基于对偶原理构造三相电流型多电平逆变器拓扑

受三相逆变器拓扑图非平面性的制约,很难直接运用对偶原理实现三相电压型逆变器拓扑与三相电流型逆变器拓扑之间的相互转换。为充分利用三相电压型多电平逆变器的研究成果以便构造三相电流型多电平逆变器拓扑,文章探讨了针对三相电压型二电平逆变器的两种拓扑图平面化处理方法,并分析了用于构造三相电流型多电平逆变器拓扑的可行性。在三相飞跨电容箝位电压型多电平逆变器拓扑基础上,通过增加一个独立电压源获得其平面化的等效电路,并以此作为原始拓扑利用对偶原理提出了一种新型的三相电流型多电平逆变器拓扑。采用多载波SPWM技术对该类逆变器的正确性与合理性进行了仿真验证。     

基于单片机的高精度数字直流电流源设计

本设计以单片机系统为核心,实现了直流电流源的程控电流输出。设计分电源,AD和DA转换,电流源输出,显示和控制模块。系统使用12位的AD和DA芯片,提高了输出电流的精度;输出模块引入PI控制器,有效控制了电路的非线性失真,输出电流无静差跟踪电流给定。实验结果表明:给定电流在20mA-2000mA内变化时,系统输出电流误差小于1mA,电流纹波小于0.2mA。     

直驱式风电机组并网动态性能研究

提出发电机侧整流器采用直接电流控制方式,用以稳定直流侧电压、使发电机侧高功率因数运行,减小发电机损耗;电网侧逆变器对有功、无功功率解耦控制,使风机运行在最大功率点,保证系统以单位功率因数并网,减少并网电流谐波,提高并网电能质量。与传统的控制方式相比,该控制方式具有控制结构简单,发电机侧功率因数高,动态响应快等优点。     

An improved model predictive control of low voltage ride through in a permanent magnet synchronous generator in wind turbine systems

This research investigates a wind energy conversion system based on a permanent magnet synchronous generator (PMSG). In addition, a model predictive control (MPC) is proposed for the PMSG in normal and fault conditions. The most efficient mode of the control algorithm is found for maximum power point tracking in normal conditions and fast dynamic response in fault conditions following the selection of the optimum voltage vector. This method prevents a sudden increase in the DC‐link voltage by storing the active power in the generator rotor inertia. Moreover, during the low voltage, the grid code adoption of the reactive current is injected into the grid side. The performance of the proposed control scheme is evaluated for a wind power generator using MATLAB software. The simulation results demonstrate that the proposed method can safeguard the DC‐link during the fault.     

Intelligent-controlled doubly fed induction generator system using PFNN

An intelligent-controlled doubly fed induction generator (DFIG) system using probabilistic fuzzy neural network (PFNN) is proposed in this study. This system can be applied as a stand-alone power supply system or as the emergency power system when the electricity grid fails for all sub-synchronous, synchronous, and super-synchronous conditions. The rotor side converter is controlled using the field-oriented control to produce three-phase stator voltages with constant magnitude and frequency at different rotor speeds. Moreover, the grid side converter, which is also controlled using field-oriented control, is primarily implemented to maintain the magnitude of the DC-link voltage. Furthermore, an intelligent PFNN controller is proposed for both the rotor and grid side converters to improve the transient and steady-state responses of the DFIG system at different operating conditions. The network structure, online learning algorithm, and convergence analyses of the PFNN are introduced in detail. Finally, the feasibility of the proposed control scheme is verified using some experimental results.     

基于解耦锁相的风电逆变并网控制系统仿真

采取双同步坐标系解耦锁相的方法,检测出不平衡电网电压中的正序分量和负序分量,并利用坐标变换的数学手段建立包括网侧PWM 逆变控制、电压锁相环在内的直驱式风力发电的网侧数学模型,提出电流解耦控制策略,同时结合矢量脉宽调制方法( SVPWM) 对交流侧输出电流实施有效控制。使其能独立控制输出电流的有功分量和无功分量,并使输出电流波形为正弦波且与电网电压同频率同相位,从而减少了对电网电压的谐波污染,并消除电压不平衡的影响,实现三相电网电压幅值不平衡时输出电流与电网电压的精确锁相。还利用MATLAB/Simulink 软件平台搭建了系统的仿真模型,在电网电压平衡和不平衡时分别进行仿真,仿真结果证明控制系统的可行性与有效性,提高了风力发电并网的可靠性。     

Interactive smart battery storage for a PV and wind hybrid energy management control based on conservative power theory

This paper presents interactive smart battery-based storage (BBS) for wind generator (WG) and photovoltaic (PV) systems. The BBS is composed of an asymmetric cascaded H-bridge multilevel inverter (ACMI) with staircase modulation. The structure is parallel to the WG and PV systems, allowing the ACMI to have a reduction in power losses compared to the usual solution for storage connected at the DC-link of the converter for WG or PV systems. Moreover, the BBS is embedded with a decision algorithm running real-time energy costs, plus a battery state-of-charge manager and power quality capabilities, making the described system in this paper very interactive, smart and multifunctional. The paper describes how BBS interacts with the WG and PV and how its performance is improved. Experimental results are presented showing the efficacy of this BBS for renewable energy applications.     

HIERARCHAL CONTROL SYSTEM FOR A VARIABLE SPEED CAGE MACHINE WIND GENERATION UNIT USING NEURAL NETWORKS

A hierarchal control strategy, that addresses three control objectives for a wind generation system, is proposed in this paper. It controls the local bus voltage (to avoid voltage rise), captures the maximum power in the wind and also minimizes the power loss in the induction generator. In the first level, given the instantaneous wind speed, electrical torque and output power, the designed neural networks calculate the desired rotor speed, air‐gap flux and the grid side reactive power. In the second level, the desired current wave shapes (instantaneous three‐phase currents) of the rectifier and the inverter in a double‐sided PWM converter system are calculated. In the third level, the PWM controller guides the system towards the optimum operating conditions. Simulation results show that even as the wind speed changes randomly, the proposed control strategy leads the system to the optimum operating conditions.     

开关磁阻发电系统并网逆变单元仿真研究

开关磁阻发电系统是航空电源发展的新方向,多发电机并网供电在航空电源系统中占有重要地位.为了实现输出电能平稳并网,需要输出电压在幅值、相位和频率上与主汇流条电压保持一致;在汇流条并网电压的变换过程中,采用空间矢量脉宽调制( SVPWM)波控制开关磁阻发电机的三电平逆变器输出模块,即可得到满足要求的电能.仿真实验表明,该发...     

A second-order sliding mode and fuzzy logic control to optimal energy management in wind turbine with battery storage

The optimal control of large-scale wind turbine has become a critical issue for the development of renewable energy systems and their integration into the power grid to provide reliable, secure and efficient electricity, despite any possible constraints such as sudden changes in wind speed. This paper deals with the modeling and control of a hybrid system integrating a permanent magnet synchronous generator (PMSG) in variable speed wind turbine (VSWT) and batteries as energy storage system (BESS). Moreover a new supervisory control system for the optimal management and robust operation of a VSWT and a BESS is described and evaluated by simulation under wind speed variation and grid demand changes. In this way, the proposed coordinated controller has three subsystems (generator side, BESS side and grid side converters). The main function of the first one is to extract the maximum wind power through controlling the rotational speed of the PMSG, for this a maximum power point tracking algorithm based on fuzzy logic control and a second-order sliding mode control (SOSMC) theory is designed. The task of the second one is to maintain the required direct current (DC) link voltage level of the PMSG through a bidirectional DC/DC converter, whereas in the last, a (SOSMC) is investigated to achieve smooth regulation of grid active and reactive powers quantities, which provides better results in terms of attenuation of the harmonics present in the grid courant compared with the conventional first-order sliding controller. Extensive simulation studies under different conditions are carried out in MATLAB/Simulink, and the results confirm the effectiveness of the new supervisory control system.

     

双馈系统在电网故障下不间断运行的研究

为更好地研究风力发电机在一定的电网电压跌落故障下的动态响应,以单台1.5 MW双馈风力发电机(DFIG)为研究对象,设计了Crowbar电路,通过构建电网电压跌落仿真模型,分别对机端电压、电流、转子电流、输出的有功功率和无功功率、直流侧电压、电磁转矩在故障期间的动态响应进行了仿真。探讨了相应的控制策略,为进一步研究低电压穿越标准下的控制策略提供了依据,同时也为研制兆瓦级变频器打下基础。测量结果表明这种控制方式能使DFIG在电压跌落故障下实现不间断运行,有效提高了DFIG风电机组运行的可靠性。     

基于改进型最优梯度法的光伏并网逆变综合控制研究

两级式三相光伏并网逆变器具有控制目标明确,系统效率高的优点。在两级综合协调控制系统中,采用改进型最优梯度法实现最大功率追踪控制,三相电流跟踪解耦控制空间电压矢量调制（sVPwM）实现同步并网。在MATLAB／SIMULINK平台中搭建两级式三相光伏并网逆变系统仿真模型,仿真实验结果表明：系统跟踪最大功率速度快、精度高,且输出电流快速准确跟踪电网电压。     

双馈变速恒频风力发电系统的并网控制研究及其仿真实现

随着风电机组单机容量的不断增大,发电机并网时的电流冲击已不能忽视,必须对并网控制技术进行深入研究。在总结现有风力发电并网技术的基础上,研究双馈变速恒频风力发电机的“柔性并网”问题,即可通过励磁控制调节发电机输出并满足并网条件。研究双馈电（DFIG）的空载模型、变频器的整流控制模型和并网控制模型,建立整个并网发电系统,并通过完整的仿真验证系统建模与控制的有效性。     

直驱式永磁风力发电机软并网与功率调节的控制集成

为实现直驱式永磁同步风力发电机无冲击并网与风能最大跟踪控制, 设计了一种软并网与功率调节一体化的控制集成装置. 基于广义功角特性, 提出了一种对逆变器输出功率进行直接控制, 从而实现最大风能跟踪的控制策略. 新的控制策略可使发电机的转速按所期待的动态运动, 因而具有良好的静态与动态性能. 另外, 该控制律中对电机参数具有很强的鲁棒性, 因而该控制器能适应各种不同参数的同步风力发电机, 成为同步风力发电并网与功率调节的独立装置.     

Intelligent Open Switch Fault Detection for Power Converter in Wind Energy System

This paper proposes a simple and fast fuzzy logic-based open switch fault detection method for rotor side converter (RSC) in doubly fed induction generator (DFIG) wind turbine system. In the proposed scheme, only the mean values of the three-phase rotor currents are used to identify the power switch in which the open-circuit fault has occurred.

The wind energy conversion system model developed for the design and evaluation of the proposed fault detection technique including three principal controls. the first control ensure the regulation of the electromagnetic torque and the reactive stator power (named Rotor Side Converter (RSC) control), the second regulates the DC-link voltage at the desired level (named Grid Side Converter (GSC) control) and in order to achieve maximum power at any wind speed condition a maximum power point tracking (MPPT) control strategy has been used. The simulation model was developed in MATLAB/Simulink environment. The results show that the proposed fault detection scheme is able to rapidly and effectively identify open switch faults among other fault types in a time less than one period.     

电网故障下双馈风力发电机网侧变换器的高阶滑模控制

针对电网故障下对双馈风力发电机网侧变换器的影响,本文采用滑模变结构控制方法,提出了采用增加瞬时功率前馈补偿的高阶滑模变结构控制策略,为此首先简要的分析了双馈风力发电机中双脉宽调制（PWM）型变换器的结构和控制原理,然后根据网侧变换器的数学模型,提出对网侧变换器采用电网电压定向欠量控制,以实现交流侧单位功率因数和直流环节电压控制．提出的方法提高了系统响应速度,克服参数变化和外电压波动的影响．仿真结果表明了该策略的有效性．     

电路参数对无线电能传输的影响及控制策略

无线电能传输(WPT,wireless power transmission)系统的输出电流受原边电流、频率、线圈距离(耦合系数)、负载阻抗等影响.在负载及耦合系数一定时,接收侧的补偿电容影响系统的性能.为了保证系统的传输效率且使得系统输出电流最大,首先给出了WPT电路并进行电路分析,其次讨论结构参数对系统性能的影响,为调节系统最大电流输出提供依据.给出一种系统最大电流输出控制策略,并进行仿真验证.最后仿真对比了不同耦合系数对输出电流、输出功率及传输效率的影响.仿真结果表明,在该控制策略下,适当调整系统电容参数,即可使得系统输出性能最佳.     

双馈风力发电机系统的自抗扰神经网络的励磁控制

在双馈发电机传统控制方式的基础上, 将自抗扰控制技术和BP神经网络相结合结合, 应用于双馈风力发电机并网运行的控制上, 提出了一种新的双馈风力发电机并网运行控制方案. 该控制方案具有内外两个控制环, 内环通过BP神经网络实现双馈风力发电机的转子d-q轴电流控制, 外环通过自抗扰技术实现双馈风力发电机定子侧的有功、无功控制. 由于自抗扰控制器利用一阶跟踪微分器和扩张状态观测器对系统扰动进行动态跟踪补偿, 在此基础上输出双馈电机转子交--直轴电流的参考值, 然后将该参考值作为BP神经网络训练样本的输入, 训练后的BP神经网络可以更好地逼近实际转子电压输出量. 论文设计并实现了该方案的具体控制算法. 仿真测试表明: 该控制方案具有优良的动态性能, 对系统的内外扰动具有较强的鲁棒性, 在没有精确的发电机参数情况下依然可实现并网系统的稳定运行.     

Energy-based coordinated control of wind energy conversion system with DFIG

This article presents an energy-based coordinated control of machine- and grid-side converters in a wind energy conversion system (WECS) with a doubly-fed induction generator (DFIG) based on the theory of port-controlled Hamiltonian (PCH) system. Taking into account energy transmission in the dual PWM converter rather than treating rectification and inversion as separate parts, an integrated PCH model for the whole WECS was established from physical meanings. And depending on the new model, an energy-based coordinated control approach was proposed to meet the control requirements of the WECS with an additional objective which was to limit the DC-link voltage fluctuation. The approach was applied on a 2MW WECS, and compared with the energy-based respective control strategy using MATLAB/Simulink. The results show that the proposed control approach provides faster dynamic performance since the two converters operate with the knowledge of each other's operating status, and thus is able to smooth the power flow in the DC-link more effectively.     

基于比例复数积分控制器的模块化多电平换流器环流抑制策略

根据模块化多电平换流器相间环流二倍频负序性质,提出了一种基于比例复数积分控制器的模块化多电平换流器环流抑制策略,通过将比例复数积分控制器的谐振频率设置为二倍频负序电网电压频率实现相间环流抑制。该策略中比例复数积分控制器不存在系统参数,无需旋转坐标变换以及电流前馈解耦控制,避免了因系统参数变化而导致控制效果不佳的问题。Matlab/Simulink仿真实验验证了该环流抑制策略的正确性和有效性。