不平衡及谐波电网下基于静止坐标系的并网逆变器直接功率控制

Stationary Frame Direct Power Control of Grid-Connected Inverter under Unbalanced and Harmonic Grid Voltage

为提高电网不平衡及电网背景谐波下电压源并网逆变器的运行性能,以静止坐标系下并网逆变器数学模型为基础,提出不平衡及谐波电网下并网逆变器的直接功率控制策略,实现输出功率平稳或输出电流平衡且正弦的两个独立的控制目标。所提控制策略使用降阶广义积分器实现对电网电压基频分量的快速准确提取,从而计算得到输出电流平衡且正弦控制目标下的功率参考补偿项。所提控制策略使用矢量比例积分谐振器实现对功率参考中波动分量的精确控制。最后通过构建并网逆变器实验系统,对所提控制策略的可行性和有效性进行了实验验证。

This paper proposes a direct control strategy for voltage source grid connected inverter （VSI）, based on the mathematic model of VSI on the stationary frame, to enhance the operation performance of VSI under the unbalanced and harmonic grid voltage. This strategy can implement two alternative control targets, i.e., stable output active and reactive power, as well as balanced and sinusoidal output current. The reduced order generalized integrator （ROGI） is applied to quickly decompose the positive sequence component of the grid voltage, further to calculate the power reference compensations. Vector proportional integrator （VPI） is used to control the power ripple components accrately. Finally, the experiment system of VSI is built to validate the proposed DPC strategy.