一种三阶广义积分交叉对消电流反馈控制的多逆变器并联控制策略

A Current Feedback Control Strategy for Parallel Operation of Multi-inverters Using Third-order General-integrator Crossover Cancellation Method

在微电网多逆变器并联系统中,通过引入虚拟阻抗来改变逆变器的下垂外特性是常用的方法。针对虚拟阻抗的实现,提出一种三阶广义积分交叉对消电流反馈控制方法,可避免对输出电流求导,减少运算量,系统动态响应速度显著提高。所提方法由交叉对消反馈网络和多级基于三阶广义积分器的正交发生器环节两部分构成,分别实现带通效果和滤波功能,能较好地抑制输出电流中的直流分量和谐波分量,改善输出电压波形,减小其畸变率。分析该方法对系统阻抗幅频特性的影响可知,该方法仅影响系统基波频率处附近的输出阻抗,谐波处几乎不受影响,避免了虚拟阻抗引入带来的谐波放大问题。仿真与实验结果证明了所提方法的正确性与有效性。

For parallel operation of multi-inverters in microgrid, the method of introducing virtual impedance to change drooping external characteristic of inverter is usually adopted. Aiming at the realization of the virtual impedance, a current feedback control strategy using third-order general-integrator crossover cancellation method was proposed, which can avoid the time derivation of output current and reduce the computation and increase the dynamic response speed of the system significantly. The method consists of crossover cancellation current feedback network and multi-level quadrature generator that is based on third-order general-integrator, realize bandpass effect and filtering function respectively. This method can restrain DC component and harmonic component of the output current well. At the same time, the output voltage waveform can be improved and the distortion rate is reduced. The effects on the amplitude and frequency characteristics of system impedance were analyzed, and the method only affects the output impedance near base wave frequency. Consequently, the harmonic amplification problems by introducing virtual impedance ccould be avoid. The simulation and experiment results show the correctness and effectiveness of the proposed method.