通过建立LCL滤波的光伏并网电流控制内环模型,就电网电感对谐振频率、无源阻尼效果和电容电流反馈的有源阻尼效果三者的影响进行了分析.结果表明,电网电感能降低谐振频率,增强有源阻尼效果,削弱无源阻尼效果.结合有源阻尼受延迟等控制非理想因素影响较大、而无源阻尼不受此影响的特点提出了一种采用有源阻尼与无源阻尼相结合的混合阻尼策略,它对于电网电感和控制延迟都具有良好的适应性.混合阻尼设计中以阻尼系数为对象,以阻尼系统对电网电感的适应能力为设计目标,计算和校验电流反馈系数和阻尼电阻取值,给出了具体设计方法.设计实例的仿真和实验结果证明,该方法设计的阻尼可以稳定运行,并对弱电网具有良好的适应性.%The inner current control loop of PV inverter with LCL filter is modeled and the impact of grid inductance on the active damping and passive damping of resonance frequency and capacitive current is analyzed,which shows that,the grid inductance may decrease the resonance frequency,enhance the active damping and weaken the passive damping. Based on the fact that the active damping is easily affected by the nonideal control factors while the passive damping is immune to them,a hybrid control scheme of active and passive damping is proposed, which has better adaptability to grid inductance and control delay. The scheme design takes the hybrid damping coefficient as its design object and the adaptability of damping system to grid inductance as its design objective to calculate, and verify the current feedback coefficient and damping resistance. Detailed design process is given. The simulative and experimental results show that the damping system designed stabilizes the operation, having better adaptability to weak grid.
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