低压微电网中基于虚拟电阻的逆变器并联控制策略研究

发布时间：2018-05-03 02:39

本文选题：微电网 + 下垂控制　；参考：《燕山大学》2014年硕士论文

【摘要】：微电网是在分布式发电技术的基础上发展起来的新兴电网结构。微电网中的分布式发电单元和储能装置大多通过接口逆变器与公共耦合点相连，分布式发电单元的大量接入，形成了微电网中多逆变器的工作环境。多逆变器环境下微电网系统孤岛运行时由于线路阻抗不匹配、本地负荷不一致等引起的功率分配和环流问题，严重影响了微电网的运行和负荷的用电安全。为保证并联逆变器的稳定运行，，本文提出了一种基于虚拟电阻的下垂控制策略，采用这种控制策略可以有效抑制环流、合理分配功率。本文的主要工作如下：结合逆变器的功率传输特性，分析了各种下垂控制策略的实现方法和适用范围，通过对P-V下垂控制策略的小信号建模和稳定性分析得出结论：低压微电网的传输线阻抗环境下采用P-V下垂控制器更有利于系统的稳定运行。针对低压微电网孤岛运行时，多逆变器环境下存在的系统环流问题，分析了这种环流的产生原因，影响因素及其与负荷功率分配之间的关系，提出了一种通过合理分配功率消除系统环流的控制策略，这种基于虚拟电阻的逆变器并联功率控制方案实现了负荷功率按微源额定容量比例分配、消除系统环流的控制目的。对两台DG并联以及多机并联的情况进行了仿真，仿真结果证明了这种改进的控制策略的正确性。本文最后搭建了两台三相逆变器并联的实验平台，采用型号为TMS320F2812的DSP作为主控制器对上述控制策略进行了验证，实验结果证明了该策略的可行性。
[Abstract]:Microgrid is a new power network structure developed on the basis of distributed generation technology. Most of the distributed generation units and energy storage devices in microgrid are connected with common coupling points through interface inverters, and a large number of distributed generating units are connected to each other, forming the working environment of multi-inverter in microgrid. The power distribution and circulation problems caused by line impedance mismatch and local load inconsistency in the isolated island operation of microgrid system in multi-inverter environment have seriously affected the operation of micro-grid and the safety of power consumption. In order to ensure the stable operation of the parallel inverter, a droop control strategy based on virtual resistor is proposed in this paper, which can effectively suppress the circulation and allocate power reasonably. The main work of this paper is as follows: Combined with the power transmission characteristics of the inverter, the realization methods and applicable range of various droop control strategies are analyzed. Through the small signal modeling and stability analysis of P-V droop control strategy, it is concluded that using P-V droop controller in the transmission line impedance environment of low-voltage microgrid is more conducive to the stable operation of the system. In view of the circulation problem in the environment of multi-inverter, the causes of the circulation, the influence factors and the relationship between the circulation and load power distribution are analyzed. This paper presents a control strategy to eliminate the system circulation through reasonable power allocation. This parallel power control scheme based on virtual resistance realizes the load power distribution according to the rated capacity of the micro-source, and eliminates the circulation of the system. The simulation results of two parallel DGs and multiple parallel machines show the correctness of the improved control strategy. In the end, the experiment platform of two three-phase inverters in parallel is built, and the control strategy is verified by DSP with TMS320F2812 as the main controller. The experimental results prove the feasibility of the strategy.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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