基于阻抗分析的无刷双馈独立发电系统控制参数设计方法

Parameter design method for brushless doubly-fed stand-alone generation system based on impedance analysis

无刷双馈电机由于其高可靠性在独立发电应用中优势显著,然而特殊的电机结构亦导致控制参数设计更复杂。针对常用闭环函数法即使辅以强大的计算机软件,其分析结果仍含有大量干扰信息,不便于判定系统稳定情况的问题,本文充分借鉴双馈并网系统的阻抗分析思路,提出一种无刷双馈独立发电系统的控制参数设计方法。通过分别建立机侧、荷侧阻抗模型,避免信息过度集中而增加建模复杂程度,进而以工况变化下系统稳定为核心指标,基于广义奈奎斯特稳定判据对关键电流环参数进行设计。由于反映系统稳定情况的奈奎斯特曲线与(-1, j0)相对关系不受阻抗模型复杂程度影响,本文所提控制参数设计方法无需人工简化干预,可充分发挥计算机软件的智能优势。最后,在次/超同步满载等典型工况下,基于无刷双馈独立发电仿真及实验系统验证了所得控制参数的有效性,可保证工况改变时系统稳定发电并维持较好性能。

Brushless doubly-fed induction generator(BDFIG)has the potential in stand-alone applications due to its high reliability.However,the special structure leads to difficulty of control parameter design.Even with the help of powerful computer software,the analysis results of commonly used closed-loop function method still contain a lot of interference information,making stability analysis difficult.In view of this,by referring to the impedance analysis commonly used in DFIG grid-connected system,this paper proposes a control parameter design method for BDFIG stand-alone generation system.Impedance models of machine-side and load-side subsystems are built respectively,reducing transfer function complexity caused by information coupling.Then by taking system stability under various operation conditions as the core index,the critical current-loop parameters are designed and evaluated based on generalized Nyquist stability criterion.Since the key phenomena of stability analysis,i.e.,the relative relation among Nyquist curves and(-1,j0),are not affected by the complexity of impedance models,the proposed control parameter design method does not need to be artificially simplified,and can give full play to the intelligence of the computer software.Finally,the effectiveness of designed control parameters is verified by BDFIG stand-alone simulation and experimental systems under typical conditions such as sub/super synchronous full-load conditions.