摘要
针对采用下垂控制策略的孤岛微电网中高频和低频稳定性关联问题进行研究。首先进行逆变器建模,通过基于阻抗的Nyquist稳定判据判断系统的高频稳定性。然后经过公式推导发现系统中存在的高频谐波会在功率计算中产生偏差,进而影响系统的低频稳定性。其次通过改变电压电流环控制参数或添加输出电流前馈控制方案去除高频谐波,同时达到改善低频稳定性的效果。最后,仿真和实验结果证明上述分析的正确性。
The connections between high-frequency and low-frequency oscillations in islanded microgrid were researched in this paper. The high-frequency harmonic stability was assessed by the impedance-based Nyquist stability criterion. The instantaneous power calculation is affected by the high-frequency harmonic components because the lowpass filter can not inhibit harmonic waves. Furthermore,the low-frequency stability margin is decreased due to the higher instantaneous power. Moreover,an inverter current feedforward control scheme was proposed to mitigate the highfrequency oscillations and improves the low-frequency stability. Lastly,the PSCAD/EMTDC simulation and experiment were performed to verify theoretical analysis and validate the effectiveness of the scheme.
引文
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