基于MMC的柔性直流输电建模及协调控制研究

发布时间：2018-06-21 20:30

本文选题：模块化多电平换流器 + 建模仿真　；参考：《广西大学》2014年硕士论文

【摘要】：模块化多电平换流器具有开关损耗低、输出电压波形谐波含量低、对开关器件要求低、可靠性高等诸多优点,已经在实际工程中得到越来越多的应用。本文主要开展了基于模块化多电平的柔性直流输电系统的基本原理、控制策略、建模仿真和多端直流系统运行等方面的研究工作。首先,分析MMC的工作原理,推导了MMC交流三相电路在d-q坐标系下的数学模型以便于控制器设计。详细介绍了换流站级的有功功率回路、无功功率回路的双闭环控制方法和换流阀级控制器的环流抑制、最近电平逼近和电容电压平衡等功能。然后,在PSCAD/EMTDC中建立11电平的两端输电系统。通过对控制目标的阶跃响应验证了所设计控制器的效果,系统能够快速跟踪控制目标的变化,性能良好。推导了MMC的平均值模型,忽略子模块间的内部差异,使用可控电压源和可控电流源来模拟MMC。仿真结果显示详细模型和平均值模型在系统级仿真中趋势一致,使用平均值模型可以极大提高仿真速度而不过多牺牲仿真精度。最后,研究了多端柔性直流输电系统的电压裕度控制方法,根据原理设计了电压裕度控制器。一个五端系统的仿真结果表明在主换流站因为到达功率极限而失去调节能力或者主换流站退出运行后,电压裕度控制很好地完成了主换流站和从换流站之间的直流电压接管,系统能够继续稳定运行。
[Abstract]:Modular multilevel converter has many advantages, such as low switching loss, low output voltage waveform harmonic content, low demand for switching devices, high reliability and so on. It has been used more and more in practical engineering. In this paper, the basic principle, control strategy and imitation of the flexible and direct current transmission system based on modularization and multilevel are mainly carried out. The research work of real and multi terminal DC system operation. First, the working principle of MMC is analyzed. The mathematical model of MMC AC three-phase circuit in d-q coordinate system is deduced to facilitate the controller design. The active power loop at the converter station level, the double closed loop control method of reactive power circuit and the circulation of the converter valve controller are introduced in detail. Suppression, recent level approximation and capacitive voltage balance. Then, the 11 level two terminal transmission system is established in PSCAD/EMTDC. The effect of the designed controller is verified by the step response to the control target. The system can quickly track the change of the control target and have good performance. The average value model of MMC is derived, and the sub module is ignored. In the internal difference, the simulation results of MMC. simulation using the controllable voltage source and the controllable current source show that the detailed model and the mean value model have the same trend in the system level simulation, and the average value model can greatly improve the simulation speed, but the simulation precision is much more sacrificed. Finally, the voltage margin control of the multiterminal flexible DC transmission system is studied. The voltage margin controller is designed according to the principle. The simulation results of a five terminal system show that the voltage margin control completes the DC voltage takeover well between the main converter station and the converter station after the main converter station loses its adjustment capacity or the main converter station because of the power limit. The system can continue to stabilize. Function.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1

【共引文献】