基于内模控制的单相并网锁相环研究

Research on a Single-phase Grid-connected PLL Strategy Based on Internal Model Control

快速准确地跟踪电网电压相位对于并网逆变器而言是保证其能稳定运行最为重要的条件之一。在单相并网逆变器中,常规的过零点电压检测的方法对于电网电压的畸变敏感,尤其是在电网电压出现缺口时,容易出现锁相失效,使得逆变器性能降低。而瞬时无功理论方法由于未考虑有功分量带来的影响,因此难以克服在实际运行中有一个较长的时间延迟的缺点。针对上述问题此处提出基于内模控制和改进瞬时无功理论的方法,并将此方法应用于单相并网系统,仿真和实验均证明了该方法有提高锁相精度和抑制波形畸变的作用。

Quickly and accurately track the phase of the grid voltage is one of the most important conditions to ensure its stable operation for the grid-connected inverter.In single-phase grid-connected inverter,the conventional method that using zero-crossing voltage detection is sensitve to the grid voltage distortion, especially in the face of the grid voltage gap,may lead the phase-locked fail,making the inverter performance degradation.For instantaneous reactive power theory, without considering the impact of active power, it is difficult to avoid the disadvantage of the longer time delay in operation.In order to solve the problem,the method is proposed which based on internal model control and improved instantaneous reactive power theory, and it is applied into single-phase grid-connected system.The simulation and experiment prove that this method improve the accuracy of phase-locked and the inhibition of the voltage waveform distortion.