有源中点钳位型三电平并网逆变器多目标优化预测控制

Multi-objective optimal model predictive control for active neutral-point-clamped three-level inverter

有源中点钳位型(ANPC)三电平变换器作为并网逆变器能够实现功率器件的热损耗平衡,适用于光伏发电系统。针对传统中点钳位型(NPC)三电平并网逆变器开关管发热不均衡等问题,本文提出一种ANPC三电平并网逆变器的多目标模型优化预测控制方法,基于三电平输出的开关状态需要遵循单位电平跳变的原则,剔除不符合跳变原则的开关状态,减少模型滚动优化的次数。针对开关管的发热不均衡问题,根据ANPC三电平并网逆变器的结构特点,通过对开关管的开通和关断损耗进行线性拟合,实时计算各开关管的功率损耗,把各开关管的不均衡损耗加入目标价值函数以实现不均衡损耗的最小化。最后通过ANPC三电平并网逆变器直接功率控制的实验结果验证了所提控制方法的正确性和有效性。

Active neutral-point-clamped(ANPC)three-level converter,as a grid-connected inverter,can realize the heat loss balance of power devices and is suitable for photovoltaic power generation system.Aiming at the unbalanced heating of switches in traditional neutral-point-clamped(NPC)three-level grid connected inverter,a multi-objective optimal model predictive control(MO2-MPC)method for ANPC three-level grid connected inverter is proposed,using the principle that three-level output switch state needs to follow the unit level jump to exclude the switch state which doesn’t follow the principle and reduce the number of model optimization.According to the structural characteristics of ANPC three-level grid-connected inverter,the power loss of each switch is calculated in real time by linear fitting of the on and off losses of switches,and the unbalanced loss of each switch is added to the objective value function to minimize the unbalanced loss.Finally,the correctness and effectiveness of the proposed control method are verified by the experimental results of direct power control of ANPC three-level grid-connected inverter.