两级式光伏并网逆变器无差拍控制研究

Research on dead-beat control for two-stage PV grid-connected inverter

针对两级式三相光伏并网逆变器的特点,文章采用瞬时功率外环和无差拍控制电流内环的双环控制策略。推导了三相光伏并网逆变器的离散数学模型,外环采取瞬时功率控制方法,省略了传统无差拍电流控制方法中的电流预测环节,简化了逆变器的控制系统。仿真结果表明,在光照导致光伏电池输出功率波动的情况下,该控制策略依然能保证光伏并网逆变器最大限度地输出功率,且并网逆变器的输出电流能够准确、快速地跟踪电网电压,实现了功率因数接近1。

In view of the characteristics of two levels three-phase photovoltaic （PV） grid-connected inverter, a double-loop control strategy which consists of instantaneous power outer loop and dead-beat control current inner loop is proposed. A discrete mathematical model of three-phase PV inverter is de- duced in which omission of current forecast section in traditional dead-beat current control simplifies the inverter control system because of adoption of instantaneous power control for outer loop. Matlab/ Simulink software simulation results show that the control strategy can keep the maximum output power of PV grid-connected inverter in which output current can accurately and quickly track grid voltage, and power factor is close to 1 while the PV battery output power is fluctuating caused by light radiation.