基于固定时间滑模的直流微电网系统电压控制

Voltage control of direct‑current microgrid system based on fixed‑time sliding mode

针对含有恒功率负载的直流微电网系统,为了抑制恒功率负载的负阻抗性造成的系统直流母线电压振荡现象,采用固定时间滑模控制方法研究直流母线电压的控制问题。首先,建立含恒功率负载和储能单元的直流微电网系统的数学模型;其次,结合固定时间稳定性理论,设计积分型滑模面,在此基础上构造固定时间滑模控制器,通过对系统状态进行可达性分析,给出系统收敛时间上界的估计值;然后,通过对滑动模态进行稳定性分析,结合线性矩阵不等式求解得到控制器增益;最后,以含有2个恒功率负载和1个储能单元的直流微电网系统为例进行仿真实验,仿真结果表明,所设计控制器能够有效抑制恒功率负载扰动对直流母线电压带来的不良影响。

For the direct-current(dc)microgrid system with constant power load,in order to suppress the dc bus voltage oscillation caused by constant power load disturbance,the fixed-time sliding mode control method is used to deal with the issue of the dc bus voltage control.Firstly,the mathematical model of a dc microgrid system with constant power loads and an energy storage unit is established.Secondly,based on the fixed-time stability theory,an integral sliding surface and a fixed-time sliding mode controller are constructed.By analyzing the accessibility of the system states,the value of upper bound on convergence time of the system is estimated.Then,through the stability analysis of the sliding mode,the controller gain is obtained with the combination of the linear matrix inequality method.Finally,a dc microgrid system with two constant power loads and one energy storage unit is taken as an example for simulation verification.It is shown that the fixed-time sliding-mode controller can effectively resist the negative influence of constant power load disturbance on the dc bus voltage.