考虑故障穿越和时变延迟的孤岛微网电压功率控制

Voltage and Power Control of Isolated Island Microgrid Considering Fault Crossing and Time-varying Delay

为了解决孤岛交流微电网由时变通信延迟和不确定性故障引起的不稳定性问题,提出1种新型鲁棒分层控制方法。该方法包括级联结构的电流环、电压环、虚拟阻抗和下垂控制环。首先,在电流环中设计1种基于自适应反推积分非奇异快速终端滑模控制的鲁棒控制器,用于在未知有界不确定性和外部干扰时调节和跟踪电流参考值;接着,在电压环中采用混合H_(2)/H_(∞)控制,利用状态反馈控制律生成内环参考值,增加控制器对扰动的鲁棒性,并在线性矩阵不等式基础上给出充分条件。考虑到时变延迟TVD(time-varyingdelay)的不稳定影响,在第二控制层采用基于一致性的分布式协议,以提高控制器应对TVD的鲁棒性。然后,为提高系统的功率分配精度,采用下垂控制和虚阻抗环;最后,通过半实物仿真,评估了控制方法的性能,并验证了所提控制方法的有效性。与已有研究进行对比分析,仿真结果表明:所提方法在大、小信号扰动下的瞬态响应、稳态性能和故障穿越能力等方面具有一定的优越性。

To solve the instability problem caused by time-varying communication delay and uncertain faults in an isolated island AC microgrid,a novel robust hierarchical control method is proposed,which includes cascade current loop,voltage loop,virtual impedance and droop control loop.First,a robust controller based on adaptive backward integral non-singular fast terminal sliding mode control is designed in the current loop to adjust and track the current reference value under unknown bounded uncertainties and external disturbances.Second,the hybrid H_2/H_∞ control is used in the voltage loop,and the state feedback control law is used to generate the inner loop reference value to increase the robustness of the controller to disturbances,and sufficient conditions are given based on the linear matrix inequalities.Considering the unstable effects of time-varying delay( TVD),a distributed protocol based on consistency is adopted in the second control layer to improve the robustness of the controller against TVD.Third,droop control and virtual impedance loop are used to improve the system's power distribution accuracy.Finally,the performance of the proposed control method was evaluated by hardware-in-the-loop simulation,and its effectiveness was verified.Simulation results show that compared with the existing methods,the proposedmethod has advantages in transient response,steady-state performance and fault crossing capability under large and small signal disturbances.