Abstract
A grid-connected inverter must be designed to assure stable operation. Stability analysis of the system is one of the most important design process. This paper investigates and compares these stability analysis methods. In frequency domain, according to the impedance method, frequency characteristics of an output impedance or admittance are calculated and checked if it satisfies the Nyquist criterion. Three types of meth- ods are often utilized for this frequency analysis. In time domain, a unique analysis method, which is based on the eigenvalue analysis of the Poincar´e map or the sensitivity matrix of state-variables for perturbations along an operating trajectory, is also utilized. These four methods are compared and discussed for their features to investigate and design stable grid-connected inverter systems by simulation and experiment.
