论文总字数：31193字

摘 要

本文研究了多端柔性直流输电系统（Multi-terminal VSC-HVDC, VSC-MTDC）的各种协调控制策略，分析并比较了各种VSC-MTDC系统级拓扑结构。本文利用了Matlab软件实现了基于节点电流关系的VSC-MTDC多端直流输电的直流潮流算法编程。通过选取具有典型性和代表性的四端辐射状和六端网状的直流网络拓扑，对不同的多端柔性直流输电的控制方式进行了测试和分析。结果显示，该程序能够完成系统在正常工况下辐射状和网状等直流网络拓扑的主从控制、裕度控制和下垂控制模式的直流潮流计算。此外，该程序也能够用来模拟直流系统中某端换流站退出运行或直流线路断线的故障工况以及对直流网络拓扑后期扩建（线路或换流站节点增加）的情况进行潮流计算。

本文采用一种基于节点电流关系的多端柔性直流网络系统潮流计算方法，与传统的基于节点功率关系的潮流算法相比，其避免了繁琐的编程过程，且能够通过更少的迭代次数达到相同的潮流预定计算精度。此外，该算法对给定的电压初始参考值不敏感，更加适用于工程中多端柔性直流网络系统的潮流计算。

关键词：柔性直流输电，多端直流输电，直流潮流计算

ABSTRACT

In this paper, various coordinated control strategies for multi-terminal VSC-HVDC (VSC-MTDC) are studied, and various VSC-MTDC system-level topologies are analyzed and compared. In this paper, Matlab software is used to implement the DC power flow algorithm based on node current relationship for VSC-MTDC multi-terminal DC transmission. By selecting typical and representative four-terminal radiation type and six-terminal network type DC network topologies, different multi-end flexible DC transmission control methods have been tested and analyzed. The results show that the program can complete the master-slave control, margin control, and DC power flow calculation of droop control modes of the radiating and ring-type DC networks under normal conditions. In addition, this program can also be used to simulate the fault conditions at which the converter station exits from the operation or the DC line is disconnected at one end of the DC system, and to calculate the power flow in the case of the extension of the topology of the DC network (increase of the line or converter station node).

In this paper, a method based on nodal current relationship is proposed for multi-terminal flexible DC power flow calculation. Compared with the traditional power flow algorithm based on node power, it avoids the tedious programming process and can achieve the same number of iterations with fewer iterations. Trend booking accuracy. In addition, this algorithm is not sensitive to the initial reference value of a given voltage and is more suitable for the power flow calculation of a multi-terminal flexible DC network system in engineering.

Key words: flexible HVDC transmission, multi-terminal DC transmission, DC power flow calculation

目 录

摘 要 I

ABSTRACT II

第一章 绪论 5

1.1 课题背景及研究意义 5

1.2 研究现状 6

1.3 本文研究工作 6

第二章 换流器的结构与原理 8

2.1 三种常用电压源换流器的结构 8

2.1.1 两电平VSC 8

2.1.2 三电平VSC 9

2.1.3 模块化多电平换流器MMC 9

2.2 换流器的控制原理 11

2.3 换流站的有功无功解耦控制策略 13

第三章 多端柔性直流输电（VSC-MTDC）协调控制策略及拓扑结构 16

3.1 VSC-MTDC协调控制策略 16

3.1.1 主从控制 16

3.1.2 裕度控制 16

3.1.3 下垂控制 17

3.2 VSC-MTDC系统级拓扑结构 18

3.2.1 串联型系统 18

3.2.2 并联型系统 18

3.2.3 混合型系统 21

第四章 基于节点电流的VSC-MTDC直流潮流算法分析 23

4.1 基于节点电流的VSC-MTDC直流潮流算法 23

4.2 算法特性分析 24

4.3 系统拓扑结构变化的方法实现 24

第五章 基于MATLAB的仿真验证 27

5.1 四端辐射状VSC-MTDC仿真验证 27

5.1.1主从控制算例 27

5.1.2裕度控制算例 28

5.1.3下垂控制算例 30

5.2 六端网状VSC-MTDC仿真验证 32

5.2.1主从控制算例 33

5.2.2裕度控制算例 33

5.2.3下垂控制算例 35

第六章 总结与展望 38

6.1总结 38

6.2展望 38

参考文献（References） 39

附 录 41

节点初始数据 41

支路原始数据 41

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