采用改进重复控制的大功率电力电子负载

Improved Repetitive Control Scheme for Power Electronic Load

电力电子负载包含模拟电源负荷的模拟变换器和将能量馈回电网的并网变换器。它必须能模拟电流谐波含量丰富的非线性负荷,传统的PI控制器难以满足波形跟踪需要。该文采用改进重复控制策略用于电力电子负载(power electronic load,PEL)电流控制器设计,通过串联校正调整控制对象幅频、相频特性,重复控制器可提高系统稳态性能,P控制器保障其动态响应速度。由此,模拟变换器快速、近乎无差地跟踪线性或非线性电流指令;能量以高功率因数经并网变换器馈回电网。该方法克服采样、计算延时和死区、参数漂移等因素对系统稳定性的影响,增强了系统鲁棒性。给出了控制器设计步骤和方法,仿真和搭建的10 kVA电力电子负载样机实验证明了方案和分析的正确性。

Power electronic load （PEL） includes two parts： input simulation converter （SC） that simulates various loads and output grid-connection converter （GCC） that sends back the recycling energy to the power grid. To examine the tested power source strictly, the PEL should simulate the nonlinear load with high crest factor （CF） because the nonlinear current includes a great deal of harmonics. Traditional PI controller can not track the reference precisely. An improved repetitive control scheme was applied in the current control loop of PEL. Cascade compensation link was applied to adjust the magnitude and phase characteristic of the plant. Repetitive controller achieves good steady-state performance and P controller ensures that the system has fast dynamic response. SC quickly tracks the linear or nonlinear current reference with zero error and GCC has a near unit power factor to recycle the tested energy. The control scheme reduces the influences of the factors, such as sampling and calculation delay, dead-zone, parameters＇ shift, on the system stability and enhances the robustness of the whole system. The whole design was provided. Simulation and experimental results on 10kVA prototype testify the effectiveness of the proposed control scheme.