【作者】 阚加荣；

【导师】 谢少军；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2007， 硕士

【摘要】 分布式电源系统DPS以其电源单元模块化、便于扩容、易于维护和可以实现冗余供电而越来越受到业界的重视。交流分布式供电系统的核心是逆变器并联技术。在众多的逆变器并联控制技术中,无互联线并联方式较其它并联运行方式有系统配置方便、并联时接线少、抗干扰能力强、冗余度高等优点,但无互联线并联系统也存在一些问题急待解决。本文以无互联线逆变器并联技术作为研究对象。本文首先介绍了传统无互联线逆变器并联系统的基本控制方法(P/Q下垂控制),并给出了P/Q下垂系数的推导过程;针对UPS所通用的数字锁相环应用于无互联线逆变器并联系统中并机时刻环流过大的缺点,提出一种可以改善数字锁相环锁相精度的方法,从而使逆变器并联系统在并机过程中环流大大降低,减小了并机时刻过大的环流对并联系统的冲击,进而提高了并机的可靠性;通过并联系统的小信号模型分析,减小单台逆变器的功率计算时间可以提高并联系统的稳定性,在此基础上,提出了减小单台逆变器的功率计算时间的一种新方法,可将功率计算时间较传统方法大大减小,从而提高了系统的稳定性;针对并联系统中各逆变单元各元件参数离散而造成各逆变单元对负载的功率不能均分和普通的下垂控制可能引起系统误调节的问题,提出了一种新型的功率解耦下垂控制方法,有效地提高了并联系统并机后调节的快速性和稳态运行时功率的均分程度。设计了两台500VA的实验样机,进行了并联实验,实验结果表明,本文所采取的控制方案取得了很好的电流均分效果。更多还原

【Abstract】 The Distributed Power System (DPS) has attracted more and more attentions because it has many desirable features such as modularity, expandability, maintainability, redundancy and increased reliability. The kernel of the AC DPS is the control technique of parallel inverters. Compared to other methods of parallel inverters, the scheme without control interconnection has a lot of merits such as the convenient of placement, fewer interconnection, the stronger anti-interference and the better redundancy. However, this control method also has some problems which need to be solved. So, this paper focus on the parallel inverters, which controlled by droop method, as the investigated subject.The conventional droop method used in parallel inverters is introduced and a method for calculating the droop coefficient is proposed. In order to decrease the loop current of the system in the paralleling moment, a digital phase lock loop (DPLL) is designed, which can improve the precision of the phase difference between the inverter module and the AC bus. The stability of the parallel system is related to calculation interval of the active and reactive power according to the analysis result of small-signal model. Basing on this result, a novel calculation method is brought forward, which can shorten the time as 1/40 as the conventional computing time and improve the stability of the parallel system. In the parallel system controlled by conventional droop method, the power can’t be shared properly because of the parameters difference between the inverter modules. Furthermore, the difference between the line impedance and output impedance of inverters is neglected, which can result in the oscillation of loop current. For eliminate these problem a new decoupling droop control method is presented. Two 500VA prototypes are developed. The simulation and experiment results show that paralleled inverter modules have a good performance.更多还原