基于滑模变结构控制的VSC-MTDC输电系统控制策略研究

以提高电压源型多端直流输电系统运行的可靠性和稳定性为目的,对整个输电系统进行了控制策略的研究。首先通过分析变流站的拓扑结构建立了变流站在dq坐标系下的仿射非线性数学模型,针对该模型采用基于精确线性化解耦的滑模变结构控制方法设计了变流站自身控制器。然后结合直流电压偏差控制和直流电压斜率控制各自的优点,设计了基于直流电压分段控制的多变流站间协调控制器,实现了在主导变流站故障退出后,系统仍能保证直流电压稳定和功率平衡。最后以一个典型的四端直流输电系统为例,在MATLAB/Simulink中建立了详细的模型,通过仿真验证了其具有良好的动态性能,并且通过与传统控制策略对比表明了本控制策略的优越性。

A Study on Control Strategy for VSC-MTDC Transmission System Based on Sliding Mode Variable Structure Control

A study on the control strategy for the whole power transmission system is made to improve the reliability and stability of the voltage source multi-terminal DC HVDC.Firstly,an affine nonlinear mathematical model of the converter station in the dq coordinate system is established through analysis of the topological structure of the converter station,and a controller for the converter station itself is designed under consideration of the fact that the model adopts sliding mode variable structure control based on exact linear decoupling.Then,a coordination controller between converter stations based on DC voltage segmented control is designed by taking advantage of the strong points of DC voltage deviation control and DC voltage slope control to realize that the system can still ensure DC voltage stability and power balance after the leading converter station has switched off because of fault.Finally,taking a typical four-terminal DC transmission system as an example,we build up a detailed model in MATLAB/Simulink.Through simulation,it is verified that the system has a good dynamic performance,and comparison with conventional control strategy shows the superiority of this control strategy.