光伏反激并网微型逆变器THD性能仿真研究

Simulation on THD performance of photovoltaic flyback grid-connected micro-inverter

针对光伏反激并网微型逆变器的输出功率随着太阳能电池输出功率不断地变化,且在逆变器的输出功率比较低时并网输出电流的总谐波失真(THD)指标不能满足并网要求的问题,研究利用PI准谐振控制器对光伏反激并网逆变器进行了并网控制。通过运用状态空间平均法建立了光伏反激并网微型逆变器的数学模型,基于该数学模型建立了仿真模型,对传统的PI控制器与PI准谐振控制器的控制性能进行了仿真分析。研究结果表明,在不同输入电压、负载条件下,采用PI控制器的逆变器输出并网电流的THD较大,不能满足并网要求;而采用PI准谐振控制器时THD均小于5%,能满足并网要求,从而验证了新控制方法的有效性。

Aiming at the problem of photovoltaic flyback grid-connected micro-inverter output power changing continuously with the solar cell output power in a relatively low output power level,the total harmonic distortion（THD） performance of grid-connected current can not meet requirement of the utility grid,the PI quasi resonant controller for flyback grid-connected inverter was investigated.The mathematical model of photovoltaic flyback grid-connected micro-inverter was set up by using the state space averaging method.The simulation model based on the mathematical model was established and the performance of traditional PI controller and PI quasi resonant controller were analyzed.The results indicate that the THD of grid-connected inverter output current is the larger by using PI controller which can not meet the requirement of the utility grid and the THD is less then 5％ by using PI quasi resonant controller which can meet the demand of utility grid at the different input voltages and load conditions.So this method can verify the effectiveness of the new control method.