Impact of phase-locked loop dynamics on the stability boundary of LCL-filtered grid-connected inverters

The existing field operation data shows that the dynamic characteristics of the grid-connected inverter are closely related to the working point. Affected by external factors such as new energy output fluctuation and load switching, the working point of the inverter shows changing characteristics, and it is critical to analyze the stability limit of the working point of the entire inverter to guide the stable operation of the inverter. The traditional impedance/admittance analysis method can effectively analyze the stability of the inverter when it runs at a specific operating point, but it is difficult to analyze the stability limit. In order to solve this problem, a multivariable single input single output (SISO) model considering the operating point variables was proposed, and the operating point variables were introduced into the admittance model to calculate the stability limit of the inverter working point, and the accurate solution of the stability limit was obtained, which reduced the computational complexity.