统一电能质量控制器并联侧的改进双滞环电流控制策略研究

Research of modified double hysteresis current control method on parallel side of UPQC

为提高统一电能质量控制器的电流控制策略水平,提出了一种基于最优电压空间矢量的有源电力滤波器双滞环电流控制方法。该方法先利用常规双滞环控制法,以参考电压矢量的空间分布和误差电流矢量的越界情况及所在区域为依据,给出最佳电压矢量输出,以快速控制相间误差电流。虽然该方法能保证了系统暂态过程中的响应速度,也显著降低了开关频率,但误差电流在内环时逆变器不动作导致统一电能质量控制器的补偿精确度有所降低。针对此问题,将自抗扰控制方法引入误差电流内环控制上,它将内环时系统内部模型的不确定性与系统的外部不确定性统一视为系统的未知干扰,通过扩张状态观测器来估计,然后利用非线性反馈控制律进行补偿,最后利用混沌粒子群优化算法对各个参数进行优化。该方法不需要精确地测量谐波,并且对于不同的典型负载、负荷侧电流大小和相位的变化都有很强的适应性,Matlab软件仿真和采用DSP硬件实验结果验证了所提出的电流控制方法的动静态性能和鲁棒性良好。

In order to improve the current tracking performance of unified power quality conditioner, a double hysteresis current control method based on the optimal voltage space vector was proposed. Firstly the optimal voltage vector output was selected to control the phase error current quickly according to the location area of error current vector and the error current beyond the mark or by not using the ordinary double hysteresis control method. Although this method ensures a fast current response, decreases high-order harmonics and limits the switching frequency, it decreases the compensation accuracy because the inverter is kept in the former state when the error current is in the inner loop. In view of this problem, the active disturbance rejection controller was used in the control of inner loop. The load current and the source voltage were contributed to total disturbances and the expending state observer was used to esti-mate. Then the disturbance was compensated by the nonlinear state error feedback control law. So the complicated current reference calculation was avoided, which make the system adaptive to the different load. At last, the PSO algorithm was used to optimize the parameter in the ADRC controller. Compared with other current control method,this method improves the utilization ratio of voltage. The software simu-lation on MATLAB and the hardware experiment on DSP are presented to verify good static and dynamic performance, and strong robustness of the proposed control strategy.