一种基于LLCL型滤波器的光伏逆变器分析与设计

提出了新型并网逆变器的高阶功率滤波器的拓扑电路,称为LLCL滤波器。采用新型LLCL型滤波器对单相光伏并网逆变器进行滤波,LLCL滤波器通过在传统LCL滤波器的电容支路中串联一个小的电感达到在开关频率处产生串联谐振,相比LCL型滤波器能够更大程度地对串联谐振频率处的电流谐波进行衰减,可以减少电感装置的体积和重量,减少动态响应时间。更重要的是,能够减少电网侧的电感值,这样可以提高特征谐振频率点,有利于并网逆变器的控制。对比分析了传统LCL滤波器和LLCL滤波器的性能,证实和评估LLCL滤波器的优越性。对LLCL滤波器进行了参数设计,使用Matlab仿真软件搭建模型,仿真结果表明系统具有较好的稳态性能,且抗干扰性能好。     

基于LCL型滤波器的光伏并网逆变器的控制策略研究

光伏并网逆变器的LCL型滤波器与传统的L型﹑LC型相比较而言,在相同的电感量的情况下,LCL型滤波器对注入电网的高阶次谐波具有更好的抑制能力,谐波衰减十分明显,但是用LCL型滤波器作为光伏并网接口,容易产生谐振尖峰,影响整个系统的稳定性。本文主要对基于LCL型的光伏并网逆变器的直接转矩控制策略分析研究,提出改进的基于准直接功率控制(DPC)的控制策略,对LCL型滤波器的谐振问题进行有效抑制并且提高对光伏并网电压电流的控制能力。     

基于虚拟电阻法的LCL滤波器特性分析

LCL滤波器与传统的L滤波器相比,有着更好的滤波效果,但是,同时LCL滤波器会有谐振问题,导致了系统不稳定。为了要抑制其谐振特性,将虚拟电阻法和无源阻尼法这两种控制策略进行了研究分析,还将虚拟电阻法运用到了光伏并网逆变器中,最后通过仿真结果的对比,表明了虚拟电阻法可以有效地抑制LCL滤波器的谐振峰,降低了输出电流的谐波,系统的稳定性也得到了增强。     

基于谐波频谱的LCL滤波器性能分析

为了减少逆变器中的谐波干扰,常采用LCL滤波器,该滤波器性能优良,被广泛采用,但目前LCL滤波器的电感电容仍然较大,系统成本仍较高,据此提出一种新型的设计方法,即通过逆变器输出的高次谐波峰值及其频谱,采用直线交截法依次获得谐振频率等相关滤波参数。与此同时,在此基础上对基于谐波频谱的LCL滤波器的各参数再次进行优化,然后通过与未经优化的LCL滤波器进行性能分析比较,从理论上揭示了该滤波器的优越性。最后通过在三相并网逆变器上进行实验验证,最终设计出了总电感电容较小,且满足并网要求的LCL滤波器。     

光伏并网输出滤波器的研究与设计

逆变器的输出滤波对于电网安全工作尤为重要.首先对并网逆变器的滤波器进行研究,导出了LCL滤波器的传递函数,分析了不同参数变化对传递函数的影响.其次基于电路模型、传递函数及谐波分量的特点,介绍了LCL滤波器的设计方法并给出了消振措施.最后根据并网控制系统,建立光伏并网系统的仿真模型,对系统输出进行仿真,得到较好的仿真数据,实验证明了这种LCL滤波器设计方法的优越性.     

基于电网电压矢量定向的三相并网逆变系统设计

本文介绍了并网逆变用LCL输出滤波器的设计步骤和基干电网电压矢量定向的并网逆变系统直接电流控制方案的基本原理与推导过程,利用数字信号处理器TMS320F2812设计了一台原理样机。仿真和实验结果表明：网侧电流比逆变器侧电流高次谐波得到更好地衰减,并网电流与电网电压保持同相位,系统以单位功率因数向电网馈送电能。     

三相并网逆变器LCL滤波器的简明设计

LCL滤波器以其较好的滤波性能被广泛地用于并网逆变器,但无阻尼时系统产生谐振,给系统的稳定性控制带来困难。文中在建立三相并网逆变器数学模型的基础上,采用基于d,q同步旋转坐标系的电网电压定向控制策略,利用被动阻尼抑制谐振提高了并网逆变器的稳定性能。文中给出了被动阻尼LCL滤波器的详细设计方法,并比较其与单L滤波器的滤波效果,运用Matlab/simulink建立系统模型并进行仿真,实现了单位功率因数并网。     

基于LCL滤波的光伏并网逆变器的研究

为了减少电力电子器件给光伏并网系统带来的大量谐波,研究了半周期SVPWM控制的三相双向双Buck/Boost变流器可以有效减少开关损耗和导通损耗,在SVPWM控制策略上引入模糊PI控制增加了系统的稳定性,降低了超调量,并采用了对高频谐波有较强抑制作用的LCL滤波器,实现系统的单位功率因数并网。采用Matlab/Simulink进行仿真实验,仿真结果表明,该闭环系统可以有效地实现单位功率因数并网,提高了系统稳定性和并网电流质量,减小了输出超调量,增强了系统鲁棒性。     

500kW大功率光伏并网逆变器的LCL滤波电路设计

本文在对比逆变器输出侧L及LCL滤波器优劣的基础上,对500kW大功率光伏逆变器上的LCL滤波器参数选型做了详细分析。最后,在所选参数基础上,基于D—Q分解法,对500kW光伏逆变器进行了并网仿真,实现了单位功率因素并网运行。仿真证明了LCL滤波电路选型的正确性。     

光伏发电系统并网控制技术现状与发展(下)

由于LCL滤波器针对高频谐波的滤除效果优于L型滤波器,因而广泛应用于电流源控制型的光伏并网逆变电路中,但也导致了基于LCL滤波器的光伏并网逆变器控制策略更为复杂,因此本文并从并网控制策略角度分析了间接电流控制与直接电流控制两种并网策略,并预测了未来光伏发电系统并网控制策略的发展趋势。     

Quasi-Z Source Inverter Control of PV Grid-Connected Based on Fuzzy PCI

The photovoltaic grid-connected inverter is an important interface between the photovoltaic power generation system and power grid. Its high-quality operation is directly related to the output power quality of the power grid. In order to further optimize the control effect of the quasi-Z source grid-connected photovoltaic inverter, a fuzzy proportional complex integral control (PCI) method is proposed for the current internal loop control. This method can eliminate the steady-state error, and has the characteristic of zero steady-state error adjustment for the AC disturbance signal of a specific frequency. The inductance-capacitance-inductance (LCL) filter is adopted in the grid-connected circuit, and the feedback capacitive current is taken as the control variable of the inner loop to form the active damping control method, which can not only effectively suppress the resonance of the LCL circuit, but also significantly inhibit the high-order harmonics in the grid-connected current. Finally, a system simulation model is built in MATLAB/Simulink to verify the superiority and effectiveness of the proposed method.     

Grid current regulation of a three-phase voltage source inverter with an LCL input filter

Many grid connected power electronic systems, such as STATCOMs, UPFCs, and distributed generation system interfaces, use a voltage source inverter (VSI) connected to the supply network through a filter. This filter, typically a series inductance, acts to reduce the switching harmonics entering the distribution network. An alternative filter is a LCL network, which can achieve reduced levels of harmonic distortion at lower switching frequencies and with less inductance, and therefore has potential benefits for higher power applications. However, systems incorporating LCL filters require more complex control strategies and are not commonly presented in literature. This paper proposes a robust strategy for regulating the grid current entering a distribution network from a three-phase VSI system connected via a LCL filter. The strategy integrates an outer loop grid current regulator with inner capacitor current regulation to stabilize the system. A synchronous frame PI current regulation strategy is used for the outer grid current control loop. Linear analysis, simulation, and experimental results are used to verify the stability of the control algorithm across a range of operating conditions. Finally, expressions for ""harmonic impedance" of the system are derived to study the effects of supply voltage distortion on the harmonic performance of the system.     

LCL滤波并网逆变器的控制策略

本文关于LCL滤波并网逆变器的控制研究,研究了最合适的关于LCL滤波并网逆变器的控制方案。在开关的频率保持在同一个水准的时候在一个开关的周期内,研究组进行了对于逆变器的多次采样研究,有效地减少了在数字技术下控制的延时情况,提高了系统中本来的控制范围与延时时间。在定量分析的方式下,小组中的研究人员已经证实的开展了对LCL滤波并网逆变器本质性能的研究,分析了它的优势性能。与常规有源阻尼多环结构相比,该方案采用电流单环控制即可实现系统稳定,无需增加传感器,从而简化了控制结构。在最后,研究人员也同时通过了实验来对LCL滤波并网逆变器的性能进行了验证分析。     

Improved harmonic suppression efficiency of single-phase APFs in distorted distribution systems

In this study, a control method is proposed to improve the harmonic suppression efficiency of the single-phase active power filter in a distorted power system to suppress current harmonics and reactive power. The proposed method uses the self-tuning filter (STF) algorithm to process single-phase grid voltage in order to provide a uniform reference grid current, which increases the efficiency of the system. The results of the simulation study are presented to verify the effectiveness of the proposed control technique in this study.     

Model-based generation of low distortion currents in grid-coupled PWM-inverters using an LCL output filter

In this paper, a single phase inductance-capacitance-inductance (LCL) output stage for grid coupled inverters is designed and built. An accurate model and observer of the output filter and the distorted grid voltage are implemented. The paper deals with the construction of a 14-state model, and the feedback control loop to obtain adequate closed loop response. Simulations indicate a good performance of the controller, with a total harmonic current distortion (THD) below 1%. Experimental results confirm simulations, and illustrate the correct operation of the Kalman observer to estimate the distorted grid voltage (THD 3%). The observer only uses the inverter current measurement as input. The output filter effectively reduces the pulsewidth modulation harmonics in the grid current.     

基于双电流环控制的并网逆变器设计

LCL滤波器可以有效抑制高次谐波,然而LCL滤波器的使用增加了系统阶数,对系统控制策略提出了更高的要求。为此,采用一种基于极点配置的电流双环控制策略,以DSP作为主控制器,充分利用DSP控制器的CLA、高精度PWM和AD等模块,使其硬件电路大大简化。最后,通过极点配置的方法选定控制参数,整个系统操作简单、控制灵活、功能强大,实现了节能降耗和精密制动。