Maximum Capacity Assessment for Multi-paralleled Grid-connected Inverters using Global-Admittance based Harmonic Stability Analysis

With the increasing demand for the renewable energy, the stability of the multi-paralleled grid-connected inverters is the important factor for evaluation the capacity of the inverters connected to power grid. In this paper the maximum capacity assessment for multi-paralleled grid-connected inverters using global-admittance based harmonic stability analysis is proposed. The stability analysis method with global admittance has clear physical concept and is convenient for real-time analysis and calculation. The global admittance method is illustrated first. The inverters are sorted by the capacity. The inverters sequence can be divided into two groups based on the stable critical point obtained by the global admittance method. The group with large capacity is taken as a unit. The stability of the combinations formed by this unit and other inverters in the other group is analyzed further. So the maximum capacity of the grid-connected inverters can be assessed. The application example is used to illustrate and verify the proposed method in this paper.