考虑数字控制影响的虚拟阻抗控制改进

Improved virtual impedance control considering effect of digital control

交流模拟电源装置基本运行状态需要模拟出大电网的特性,但其电压及阻抗性能常受到被测设备的影响而无法满足设计需要。为保证其输出特性,对交流模拟电源的控制器进行设计。通过分析基于电感或电容电流反馈的虚拟阻抗控制方法的输出特性,选择更为有效的电容电流反馈的控制方式,该方式下改变虚拟阻抗系数来调整系统输出阻抗及增益特性。考虑数字延时对虚拟阻抗控制的影响,采用减小控制延时的方式,提高系统的鲁棒性,保证交流模拟电源装置对被测设备输出的稳定性。仿真及实验验证了所提方法的有效性。

The basic operating conditions of AC grid simulator should simulate the characteristics of large power grid,but normally its voltage and impedance could not meet the design requirements due to the impact of the tested equipment,aiming at which,its controller design is improved to guarantee its output characteristics. The output characteristics of the virtual impedance control based on inductive or capacitive current feedback are analyzed respectively and the more effective virtual impedance control based on capacitive current feedback is adopted,under which,the characteristics of system output impedance and gain are adjustable by changing the virtual impedance coefficient. The impact of digital delay on the virtual impedance control is considered and a corresponding method is applied to reduce the control delay for improving the system robustness and ensuring the stability of system output to the tested equipment.Simulation and experiment verify the effectiveness of the proposed method.