基于改进锁相环和谐振控制的分布式电源逆变器谐波抑制方法

Harmonic Suppression Method of Distributed Power Inverter Based on Improved PLL and Resonance Control

针对目前分布式逆变器谐波抑制能力不足的问题,提出一种基于改进锁相环和谐振控制的谐波抑制方法。首先建立了电网电压谐波数学模型,分析了锁相误差的根本原因;其次,为滤除谐波电压对锁相环节的干扰,在传统双同步坐标系下的解耦锁相环方法的基础上,增加重复控制环节以减少多次谐波含量对锁相精度的影响;最后,为进一步消除多次电压谐波对输出电压的干扰,通过二阶广义积分器快速准确合成虚拟谐波阻抗,并在逆变器电流控制环节中引入虚拟谐波阻抗实现谐波电压的补偿。为验证该控制算法的有效性,搭建了Matlab仿真模型,并与传统方法仿真对比分析。仿真结果表明:相比传统控制方法,该方法q轴电压在谐波背景下减小了±6 V左右,频率精度提高了±0 5 Hz,电流总谐波失真减小了近20%,验证了所提方法的有效性。

Aiming at the the insufficient harmonic suppression ability of distributed generation inverter,a harmonic suppression method based on the improved phase locked loop and the resonant control is proposed in this paper.Firstly,the mathematical model of voltage harmonic in grid is established,and the essential reason of phase locked error is analyzed.Secondly,in order to filter the influence of harmonic voltages on the phase locked loop,the repetitive control loop is embedded in traditional double synchronous reference frame phase locked loop to reduce the influence of multiple harmonics on the phase locked accuracy.Finally,in Order to further eliminate the influence of multiple voltage harmonics on the output voltage of inverter,the virtual harmonic impedance is synthesized quickly and ac curately through the second order generalized integrator.The virtual harmonic impedance is introduced into the inverter current control loop to realize harmonic voltage compensation.In order to verify the effectiveness of the proposed control method,Matlab simulation model is built.Simulation results show that,compared with the traditional control method,the q axis voltage of the proposed method is reduced by±6 V under the steady state condition,the frequency accuracy is improved by±0 5 Hz,and the total harmonic distortion of current is reduced by nearby 20%,which verifies the effectiveness of the proposed method.