单相光伏并网逆变器瞬时电流检测与补偿控制

Instantaneous Current Detection and Compensation of Single-phase Photovoltaic Grid-connected Inverter

为拓展单相光伏并网无功补偿功能,实现单相并网系统无功和谐波电流的精确检测和补偿,提出一种改进的新型瞬时无功与谐波电流检测及补偿方法。该方法以瞬时无功理论为基础,推导出单相并网逆变器瞬时无功控制规律,可以简便、快速地分离所需电流分量;并结合无差拍理论,给出基于无差拍控制的单相并网逆变器的脉宽调制(PWM)算法,可以对瞬时谐波及无功电流进行补偿。将该控制策略应用于单相光伏并网系统,使光伏并网系统除提供有功功率外,同时兼备无功与谐波补偿功能,增强了光伏并网功能。

In order to enhance the function of reactive power compensation of a single-phase photovoltaic system in grid connection and realize precise detection and compensation of reactive and harmonic current of the single-phase grid-connected inverter, an improved method of detecting instantaneous reactive and harmonic current in the single-phase grid-connected photovoltaic system is presented. Based on instantaneous reactive power theory, algorithms of current decoupling in the singlephase system are derived for performing the reactive power control of single-phase photovoltaic grid-connected inverter. The method proposed effectively solves the difficulties of the current detection in single-phase connection. The paper proposes to adopt a deadbeat control strategy and derives the algorithm of deadbeat PWM. With this system used in the photovoltaic gridconnected inverter, not only the system has the function of supplying active power, but also can effectively perform reactive power compensation and harmonic suppression,