交直流混合配电网及其控制策略研究

发布时间：2018-06-08 15:28

本文选题：交直流混合 + 配电网　；参考：《华北电力大学》2017年硕士论文

【摘要】：近年来,随着社会经济的高速发展和现代城市的快速建设,城市配电网中负荷的大小和种类不断增加,传统交流配电网面临着供电质量下降、供电走廊紧张、换流过程繁多等诸多问题。与此同时,具有提高供电容量、改善供电质量、便于分布式电源及直流负荷并网等众多优势的直流配电网受到了世界范围内专家学者的关注,在传统的交流配电网上发展优点众多的直流配电已经成为了未来配电网建设的趋势。因此,对兼具交流配电基础和直流配电优势的交直流混合配电网的研究具有很高的现实意义和应用价值。本文以传统“手拉手”接线的交流中压配电网为基础,提出了一种新的交直流混合配电网的网架结构,利用柔性直流技术在交流配网中构建直流环节,在具备直流配电网优点的同时也兼顾了交流配电网的基础。分析表明,交直流混合配电网能够有效提高配电网的整体供电质量,减少配电网中的换流过程,节省供电线路走廊。随后,本文从一次设备投资和运行损耗两方面对交直流混合配电网进行了经济性分析,并以辽宁省某供电区域作为实例,将交直流混合网改造与增建交流配电网和增建直流配电网进行了经济性对比。其中,一次设备投资主要包括换流站与变电站、线路电缆、断路器、变压器及整流逆变器;运行损耗主要包括变电损耗、换流损耗以及线路传输损耗。对比结果显示,当配电网运行年数较长时,交直流混合配电网因具有更低的运行损耗而具有更好的经济性。之后,本文在分析了已有的应用于多端直流系统的众多VSC控制策略之后,以综合性能较优的组合控制策略为基础,提出了新的改进组合控制策略。分析表明,改进组合控制策略能够在直流电压主控VSC故障之后,将直流母线电压控制在更接近于额定电压的水平,并使之具有更高的稳定性,因而比已有的组合控制具有更佳的控制性能。最后,本文利用Matlab/Simulink仿真平台搭建了交直流混合配电网的简化仿真模型,通过设置不同的系统状态对模型进行了仿真运行分析,对本文提出的交直流混合配电网的网架结构和控制策略的可行性进行研究。仿真结果表明,与交流线路相连的VSC可以通过提供适当的无功补偿来改善交流线路的电压分布和供电质量,改进组合控制策略在正常运行以及直流电压主控VSC故障时,均能对直流系统的母线电压和功率平衡进行良好的控制。
[Abstract]:In recent years, with the rapid development of social economy and the rapid construction of modern cities, the size and variety of load in urban distribution network is increasing, the traditional AC distribution network is facing the decline of power supply quality, power supply corridor is tight. There are many problems in the commutation process. At the same time, the DC distribution network, which has many advantages, such as increasing the power supply capacity, improving the power supply quality and facilitating the distribution of power and DC load connected to the grid, has attracted the attention of experts and scholars all over the world. The development of DC distribution with many advantages on the traditional AC distribution network has become the trend of distribution network construction in the future. Therefore, the study of AC / DC hybrid distribution network with both AC and DC distribution advantages has high practical significance and application value. In this paper, a new AC / DC hybrid distribution network is proposed based on the traditional "hand-held" AC / MV distribution network. The flexible DC technology is used to construct the DC link in the AC / DC distribution network. At the same time, the basis of AC distribution network is also taken into account. The analysis shows that the AC / DC hybrid distribution network can effectively improve the overall power supply quality of the distribution network, reduce the commutation process in the distribution network, and save the power supply line corridor. Then, this paper analyzes the economy of AC / DC hybrid distribution network from two aspects of primary equipment investment and operation loss, and takes a power supply area of Liaoning Province as an example. The economic comparison between the AC / DC hybrid network and the additional AC distribution network and the additional DC distribution network is carried out. Among them, primary equipment investment mainly includes converter station and substation, line cable, circuit breaker, transformer and rectifier inverter, and operation loss mainly includes transformer loss, commutation loss and line transmission loss. The comparison results show that the AC / DC hybrid distribution network has better economy because of its lower operating loss when the number of years of operation is longer. Then, after analyzing the existing VSC control strategies for multi-terminal DC systems, a new improved combinatorial control strategy is proposed based on the combinatorial control strategy with better comprehensive performance. The analysis shows that the improved combined control strategy can control the DC bus voltage closer to the rated voltage level after the DC voltage main control VSC fault, and make it more stable. Therefore, it has better control performance than the existing combinatorial control. Finally, the simplified simulation model of AC / DC hybrid distribution network is built by using Matlab / Simulink simulation platform, and the simulation operation of the model is analyzed by setting different system states. The feasibility of the structure and control strategy of AC / DC hybrid distribution network proposed in this paper is studied. The simulation results show that the VSC connected with AC circuit can improve the voltage distribution and power supply quality by providing appropriate reactive power compensation. The bus voltage and power balance of DC system can be controlled well.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM721.3

【参考文献】