Modal Analysis of Stability in Microgrids: A Frequency-Based Approach to Power Electrical Systems

Abstract

As microgrids correspond to a portion of power systems, they directly impact the behavior of electrical variables, especially due to the bidirectional power flow. Given this scenario, the evaluation of electromechanical modes originating from distributed generators present into the microgrids is essential to analyze the stability limits due to different operational scenarios, both in islanded and connected conditions. This research proposes the use of electrical frequency as an alternative variable for modal analysis in microgrids, employing methods that involve measurements that are easily carried out by phasor measurement units, such as three-phase bus voltages. The electrical frequency was estimated by an adaptive algorithm based on least mean square and, next, the Prony method was applied to identify the electromechanical modes. To validate the proposed approach, several cases were analyzed, changing the system’s operating conditions.