弱电网下并网逆变器基于PI和PR控制技术对比研究

Research on the Comparison Analysis of the PI and PR Control in the Gridconnected Inverter System under Weak Grid

弱电网是在电网线路阻抗不可忽略时出现的电网新状态。考虑电网阻抗时,并网逆变器控制系统参数的选取与强电网下不同。本文推导了比例积分控制(PI)和比例谐振控制(PR)在弱电网下并网逆变器控制系统的解析模型,根据并网逆变器系统稳定性分析了两种控制方法的控制参数取值,为两种控制在弱电网下的合理取值提供了参考。以并网电流质量(THD)和稳态误差为指标,分析了每种控制方法中比例系数和积分系数(谐振系数)对逆变器系统的具体影响,验证了上述分析取值的合理性。

The weak grid is a new state of power grid.It appears when line impedance in the system is not negligible.Considering the impedance of power grid,it is different to select the control system parameters of the grid-connected inverter in the weak grid and the strong grid.In this paper an analytic model which compares proportional integral control(PI)with proportional resonance control(PR)in the control system of grid-connected inverter in the weak grid is derived.According to the the stability of the grid-connected inverter,the parameters with these two control methods is analyzed,which provides reference for the parameters selections of the two methods in the weak grid.The specific impact of proportional coefficient and integral coefficient(resonance coefficient)on inverters in each control method is also analyzed,which validates the abovementioned analyzing reasonability.