂电池量化寿命的混合储能系统协调控制参数优化模型。算例分析表明,合理选择混合储能系统协调控制参数可延长锂电池使用寿命,进而提高混合储能系统的整体性能。     

带储能的光伏发电能量优化控制方案设计

以带储能的光伏发电系统为研究对象,通过对系统结构的分析,得到系统各部分之间的能量关系。介绍了各功能模块的控制方法,在此基础上以系统经济效益最大化以及提高负荷利用效率为目标,提出一种能量优化控制方案,并对该方案进行了算例分析。结果表明,该方案可使系统节约用户电费约10%,在保证光伏电能就地有效利用的同时,有效地提高了系统经济性。