基于固态变压器的含DG接入的配网无功优化控制研究

发布时间：2018-01-23 02:21

本文关键词： 固态变压器 DG 交直流配网无功优化配网重构　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着智能电网发展进程的不断推进,越来越多的分布式电源发电(Distributed Generation,DG)在配网中出现。尽管分布式电源发电有其特有的优势,但是其比例的提高也给传统配网带来了新的问题。这包括传统的交流配网变成一定范围内的交直流混合配网、无功分布的改变引起的配网电压稳定问题以及谐波增加等。传统的配网优化相关的模型已经不再适合新的环境,如何应对这些问题具有十分重要的现实意义。固态变压器(Solid State Transformer,SST)相比传统的电力变压器具有改善谐波、稳定电压和无功控制以及具有高低压直流输出能力等的特点。随着柔性变电站相关项目的启动,在固态变压器对配网进行无功控制时,如何建立一个基于固态变压器下的含DG的配网无功优化模型和利用优化算法求解便显得十分关键。首先,介绍了固态变压器的原理及其常见拓扑;建立了 AC/DC/AC型固态变压器的模型并给出了相应的控制策略;根据固态变压器的典型简化结构及控制策略,在Matlab/Simulink环境中搭建了固态变压器的仿真模型,并进行多种工况下的仿真分析,一方面验证了固态变压器的功能,另一方面说明固态变压器的无功控制原理。其次,对各类DG的特点分析了其在系统中接口的潮流模型,以及固态变压器的无功控制方法及其潮流计算模型,并给出固态变压器接入配网的方式;分析了配网潮流计算的常用方法,针对含DG的交直流混合配网的特点,给出了潮流计算方法和计算流程。再次,分析并给出了基于SST的含DG配网的无功优化的目标函数和约束条件,以及无功优化的算法的主要步骤和算法流程;通过算例,对基于SST下的含DG配网和基于OLTC电力变压器的含DG配网的无功优化进行计算对比,结果显示,基于SST下的优化结果较之基于电力变压器的优化结果更优,电压偏差也有很大的降低,体现了SST的优势。最后,为了在配网运行中实现更大程度地优化,采用结合配网重构与无功优化的综合优化方法。因此首先提出了一种新的配网重构算法,并构建了重构后的算例模型。通过算例计算对比分析,其结果显示在综合优化方案下网损和电压偏差指标上,基于SST的优化结果优于基于OLTC电力变压器的优化结果,体现了固态变压器的优势。此外,对比单一无功优化方案,综合优化方案优化结果更优。体现了结合配网重构与无功优化的综合优化方法的优势。
[Abstract]:With the development of smart grid, more and more distributed Generation are generated by distributed generation. DGs appear in distribution networks, despite the unique advantages of distributed power generation. But the increase of the proportion also brings new problems to the traditional distribution network, which includes the traditional AC distribution network into a certain range of AC and DC hybrid distribution network. The problem of voltage stability and harmonic increase caused by the change of reactive power distribution is no longer suitable for the new environment. How to deal with these problems is of great practical significance. Solid State Transformer is a solid state transformer. Compared with traditional power transformers, SSTs have the characteristics of improving harmonics, stabilizing voltage and reactive power control and having high and low voltage DC output capability. How to establish a DG based reactive power optimization model for distribution network based on solid state transformer and how to solve it by using optimization algorithm is very important in the reactive power control of distribution network by solid-state transformer. The principle and common topology of solid-state transformer are introduced. The model of AC/DC/AC solid state transformer is established and the corresponding control strategy is given. According to the typical simplified structure and control strategy of solid-state transformer, the simulation model of solid-state transformer is built in Matlab/Simulink environment, and the simulation analysis is carried out under various operating conditions. On the one hand, the function of solid-state transformer is verified, on the other hand, the principle of reactive power control of solid-state transformer is explained. Secondly, the power flow model of interface of various DG is analyzed. The reactive power control method of solid-state transformer and its power flow calculation model are also given, and the way of connecting solid-state transformer to distribution network is given. The common methods of power flow calculation in distribution network are analyzed. According to the characteristics of AC / DC hybrid distribution network with DG, the power flow calculation method and calculation flow are given. The objective function and constraint conditions of reactive power optimization with DG distribution network based on SST are analyzed and given, as well as the main steps and algorithm flow of reactive power optimization algorithm. Through an example, the reactive power optimization of DG distribution network based on SST and DG distribution network based on OLTC power transformer is calculated and compared, and the results show that. The optimization result based on SST is better than that based on power transformer, and the voltage deviation is also greatly reduced, which reflects the advantages of SST. Finally. In order to optimize the distribution network to a greater extent, a new algorithm of distribution network reconfiguration is proposed in this paper, which combines the reconfiguration of distribution network with the optimization of reactive power. The example model is constructed, and the results are shown on the index of network loss and voltage deviation. The optimization result based on SST is better than that based on OLTC power transformer, which reflects the advantages of solid-state transformer. In addition, the single reactive power optimization scheme is compared. The optimization result of comprehensive optimization scheme is better, which reflects the advantages of integrated optimization method combining distribution network reconfiguration and reactive power optimization.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM714.3

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