电网不平衡电压下基于PCHD模型的MMC-HVDC无源控制策略

文中针对模块化多电平变流器(Modular Multilevel Converter,MMC)的高压直流输电(High-voltage direct current)系统的变流站级控制,提出一种电网不平衡电压下基于端口受控耗散哈密尔顿(Port-controlled Hamiltonian with Dissipation,PCHD)模型的无源策略(Passivity-based Control,PBC)。文中针对系统的数学模型,通过功率表达式,得出三种控制目标,针对每种控制目标得出相应的电流参考量;通过基于PCHD模型的无源控制理论,推导出系统能量函数和相应的无源控制器;针对三相不平衡电网中产生的负序分量的情况,文中系统加入正负序分离思想,进一步提高了系统的控制精度;通过Matlab/Simulink仿真平台,搭建了不平衡电网电压下的MMC-HVDC系统,并在三种控制目标下验证了所提控制策略的有效性和优越性。

Passivity-based control strategy of MMC-HVDC based on PCHD model under unbalanced grid voltage

In this paper,a passivity-based control(PBC)strategy based on port-controlled Hamiltonian with dissipation(PCHD)model is proposed for substation level control of high-voltage direct current(HVDC)transmission system with modular multilevel converter(MMC).Based on the mathematical model of the system,this paper obtains three kinds of control targets through power expressions,and obtains the corresponding current reference amount for each control target.Based on the passivity-based control theory of PCHD model,the system energy function and the corresponding passive controller are derived.In view of the situation of the negative sequence component in three-phase unbalanced power grid,this paper adds the idea of positive and negative sequence separation to the system,which further improves the control precision of the system.The MMC-HVDC system under unbalanced grid voltage is built through Matlab/Simulink simulation platform,and the effectiveness and superiority of the control strategy proposed in this paper are verified under three kinds of control objectives.