A distributed framework for stability evaluation and enhancement of inverter-based microgrids

In this paper, a distributed framework is established to evaluate and improve the small-disturbance stability of a microgrid with inverter-based distributed generators (DGs). First, we propose a distributed protocol such that a selected pilot DG bus collects necessary data from finite steps of communication between physically neighboring buses. Then, we design an algorithm that enables the pilot DG bus to reconstruct the system dynamic Jacobian matrix from the data and carry out stability evaluation locally. Further, if the evaluation result does not meet a preset requirement, we develop a distributed successive linear programming algorithm to enhance the system stability via sparse communication among a minority of DG buses. The proposed algorithms have high efficiency and versatility-they apply to lossy microgrids with either radial or meshed topology under various operation scenarios. Moreover, the control actions for stability enhancement preserve the predefined economic dispatch and power sharing schemes. The results are validated by the case study of a 14-bus microgrid.