改进双闭环状态反馈的LCL逆变器控制策略

摘要

LCL滤波电路存在谐振尖峰,易导致系统不稳定.为解决该问题,提出一种基于组合状态反馈的双闭环控制策略,其内环采用电容电流、并网电流组合状态反馈,外环采用并网电流反馈.该策略提高了系统阶数,增加了系统阻尼,可有效抑制谐振尖峰.通过理论推导确定了组合状态反馈系数的实现方法,简化了比例积分(PI)调节器参数的整定.最后通过仿真实验分析了比例积分系数对系统稳定性的影响,并设计了一台原理样机,实验表明该策略不仅保证了并网电流高功率因数运行,同时实现了并网电流与电网电压之间较小的相位差.%LCL-type filter is likely to trigger a problem of system stability due to the existence of resonance peak.To solve the problem,a double closed-loop control strategy based on the combination state feedback has been proposed.The combination state feedback of the grid-connected current plus capacitor current is applied in the internal loop,the external loop is the feedback of grid-connected current.The control strategy not only improves system order,but also increases systematic damping which can effectively stop resonance peak.By means of theoretical derivation,the implementation method for coefficients of the combination state feedback has been determined.In addition,the setting methods of proportional-integral(PI) regulator parameters are availably simplified.Finally,the influence of the stability of the system has been analyzed by simulation experiment and a principled sample machine is designed.The result manifests that this strategy guarantees the grid-connected current running with high power factor.Simultaneously,the smaller phase difference between the grid-connected current and the voltage has been realized.