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Recently, photovoltaic (PV) power systems have attracted considerable attention in attempts to mitigate global warming. In a PV power system, it is necessary to synchronize the grid voltage when a PV inverter is interconnected with a grid. This paper proposes a high‐speed and high‐precision phase‐locked loop (PLL) using complex‐coefficient filters for a single‐phase grid‐connected inverter. The proposed PLL can detect the phase of grid voltage that has superimposed harmonic components for grid fault. Moreover, numerical results show the effectiveness of the proposed method. 相似文献
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单周期数字控制光伏并网逆变器的仿真与实验 总被引:1,自引:0,他引:1
单周控制的单级全桥光伏并网系统具有容量大、效率高、成本低等优点。在分析单周期控制工作原理的基础上,建立单相单极性光伏并网系统的数学模型,给出了对控制效果影响较大的输出电流的检测方法,基于PSIM软件平台对控制算法进行了仿真,并将算法应用到6kW单相单极性光伏并网系统的电流控制。仿真和样机实验结果均表明该方法具有良好的动静态特性。 相似文献
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发现并解释了一种在逆变器输出阻抗高频处因数字控制延时而产生的"阻抗谷"的现象。在此阻抗谷处,逆变器输出阻抗的幅值急剧下降,而相位明显上升。通过波特图和复频域表征这两种方式,详细分析了电流环动态及数字控制延时对单电流环控制型逆变器的dq坐标系输出阻抗的影响,通过研究逆变器的输出阻抗模型,获得了阻抗谷的来源及其与电流环动态和延时大小之间的关系。同时,通过d-d通道阻抗匹配和广义奈奎斯特判据GNC(generalized Nyquist criterion),研究了阻抗谷对并网逆变器稳定性的影响。通过分析发现,电流环的动态和延时大小的改变均会导致d-d通道输出阻抗的幅度和相位发生剧烈变化,从而导致并网系统发生振荡。最后,实验结果验证了分析的正确性。 相似文献
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HIROKI WATANABE KAZUHIRO KOIWA JUN‐ICHI ITOH YOSHIYA OHNUMA SATOSHI MIYAWAKI 《Electrical Engineering in Japan》2016,196(3):39-48
This paper proposes a configuration of a single‐phase voltage source inverter that features power decoupling capability. Generally, the converter connected to a single‐phase grid employs bulky dc link capacitors such as electrolytic capacitors in order to decouple the power ripple with twice the frequency of the power supply. The power ripple in the proposed circuit is compensated by an active buffer with small capacitors. In this paper, the fundamental operations of the proposed converter are confirmed by experimental results. From the experimental results, the output current total harmonic distortion (THD) is 3.51%, the ratio of the input current is 14.3%, and the output power factor is over 99%. In addition, the volume of the proposed circuit is reduced by 61% when the carrier frequency is 64 kHz compared to that with a carrier frequency of 16 kHz. Finally, from an evaluation of the power density using Pareto front curves, the proposed circuit achieves high power density in comparison with the conventional circuit. 相似文献
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Chienru Lung Toshinobu Shintai Hiroaki Kakigano Yushi Miura Toshifumi Ise 《Electrical Engineering in Japan》2015,190(4):26-36
The home applications of distributed generations facilities such as photovoltaic and gas engine cogeneration systems are growing and many distributed generations are connected to a grid by a DC/AC inverter. The DC/AC inverter is controlled by a phase‐locked loop (PLL) in order to be synchronized with the power system frequency. However, the control scheme of stand‐alone operation uses voltage control, and the PLL is unnecessary. Therefore, it is hard to realize uninterrupted change between stand‐alone and grid‐connected operation. In this paper, we propose a virtual synchronous generator control scheme in order to use the same control scheme in stand‐alone and grid‐connected operation. We carried out experiments to demonstrate the control characteristics. 相似文献
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针对单相电压型并网逆变系统,设计了电流内环、电压外环的双闭环控制系统,建立了内外环数学模型;运用MATLAB/Simulink建立了单相并网逆变系统仿真模型,对双闭环控制系统及滤波电路的性能进行了验证分析。结果表明,基于三角波载波的双闭环控制,具有较高的稳态精度和较快的动态响应。 相似文献
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首先分析了并网逆变器拓扑结构及数学模型,然后将并网控制策略进行了分类,针对直接电流控制进行了进一步深入研究,详细阐述了滞环控制和无差拍控制两种控制策略。 相似文献
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The present paper introduces a single‐phase utility interactive inverter with a power decoupling function. In a conventional single‐phase inverter, power pulsation at twice the grid frequency appears in the input power. Hence, electrolytic capacitors having large capacitances have been connected to the DC input terminal to stabilize the input DC‐bus voltage. Because the lifetime of the electrolytic capacitor is relatively shorter than that of another component, the lifetime of the inverter is affected by the capacitor. In order to prevent such a problem, a novel single‐phase inverter circuit with an active power decoupling function is introduced. The pulsating power on the input DC‐bus line and the pulsated energy on the input DC capacitor is transferred to the energy in a small film capacitor. Hence, the extension of the inverter lifetime can be expected by substituting a small film capacitor for the large electrolytic capacitors. In addition, the loss in the power decoupling circuit is very small; hence, the reduction in the overall conversion efficiency of the inverter can be minimized. The effectiveness of the proposed method is verified using a 300 W experimental setup. 相似文献
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Toshiji Kato Kaoru Inoue Yusuke Nakajima Yuki Yamamoto 《Electrical Engineering in Japan》2019,207(2):49-58
Instabilities due to mutual interactions between inverters and grid impedance are observed sometimes. This paper proposes a new stabilization method, which improves the output frequency impedance characteristics, satisfying the Nyquist stability criterion. The principle is that the output impedance is designed to be passive with the feedfoward loop characteristics and the system is stable even for an unknown grid system impedance. The design principle for the proposed stabilization method is described and investigated and validated on the basis of simulation and experimental results. 相似文献
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研究了一种两级式非隔离式光伏并网方案,前级采用交错并联双Boost电路,后级使用半桥逆变器。分析了无变压器式逆变器的剩余电流问题及半桥逆变器抑制剩余电流的机制。给出了Boost电感和逆变电感关键参数的设计方法。给出了数字方法实现的两级电路复合控制策略及实现方法。重点分析并提出了单定时器交错并联驱动生成策略。试验验证了控制方法的有效性和可行性。 相似文献
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来自电网的扰动,包括电压跌落、谐波以及电网阻抗的变化等,会影响采用LCL滤波器的光伏并网逆变器的正常并网。提出了一种使用重复控制的双闭环加前馈的单相光伏逆变器控制方法。采用比例控制器的反馈和前馈虽然不能彻底消除谐波影响,却可以抑制LCL滤波器谐振峰,并提供需要的增益和快速的响应,而重复控制则可以保证系统对电网谐波的抑制以及使系统具有良好的鲁棒性,并易于设计和实现。仿真和实验结果表明,控制系统在各种电网扰动发生时,仍然能够保证并网电流指标满足标准的要求。 相似文献
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随着新能源装机容量和渗透率的增加,电网逐渐呈现出较大等效电网阻抗的弱电网特性,此时常规强电网下设计的并网逆变器比例-积分(PI)参数往往会引起系统谐振等不稳定问题。针对弱电网下如何优化设计并网逆变器PI参数的问题,常规方法往往需要近似处理或反复试凑,而且无法结合多个性能指标进行参数整定。因此,文中基于D分割法得到了弱电网下的并网逆变器同时满足相角裕度、幅值裕度、电流环带宽和短路比等多性能指标下的PI参数稳定域,并通过图形可视化地表现出来,从而快速、准确地获取弱电网下的PI参数,避免了反复试凑。最后,得出了弱电网下的并网逆变器即使将锁相环带宽设置得很低,其PI参数也需要合理进行设计和选取才能使其稳定、高效运行的结论,并基于30 k W实验平台验证了该设计方法和结论的正确性。 相似文献
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随着光伏并网发电容量在电网中的渗透率越来越高,用户和电网对光伏并网系统的优化设计和控制性能提出了更高的要求。论述了光伏并网系统的技术发展现状;给出了光伏并网逆变器的拓扑结构发展情况,并将其总结为隔离型与非隔离型并网逆变器、单级式与双级式并网逆变器、两电平与多电平逆变器等3种类型;对并网逆变器与无功补偿装置的协调控制、并网逆变器间的虚拟同步机控制以及全局同步脉宽调制技术进行了分析和展望。 相似文献
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非隔离光伏并网逆变系统的地电流分析与验证 总被引:1,自引:0,他引:1
分析了非隔离光伏并网逆变系统的地电流大小。介绍了包括单级结构的传统三相逆变器和三相半桥逆变器,以及两级结构的带2电平升压变换器的三相逆变器和带3电平升压变换器的三相逆变器。建立了地电流解析计算方法,给出了各种拓扑的共模简化模型及地电流的傅里叶表达式,以及参数变化对地电流的影响。分析了不同前级升压拓扑对地电流的影响,进行了仿真和实验。 相似文献